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Re: [mill_drill] RF-31 CNC Conversion

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  • Guenther Paul
    Art How much did it cost you ? I am about to do a conversion but dont know for sure if i want to do it on the machine i have or buy a diverant mill GP
    Message 1 of 21 , Apr 27, 2013
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      Art
      How much did it cost you ? I am about to do a conversion but dont know for sure if i want to do it on the machine i have or buy a diverant mill 
      GP



      From: Art Eckstein <art.eckstein@...>
      To: mill_drill@yahoogroups.com
      Sent: Sat, April 27, 2013 9:05:43 AM
      Subject: Re: [mill_drill] RF-31 CNC Conversion

       

      I converted my RF31 several years ago using servo motors but have
      been very happy with it.

      1. Yes, definately upgrade to Ball Screws. My first iteration used
      the stock lead screws and I wore the nut out inside of 2 months. It
      was so loose that I could "walk" it down the screw without even
      turning it. Backlash was .25" plus. For the ball screws, I used the
      common (read less expensive) 5TPI 5/8" screws. Because my servos are
      rated at a higher speed, I used a belt reduction.

      2. Software:
      For cad, I presently use Draftsight which requires
      registration, but otherwise if free. It is an Autocad
      clone. www.draftsight.com
      Cam, you mention Lazycad, but I don't think it is really
      supported anymore. I use Sheetcam and have been well pleased with it.
      www.sheetcam.com
      For a controller, I use Turbocnc, but then I am a dos fan
      and not a windows fan. You might also want to look at linuxcnc as it
      is open source software and I have a couple of friends running it.
      One used it on his second build after using Mach on his first and the
      other day said he should have gone the linux route as it is more
      powerful, and of course open source. They have a "live cd" that you
      can download to try. http://www.linuxcnc.org/

      Hardware
      Breakout Board For a decent BOB, you want all lines to be buffered
      at least (if your going the parallel port route) and I like the other
      I/o to be opto isolated.

      Motor Drives My personal preference is Gecko. I have them on my
      two machines (one is servo and one is stepper)

      Stepper Motors For this, I think your in the right range for a RF31,
      but look around as you want units with low inductance to maximise
      your output. Read the white papers on the Gecko site for insight into
      proper sizing of the matching power supply voltage and maximum
      performance. This will also give info on proper sizing for current.

      Power supply For the steppers/servos, I prefer a plain ole
      transformer, bridge rectifier, and humongous capacitor. A wall wort
      or small switching supply can be included to handle the 5V etc
      duties. In my case, I converted a microwave transformer and added
      additional windings for my 5 and 12V supplies.

      Mounting brackets I made myself and beware that all of the RF31 class
      machines I have run across are not created equal when it comes to
      bolt patterns! AS some others have done, I made some temp ones to be
      able to make up the final product. Sure, it was additional work; but
      I learned a lot and also what might not work in some cases.

      Timing belts and pulleys. I used XL37 belts and pulleys on my
      system. In one case, I found using the (relatively) weak belt was a
      blessing as I had a run away one time and the belt broke before and
      real damage was done to the machine when it hit the hard stop.
      As to ratios, If I were to run the steppers, I would either direct
      drive or 1:1 ratio if using belts. Don't forget, most all drives use
      micro stepping and that must be taken into account when figuring steps/in.

      HAND WHEELS: WAY back when I was about to embark on my conversion
      this group was my main source of information and I also wanted to
      keep the hand wheels. Well, several of the good members at the time
      hit me up side the head and recommended loosing the hand wheels for
      several reasons including safety of not having that thing sticking
      that that could whack you and possibly damage YOU.
      Fortunately, I listened to them and in the past many years have not
      missed them. Any movement I want I use MDI commands. You mention
      drilling specifically, and think of it this way; MDI feeds is a power
      feed! Also, the ball screws will "back feed" and you will have to
      have some sort of braking action to hold them in place.
      Again as to TPI of the screw, I used 5TPI ones as they are relatively
      speaking the cheapest ones for size. No you don't need to have exact
      numbers as the controllers will accept several digits beyond the
      decimal point. You also may want to search ebay for a seller by the
      name of linearmotion I think it is as he sells ball screws at a
      reasonable price and will machine the ends for you also. One word
      of caution on mounting the motor on the X axis. When I did mine, I
      mounted the plate right on the end of the table and therefore lost
      some X axis movement as the table can no longer go beyond the end of
      the dovetail on the saddle. I haven't really missed that inch or so
      of travel, but just a word of caution.

      Costwise, I think your in the ball park if you shop wisely and do
      most of the work yourself as opposed to out sourceing it.

      Art
      Country Bubba

      At 12:19 AM 4/27/2013, you wrote:

      >I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems
      >that most everyone that does this upgrade does it a little
      >differently. It also seems that a lot of people sell stuff that I
      >could use, but very few sell a comprehensive kit and the prices for
      >the kits are unaffordable to me.
      >
      >This is totally new to me, so I have done a lot of reading. Here is
      >a general list of what I think that I need:
      >
      >Mill
      >1. Upgrade to ball screws
      >
      >Software
      >2. CAD
      >3. CAM
      >4. Controller
      >
      >Hardware
      >5. Breakout box
      >6. Motor drives
      >7. Stepper Motors
      >8. Power supply
      >9. Mounting brackets
      >10. Timing pulleys/belts
      >
      >Here are my questions:
      >
      >1. I have seen good prices on Ebay. Does
      anyone have suggestions on
      >what fits best on a RF-31, TPI, installation ease?
      >
      >2. & 3. I am looking at some open source CAD/CAM software. Anyone
      >know of a really good and inexpensive package?
      >
      >4. I was planning to use Mach3. I noticed that it comes with
      >LazyCam. Is this decent enough or should I look for something else
      >to generate the G-code?
      >
      >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
      >packages on Ebay that would work with Mach3. My concern is getting
      >steppers that have the needed torque. Does anyone have a
      >recommendation. It seems that others have used motors in the
      >350-420oz/in range. Is this about right for low-med volume on this
      >machine? The price on steppers goes up with torque. I want something
      >that will work, but I don't want to waste money on overkill.
      >
      >9. I have not found brackets
      sold individually, so I guess I am on my own.
      >
      >10. McMaster-Carr looks like they have everything I'd need, but does
      >anyone have advice on ratios? I did a little quick math and realized
      >that a ball screw with 8 TPI matched to a stepper capable of 200
      >steps has a resolution of .000625". My first thought was to gear it
      >to minimize motor load, but then I thought about getting a round
      >number such as one step being .00025" making 4 steps .001". Not
      >having used a a cnc before, I am not sure if it matters to have
      >round numbers or not. Is this an issue?
      >
      >Seems like $1200-$1500 for everything is where I'd be on this
      >project. Does that sound high, low, about right? Have I missed
      >anything that I'll need or can save money doing it differently?
      >
      >Lastly, I'd also like to use the mill manually especially as a drill
      >press. Are there any special
      design considerations to make this
      >possible? Can the steppers be put into "neutral" to spin freely or
      >would I have to remove the belts?

    • Art Eckstein
      GP, According to the spreadsheet that I tried to maintain for the project, I have about $750 in parts and pieces. I bought surplus servo motors and that helped
      Message 2 of 21 , Apr 27, 2013
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        GP,
        According to the spreadsheet that I tried to maintain for the
        project, I have about $750 in parts and pieces. I bought surplus
        servo motors and that helped tremendously. I had some (not much)
        material on hand so that is not included. Also these are year 2000 or
        there abouts prices. Nor does it include computer (handme down
        freeby) nor software. The BOB was a prototype that was given to me
        by a friend for "testing" and it is still working after all these
        years. The controller cabinet was a dumpster dive, with the power
        transformer being a free microwave unit that was modified. Most
        electrical stuff was from surplus.

        HTH

        Art
        Country Bubba



        At 09:26 AM 4/27/2013, you wrote:
        >
        >
        >Art
        >How much did it cost you ? I am about to do a conversion but dont
        >know for sure if i want to do it on the machine i have or buy a diverant mill
        >GP
      • Edgar
        Sorry Guenther, all I know is what is on the web page. All his stuff was purchased in Japan and I have no idea how expensive equipment is there. Orlin in
        Message 3 of 21 , Apr 27, 2013
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          Sorry Guenther, all I know is what is on the web page. All his stuff was purchased in Japan and I have no idea how expensive equipment is there.

          Orlin in SC/USA

          --- In mill_drill@yahoogroups.com, Guenther Paul <paulguenter@...> wrote:
          >
          > Edgar
          > You have any idea how much the cost was on this conversion
          >  GP
        • mpoore10
          Thanks for the link. These conversions all use the same basic idea, but are still quite different.
          Message 4 of 21 , Apr 27, 2013
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            Thanks for the link. These conversions all use the same basic idea, but are still quite different.

            --- In mill_drill@yahoogroups.com, "Edgar" <aceroadholder@...> wrote:
            >
            > Here is a conversion that the builder was pleased with:
            >
            > http://homepage3.nifty.com/amigos/53_cnc_system/cnc_system.htm
            >
            > Orlin in SC/USA
            >
            > --- In mill_drill@yahoogroups.com, "mpoore10" <mpoore10@> wrote:
            > >
            > > I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems that most everyone that does this upgrade does it a little differently. It also seems that a lot of people sell stuff that I could use, but very few sell a comprehensive kit and the prices for the kits are unaffordable to me.
            > >
            >
          • jdkmlw
            I can t give as good of advice as what s already been giving, still a newb at this and trying to figure out some of the software. But I converted my mill/drill
            Message 5 of 21 , Apr 27, 2013
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              I can't give as good of advice as what's already been giving, still a newb at this and trying to figure out some of the software.


              But I converted my mill/drill last year (2012) it's an older round column (the larger 700 lb model), it cost me about $1100-1200 to do the conversion, and I wasted a few bucks on aluminum for the mounts and a few parts that I thought I need but didn't. So $1k or less to convert it is do able.

              I got the ball screws & nuts from Roton, as mentioned the 5/8x.200 (5 turns per inch, 5 TPI) is a good size and is a good price, the next size up is about twice the price. I turned the ends myself (never checked to see if they would do it), I bought two 3 foot sections and that was more then enough and I have a little left over.
              http://www.roton.com/Mating_Components.aspx?family=7059321

              For the stepper motors I used NEMA23 at 495oz, which is more then I needed, but anything in the 350-400 range would be enough.
              The power supply is a 48v/7.3amp, I got these here
              http://www.automationtechnologiesinc.com/

              Using a Gecko G540 motor controller, 4 Axis controllers in one, can't remember where I got this, waited for someone to put it on sale.
              The motor controller(s) will be the most expensive parts to buy, I paid more for the G540 then I did for the three motors & power supply.

              I made some simple motor mounts to start with just to get it started and made my own ball nut mounts with the same mill, it was a pain doing this since I had to take the table apart several times for measurements and test fitting.

              I'm trying to use MACH3 but I'm having trouble figuring it out, haven't found any real simple instructions for it. I wanted to try LinuxCNC but for some reason I couldn't get it to load on the pc.

              As for LazyCAM, don't bother, I messed with it for a little and had nothing but problems, I looked around for info and almost everyone says it sucks.
              I haven't decided on a CAM program yet, tried a few trial versions so far.
            • mpoore10
              Art, Thanks so much for the detailed response. I have looked for linearmotion on ebay and can t find them. I have found some sellers in Hong Kong & China
              Message 6 of 21 , Apr 27, 2013
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                Art,

                Thanks so much for the detailed response.

                I have looked for linearmotion on ebay and can't find them. I have found some sellers in Hong Kong & China selling very inexpensive ball screws, but I am leery. Having never had anything shipped to me internationally, I don't know about all the ins and outs of the process. It seems like the ones they sell are possibly geared toward cnc routers/cutters. They advertise that they will manufacture it to whatever specs I want. The pictures of the nut don't look right to me. I don't see a tube to recirculate the balls. If you are interested in seeing an example of what I'm talking about, here is an example of what they sell: ball screw

                Gecko seems to be the "Cadillac" of motor drives. Perhaps I am being penny smart and pound foolish, but I've been looking at some less expensive alternatives. I found a package on Ebay (international again) that is really enticing given that everything is already supposed to work together and the price is outstanding ($475). I'd spend that much on Geckos. Here's a link for the package: package If you or anyone else could check it out and provide feedback, I'd sure appreciate it.

                Looks like I can get by with $0 on software. I don't mind DOS or Linux. It's been a while since I used DOS. Linux, on the other hand, with a live cd might be a nice option. I'll have to check it out and see. It seems like I have to look up every command for Linux because of the syntax differences between it and DOS/Windows. If the live cd has a GUI, I should be good.

                You are probably right about the hand wheels. I guess it is hard to give up on the option of being able to grab the crank and do things sans electronics.

                Mike

                --- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                >
                > I converted my RF31 several years ago using servo motors but have
                > been very happy with it.
                >
                > 1. Yes, definately upgrade to Ball Screws. My first iteration used
                > the stock lead screws and I wore the nut out inside of 2 months. It
                > was so loose that I could "walk" it down the screw without even
                > turning it. Backlash was .25" plus. For the ball screws, I used the
                > common (read less expensive) 5TPI 5/8" screws. Because my servos are
                > rated at a higher speed, I used a belt reduction.
                >
                > 2. Software:
                > For cad, I presently use Draftsight which requires
                > registration, but otherwise if free. It is an Autocad
                > clone. www.draftsight.com
                > Cam, you mention Lazycad, but I don't think it is really
                > supported anymore. I use Sheetcam and have been well pleased with it.
                > www.sheetcam.com
                > For a controller, I use Turbocnc, but then I am a dos fan
                > and not a windows fan. You might also want to look at linuxcnc as it
                > is open source software and I have a couple of friends running it.
                > One used it on his second build after using Mach on his first and the
                > other day said he should have gone the linux route as it is more
                > powerful, and of course open source. They have a "live cd" that you
                > can download to try. http://www.linuxcnc.org/
                >
                > Hardware
                > Breakout Board For a decent BOB, you want all lines to be buffered
                > at least (if your going the parallel port route) and I like the other
                > I/o to be opto isolated.
                >
                > Motor Drives My personal preference is Gecko. I have them on my
                > two machines (one is servo and one is stepper)
                >
                > Stepper Motors For this, I think your in the right range for a RF31,
                > but look around as you want units with low inductance to maximise
                > your output. Read the white papers on the Gecko site for insight into
                > proper sizing of the matching power supply voltage and maximum
                > performance. This will also give info on proper sizing for current.
                >
                > Power supply For the steppers/servos, I prefer a plain ole
                > transformer, bridge rectifier, and humongous capacitor. A wall wort
                > or small switching supply can be included to handle the 5V etc
                > duties. In my case, I converted a microwave transformer and added
                > additional windings for my 5 and 12V supplies.
                >
                > Mounting brackets I made myself and beware that all of the RF31 class
                > machines I have run across are not created equal when it comes to
                > bolt patterns! AS some others have done, I made some temp ones to be
                > able to make up the final product. Sure, it was additional work; but
                > I learned a lot and also what might not work in some cases.
                >
                > Timing belts and pulleys. I used XL37 belts and pulleys on my
                > system. In one case, I found using the (relatively) weak belt was a
                > blessing as I had a run away one time and the belt broke before and
                > real damage was done to the machine when it hit the hard stop.
                > As to ratios, If I were to run the steppers, I would either direct
                > drive or 1:1 ratio if using belts. Don't forget, most all drives use
                > micro stepping and that must be taken into account when figuring steps/in.
                >
                > HAND WHEELS: WAY back when I was about to embark on my conversion
                > this group was my main source of information and I also wanted to
                > keep the hand wheels. Well, several of the good members at the time
                > hit me up side the head and recommended loosing the hand wheels for
                > several reasons including safety of not having that thing sticking
                > that that could whack you and possibly damage YOU.
                > Fortunately, I listened to them and in the past many years have not
                > missed them. Any movement I want I use MDI commands. You mention
                > drilling specifically, and think of it this way; MDI feeds is a power
                > feed! Also, the ball screws will "back feed" and you will have to
                > have some sort of braking action to hold them in place.
                > Again as to TPI of the screw, I used 5TPI ones as they are relatively
                > speaking the cheapest ones for size. No you don't need to have exact
                > numbers as the controllers will accept several digits beyond the
                > decimal point. You also may want to search ebay for a seller by the
                > name of linearmotion I think it is as he sells ball screws at a
                > reasonable price and will machine the ends for you also. One word
                > of caution on mounting the motor on the X axis. When I did mine, I
                > mounted the plate right on the end of the table and therefore lost
                > some X axis movement as the table can no longer go beyond the end of
                > the dovetail on the saddle. I haven't really missed that inch or so
                > of travel, but just a word of caution.
                >
                > Costwise, I think your in the ball park if you shop wisely and do
                > most of the work yourself as opposed to out sourceing it.
                >
                > Art
                > Country Bubba
                >
                >
                >
                >
                >
                > At 12:19 AM 4/27/2013, you wrote:
                > >I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems
                > >that most everyone that does this upgrade does it a little
                > >differently. It also seems that a lot of people sell stuff that I
                > >could use, but very few sell a comprehensive kit and the prices for
                > >the kits are unaffordable to me.
                > >
                > >This is totally new to me, so I have done a lot of reading. Here is
                > >a general list of what I think that I need:
                > >
                > >Mill
                > >1. Upgrade to ball screws
                > >
                > >Software
                > >2. CAD
                > >3. CAM
                > >4. Controller
                > >
                > >Hardware
                > >5. Breakout box
                > >6. Motor drives
                > >7. Stepper Motors
                > >8. Power supply
                > >9. Mounting brackets
                > >10. Timing pulleys/belts
                > >
                > >Here are my questions:
                > >
                > >1. I have seen good prices on Ebay. Does anyone have suggestions on
                > >what fits best on a RF-31, TPI, installation ease?
                > >
                > >2. & 3. I am looking at some open source CAD/CAM software. Anyone
                > >know of a really good and inexpensive package?
                > >
                > >4. I was planning to use Mach3. I noticed that it comes with
                > >LazyCam. Is this decent enough or should I look for something else
                > >to generate the G-code?
                > >
                > >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
                > >packages on Ebay that would work with Mach3. My concern is getting
                > >steppers that have the needed torque. Does anyone have a
                > >recommendation. It seems that others have used motors in the
                > >350-420oz/in range. Is this about right for low-med volume on this
                > >machine? The price on steppers goes up with torque. I want something
                > >that will work, but I don't want to waste money on overkill.
                > >
                > >9. I have not found brackets sold individually, so I guess I am on my own.
                > >
                > >10. McMaster-Carr looks like they have everything I'd need, but does
                > >anyone have advice on ratios? I did a little quick math and realized
                > >that a ball screw with 8 TPI matched to a stepper capable of 200
                > >steps has a resolution of .000625". My first thought was to gear it
                > >to minimize motor load, but then I thought about getting a round
                > >number such as one step being .00025" making 4 steps .001". Not
                > >having used a a cnc before, I am not sure if it matters to have
                > >round numbers or not. Is this an issue?
                > >
                > >Seems like $1200-$1500 for everything is where I'd be on this
                > >project. Does that sound high, low, about right? Have I missed
                > >anything that I'll need or can save money doing it differently?
                > >
                > >Lastly, I'd also like to use the mill manually especially as a drill
                > >press. Are there any special design considerations to make this
                > >possible? Can the steppers be put into "neutral" to spin freely or
                > >would I have to remove the belts?
                >
              • Art Eckstein
                Mike, I referenced Ebay as that is what a lot of people seem to be happy with lately. Those ball nuts have internal reticulation and some claim less backlash.
                Message 7 of 21 , Apr 27, 2013
                • 0 Attachment
                  Mike,
                  I referenced Ebay as that is what a lot of people seem to be happy with lately. Those ball nuts have internal reticulation and some claim less backlash.  I personally got my screws and nuts from Roton here in the states and did my own machining.

                  I agree, Gecko is a high class outfit and I am a happy customer of theirs (total of 7 drives in service at this time). They also have an EXCELLENT support policy. If you blow a drive (first time) for ANY reason, send it in and they will repair/replace, and ship back for free. I have used that one time! There are some other drives out there that some people like and I refer you to Hoss on the cnczone as he went away from Gecko because of price. Be VERY aware of the problems that many have had with the TB series drives. They seem to have problems. As for the motors you referenced in the ebay add, they have a 7mh inductance and according to the white paper I referenced on the gecko site, they would require about 87VDC to achieve optimum performance and that package has only a 24V supply!  The formula is 32 x the sq rt of the inductance in mh. You need to match your steppers, drives, and power supplies for optimum preformance or even close to it.
                  As for the latest linuxcnc packages, they are fully GUI and about the only time you type any command is when your using MDI commands in G code! You boot the cd up and are given on the startup screen the option to run the program or to install to a hard drive. The live cd is great for checking things out, but I would not try to run a system off the cd due to speed required. As for Turbocnc (the program I use), again typing is for MDI and one thing I like is it does not really like the use of a mouse and about the only typed in dos command is "turbocnc" at the prompt and that is even handled by my autoexec to bring it up. There again, my cnc controllers are all dedicated machines to run cnc. I highly recommend that it be that way. Timing is critical and you don't want to ruin a project because your trying to google something on the net while machining!

                  IF you really insist in the end analysis to having a hand wheel to move an axis, add an MPG (Manual Pulse Generator) to your controller and then twist away:})  Oh and you can also set the MPG up to move a certain distance with each click!  Say .0001" up to say 1" per click AND it will show the appropriate location on the DRO of the computer screen. No more counting turns and loosing count. (been there done that too)

                  Art
                  Country Bubba



                   At 03:28 PM 4/27/2013, you wrote:


                  Art,

                  Thanks so much for the detailed response.

                  I have looked for linearmotion on ebay and can't find them. I have found some sellers in Hong Kong & China selling very inexpensive ball screws, but I am leery. Having never had anything shipped to me internationally, I don't know about all the ins and outs of the process. It seems like the ones they sell are possibly geared toward cnc routers/cutters. They advertise that they will manufacture it to whatever specs I want. The pictures of the nut don't look right to me. I don't see a tube to recirculate the balls. If you are interested in seeing an example of what I'm talking about, here is an example of what they sell: ball screw

                  Gecko seems to be the "Cadillac" of motor drives. Perhaps I am being penny smart and pound foolish, but I've been looking at some less expensive alternatives. I found a package on Ebay (international again) that is really enticing given that everything is already supposed to work together and the price is outstanding ($475). I'd spend that much on Geckos. Here's a link for the package: package If you or anyone else could check it out and provide feedback, I'd sure appreciate it.

                  Looks like I can get by with $0 on software. I don't mind DOS or Linux. It's been a while since I used DOS. Linux, on the other hand, with a live cd might be a nice option. I'll have to check it out and see. It seems like I have to look up every command for Linux because of the syntax differences between it and DOS/Windows. If the live cd has a GUI, I should be good.

                  You are probably right about the hand wheels. I guess it is hard to give up on the option of being able to grab the crank and do things sans electronics.

                  Mike

                  --- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                  >
                  > I converted my RF31 several years ago using servo motors but have
                  > been very happy with it.
                  >
                  > 1. Yes, definately upgrade to Ball Screws. My first iteration used
                  > the stock lead screws and I wore the nut out inside of 2 months. It
                  > was so loose that I could "walk" it down the screw without even
                  > turning it. Backlash was .25" plus. For the ball screws, I used the
                  > common (read less expensive) 5TPI 5/8" screws. Because my servos are
                  > rated at a higher speed, I used a belt reduction.
                  >
                  > 2. Software:
                  > For cad, I presently use Draftsight which requires
                  > registration, but otherwise if free. It is an Autocad
                  > clone. www.draftsight.com
                  > Cam, you mention Lazycad, but I don't think it is really
                  > supported anymore. I usight range for a RF31,
                  > but look around as you want units with low inductance to maximise
                  > your output. Read the white papers on the Gecko site for insight into
                  > proper sizing of the matching power supply voltage and maximum
                  > performance. This will also give info on proper sizing for current.
                  >
                  > Power supply For the steppers/servos, I prefer a plain ole
                  > transformer, bridge rectifier, and humongous capacitor. A wall wort
                  > or small switching supply can be included to handle the 5V etc
                  > duties. In my case, I converted a microwave transformer and added
                  > additional windings for my 5 and 12V supplies.
                  >
                  > Mounting brackets I made myself and beware that all of the RF31 class
                  > machines I have run across are not created equal when it comes to
                  > bolt patterns! AS some others have done, I made some temp ones to be
                  > able to make up the final product. Sure, it was additional work; but
                  > I learned a lot and also what might not work in some cases.
                  >
                  > Timing belts and pulleys. I used XL37 belts and pulleys on my
                  > system. In one case, I found using the (relatively) weak belt was a
                  > blessing as I had a run away one time and the belt broke before and
                  > real damage was done to the machine when it hit the hard stop.
                  > As to ratios, If I were to run the steppers, I would either direct
                  > drive or 1:1 ratio if using belts. Don't forget, most all drives use
                  > micro stepping and that must be taken into account when figuring steps/in.
                  >
                  > HAND WHEELS: WAY back when I was about to embark on my conversion
                  > this group was my main source of information and I also wanted to
                  > keep the hand wheels. Well, several of the good members at the time
                  > hit me up side the head and recommended loosing the hand wheels for
                  > several reasons including safety of not having that thing sticking
                  > that that could whack you and possibly damage YOU.
                  > Fortunately, I listened to them and in the past many years have not
                  > missed them. Any movement I want I use MDI commands. You mention
                  > drilling specifically, and think of it this way; MDI feeds is a power
                  > feed! Also, the ball screws will "back feed" and you will have to
                  > have some sort of braking action to hold them in place.
                  > Again as to TPI of the screw, I used 5TPI ones as they are relatively
                  > speaking the cheapest ones for size. No you don't need to have exact
                  > numbers as the controllers will accept several digits beyond the
                  > decimal point. You also may want to search ebay for a seller by the
                  > name of linearmotion I think it is as he sells ball screws at a
                  > reasonable price and will machine the ends for you also. One word
                  > of caution on mounting the motor on the X axis. When I did mine, I
                  > mounted the plate right on the end of the table and therefore lost
                  > some X axirade to ball screws
                  > >
                  > >Software
                  > >2. CAD
                  > >3. CAM
                  > >4. Controller
                  > >
                  > >Hardware
                  > >5. Breakout box
                  > >6. Motor drives
                  > >7. Stepper Motors
                  > >8. Power supply
                  > >9. Mounting brackets
                  > >10. Timing pulleys/belts
                  > >
                  > >Here are my questions:
                  > >
                  > >1. I have seen good prices on Ebay. Does anyone have suggestions on
                  > >what fits best on a RF-31, TPI, installation ease?
                  > >
                  > >2. & 3. I am looking at some open source CAD/CAM software. Anyone
                  > >know of a really good and inexpensive package?
                  > >
                  > >4. I was planning to use Mach3. I noticed that it comes with
                  > >LazyCam. Is this decent enough or should I look for something else
                  > >to generate the G-code?
                  > >
                  > >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
                  > >packages on Ebay that would work with Mach3. My concern is getting
                  > >steppers that have the needed torque. Does anyone have a
                  > >recommendation. It seems that others have used motors in the
                  > >350-420oz/in range. Is this about right for low-med volume on this
                  > >machine? The price on steppers goes up with torque. I want something
                  > >that will work, but I don't want to waste money on overkill.
                  > >
                  > >9. I have not found brackets sold individually, so I guess I am on my own.
                  > >
                  > >10. McMaster-Carr looks like they have everything I'd need, but does
                  > >anyone have advice on ratios? I did a little quick math and realized
                  > >that a ball screw with 8 TPI matched to a stepper capable of 200
                  > >steps has a resolution of .000625". My first thought was to gear it
                  > >to minimize motor load, but then I thought about getting a round
                  > >number such as one step being .00025" making 4 steps .001". Not
                  > >having used a a cnc before, I am not sure if it matters to have
                  > >round numbers or not. Is this an issue?
                  > >
                  > >Seems like $1200-$1500 for everything is where I'd be on this
                  > >project. Does that sound high, low, about right? Have I missed
                  > >anything that I'll need or can save money doing it differently?
                  > >
                  > >Lastly, I'd also like to use the mill manually especially as a drill
                  > >press. Are there any special design considerations to make this
                  > >possible? Can the steppers be put into "neutral" to spin freely or
                  > >would I have to remove the belts?
                  >
                • Edgar
                  Mike, notice the RF-31 conversion I linked to has the hand wheels arranged so they may be de-clutched when running CNC. I wouldn t give up manual control..
                  Message 8 of 21 , Apr 27, 2013
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                    Mike, notice the RF-31 conversion I linked to has the hand wheels arranged so they may be de-clutched when running CNC. I wouldn't give up manual control.. most of the time the one-off milling work you need to do on this type mill is done faster manually.

                    Orlin in SC/USA





                    > You are probably right about the hand wheels. I guess it is hard to give
                    > up on the option of being able to grab the crank and do things sans
                    > electronics.
                    >
                    > Mike
                  • mpoore10
                    Art, I am having trouble understanding the inductance of the motors in that package I looked at on Ebay and how it impacts the voltage requirement of the power
                    Message 9 of 21 , Apr 28, 2013
                    • 0 Attachment
                      Art,

                      I am having trouble understanding the inductance of the motors in that package I looked at on Ebay and how it impacts the voltage requirement of the power supply.

                      I read the whitepaper on the Gecko site you referenced on Gecko. Here is the relevant section, in case others are following along:

                      The voltage of your power supply is entirely dependent on the inductance rating of your motor, which we learned is translatable to the number of turns of wire in the stator. Every motor model will have a different inductance rating and will therefore have a different maximum voltage. To figure out what the maximum power supply voltage should be, use the following formula with the motor's inductance in millihenries (mH) used for the L value.

                      32 * vL = VMAX

                                      If you are using several different models of motors on the same power supply use the lowest inductance rating in the above formula. This will ensure that your motors will not overheat due to the voltage being too high.

                                      Should a motor not list the inductance it will generally list the voltage rating of each winding, which will be very low. An acceptable way of determining your power supply voltage if this is the only information you have is to multiply this number by any number between 4 and 20.

                      You stated that Vmax = 32 * (sq. root of inductance).  I assume that is the equation above written differently.

                      The spec sheet lists motor inductance as follows: 7.5x(1+20%)mH/Phase

                      The above specification is confusing to me. It looks to me more like an equation than a specification. Since there are 2 phases do I divide by 2 to determine inductance?

                      Plugging the 7.5 number into the equation, I get a Vmax of 87.6 as you wrote.

                      The rule of thumb Gecko provides for sizing power supplies when inductance is unknown would indicate the power supply is minimally okay where voltage is 6v * 4=24Vmax

                      Clearly, the power supply does not meet the requirement calculated and is right at the minimum of the rule of thumb.

                      I am trying to figure out why a seller would put this package together? If this package was meant to drive a router table or other machine not requiring the full capability of the motor could this explain the lower voltage of the power supply? If the power supply is regulated as it appears does that change anything as far as preventing equipment damage?  If running at a regulated 24v does that mean that the 420 oz/in steppers are simply going to be running equivalent to a 116 oz/in where the voltage is 27.5% of maximum computed by dividing Vmax by the regulated 24v?

                      Either way, I guess the package will not work. Even if the package would work without burning up, I don't think 116oz/in would be enough torque even with ball screws. Would it? At the same time, I am trying to make sure that I understand this well enough to evaluate other equipment.


                      Mike

                      --- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                      >
                      > Mike,
                      > I referenced Ebay as that is what a lot of people seem to be happy
                      > with lately. Those ball nuts have internal reticulation and some
                      > claim less backlash. I personally got my screws and nuts from Roton
                      > here in the states and did my own machining.
                      >
                      > I agree, Gecko is a high class outfit and I am a happy customer of
                      > theirs (total of 7 drives in service at this time). They also have an
                      > EXCELLENT support policy. If you blow a drive (first time) for ANY
                      > reason, send it in and they will repair/replace, and ship back for
                      > free. I have used that one time! There are some other drives out
                      > there that some people like and I refer you to Hoss on the cnczone as
                      > he went away from Gecko because of price. Be VERY aware of the
                      > problems that many have had with the TB series drives. They seem to
                      > have problems. As for the motors you referenced in the ebay add, they
                      > have a 7mh inductance and according to the white paper I referenced
                      > on the gecko site, they would require about 87VDC to achieve optimum
                      > performance and that package has only a 24V supply! The formula is
                      > 32 x the sq rt of the inductance in mh. You need to match your
                      > steppers, drives, and power supplies for optimum preformance or even
                      > close to it.
                      > As for the latest linuxcnc packages, they are fully GUI and about the
                      > only time you type any command is when your using MDI commands in G
                      > code! You boot the cd up and are given on the startup screen the
                      > option to run the program or to install to a hard drive. The live cd
                      > is great for checking things out, but I would not try to run a system
                      > off the cd due to speed required. As for Turbocnc (the program I
                      > use), again typing is for MDI and one thing I like is it does not
                      > really like the use of a mouse and about the only typed in dos
                      > command is "turbocnc" at the prompt and that is even handled by my
                      > autoexec to bring it up. There again, my cnc controllers are all
                      > dedicated machines to run cnc. I highly recommend that it be that
                      > way. Timing is critical and you don't want to ruin a project because
                      > your trying to google something on the net while machining!
                      >
                      > IF you really insist in the end analysis to having a hand wheel to
                      > move an axis, add an MPG (Manual Pulse Generator) to your controller
                      > and then twist away:}) Oh and you can also set the MPG up to move a
                      > certain distance with each click! Say .0001" up to say 1" per click
                      > AND it will show the appropriate location on the DRO of the computer
                      > screen. No more counting turns and loosing count. (been there done that too)
                      >
                      > Art
                      > Country Bubba
                      >
                      >
                      >
                      > At 03:28 PM 4/27/2013, you wrote:
                      >
                      >
                      > >Art,
                      > >
                      > >Thanks so much for the detailed response.
                      > >
                      > >I have looked for linearmotion on ebay and can't find them. I have
                      > >found some sellers in Hong Kong & China selling very inexpensive
                      > >ball screws, but I am leery. Having never had anything shipped to me
                      > >internationally, I don't know about all the ins and outs of the
                      > >process. It seems like the ones they sell are possibly geared toward
                      > >cnc routers/cutters. They advertise that they will manufacture it to
                      > >whatever specs I want. The pictures of the nut don't look right to
                      > >me. I don't see a tube to recirculate the balls. If you are
                      > >interested in seeing an example of what I'm talking about, here is
                      > >an example of what they sell:
                      > > ball
                      > >screw
                      > >
                      > >Gecko seems to be the "Cadillac" of motor drives. Perhaps I am being
                      > >penny smart and pound foolish, but I've been looking at some less
                      > >expensive alternatives. I found a package on Ebay (international
                      > >again) that is really enticing given that everything is already
                      > >supposed to work together and the price is outstanding ($475). I'd
                      > >spend that much on Geckos. Here's a link for the package:
                      > > package
                      > >If you or anyone else could check it out and provide feedback, I'd
                      > >sure appreciate it.
                      > >
                      > >Looks like I can get by with $0 on software. I don't mind DOS or
                      > >Linux. It's been a while since I used DOS. Linux, on the other hand,
                      > >with a live cd might be a nice option. I'll have to check it out and
                      > >see. It seems like I have to look up every command for Linux because
                      > >of the syntax differences between it and DOS/Windows. If the live cd
                      > >has a GUI, I should be good.
                      > >
                      > >You are probably right about the hand wheels. I guess it is hard to
                      > >give up on the option of being able to grab the crank and do things
                      > >sans electronics.
                      > >
                      > >Mike
                      > >
                      > >--- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                      > > >
                      > > > I converted my RF31 several years ago using servo motors but have
                      > > > been very happy with it.
                      > > >
                      > > > 1. Yes, definately upgrade to Ball Screws. My first iteration used
                      > > > the stock lead screws and I wore the nut out inside of 2 months. It
                      > > > was so loose that I could "walk" it down the screw without even
                      > > > turning it. Backlash was .25" plus. For the ball screws, I used the
                      > > > common (read less expensive) 5TPI 5/8" screws. Because my servos are
                      > > > rated at a higher speed, I used a belt reduction.
                      > > >
                      > > > 2. Software:
                      > > > For cad, I presently use Draftsight which requires
                      > > > registration, but otherwise if free. It is an Autocad
                      > > > clone. www.draftsight.com
                      > > > Cam, you mention Lazycad, but I don't think it is really
                      > > > supported anymore. I usight range for a RF31,
                      > > > but look around as you want units with low inductance to maximise
                      > > > your output. Read the white papers on the Gecko site for insight into
                      > > > proper sizing of the matching power supply voltage and maximum
                      > > > performance. This will also give info on proper sizing for current.
                      > > >
                      > > > Power supply For the steppers/servos, I prefer a plain ole
                      > > > transformer, bridge rectifier, and humongous capacitor. A wall wort
                      > > > or small switching supply can be included to handle the 5V etc
                      > > > duties. In my case, I converted a microwave transformer and added
                      > > > additional windings for my 5 and 12V supplies.
                      > > >
                      > > > Mounting brackets I made myself and beware that all of the RF31 class
                      > > > machines I have run across are not created equal when it comes to
                      > > > bolt patterns! AS some others have done, I made some temp ones to be
                      > > > able to make up the final product. Sure, it was additional work; but
                      > > > I learned a lot and also what might not work in some cases.
                      > > >
                      > > > Timing belts and pulleys. I used XL37 belts and pulleys on my
                      > > > system. In one case, I found using the (relatively) weak belt was a
                      > > > blessing as I had a run away one time and the belt broke before and
                      > > > real damage was done to the machine when it hit the hard stop.
                      > > > As to ratios, If I were to run the steppers, I would either direct
                      > > > drive or 1:1 ratio if using belts. Don't forget, most all drives use
                      > > > micro stepping and that must be taken into account when figuring steps/in.
                      > > >
                      > > > HAND WHEELS: WAY back when I was about to embark on my conversion
                      > > > this group was my main source of information and I also wanted to
                      > > > keep the hand wheels. Well, several of the good members at the time
                      > > > hit me up side the head and recommended loosing the hand wheels for
                      > > > several reasons including safety of not having that thing sticking
                      > > > that that could whack you and possibly damage YOU.
                      > > > Fortunately, I listened to them and in the past many years have not
                      > > > missed them. Any movement I want I use MDI commands. You mention
                      > > > drilling specifically, and think of it this way; MDI feeds is a power
                      > > > feed! Also, the ball screws will "back feed" and you will have to
                      > > > have some sort of braking action to hold them in place.
                      > > > Again as to TPI of the screw, I used 5TPI ones as they are relatively
                      > > > speaking the cheapest ones for size. No you don't need to have exact
                      > > > numbers as the controllers will accept several digits beyond the
                      > > > decimal point. You also may want to search ebay for a seller by the
                      > > > name of linearmotion I think it is as he sells ball screws at a
                      > > > reasonable price and will machine the ends for you also. One word
                      > > > of caution on mounting the motor on the X axis. When I did mine, I
                      > > > mounted the plate right on the end of the table and therefore lost
                      > > > some X axirade to ball screws
                      > > > >
                      > > > >Software
                      > > > >2. CAD
                      > > > >3. CAM
                      > > > >4. Controller
                      > > > >
                      > > > >Hardware
                      > > > >5. Breakout box
                      > > > >6. Motor drives
                      > > > >7. Stepper Motors
                      > > > >8. Power supply
                      > > > >9. Mounting brackets
                      > > > >10. Timing pulleys/belts
                      > > > >
                      > > > >Here are my questions:
                      > > > >
                      > > > >1. I have seen good prices on Ebay. Does anyone have suggestions on
                      > > > >what fits best on a RF-31, TPI, installation ease?
                      > > > >
                      > > > >2. & 3. I am looking at some open source CAD/CAM software. Anyone
                      > > > >know of a really good and inexpensive package?
                      > > > >
                      > > > >4. I was planning to use Mach3. I noticed that it comes with
                      > > > >LazyCam. Is this decent enough or should I look for something else
                      > > > >to generate the G-code?
                      > > > >
                      > > > >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
                      > > > >packages on Ebay that would work with Mach3. My concern is getting
                      > > > >steppers that have the needed torque. Does anyone have a
                      > > > >recommendation. It seems that others have used motors in the
                      > > > >350-420oz/in range. Is this about right for low-med volume on this
                      > > > >machine? The price on steppers goes up with torque. I want something
                      > > > >that will work, but I don't want to waste money on overkill.
                      > > > >
                      > > > >9. I have not found brackets sold individually, so I guess I am on my own.
                      > > > >
                      > > > >10. McMaster-Carr looks like they have everything I'd need, but does
                      > > > >anyone have advice on ratios? I did a little quick math and realized
                      > > > >that a ball screw with 8 TPI matched to a stepper capable of 200
                      > > > >steps has a resolution of .000625". My first thought was to gear it
                      > > > >to minimize motor load, but then I thought about getting a round
                      > > > >number such as one step being .00025" making 4 steps .001". Not
                      > > > >having used a a cnc before, I am not sure if it matters to have
                      > > > >round numbers or not. Is this an issue?
                      > > > >
                      > > > >Seems like $1200-$1500 for everything is where I'd be on this
                      > > > >project. Does that sound high, low, about right? Have I missed
                      > > > >anything that I'll need or can save money doing it differently?
                      > > > >
                      > > > >Lastly, I'd also like to use the mill manually especially as a drill
                      > > > >press. Are there any special design considerations to make this
                      > > > >possible? Can the steppers be put into "neutral" to spin freely or
                      > > > >would I have to remove the belts?
                      > > >
                      >
                    • Jerry Durand
                      ... On stepping motors the higher the voltage the faster you can step them (the faster the magnetic flux changes), but if you re using simple drivers that
                      Message 10 of 21 , Apr 28, 2013
                      • 0 Attachment

                        On 04/28/2013 10:43 AM, mpoore10 wrote:
                        Art,

                        I am having trouble understanding the inductance of the motors in that package I looked at on Ebay and how it impacts the voltage requirement of the power supply.


                        On stepping motors the higher the voltage the faster you can step them (the faster the magnetic flux changes), but if you're using simple drivers that simply leave the full voltage applied to the motor you then have to worry about toasting the motors.

                        In the stepping motor drivers I've designed I always use switching drivers that apply full voltage until the current reaches whatever set point you choose and then they pulse to hold it there.  Repeat for each step.

                        It's not unusual for me to run a 6 or 12V motor at 24V with this type of driver.

                        It's also not unusual to find regular commercial drivers do NOT do this since it requires more thinking, parts, and $ to build plus the user has to set the current to match each motor axis.
                        -- 
                        Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
                        tel: +1 408 356-3886, USA toll free: 1 866 356-3886
                        Skype:  jerrydurand 
                        
                      • Michael Parrish
                        Mike, I have a couple of machines. One with Gecko and one with Xylotex drives. Each drive has a maximum voltage. My Gecko is 80 volts and the Xylotex is 30
                        Message 11 of 21 , Apr 28, 2013
                        • 0 Attachment
                          Mike, I have a couple of machines. One with Gecko and one with Xylotex drives. Each drive has a maximum voltage. My Gecko is 80 volts and the Xylotex is 30 volts. The simple answer is to run as close to the max as you can. This will greatly improve speed and power at speed. The drives are adjustable for max current to the motor. You set the drive to match the motor current. The higher the voltage, the faster it can charge the winding to max current. I run a 75 volt/6.6 amp unregulated power supply on my Gecko driven machine and a 0-60 volt/5 amp lab supply (set at 30 volts) on the Xylotex. There is some concern about back EMF adding to the voltage total when a heavy axis is stopped rapidly. I think some of the newer Gecko's are protected against this. The big machine, with the Geckos and 75 volts can move a 70#+ axis at over 1000ipm with very rapid acceleration on +-1000oz motors. The smaller machine can only muster sub 200ipm rapids on 276oz motors. The Gecko drives are far more robust. I have flogged that machine mercilessly with no problems. I am on my second Xylotex drive board. I would think the newer Gecko's with greater protection are just about idiot-proof. Good hunting, Mike

                          --- In mill_drill@yahoogroups.com, "mpoore10" <mpoore10@...> wrote:
                          >
                          > Art,
                          >
                          > I am having trouble understanding the inductance of the motors in that
                          > package I looked at on Ebay and how it impacts the voltage requirement
                          > of the power supply.
                          >
                          > I read the whitepaper on the Gecko site you referenced on Gecko. Here is
                          > the relevant section, in case others are following along:
                          >
                          > The voltage of your power supply is entirely dependent on the
                          > inductance rating of your motor, which we learned is translatable to
                          > the number of turns of wire in the stator. Every motor model will have
                          > a different inductance rating and will therefore have a different
                          > maximum voltage. To figure out what the maximum power supply voltage
                          > should be, use the following formula with the motor's inductance in
                          > millihenries (mH) used for the L value.
                          > 32 * vL = VMAX
                          >
                          > If you are using several different models of motors on
                          > the same power supply use the lowest inductance rating in the above
                          > formula. This will ensure that your motors will not overheat due to the
                          > voltage being too high.
                          >
                          > Should a motor not list the inductance it will
                          > generally list the voltage rating of each winding, which will be very
                          > low. An acceptable way of determining your power supply voltage if this
                          > is the only information you have is to multiply this number by any
                          > number between 4 and 20.
                          >
                          > You stated that Vmax = 32 * (sq. root of inductance). I assume that is
                          > the equation above written differently.
                          >
                          >
                          > The spec sheet lists motor inductance as follows: 7.5x(1+20%)mH/Phase
                          >
                          > The above specification is confusing to me. It looks to me more like an
                          > equation than a specification. Since there are 2 phases do I divide by 2
                          > to determine inductance?
                          >
                          > Plugging the 7.5 number into the equation, I get a Vmax of 87.6 as you
                          > wrote.
                          >
                          > The rule of thumb Gecko provides for sizing power supplies when
                          > inductance is unknown would indicate the power supply is minimally okay
                          > where voltage is 6v * 4=24Vmax
                          >
                          >
                          > Clearly, the power supply does not meet the requirement calculated and
                          > is right at the minimum of the rule of thumb.
                          >
                          >
                          > I am trying to figure out why a seller would put this package together?
                          > If this package was meant to drive a router table or other machine not
                          > requiring the full capability of the motor could this explain the lower
                          > voltage of the power supply? If the power supply is regulated as it
                          > appears does that change anything as far as preventing equipment damage?
                          > If running at a regulated 24v does that mean that the 420 oz/in steppers
                          > are simply going to be running equivalent to a 116 oz/in where the
                          > voltage is 27.5% of maximum computed by dividing Vmax by the regulated
                          > 24v?
                          >
                          > Either way, I guess the package will not work. Even if the package would
                          > work without burning up, I don't think 116oz/in would be enough torque
                          > even with ball screws. Would it? At the same time, I am trying to make
                          > sure that I understand this well enough to evaluate other equipment.
                          >
                          >
                          >
                          >
                          > Mike
                          >
                          > --- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                          > >
                          > > Mike,
                          > > I referenced Ebay as that is what a lot of people seem to be happy
                          > > with lately. Those ball nuts have internal reticulation and some
                          > > claim less backlash. I personally got my screws and nuts from Roton
                          > > here in the states and did my own machining.
                          > >
                          > > I agree, Gecko is a high class outfit and I am a happy customer of
                          > > theirs (total of 7 drives in service at this time). They also have an
                          > > EXCELLENT support policy. If you blow a drive (first time) for ANY
                          > > reason, send it in and they will repair/replace, and ship back for
                          > > free. I have used that one time! There are some other drives out
                          > > there that some people like and I refer you to Hoss on the cnczone as
                          > > he went away from Gecko because of price. Be VERY aware of the
                          > > problems that many have had with the TB series drives. They seem to
                          > > have problems. As for the motors you referenced in the ebay add, they
                          > > have a 7mh inductance and according to the white paper I referenced
                          > > on the gecko site, they would require about 87VDC to achieve optimum
                          > > performance and that package has only a 24V supply! The formula is
                          > > 32 x the sq rt of the inductance in mh. You need to match your
                          > > steppers, drives, and power supplies for optimum preformance or even
                          > > close to it.
                          > > As for the latest linuxcnc packages, they are fully GUI and about the
                          > > only time you type any command is when your using MDI commands in G
                          > > code! You boot the cd up and are given on the startup screen the
                          > > option to run the program or to install to a hard drive. The live cd
                          > > is great for checking things out, but I would not try to run a system
                          > > off the cd due to speed required. As for Turbocnc (the program I
                          > > use), again typing is for MDI and one thing I like is it does not
                          > > really like the use of a mouse and about the only typed in dos
                          > > command is "turbocnc" at the prompt and that is even handled by my
                          > > autoexec to bring it up. There again, my cnc controllers are all
                          > > dedicated machines to run cnc. I highly recommend that it be that
                          > > way. Timing is critical and you don't want to ruin a project because
                          > > your trying to google something on the net while machining!
                          > >
                          > > IF you really insist in the end analysis to having a hand wheel to
                          > > move an axis, add an MPG (Manual Pulse Generator) to your controller
                          > > and then twist away:}) Oh and you can also set the MPG up to move a
                          > > certain distance with each click! Say .0001" up to say 1" per click
                          > > AND it will show the appropriate location on the DRO of the computer
                          > > screen. No more counting turns and loosing count. (been there done
                          > that too)
                          > >
                          > > Art
                          > > Country Bubba
                          > >
                          > >
                          > >
                          > > At 03:28 PM 4/27/2013, you wrote:
                          > >
                          > >
                          > > >Art,
                          > > >
                          > > >Thanks so much for the detailed response.
                          > > >
                          > > >I have looked for linearmotion on ebay and can't find them. I have
                          > > >found some sellers in Hong Kong & China selling very inexpensive
                          > > >ball screws, but I am leery. Having never had anything shipped to me
                          > > >internationally, I don't know about all the ins and outs of the
                          > > >process. It seems like the ones they sell are possibly geared toward
                          > > >cnc routers/cutters. They advertise that they will manufacture it to
                          > > >whatever specs I want. The pictures of the nut don't look right to
                          > > >me. I don't see a tube to recirculate the balls. If you are
                          > > >interested in seeing an example of what I'm talking about, here is
                          > > >an example of what they sell:
                          > > > ball
                          > > >screw
                          > > >
                          > > >Gecko seems to be the "Cadillac" of motor drives. Perhaps I am being
                          > > >penny smart and pound foolish, but I've been looking at some less
                          > > >expensive alternatives. I found a package on Ebay (international
                          > > >again) that is really enticing given that everything is already
                          > > >supposed to work together and the price is outstanding ($475). I'd
                          > > >spend that much on Geckos. Here's a link for the package:
                          > > > package
                          > > >If you or anyone else could check it out and provide feedback, I'd
                          > > >sure appreciate it.
                          > > >
                          > > >Looks like I can get by with $0 on software. I don't mind DOS or
                          > > >Linux. It's been a while since I used DOS. Linux, on the other hand,
                          > > >with a live cd might be a nice option. I'll have to check it out and
                          > > >see. It seems like I have to look up every command for Linux because
                          > > >of the syntax differences between it and DOS/Windows. If the live cd
                          > > >has a GUI, I should be good.
                          > > >
                          > > >You are probably right about the hand wheels. I guess it is hard to
                          > > >give up on the option of being able to grab the crank and do things
                          > > >sans electronics.
                          > > >
                          > > >Mike
                          > > >
                          > > >--- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                          > > > >
                          > > > > I converted my RF31 several years ago using servo motors but have
                          > > > > been very happy with it.
                          > > > >
                          > > > > 1. Yes, definately upgrade to Ball Screws. My first iteration used
                          > > > > the stock lead screws and I wore the nut out inside of 2 months.
                          > It
                          > > > > was so loose that I could "walk" it down the screw without even
                          > > > > turning it. Backlash was .25" plus. For the ball screws, I used
                          > the
                          > > > > common (read less expensive) 5TPI 5/8" screws. Because my servos
                          > are
                          > > > > rated at a higher speed, I used a belt reduction.
                          > > > >
                          > > > > 2. Software:
                          > > > > For cad, I presently use Draftsight which requires
                          > > > > registration, but otherwise if free. It is an Autocad
                          > > > > clone. www.draftsight.com
                          > > > > Cam, you mention Lazycad, but I don't think it is really
                          > > > > supported anymore. I usight range for a RF31,
                          > > > > but look around as you want units with low inductance to maximise
                          > > > > your output. Read the white papers on the Gecko site for insight
                          > into
                          > > > > proper sizing of the matching power supply voltage and maximum
                          > > > > performance. This will also give info on proper sizing for
                          > current.
                          > > > >
                          > > > > Power supply For the steppers/servos, I prefer a plain ole
                          > > > > transformer, bridge rectifier, and humongous capacitor. A wall
                          > wort
                          > > > > or small switching supply can be included to handle the 5V etc
                          > > > > duties. In my case, I converted a microwave transformer and added
                          > > > > additional windings for my 5 and 12V supplies.
                          > > > >
                          > > > > Mounting brackets I made myself and beware that all of the RF31
                          > class
                          > > > > machines I have run across are not created equal when it comes to
                          > > > > bolt patterns! AS some others have done, I made some temp ones to
                          > be
                          > > > > able to make up the final product. Sure, it was additional work;
                          > but
                          > > > > I learned a lot and also what might not work in some cases.
                          > > > >
                          > > > > Timing belts and pulleys. I used XL37 belts and pulleys on my
                          > > > > system. In one case, I found using the (relatively) weak belt was
                          > a
                          > > > > blessing as I had a run away one time and the belt broke before
                          > and
                          > > > > real damage was done to the machine when it hit the hard stop.
                          > > > > As to ratios, If I were to run the steppers, I would either direct
                          > > > > drive or 1:1 ratio if using belts. Don't forget, most all drives
                          > use
                          > > > > micro stepping and that must be taken into account when figuring
                          > steps/in.
                          > > > >
                          > > > > HAND WHEELS: WAY back when I was about to embark on my conversion
                          > > > > this group was my main source of information and I also wanted to
                          > > > > keep the hand wheels. Well, several of the good members at the
                          > time
                          > > > > hit me up side the head and recommended loosing the hand wheels
                          > for
                          > > > > several reasons including safety of not having that thing sticking
                          > > > > that that could whack you and possibly damage YOU.
                          > > > > Fortunately, I listened to them and in the past many years have
                          > not
                          > > > > missed them. Any movement I want I use MDI commands. You mention
                          > > > > drilling specifically, and think of it this way; MDI feeds is a
                          > power
                          > > > > feed! Also, the ball screws will "back feed" and you will have to
                          > > > > have some sort of braking action to hold them in place.
                          > > > > Again as to TPI of the screw, I used 5TPI ones as they are
                          > relatively
                          > > > > speaking the cheapest ones for size. No you don't need to have
                          > exact
                          > > > > numbers as the controllers will accept several digits beyond the
                          > > > > decimal point. You also may want to search ebay for a seller by
                          > the
                          > > > > name of linearmotion I think it is as he sells ball screws at a
                          > > > > reasonable price and will machine the ends for you also. One word
                          > > > > of caution on mounting the motor on the X axis. When I did mine, I
                          > > > > mounted the plate right on the end of the table and therefore lost
                          > > > > some X axirade to ball screws
                          > > > > >
                          > > > > >Software
                          > > > > >2. CAD
                          > > > > >3. CAM
                          > > > > >4. Controller
                          > > > > >
                          > > > > >Hardware
                          > > > > >5. Breakout box
                          > > > > >6. Motor drives
                          > > > > >7. Stepper Motors
                          > > > > >8. Power supply
                          > > > > >9. Mounting brackets
                          > > > > >10. Timing pulleys/belts
                          > > > > >
                          > > > > >Here are my questions:
                          > > > > >
                          > > > > >1. I have seen good prices on Ebay. Does anyone have suggestions
                          > on
                          > > > > >what fits best on a RF-31, TPI, installation ease?
                          > > > > >
                          > > > > >2. & 3. I am looking at some open source CAD/CAM software. Anyone
                          > > > > >know of a really good and inexpensive package?
                          > > > > >
                          > > > > >4. I was planning to use Mach3. I noticed that it comes with
                          > > > > >LazyCam. Is this decent enough or should I look for something
                          > else
                          > > > > >to generate the G-code?
                          > > > > >
                          > > > > >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
                          > > > > >packages on Ebay that would work with Mach3. My concern is
                          > getting
                          > > > > >steppers that have the needed torque. Does anyone have a
                          > > > > >recommendation. It seems that others have used motors in the
                          > > > > >350-420oz/in range. Is this about right for low-med volume on
                          > this
                          > > > > >machine? The price on steppers goes up with torque. I want
                          > something
                          > > > > >that will work, but I don't want to waste money on overkill.
                          > > > > >
                          > > > > >9. I have not found brackets sold individually, so I guess I am
                          > on my own.
                          > > > > >
                          > > > > >10. McMaster-Carr looks like they have everything I'd need, but
                          > does
                          > > > > >anyone have advice on ratios? I did a little quick math and
                          > realized
                          > > > > >that a ball screw with 8 TPI matched to a stepper capable of 200
                          > > > > >steps has a resolution of .000625". My first thought was to gear
                          > it
                          > > > > >to minimize motor load, but then I thought about getting a round
                          > > > > >number such as one step being .00025" making 4 steps .001". Not
                          > > > > >having used a a cnc before, I am not sure if it matters to have
                          > > > > >round numbers or not. Is this an issue?
                          > > > > >
                          > > > > >Seems like $1200-$1500 for everything is where I'd be on this
                          > > > > >project. Does that sound high, low, about right? Have I missed
                          > > > > >anything that I'll need or can save money doing it differently?
                          > > > > >
                          > > > > >Lastly, I'd also like to use the mill manually especially as a
                          > drill
                          > > > > >press. Are there any special design considerations to make this
                          > > > > >possible? Can the steppers be put into "neutral" to spin freely
                          > or
                          > > > > >would I have to remove the belts?
                          > > > >
                          > >
                          >
                        • Art Eckstein
                          Mike, You have the idea correctly. The thought several years ago was to use a voltage between 4 and 20 times the rated voltage of the stepper motor for
                          Message 12 of 21 , Apr 28, 2013
                          • 0 Attachment
                            Mike,
                            You have the idea correctly. The thought several years ago was to use a voltage between 4 and 20 times the rated voltage of the stepper motor for "optimum" performance, sometime later, Mariss refined it to the current formula of 32* sq rt of the inductance (in mH) as the best way to go.
                            This is not to say that it won't work with a lower voltage, but that it will not work to its highest level.  Remember also, that steppers holding power comes from current and voltage only relates to how fast the current can build in the coils. In other words, low voltage will limit the speed at which the motor can operate maximum.  The modern drives limit the current to the max rated so you don't overheat the motor and let the magic smoke out.

                            "The spec sheet lists motor inductance as follows: 7.5x(1+20%)mH/Phase" is the way it is listed in the specs and gives the nominal rating plus the tolerance.  In other words, the inductance per phase is from 7.5 mH to 7.5 * 120% or 9 mH!  No, you do not divide by 2 as this is per phase and you have two separate phases.

                            I cannot say why the seller puts this exact package together, but would surmise it might be a cost factor?? The 420 ozin is the holding torque at 0 rpm and you need the curves for this exact motor to see what the torque rating will be at some speed. I am not qualified to really guess at what it might be at say 500 rpm.  If your using a 5TPI lead screw and direct drive that translates into 500*.2 or 100 IPM! Will it have enough torque to do what you want if that is the max speed that you want, I don't know!

                            HTH

                            Art
                            Country Bubba



                              At 01:43 PM 4/28/2013, you wrote:


                            Art,

                            I am having trouble understanding the inductance of the motors in that package I looked at on Ebay and how it impacts the voltage requirement of the power supply.

                            I read the whitepaper on the Gecko site you referenced on Gecko. Here is the relevant section, in case others are following along:

                            The voltage of your power supply is entirely dependent on the inductance rating of your motor, which we learned is translatable to the number of turns of wire in the stator. Every motor model will have a different inductance rating and will therefore have a different maximum voltage. To figure out what the maximum power supply voltage should be, use the following formula with the motor's inductance in millihenries (mH) used for the L value.

                            32 * vL = VMAX

                                            If you are using several different models of motors on the same power supply use the lowest inductance rating in the above formula. This will ensure that your motors will not overheat due to the voltage being too high.

                                            Should a motor not list the inductance it will generally list the voltage rating of each winding, which will be very low. An acceptable way of determining your power supply voltage if this is the only information you have is to multiply this number by any number between 4 and 20.

                            You stated that Vmax = 32 * (sq. root of inductance).  I assume that is the equation above written differently.

                            The spec sheet lists motor inductance as follows: 7.5x(1+20%)mH/Phase

                            The above specification is confusing to me. It looks to me more like an equation than a specification. Since there are 2 phases do I divide by 2 to determine inductance?

                            Plugging the 7.5 number into the equation, I get a Vmax of 87.6 as you wrote.

                            The rule of thumb Gecko provides for sizing power supplies when inductance is unknown would indicate the power supply is minimally okay where voltage is 6v * 4=24Vmax

                            Clearly, the power supply does not meet the requirement calculated and is right at the minimum of the rule of thumb.

                            I am trying to figure out why a seller would put this package together? If this package was meant to drive a router table or other machine not requiring the full capability of the motor could this explain the lower voltage of the power supply? If the power supply is regulated as it appears does that change anything as far as preventing equipment damage?  If running at a regulated 24v does that mean that the 420 oz/in steppers are simply going to be running equivalent to a 116 oz/in where the voltage is 27.5% of maximum computed by dividing Vmax by the regulated 24v?

                            Either way, I guess the package will not work. Even if the package would work without burning up, I don't think 116oz/in would be enough torque even with ball screws. Would it? At the same time, I am trying to make sure that I understand this well enough to evaluate other equipment.


                            Mike
                            --- In mill_drill@yahoogroups.com, Art Eckstein wrote:
                            >
                            > Mike,
                            > I referenced Ebay as that is what a lot of people seem to be happy
                            > with lately. Those ball nuts have internal reticulation and some
                            > claim less backlash. I personally got my screws and nuts from Roton
                            > here in the states and did my own machining.
                            >
                            > I agree, Gecko is a high class outfit and I am a happy customer of
                            > theirs (total of 7 drives in service at this time). They also have an
                            > EXCELLENT support policy. If you blow a drive (first time) for ANY
                            > reason, send it in and they will repair/replace, and ship back for
                            > free. I have used that one time! There are some other drives out
                            > there that some people like and I refer you to Hoss on the cnczone as
                            > he went away fe to speed required. As for Turbocnc (the program I
                            > use), again typing is for MDI and one thing I like is it does not
                            > really like the use of a mouse and about the only typed in dos
                            > command is "turbocnc" at the prompt and that is even handled by my
                            > autoexec to bring it up. There again, my cnc controllers are all
                            > dedicated machines to run cnc. I highly recommend that it be that
                            > way. Timing is critical and you don't want to ruin a project because
                            > your trying to google something on the net while machining!
                            >
                            > IF you really insist in the end analysis to having a hand wheel to
                            > move an axis, add an MPG (Manual Pulse Generator) to your controller
                            > and then twist away:}) Oh and you can also set the MPG up to move a
                            > certain distance with each click! Say .0001" up to say 1" per click
                            > AND it will show the appropriate location on the DRO of the computer
                            > screen. No more counting turns and loosing count. (been there done that too)
                            >
                            > Art
                            > Country Bubba
                            >
                            >
                            >
                            > At 03:28 PM 4/27/2013, you wrote:
                            >
                            >
                            > >Art,
                            > >
                            > >Thanks so much for the detailed response.
                            > >
                            > >I have looked for linearmotion on ebay and can't find them. I have
                            > >found some sellers in Hong Kong & China selling very inexpensive
                            > >ball screws, but I am leery. Having never had anything shipped to me
                            > >internationally, I don't know about all the ins and outs of the
                            > >process. It seems like the ones they sell are possibly geared toward
                            > >cnc routers/cutters. They advertise that they will manufacture it to
                            > >whatever specs I want. The pictures of the nut don't look right to
                            > >me. I don't see a tube to recirculate the balls. If you are
                            > >interested in seeing an example of what I'm talking about, here is
                            > >an example of what they sell:
                            > > ball
                            > >screw
                            > >
                            > >Gecko seems to be the "Cadillac" of motor drives. Perhaps I am being
                            > >penny smart and pound foolish, but I've been looking at some less
                            > >expensive alternatives. I found a package on Ebay (international
                            > >again) that is really enticing given that everything is already
                            > >supposed to work together and the price is outstanding ($475). I'd
                            > >spend that much on Geckos. Here's a link for the package:
                            > > package
                            > >If you or anyone else could check it out and provide feedback, I'd
                            > >sure appreciate it.
                            > >
                            > >Looks like I can get by with $0 on software. I don't mind DOS or
                            > >Linux. It's been a while since I used DOS. Linux, on the other hand,
                            > >with a live cd might be a nice option. I'll have to check it out and
                            > >see. It seems like I have to look up every command for Linux because
                            > &gcause my servos are
                            > > > rated at a higher speed, I used a belt reduction.
                            > > >
                            > > > 2. Software:
                            > > > For cad, I presently use Draftsight which requires
                            > > > registration, but otherwise if free. It is an Autocad
                            > > > clone. www.draftsight.com
                            > > > Cam, you mention Lazycad, but I don't think it is really
                            > > > supported anymore. I usight range for a RF31,
                            > > > but look around as you want units with low inductance to maximise
                            > > > your output. Read the white papers on the Gecko site for insight into
                            > > > proper sizing of the matching power supply voltage and maximum
                            > > > performance. This will also give info on proper sizing for current.
                            > > >
                            > > > Power supply For the steppers/servos, I prefer a plain ole
                            > > > transformer, bridge rectifier, and humongous capacitor. A wall wort
                            > > > or small switching supply can be included to handle the 5V etc
                            > > > duties. In my case, I converted a microwave transformer and added
                            > > > additional windings for my 5 and 12V supplies.
                            > > >
                            > > > Mounting brackets I made myself and beware that all of the RF31 class
                            > > > machines I have run across are not created equal when it comes to
                            > > > bolt patterns! AS some others have done, I made some temp ones to be
                            > > > able to make up the final product. Sure, it was additional work; but
                            > > > I learned a lot and also what might not work in some cases.
                            > > >
                            > > > Timing belts and pulleys. I used XL37 belts and pulleys on my
                            > > > system. In one case, I found using the (relatively) weak belt was a
                            > > > blessing as I had a run away one time and the belt broke before and
                            > > > real damage was done to the machine when it hit the hard stop.
                            > > > As to ratios, If I were to run the steppers, I would either direct
                            > > > drive or 1:1 ratio if using belts. Don't forget, most all drives use
                            > > > micro stepping and that must be taken into account when figuring steps/in.
                            > > >
                            > > > HAND WHEELS: WAY back when I was about to embark on my conversion
                            > > > this group was my main source of information and I also wanted to
                            > > > keep the hand wheels. Well, several of the good members at the time
                            > > > hit me up side the head and recommended loosing the hand wheels for
                            > > > several reasons including safety of not having that thing sticking
                            > > > that that could whack you and possibly damage YOU.
                            > > > Fortunately, I listened to them and in the past many years have not
                            > > > missed them. Any movement I want I use MDI commands. You mention
                            > > > drilling specifically, and think of it this way; MDI feeds is a power
                            > > > feed! Also, the; > > >
                            > > > >Hardware
                            > > > >5. Breakout box
                            > > > >6. Motor drives
                            > > > >7. Stepper Motors
                            > > > >8. Power supply
                            > > > >9. Mounting brackets
                            > > > >10. Timing pulleys/belts
                            > > > >
                            > > > >Here are my questions:
                            > > > >
                            > > > >1. I have seen good prices on Ebay. Does anyone have suggestions on
                            > > > >what fits best on a RF-31, TPI, installation ease?
                            > > > >
                            > > > >2. & 3. I am looking at some open source CAD/CAM software. Anyone
                            > > > >know of a really good and inexpensive package?
                            > > > >
                            > > > >4. I was planning to use Mach3. I noticed that it comes with
                            > > > >LazyCam. Is this decent enough or should I look for something else
                            > > > >to generate the G-code?
                            > > > >
                            > > > >5., 6., 7., & 8. Seems like there are a lot of reasonably prices
                            > > > >packages on Ebay that would work with Mach3. My concern is getting
                            > > > >steppers that have the needed torque. Does anyone have a
                            > > > >recommendation. It seems that others have used motors in the
                            > > > >350-420oz/in range. Is this about right for low-med volume on this
                            > > > >machine? The price on steppers goes up with torque. I want something
                            > > > >that will work, but I don't want to waste money on overkill.
                            > > > >
                            > > > >9. I have not found brackets sold individually, so I guess I am on my own.
                            > > > >
                            > > > >10. McMaster-Carr looks like they have everything I'd need, but does
                            > > > >anyone have advice on ratios? I did a little quick math and realized
                            > > > >that a ball screw with 8 TPI matched to a stepper capable of 200
                            > > > >steps has a resolution of .000625". My first thought was to gear it
                            > > > >to minimize motor load, but then I thought about getting a round
                            > > > >number such as one step being .00025" making 4 steps .001". Not
                            > > > >having used a a cnc before, I am not sure if it matters to have
                            > > > >round numbers or not. Is this an issue?
                            > > > >
                            > > > >Seems like $1200-$1500 for everything is where I'd be on this
                            > > > >project. Does that sound high, low, about right? Have I missed
                            > > > >anything that I'll need or can save money doing it differently?
                            > > > >
                            > > > >Lastly, I'd also like to use the mill manually especially as a drill
                            > > > >press. Are there any special design considerations to make this
                            > > > >possible? Can the steppers be put into "neutral" to spin freely or
                            > > > >would I have to remove the belts?

                          • melvin.stanley@ymail.com
                            I have a RF-31 and the CNC conversion intrigues me since it could save me a lot of table cranking. I have three questions: In plastic material (UHMW or HDPE) I
                            Message 13 of 21 , May 2 8:33 AM
                            • 0 Attachment
                              I have a RF-31 and the CNC conversion intrigues me since it could save me a lot of table cranking. I have three questions:

                              In plastic material (UHMW or HDPE) I need to cut a radius. Would a CNC mill have the precision to cut a curve that was smooth and without "steps"?

                              I'm a real novice at even planning a conversion. Is there a step by step guide from start to finish?

                              I have three pacific scientific stepper motors and a matching controller, is there a reference source that can tell me about compatibility?

                              Thanks
                              Mel Stanley, Utah
                            • Art Eckstein
                              Mel, I have a converted RF-31 with zero backlash ball screws and yes it will do an admirable jobv of cutting all kinds of shaped. I made a coolant pump which
                              Message 14 of 21 , May 2 8:53 AM
                              • 0 Attachment
                                Mel,
                                I have a converted RF-31 with zero backlash ball screws and yes it
                                will do an admirable jobv of cutting all kinds of shaped. I made a
                                coolant pump which has vanes that are based on a logarithmic curve
                                and it cut them very nicely. Resolution and accuracy are functions of
                                the installation you make and how closely you calibrate it.

                                I personally know of no actual "step by step" guide sheet or list
                                that is available. My suggestion is to follow builds on various sites
                                with one of the biggest being cnczone.com. There are several people
                                that have build threads there that you can follow. Don't restrict
                                yourself to just RF-31 machines as the process is similar for most of
                                the machines of this type.

                                I am not sure what you mean about "compatibility", but I would study
                                the white papers on the Gecko site as they are very informative in sizing etc.

                                Good luck and I am sure others will be able to give you more and
                                better info than I

                                Art
                                Country Bubba


                                At 11:33 AM 5/2/2013, you wrote:
                                >I have a RF-31 and the CNC conversion intrigues me since it could
                                >save me a lot of table cranking. I have three questions:
                                >
                                >In plastic material (UHMW or HDPE) I need to cut a radius. Would a
                                >CNC mill have the precision to cut a curve that was smooth and without "steps"?
                                >
                                >I'm a real novice at even planning a conversion. Is there a step by
                                >step guide from start to finish?
                                >
                                >I have three pacific scientific stepper motors and a matching
                                >controller, is there a reference source that can tell me about compatibility?
                                >
                                >Thanks
                                >Mel Stanley, Utah
                                >
                              • mrwhiz49
                                I converted my RF-31 using stepper motors and the stock leadscrews and am quite happy. For direct drive 425 oz-inch will do the trick. You can expect about 15
                                Message 15 of 21 , May 3 10:10 PM
                                • 0 Attachment
                                  I converted my RF-31 using stepper motors and the stock leadscrews and am quite happy. For direct drive 425 oz-inch will do the trick. You can expect about 15 to 20 inches per minute. It's faster than you can spin by hand and won't tear up the lead screws. You can see pictures in the photo section under Paul's CNC. I've sold 7 kits and everybody has been happy. I use Mach3 and it does a good job compensating for backlash. The key is to finish with a light cut. It does accurate turning in the spindle which is demanding on positioning accuracy. I adopted an unconventional scheme for mounting the motor drives. The lead screws support everything. They are plenty strong and the assembly just slides on where the handle goes. All you need to do is stop the drive assembly from rotating. I use a worm drive clamp around the bearing boss. The beauty is nothing needs to be modified, it goes on and off in seconds and you still can use the handles. The pictures show gear drives for all three axes but now I use direct drive for X and Y. Either way works fine. I also converted an X2 mill using the same methods.

                                  --- In mill_drill@yahoogroups.com, "mpoore10" <mpoore10@...> wrote:
                                  >
                                  > I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems that most everyone that does this upgrade does it a little differently. It also seems that a lot of people sell stuff that I could use, but very few sell a comprehensive kit and the prices for the kits are unaffordable to me.
                                  >
                                  > This is totally new to me, so I have done a lot of reading. Here is a general list of what I think that I need:
                                  >
                                  > Mill
                                  > 1. Upgrade to ball screws
                                  >
                                  > Software
                                  > 2. CAD
                                  > 3. CAM
                                  > 4. Controller
                                  >
                                  > Hardware
                                  > 5. Breakout box
                                  > 6. Motor drives
                                  > 7. Stepper Motors
                                  > 8. Power supply
                                  > 9. Mounting brackets
                                  > 10. Timing pulleys/belts
                                  >
                                  > Here are my questions:
                                  >
                                  > 1. I have seen good prices on Ebay. Does anyone have suggestions on what fits best on a RF-31, TPI, installation ease?
                                  >
                                  > 2. & 3. I am looking at some open source CAD/CAM software. Anyone know of a really good and inexpensive package?
                                  >
                                  > 4. I was planning to use Mach3. I noticed that it comes with LazyCam. Is this decent enough or should I look for something else to generate the G-code?
                                  >
                                  > 5., 6., 7., & 8. Seems like there are a lot of reasonably prices packages on Ebay that would work with Mach3. My concern is getting steppers that have the needed torque. Does anyone have a recommendation. It seems that others have used motors in the 350-420oz/in range. Is this about right for low-med volume on this machine? The price on steppers goes up with torque. I want something that will work, but I don't want to waste money on overkill.
                                  >
                                  > 9. I have not found brackets sold individually, so I guess I am on my own.
                                  >
                                  > 10. McMaster-Carr looks like they have everything I'd need, but does anyone have advice on ratios? I did a little quick math and realized that a ball screw with 8 TPI matched to a stepper capable of 200 steps has a resolution of .000625". My first thought was to gear it to minimize motor load, but then I thought about getting a round number such as one step being .00025" making 4 steps .001". Not having used a a cnc before, I am not sure if it matters to have round numbers or not. Is this an issue?
                                  >
                                  > Seems like $1200-$1500 for everything is where I'd be on this project. Does that sound high, low, about right? Have I missed anything that I'll need or can save money doing it differently?
                                  >
                                  > Lastly, I'd also like to use the mill manually especially as a drill press. Are there any special design considerations to make this possible? Can the steppers be put into "neutral" to spin freely or would I have to remove the belts?
                                  >
                                • Guenther Paul
                                  Mrwhiz I have a big red and have bean thinking about converting to a cnc. Don t have a fine quill down feed yet but will be building it. Do you have any
                                  Message 16 of 21 , May 4 2:47 AM
                                  • 0 Attachment
                                    Mrwhiz
                                    I have a big red and have bean thinking about converting to a cnc. Don't have a fine quill down feed yet but will be
                                    building it. Do you have any recommendations 
                                    GP

                                     


                                    From: mrwhiz49 <pthomps2@...>
                                    To: mill_drill@yahoogroups.com
                                    Sent: Sat, May 4, 2013 1:10:11 AM
                                    Subject: [mill_drill] Re: RF-31 CNC Conversion

                                     

                                    I converted my RF-31 using stepper motors and the stock leadscrews and am quite happy. For direct drive 425 oz-inch will do the trick. You can expect about 15 to 20 inches per minute. It's faster than you can spin by hand and won't tear up the lead screws. You can see pictures in the photo section under Paul's CNC. I've sold 7 kits and everybody has been happy. I use Mach3 and it does a good job compensating for backlash. The key is to finish with a light cut. It does accurate turning in the spindle which is demanding on positioning accuracy. I adopted an unconventional scheme for mounting the motor drives. The lead screws support everything. They are plenty strong and the assembly just slides on where the handle goes. All you need to do is stop the drive assembly from rotating. I use a worm drive clamp around the bearing boss. The beauty is nothing needs to be modified, it goes on and off in seconds and you still can use the handles. The pictures show gear drives for all three axes but now I use direct drive for X and Y. Either way works fine. I also converted an X2 mill using the same methods.

                                    --- In mill_drill@yahoogroups.com, "mpoore10" <mpoore10@...> wrote:
                                    >
                                    > I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems that most everyone that does this upgrade does it a little differently. It also seems that a lot of people sell stuff that I could use, but very few sell a comprehensive kit and the prices for the kits are unaffordable to me.
                                    >
                                    > This is totally new to me, so I have done a lot of reading. Here is a general list of what I think that I need:
                                    >
                                    > Mill
                                    > 1. Upgrade to ball screws
                                    >
                                    > Software
                                    > 2. CAD
                                    > 3. CAM
                                    > 4. Controller
                                    >
                                    > Hardware
                                    > 5. Breakout box
                                    > 6. Motor drives
                                    > 7. Stepper Motors
                                    > 8. Power supply
                                    > 9. Mounting brackets
                                    > 10. Timing pulleys/belts
                                    >
                                    > Here are my questions:
                                    >
                                    > 1. I have seen good prices on Ebay. Does anyone have suggestions on what fits best on a RF-31, TPI, installation ease?
                                    >
                                    > 2. & 3. I am looking at some open source CAD/CAM software. Anyone know of a really good and inexpensive package?
                                    >
                                    > 4. I was planning to use Mach3. I noticed that it comes with LazyCam. Is this decent enough or should I look for something else to generate the G-code?
                                    >
                                    > 5., 6., 7., & 8. Seems like there are a lot of reasonably prices packages on Ebay that would work with Mach3. My concern is getting steppers that have the needed torque. Does anyone have a recommendation. It seems that others have used motors in the 350-420oz/in range. Is this about right for low-med volume on this machine? The price on steppers goes up with torque. I want something that will work, but I don't want to waste money on overkill.
                                    >
                                    > 9. I have not found brackets sold individually, so I guess I am on my own.
                                    >
                                    > 10. McMaster-Carr looks like they have everything I'd need, but does anyone have advice on ratios? I did a little quick math and realized that a ball screw with 8 TPI matched to a stepper capable of 200 steps has a resolution of .000625". My first thought was to gear it to minimize motor load, but then I thought about getting a round number such as one step being .00025" making 4 steps .001". Not having used a a cnc before, I am not sure if it matters to have round numbers or not. Is this an issue?
                                    >
                                    > Seems like $1200-$1500 for everything is where I'd be on this project. Does that sound high, low, about right? Have I missed anything that I'll need or can save money doing it differently?
                                    >
                                    > Lastly, I'd also like to use the mill manually especially as a drill press. Are there any special design considerations to make this possible? Can the steppers be put into "neutral" to spin freely or would I have to remove the belts?
                                    >

                                  • mrwhiz49
                                    I would recommend the same approach as I used in the pictures. You can use direct drive and avoid making some of the gears. They stick out a lot farther
                                    Message 17 of 21 , May 9 2:15 AM
                                    • 0 Attachment
                                      I would recommend the same approach as I used in the pictures. You can use direct drive and avoid making some of the gears. They stick out a lot farther though. The mounting scheme is very flexible and you don't have to figure out how to mount a bracket or have to make new bearing blocks. Two kits I sold were easily modified to fit RF-45's. One bit of advice is to avoid the temptation to mount the motors with too much rigidity. This requires you to use a flexible coupling to avoid an over-constrained design. That is, you might develop tight spots as you turn the shaft. You can use one of the popular stepper drivers that come combined with a breakout board. I see them referred to as TB6560. These are very attractive price-wise and are compact but I haven't had much luck with them, especially at 36 volts (24 seems OK). It is a good thing I bought five extra chips because I've replaced three so far. Also, they require at least a ten microsecond pulse. Mach3 puts out about one microsecond pulses and operation can be erratic. You can fix this in motor tuning configuration at the bottom of the page by telling it fifteen or whatever it lets you put. Good luck with your project. It is so worth doing.




                                      --- In mill_drill@yahoogroups.com, Guenther Paul <paulguenter@...> wrote:
                                      >
                                      > Mrwhiz
                                      > I have a big red and have bean thinking about converting to a cnc. Don't have a
                                      > fine quill down feed yet but will be
                                      >
                                      > building it. Do you have any recommendations GP
                                      >
                                      >  
                                      >
                                      >
                                      >
                                      > ________________________________
                                      > From: mrwhiz49 <pthomps2@...>
                                      > To: mill_drill@yahoogroups.com
                                      > Sent: Sat, May 4, 2013 1:10:11 AM
                                      > Subject: [mill_drill] Re: RF-31 CNC Conversion
                                      >
                                      >  
                                      > I converted my RF-31 using stepper motors and the stock leadscrews and am quite
                                      > happy. For direct drive 425 oz-inch will do the trick. You can expect about 15
                                      > to 20 inches per minute. It's faster than you can spin by hand and won't tear up
                                      > the lead screws. You can see pictures in the photo section under Paul's CNC.
                                      > I've sold 7 kits and everybody has been happy. I use Mach3 and it does a good
                                      > job compensating for backlash. The key is to finish with a light cut. It does
                                      > accurate turning in the spindle which is demanding on positioning accuracy. I
                                      > adopted an unconventional scheme for mounting the motor drives. The lead screws
                                      > support everything. They are plenty strong and the assembly just slides on where
                                      > the handle goes. All you need to do is stop the drive assembly from rotating. I
                                      > use a worm drive clamp around the bearing boss. The beauty is nothing needs to
                                      > be modified, it goes on and off in seconds and you still can use the handles.
                                      > The pictures show gear drives for all three axes but now I use direct drive for
                                      > X and Y. Either way works fine. I also converted an X2 mill using the same
                                      > methods.
                                      >
                                      > --- In mill_drill@yahoogroups.com, "mpoore10" <mpoore10@> wrote:
                                      > >
                                      > > I am going to convert a Jet JMD-15 (RF-31) mill to cnc. It seems that most
                                      > >everyone that does this upgrade does it a little differently. It also seems that
                                      > >a lot of people sell stuff that I could use, but very few sell a comprehensive
                                      > >kit and the prices for the kits are unaffordable to me.
                                      > >
                                      > > This is totally new to me, so I have done a lot of reading. Here is a general
                                      > >list of what I think that I need:
                                      > >
                                      > > Mill
                                      > > 1. Upgrade to ball screws
                                      > >
                                      > > Software
                                      > > 2. CAD
                                      > > 3. CAM
                                      > > 4. Controller
                                      > >
                                      > > Hardware
                                      > > 5. Breakout box
                                      > > 6. Motor drives
                                      > > 7. Stepper Motors
                                      > > 8. Power supply
                                      > > 9. Mounting brackets
                                      > > 10. Timing pulleys/belts
                                      > >
                                      > > Here are my questions:
                                      > >
                                      > > 1. I have seen good prices on Ebay. Does anyone have suggestions on what fits
                                      > >best on a RF-31, TPI, installation ease?
                                      > >
                                      > > 2. & 3. I am looking at some open source CAD/CAM software. Anyone know of a
                                      > >really good and inexpensive package?
                                      > >
                                      > > 4. I was planning to use Mach3. I noticed that it comes with LazyCam. Is this
                                      > >decent enough or should I look for something else to generate the G-code?
                                      > >
                                      > > 5., 6., 7., & 8. Seems like there are a lot of reasonably prices packages on
                                      > >Ebay that would work with Mach3. My concern is getting steppers that have the
                                      > >needed torque. Does anyone have a recommendation. It seems that others have used
                                      > >motors in the 350-420oz/in range. Is this about right for low-med volume on this
                                      > >machine? The price on steppers goes up with torque. I want something that will
                                      > >work, but I don't want to waste money on overkill.
                                      > >
                                      > > 9. I have not found brackets sold individually, so I guess I am on my own.
                                      > >
                                      > > 10. McMaster-Carr looks like they have everything I'd need, but does anyone
                                      > >have advice on ratios? I did a little quick math and realized that a ball screw
                                      > >with 8 TPI matched to a stepper capable of 200 steps has a resolution of
                                      > >.000625". My first thought was to gear it to minimize motor load, but then I
                                      > >thought about getting a round number such as one step being .00025" making 4
                                      > >steps .001". Not having used a a cnc before, I am not sure if it matters to have
                                      > >round numbers or not. Is this an issue?
                                      > >
                                      > > Seems like $1200-$1500 for everything is where I'd be on this project. Does
                                      > >that sound high, low, about right? Have I missed anything that I'll need or can
                                      > >save money doing it differently?
                                      > >
                                      > > Lastly, I'd also like to use the mill manually especially as a drill press. Are
                                      > >there any special design considerations to make this possible? Can the steppers
                                      > >be put into "neutral" to spin freely or would I have to remove the belts?
                                      > >
                                      >
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