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Re: The 5 AXIS head

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  • gawnca
    ... Hi Ken, I think if you look at Rab s web site, he switched those out for bipolar steppers. I ve got a couple of those rotating satellite heads in the
    Message 1 of 17 , May 1, 2008
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      --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@...> wrote:
      >
      > I just scored one of those satellite gears that was used to Make the 5
      > axis head on here.. I noticed though that the motor seems to have been
      > changed out .. does the latest version on Rabs Site still use a SERVO
      > motor or does it uses a stepper motor now?
      >
      > Thanks!
      > Ken
      >

      Hi Ken,

      I think if you look at Rab's web site, he switched those out for
      bipolar steppers. I've got a couple of those rotating satellite heads
      in the process of being machined to make up the duel movement head.
      I'll get some photos up on my web site and then post the link. I
      guess you could use the servo motors but I just didn't want to spend
      the extra needed to make them work.

      Greg
    • middyeasy
      Hi Greg, Nice to meet you. I did notice..I was hoping that was the case as stepper motors are easier to work with. What size motors will you be using or have
      Message 2 of 17 , May 1, 2008
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        Hi Greg,
        Nice to meet you. I did notice..I was hoping that was the case as
        stepper motors are easier to work with. What size motors will you be
        using or have you determined to be good candidates? I havent the
        slightest idea but I want to buy them so I also can use them to
        start on making the machining changes.
        Thanks
        Ken



        --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@...> wrote:
        >
        > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@> wrote:
        > >
        > > I just scored one of those satellite gears that was used to Make
        the 5
        > > axis head on here.. I noticed though that the motor seems to
        have been
        > > changed out .. does the latest version on Rabs Site still use a
        SERVO
        > > motor or does it uses a stepper motor now?
        > >
        > > Thanks!
        > > Ken
        > >
        >
        > Hi Ken,
        >
        > I think if you look at Rab's web site, he switched those out for
        > bipolar steppers. I've got a couple of those rotating satellite
        heads
        > in the process of being machined to make up the duel movement head.
        > I'll get some photos up on my web site and then post the link. I
        > guess you could use the servo motors but I just didn't want to
        spend
        > the extra needed to make them work.
        >
        > Greg
        >
      • gawnca
        Ken, I ll be running the EMA 23 BIPOLAR STEPPER MOTOR 282 oz-in, ¼ Diameter Shaft with flat KL23H276-30-6A (Single Shaft)from http://www.kelinginc.net/
        Message 3 of 17 , May 2, 2008
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          Ken, I'll be running the EMA 23 BIPOLAR STEPPER MOTOR 282 oz-in, ¼"
          Diameter Shaft with flat KL23H276-30-6A (Single Shaft)from
          http://www.kelinginc.net/ Should be enough to get the job done. I've
          got some photos of the machine work that's been done so far on rotors
          and will figure out how to post photos over the week-end and you can
          see what all I've done so far.

          Greg



          --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@...> wrote:
          >
          > Hi Greg,
          > Nice to meet you. I did notice..I was hoping that was the case as
          > stepper motors are easier to work with. What size motors will you be
          > using or have you determined to be good candidates? I havent the
          > slightest idea but I want to buy them so I also can use them to
          > start on making the machining changes.
          > Thanks
          > Ken
          >
          >
          >
          > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
          > >
          > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@> wrote:
          > > >
          > > > I just scored one of those satellite gears that was used to Make
          > the 5
          > > > axis head on here.. I noticed though that the motor seems to
          > have been
          > > > changed out .. does the latest version on Rabs Site still use a
          > SERVO
          > > > motor or does it uses a stepper motor now?
          > > >
          > > > Thanks!
          > > > Ken
          > > >
          > >
          > > Hi Ken,
          > >
          > > I think if you look at Rab's web site, he switched those out for
          > > bipolar steppers. I've got a couple of those rotating satellite
          > heads
          > > in the process of being machined to make up the duel movement head.
          > > I'll get some photos up on my web site and then post the link. I
          > > guess you could use the servo motors but I just didn't want to
          > spend
          > > the extra needed to make them work.
          > >
          > > Greg
          > >
          >
        • middyeasy
          Thanks for the info Greg.. as a matter of fact i just was just on that site about to buy! What made you choose 6 wire setup over the 4 wire one? Whats
          Message 4 of 17 , May 2, 2008
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            Thanks for the info Greg.. as a matter of fact i just was just on
            that site about to buy! What made you choose 6 wire setup over the 4
            wire one? Whats controller are you using? I look forward to seeing
            your photos! Im planning on a moving table with a stationary gantry.
            I have the space for it and it seems easier and cheaper to make then
            a sliding gantry.
            Ken


            --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@...> wrote:
            >
            > Ken, I'll be running the EMA 23 BIPOLAR STEPPER MOTOR 282 oz-in,
            ¼"
            > Diameter Shaft with flat KL23H276-30-6A (Single Shaft)from
            > http://www.kelinginc.net/ Should be enough to get the job done.
            I've
            > got some photos of the machine work that's been done so far on
            rotors
            > and will figure out how to post photos over the week-end and you
            can
            > see what all I've done so far.
            >
            > Greg
            >
            >
            >
            > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@> wrote:
            > >
            > > Hi Greg,
            > > Nice to meet you. I did notice..I was hoping that was the case
            as
            > > stepper motors are easier to work with. What size motors will
            you be
            > > using or have you determined to be good candidates? I havent the
            > > slightest idea but I want to buy them so I also can use them to
            > > start on making the machining changes.
            > > Thanks
            > > Ken
            > >
            > >
            > >
            > > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
            > > >
            > > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@>
            wrote:
            > > > >
            > > > > I just scored one of those satellite gears that was used to
            Make
            > > the 5
            > > > > axis head on here.. I noticed though that the motor seems to
            > > have been
            > > > > changed out .. does the latest version on Rabs Site still
            use a
            > > SERVO
            > > > > motor or does it uses a stepper motor now?
            > > > >
            > > > > Thanks!
            > > > > Ken
            > > > >
            > > >
            > > > Hi Ken,
            > > >
            > > > I think if you look at Rab's web site, he switched those out
            for
            > > > bipolar steppers. I've got a couple of those rotating
            satellite
            > > heads
            > > > in the process of being machined to make up the duel movement
            head.
            > > > I'll get some photos up on my web site and then post the
            link. I
            > > > guess you could use the servo motors but I just didn't want to
            > > spend
            > > > the extra needed to make them work.
            > > >
            > > > Greg
            > > >
            > >
            >
          • gawnca
            Hi Ken I went with 6 wire because they can be used either bipolar or unipolar and I have both setups here. I guess when I go to full 5 axis I ll go with Gecho
            Message 5 of 17 , May 3, 2008
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              Hi Ken

              I went with 6 wire because they can be used either bipolar or unipolar
              and I have both setups here. I guess when I go to full 5 axis I'll go
              with Gecho controllers, or look at stacking a controller that my buddy
              Dave is building.

              I've got just too many irons in the fire right now and the Wife is
              taking priority starting this next week. SO my CNC building is going
              to be put on hold for a couple of months.

              Greg

              --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@...> wrote:
              >
              > Thanks for the info Greg.. as a matter of fact i just was just on
              > that site about to buy! What made you choose 6 wire setup over the 4
              > wire one? Whats controller are you using? I look forward to seeing
              > your photos! Im planning on a moving table with a stationary gantry.
              > I have the space for it and it seems easier and cheaper to make then
              > a sliding gantry.
              > Ken
              >
              >
              > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
              > >
              > > Ken, I'll be running the EMA 23 BIPOLAR STEPPER MOTOR 282 oz-in,
              > ¼"
              > > Diameter Shaft with flat KL23H276-30-6A (Single Shaft)from
              > > http://www.kelinginc.net/ Should be enough to get the job done.
              > I've
              > > got some photos of the machine work that's been done so far on
              > rotors
              > > and will figure out how to post photos over the week-end and you
              > can
              > > see what all I've done so far.
              > >
              > > Greg
              > >
              > >
              > >
              > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@> wrote:
              > > >
              > > > Hi Greg,
              > > > Nice to meet you. I did notice..I was hoping that was the case
              > as
              > > > stepper motors are easier to work with. What size motors will
              > you be
              > > > using or have you determined to be good candidates? I havent the
              > > > slightest idea but I want to buy them so I also can use them to
              > > > start on making the machining changes.
              > > > Thanks
              > > > Ken
              > > >
              > > >
              > > >
              > > > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
              > > > >
              > > > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@>
              > wrote:
              > > > > >
              > > > > > I just scored one of those satellite gears that was used to
              > Make
              > > > the 5
              > > > > > axis head on here.. I noticed though that the motor seems to
              > > > have been
              > > > > > changed out .. does the latest version on Rabs Site still
              > use a
              > > > SERVO
              > > > > > motor or does it uses a stepper motor now?
              > > > > >
              > > > > > Thanks!
              > > > > > Ken
              > > > > >
              > > > >
              > > > > Hi Ken,
              > > > >
              > > > > I think if you look at Rab's web site, he switched those out
              > for
              > > > > bipolar steppers. I've got a couple of those rotating
              > satellite
              > > > heads
              > > > > in the process of being machined to make up the duel movement
              > head.
              > > > > I'll get some photos up on my web site and then post the
              > link. I
              > > > > guess you could use the servo motors but I just didn't want to
              > > > spend
              > > > > the extra needed to make them work.
              > > > >
              > > > > Greg
              > > > >
              > > >
              > >
              >
            • trama_molaf
              Hello Greg,Ken I too am considering building a 5th axis head using these rotary tables-but- I ve heard that they have a bit of backlash. Is this true? How can
              Message 6 of 17 , May 5, 2008
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                Hello Greg,Ken

                I too am considering building a 5th axis head
                using these rotary tables-but-
                I've heard that they have a bit of backlash.
                Is this true? How can this be corrected?

                Mark



                --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@...> wrote:
                >
                > Hi Ken
                >
                > I went with 6 wire because they can be used either bipolar or
                unipolar
                > and I have both setups here. I guess when I go to full 5 axis I'll
                go
                > with Gecho controllers, or look at stacking a controller that my
                buddy
                > Dave is building.
                >
                > I've got just too many irons in the fire right now and the Wife is
                > taking priority starting this next week. SO my CNC building is
                going
                > to be put on hold for a couple of months.
                >
                > Greg
                >
                > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@> wrote:
                > >
                > > Thanks for the info Greg.. as a matter of fact i just was just on
                > > that site about to buy! What made you choose 6 wire setup over
                the 4
                > > wire one? Whats controller are you using? I look forward to
                seeing
                > > your photos! Im planning on a moving table with a stationary
                gantry.
                > > I have the space for it and it seems easier and cheaper to make
                then
                > > a sliding gantry.
                > > Ken
                > >
                > >
                > > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
                > > >
                > > > Ken, I'll be running the EMA 23 BIPOLAR STEPPER MOTOR 282 oz-
                in,
                > > ¼"
                > > > Diameter Shaft with flat KL23H276-30-6A (Single Shaft)from
                > > > http://www.kelinginc.net/ Should be enough to get the job
                done.
                > > I've
                > > > got some photos of the machine work that's been done so far on
                > > rotors
                > > > and will figure out how to post photos over the week-end and
                you
                > > can
                > > > see what all I've done so far.
                > > >
                > > > Greg
                > > >
                > > >
                > > >
                > > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy" <middyeasy@>
                wrote:
                > > > >
                > > > > Hi Greg,
                > > > > Nice to meet you. I did notice..I was hoping that was the
                case
                > > as
                > > > > stepper motors are easier to work with. What size motors will
                > > you be
                > > > > using or have you determined to be good candidates? I havent
                the
                > > > > slightest idea but I want to buy them so I also can use them
                to
                > > > > start on making the machining changes.
                > > > > Thanks
                > > > > Ken
                > > > >
                > > > >
                > > > >
                > > > > --- In CNC_Toolkit@yahoogroups.com, "gawnca" <gregaw@> wrote:
                > > > > >
                > > > > > --- In CNC_Toolkit@yahoogroups.com, "middyeasy"
                <middyeasy@>
                > > wrote:
                > > > > > >
                > > > > > > I just scored one of those satellite gears that was used
                to
                > > Make
                > > > > the 5
                > > > > > > axis head on here.. I noticed though that the motor seems
                to
                > > > > have been
                > > > > > > changed out .. does the latest version on Rabs Site still
                > > use a
                > > > > SERVO
                > > > > > > motor or does it uses a stepper motor now?
                > > > > > >
                > > > > > > Thanks!
                > > > > > > Ken
                > > > > > >
                > > > > >
                > > > > > Hi Ken,
                > > > > >
                > > > > > I think if you look at Rab's web site, he switched those
                out
                > > for
                > > > > > bipolar steppers. I've got a couple of those rotating
                > > satellite
                > > > > heads
                > > > > > in the process of being machined to make up the duel
                movement
                > > head.
                > > > > > I'll get some photos up on my web site and then post the
                > > link. I
                > > > > > guess you could use the servo motors but I just didn't want
                to
                > > > > spend
                > > > > > the extra needed to make them work.
                > > > > >
                > > > > > Greg
                > > > > >
                > > > >
                > > >
                > >
                >
              • gcode fi (hanermo)
                I have 2 of the 6 inch rotaries, with cnc as a 4 axis head. They have about 3 mm or 0.5 degrees of backlash. It cannot be corrected or built out. A worm drive,
                Message 7 of 17 , May 5, 2008
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                  I have 2 of the 6 inch rotaries, with cnc as a 4 axis head.
                  They have about 3 mm or 0.5 degrees of backlash.

                  It cannot be corrected or built out.
                  A worm drive, which is what these are all based on, will always have
                  some backlash.
                  The very good ones (eg sherline, although small) have bearings on the
                  shafts and precision ground worms. They still have backlash, maybe 0.1 mm.

                  Some of the common solutions are;
                  1.do not do climb milling, it won´t work on the rotary
                  2.always mill from the same side of the cut ie against the backlash
                  3.when changing direction, go a bit past and then back again to take out
                  the backlash ie backlash compensation

                  Another good solution, is a non-backlash rotary table.
                  I am now building some.
                  Expected weight will be around 10 kg. Heavier is much better. I expect
                  about 150x times better performance (commercial industrial quality).


                  trama_molaf wrote:
                  >
                  > Hello Greg,Ken
                  >
                  > I too am considering building a 5th axis head
                  > using these rotary tables-but-
                  > I've heard that they have a bit of backlash.
                  > Is this true? How can this be corrected?
                  >
                  > Mark
                  >
                • gawnca
                  Here s where I have to differ with you. My rotary tables are not worm driven, they are ring and pinion driven. If here is any backlash, I ll have to check it
                  Message 8 of 17 , May 5, 2008
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                    Here's where I have to differ with you. My rotary tables are not worm
                    driven, they are ring and pinion driven. If here is any backlash,
                    I'll have to check it with a dial indicator. I have 6 of the rotary
                    table like Rab used and they were originally designed for satellite
                    tracking systems.

                    --- In CNC_Toolkit@yahoogroups.com, "gcode fi (hanermo)" <yahoog@...>
                    wrote:
                    >
                    > I have 2 of the 6 inch rotaries, with cnc as a 4 axis head.
                    > They have about 3 mm or 0.5 degrees of backlash.
                    >
                    > It cannot be corrected or built out.
                    > A worm drive, which is what these are all based on, will always have
                    > some backlash.
                    > The very good ones (eg sherline, although small) have bearings on the
                    > shafts and precision ground worms. They still have backlash, maybe
                    0.1 mm.
                    >
                    > Some of the common solutions are;
                    > 1.do not do climb milling, it won´t work on the rotary
                    > 2.always mill from the same side of the cut ie against the backlash
                    > 3.when changing direction, go a bit past and then back again to take
                    out
                    > the backlash ie backlash compensation
                    >
                    > Another good solution, is a non-backlash rotary table.
                    > I am now building some.
                    > Expected weight will be around 10 kg. Heavier is much better. I expect
                    > about 150x times better performance (commercial industrial quality).
                    >
                    >
                    > trama_molaf wrote:
                    > >
                    > > Hello Greg,Ken
                    > >
                    > > I too am considering building a 5th axis head
                    > > using these rotary tables-but-
                    > > I've heard that they have a bit of backlash.
                    > > Is this true? How can this be corrected?
                    > >
                    > > Mark
                    > >
                    >
                  • gcode fi (hanermo)
                    1. Rack and pinion ? In any case, due to where they came from, the situation may be totally different. Satellite tracking systems should probably not care
                    Message 9 of 17 , May 5, 2008
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                      1.
                      Rack and pinion ?
                      In any case, due to where they came from, the situation may be totally
                      different.
                      Satellite tracking systems should probably not care about backlash at
                      all - but accuracy and smoothness would be totally important.
                      The satellite and stars are unlikely to change course, so one-way motion
                      smoothness is all important.
                      Are any available somewhere and if so at what cost ?

                      2.
                      And backlash checked with a dial indicator - how else ?
                      Or lock the table and measure the turns you can make at the shaft end
                      back and forth.
                      It is probably not absolutely rigid, which would indicate backlash.
                      At 1 typical 90:1 a 1 degree possible movement at the shaft would be
                      1/90 degrees at the table.

                      Zero-backlash systems, where they exist, are ones that are pre-loaded
                      against both ends of their movement.

                      BTW -
                      The guys who built a private observatory (maybe 1/4 M $) with a big
                      telescope use a stepper with about 20.000 microsteps ...
                      and they can through stellar photos prove that the movement is very very
                      smooth. Of course, their telescope tracking movement is very slow and
                      stepper powers are tiny.
                      IIRC their telescope is about 1.2 - 1.5 M in diameter with a maybe 12 M
                      diameter dome - which I think is a great accomplishment. B.G. ;)

                      ? Differ - how ?
                      I referred to the commonly available rotaries, that the first poster
                      asked about, as I understood it.
                      When the mechanical accuracy increases the backlash reduces.

                      gawnca wrote:
                      >
                      > Here's where I have to differ with you. My rotary tables are not worm
                      > driven, they are ring and pinion driven. If here is any backlash,
                      > I'll have to check it with a dial indicator. I have 6 of the rotary
                      > table like Rab used and they were originally designed for satellite
                      > tracking systems.
                      >
                      > .
                      >
                      >
                    • Colin Doughty
                      Hi All, You may like to consider the Doughty Drive 5 axis units which have no backlash. Colin Doughty www.doughtydrive.com ... motion ... very
                      Message 10 of 17 , May 5, 2008
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                        Hi All,

                        You may like to consider the Doughty Drive 5 axis units which have no
                        backlash.

                        Colin Doughty
                        www.doughtydrive.com



                        --- In CNC_Toolkit@yahoogroups.com, "gcode fi (hanermo)" <yahoog@...>
                        wrote:
                        >
                        > 1.
                        > Rack and pinion ?
                        > In any case, due to where they came from, the situation may be totally
                        > different.
                        > Satellite tracking systems should probably not care about backlash at
                        > all - but accuracy and smoothness would be totally important.
                        > The satellite and stars are unlikely to change course, so one-way
                        motion
                        > smoothness is all important.
                        > Are any available somewhere and if so at what cost ?
                        >
                        > 2.
                        > And backlash checked with a dial indicator - how else ?
                        > Or lock the table and measure the turns you can make at the shaft end
                        > back and forth.
                        > It is probably not absolutely rigid, which would indicate backlash.
                        > At 1 typical 90:1 a 1 degree possible movement at the shaft would be
                        > 1/90 degrees at the table.
                        >
                        > Zero-backlash systems, where they exist, are ones that are pre-loaded
                        > against both ends of their movement.
                        >
                        > BTW -
                        > The guys who built a private observatory (maybe 1/4 M $) with a big
                        > telescope use a stepper with about 20.000 microsteps ...
                        > and they can through stellar photos prove that the movement is very
                        very
                        > smooth. Of course, their telescope tracking movement is very slow and
                        > stepper powers are tiny.
                        > IIRC their telescope is about 1.2 - 1.5 M in diameter with a maybe 12 M
                        > diameter dome - which I think is a great accomplishment. B.G. ;)
                        >
                        > ? Differ - how ?
                        > I referred to the commonly available rotaries, that the first poster
                        > asked about, as I understood it.
                        > When the mechanical accuracy increases the backlash reduces.
                        >
                        > gawnca wrote:
                        > >
                        > > Here's where I have to differ with you. My rotary tables are not worm
                        > > driven, they are ring and pinion driven. If here is any backlash,
                        > > I'll have to check it with a dial indicator. I have 6 of the rotary
                        > > table like Rab used and they were originally designed for satellite
                        > > tracking systems.
                        > >
                        > > .
                        > >
                        > >
                        >
                      • gcode fi (hanermo)
                        Cool ! Why no prices ie what do they cost ? Delivery timeframe ? What are the bearings ? How strong is it ? IE. can I put it on my 3/4 axis mill ? Whats the
                        Message 11 of 17 , May 5, 2008
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                          Cool !
                          Why no prices ie what do they cost ?
                          Delivery timeframe ?

                          What are the bearings ?
                          How strong is it ? IE. can I put it on my 3/4 axis mill ?
                          Whats the material ie alu, tools steel, chrome moly or something else ?

                          It looks nice.
                          More technical info and price sorely needed.
                          I wish the web site had more info ... looks good.

                          You can reply offlist if you want ...

                          Colin Doughty wrote:
                          >
                          > Hi All,
                          >
                          > You may like to consider the Doughty Drive 5 axis units which have no
                          > backlash.
                          >
                          > Colin Doughty
                          > www.doughtydrive.com
                          >
                          > .
                          >
                          >
                        • wes.spence@comcast.net
                          Hello, I have been wondering about the prices too since I first saw them! I don t have immediate need for them but knowing a price range will help in the
                          Message 12 of 17 , May 5, 2008
                          • 0 Attachment
                            Hello,
                            I have been wondering about the prices too since I first saw them! I don't have immediate need for them but knowing a price range will help in the planning stages. Great looking units!

                            Best regards,
                            Wes

                            -------------- Original message --------------
                            From: "gcode fi (hanermo)" <yahoog@...>
                            Cool !
                            Why no prices ie what do they cost ?
                            Delivery timeframe ?

                            What are the bearings ?
                            How strong is it ? IE. can I put it on my 3/4 axis mill ?
                            Whats the material ie alu, tools steel, chrome moly or something else ?

                            It looks nice.
                            More technical info and price sorely needed.
                            I wish the web site had more info ... looks good.

                            You can reply offlist if you want ...

                            Colin Doughty wrote:
                            >
                            > Hi All,
                            >
                            > You may like to consider the Doughty Drive 5 axis units which have no
                            > backlash.
                            >
                            > Colin Doughty
                            > www.doughtydrive.com
                            >
                            > .
                            >
                            >




                            [Non-text portions of this message have been removed]
                          • middyeasy
                            Thanks for the insight! Im new to CNC so naturally I started with the most advanced aspect of it. Sink or swim is my motto! Can you explain to me what you mean
                            Message 13 of 17 , May 5, 2008
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                              Thanks for the insight!

                              Im new to CNC so naturally I started with the most advanced aspect
                              of it. Sink or swim is my motto!

                              Can you explain to me what you mean by climb milling?

                              I hope you post pixs of your new 5th axis head i would love to see
                              them.

                              Ken



                              --- In CNC_Toolkit@yahoogroups.com, "gcode fi (hanermo)"
                              <yahoog@...> wrote:
                              >
                              > I have 2 of the 6 inch rotaries, with cnc as a 4 axis head.
                              > They have about 3 mm or 0.5 degrees of backlash.
                              >
                              > It cannot be corrected or built out.
                              > A worm drive, which is what these are all based on, will always
                              have
                              > some backlash.
                              > The very good ones (eg sherline, although small) have bearings on
                              the
                              > shafts and precision ground worms. They still have backlash, maybe
                              0.1 mm.
                              >
                              > Some of the common solutions are;
                              > 1.do not do climb milling, it won´t work on the rotary
                              > 2.always mill from the same side of the cut ie against the backlash
                              > 3.when changing direction, go a bit past and then back again to
                              take out
                              > the backlash ie backlash compensation
                              >
                              > Another good solution, is a non-backlash rotary table.
                              > I am now building some.
                              > Expected weight will be around 10 kg. Heavier is much better. I
                              expect
                              > about 150x times better performance (commercial industrial
                              quality).
                              >
                              >
                              > trama_molaf wrote:
                              > >
                              > > Hello Greg,Ken
                              > >
                              > > I too am considering building a 5th axis head
                              > > using these rotary tables-but-
                              > > I've heard that they have a bit of backlash.
                              > > Is this true? How can this be corrected?
                              > >
                              > > Mark
                              > >
                              >
                            • gcode fi (hanermo)
                              Just start and learn by doing ... if you are persistent, you get good. Its not very hard, incremental improvements will get you there. Normal milling is always
                              Message 14 of 17 , May 5, 2008
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                                Just start and learn by doing ... if you are persistent, you get good.
                                Its not very hard, incremental improvements will get you there.

                                Normal milling is always done against the rotation of the cutter ie
                                against the teeth.
                                Climb milling is the opposite. In it, you mill towards the teeth.

                                In normal milling, your drivetrain (rack & pinion, ballscrew, aceme
                                screw, timing belt, linear stage, whatever) pushes the cutter towards
                                the cut. The cutters teeth touch the work and load the cutter against
                                the drivetrain. Therefore any backlash in you drivetrain does not matter
                                too much, as the drivetrain just advances the tool until the teeth start
                                cutting.

                                Now, in climb milling, the teeth rotate towards the work, and the
                                drivetrain pushes the cutter in the same (not opposite) direction. When
                                the teeth catch, in that short amount of time, the cutter is grabbed by
                                the cutting force and pushed into the work. Within the time of one
                                cutters teeth engaging, the load is reversed and the cutter is janked
                                towards the workpiece. If you have backlash, your cutter grabs until it
                                either breaks, jams, something breaks in the machine or your drivetrain
                                stops the movement.

                                The time is;
                                say 6 mm cutter, mild steel, 600 rpm, 2 flute cutter; 600 rpm = 10
                                times/sec. 2 flutes = 2 teeth, so 0.1 secs / 2 = 0.05 secs. Within that
                                time, the drivetrain must stop the carriage from advancing.
                                Essentially, climb milling is done only with equipment that has no
                                backlash. Most are driven by ballscrews with preload.

                                These caveats do not matter with wood, and a little less with aluminum.
                                They are critical with mild steel, and double so with 316L, the marine
                                stainless alloy, and titanium alloys. In these materials you MUST take
                                big cuts, ie you cannot cut the material a bit at a time, as they work
                                harden very easily and quickly. If that happens, it means you cannot
                                make any cuts, and the tools just rubs the workpiece, elading to
                                localised heating, pitting, tool failure and often workpiece failure.
                                The surface is cosmetically very bad. With correct cutters and feeds,
                                the heat is in the part that the tools just cut away.

                                Why climb mill ? Well ...
                                it may need 1/3 less power, and the surface is usually much better
                                looking. It results in better tool life.
                                If you can, you often or mostly want to climb mill.

                                All traditional milling was normal against the rotation, i.e. not climb
                                milling.

                                Cheers,
                                h-
                                middyeasy wrote:
                                >
                                > Thanks for the insight!
                                >
                                > Im new to CNC so naturally I started with the most advanced aspect
                                > of it. Sink or swim is my motto!
                                >
                                > Can you explain to me what you mean by climb milling?
                                >
                                > I hope you post pixs of your new 5th axis head i would love to see
                                > them.
                                >
                                > Ken
                                >
                                > -
                                >
                              • middyeasy
                                Hey thanks for the informative Reply. Very interesting read indeed. Ken ... good. ... ie ... aceme ... towards ... against ... matter ... start ... When ...
                                Message 15 of 17 , May 5, 2008
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                                  Hey thanks for the informative Reply. Very interesting read indeed.

                                  Ken


                                  --- In CNC_Toolkit@yahoogroups.com, "gcode fi (hanermo)"
                                  <yahoog@...> wrote:
                                  >
                                  > Just start and learn by doing ... if you are persistent, you get
                                  good.
                                  > Its not very hard, incremental improvements will get you there.
                                  >
                                  > Normal milling is always done against the rotation of the cutter
                                  ie
                                  > against the teeth.
                                  > Climb milling is the opposite. In it, you mill towards the teeth.
                                  >
                                  > In normal milling, your drivetrain (rack & pinion, ballscrew,
                                  aceme
                                  > screw, timing belt, linear stage, whatever) pushes the cutter
                                  towards
                                  > the cut. The cutters teeth touch the work and load the cutter
                                  against
                                  > the drivetrain. Therefore any backlash in you drivetrain does not
                                  matter
                                  > too much, as the drivetrain just advances the tool until the teeth
                                  start
                                  > cutting.
                                  >
                                  > Now, in climb milling, the teeth rotate towards the work, and the
                                  > drivetrain pushes the cutter in the same (not opposite) direction.
                                  When
                                  > the teeth catch, in that short amount of time, the cutter is
                                  grabbed by
                                  > the cutting force and pushed into the work. Within the time of one
                                  > cutters teeth engaging, the load is reversed and the cutter is
                                  janked
                                  > towards the workpiece. If you have backlash, your cutter grabs
                                  until it
                                  > either breaks, jams, something breaks in the machine or your
                                  drivetrain
                                  > stops the movement.
                                  >
                                  > The time is;
                                  > say 6 mm cutter, mild steel, 600 rpm, 2 flute cutter; 600 rpm = 10
                                  > times/sec. 2 flutes = 2 teeth, so 0.1 secs / 2 = 0.05 secs. Within
                                  that
                                  > time, the drivetrain must stop the carriage from advancing.
                                  > Essentially, climb milling is done only with equipment that has no
                                  > backlash. Most are driven by ballscrews with preload.
                                  >
                                  > These caveats do not matter with wood, and a little less with
                                  aluminum.
                                  > They are critical with mild steel, and double so with 316L, the
                                  marine
                                  > stainless alloy, and titanium alloys. In these materials you MUST
                                  take
                                  > big cuts, ie you cannot cut the material a bit at a time, as they
                                  work
                                  > harden very easily and quickly. If that happens, it means you
                                  cannot
                                  > make any cuts, and the tools just rubs the workpiece, elading to
                                  > localised heating, pitting, tool failure and often workpiece
                                  failure.
                                  > The surface is cosmetically very bad. With correct cutters and
                                  feeds,
                                  > the heat is in the part that the tools just cut away.
                                  >
                                  > Why climb mill ? Well ...
                                  > it may need 1/3 less power, and the surface is usually much better
                                  > looking. It results in better tool life.
                                  > If you can, you often or mostly want to climb mill.
                                  >
                                  > All traditional milling was normal against the rotation, i.e. not
                                  climb
                                  > milling.
                                  >
                                  > Cheers,
                                  > h-
                                  > middyeasy wrote:
                                  > >
                                  > > Thanks for the insight!
                                  > >
                                  > > Im new to CNC so naturally I started with the most advanced
                                  aspect
                                  > > of it. Sink or swim is my motto!
                                  > >
                                  > > Can you explain to me what you mean by climb milling?
                                  > >
                                  > > I hope you post pixs of your new 5th axis head i would love to
                                  see
                                  > > them.
                                  > >
                                  > > Ken
                                  > >
                                  > > -
                                  > >
                                  >
                                • guzakaka
                                  Colin s units are more expensive than the sat units, but built so much better. As for strength, do a search on youtube pineapple carving on cnc and you will
                                  Message 16 of 17 , May 6, 2008
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                                    Colin's units are more expensive than the sat units, but built so
                                    much better. As for strength, do a search on youtube "pineapple
                                    carving on cnc" and you will see on of the units rotating a pineapple
                                    where a cut was made that I would not have though possible without
                                    losing position! I went and got the link for you.

                                    http://youtube.com/watch?v=O3d0fueNr30

                                    This will tell you what they are capable of and still hold.

                                    Price, unless it has changed is somewhere between $900-1000 per unit,
                                    I think! Don't hold that to be the exact price.

                                    Mike

                                    --- In CNC_Toolkit@yahoogroups.com, "gcode fi (hanermo)" <yahoog@...>
                                    wrote:
                                    >
                                    > Cool !
                                    > Why no prices ie what do they cost ?
                                    > Delivery timeframe ?
                                    >
                                    > What are the bearings ?
                                    > How strong is it ? IE. can I put it on my 3/4 axis mill ?
                                    > Whats the material ie alu, tools steel, chrome moly or something
                                    else ?
                                    >
                                    > It looks nice.
                                    > More technical info and price sorely needed.
                                    > I wish the web site had more info ... looks good.
                                    >
                                    > You can reply offlist if you want ...
                                    >
                                    > Colin Doughty wrote:
                                    > >
                                    > > Hi All,
                                    > >
                                    > > You may like to consider the Doughty Drive 5 axis units which
                                    have no
                                    > > backlash.
                                    > >
                                    > > Colin Doughty
                                    > > www.doughtydrive.com
                                    > >
                                    > > .
                                    > >
                                    > >
                                    >
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