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Re: [SherlineCNC] Z-axis ballscrew (again!)

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  • Alan Marconett KM6VV
    Hi Daniel, list, I picked up three short THK leadscrews and ball nuts, surplus, with the idea of someday making up a small mill to fit the parts . I got a
    Message 1 of 20 , Jan 6, 2004
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      Hi Daniel, list,

      I picked up three short THK leadscrews and ball nuts, surplus, with the
      idea of someday making up a small mill to "fit the parts". I got a set
      of 3 for under $100, and if I ever get around to it, I feel I can make
      it on my larger RF-31 mill (still manual). Smaller parts would be made
      on the Sherline. BUT, as with several other ideas I've had, NO TIME to
      make it all up!

      I know it's a lot of work, but I think this might be way to do it. Make
      the mill fit the parts available. MAYBE, When I get more time!

      Alan KM6VV


      "Statman Designs, LLC" wrote:
      >
      > To all interested parties. I just got my e-mail quote for the ballscrew
      > that just fits the Sherline Z-axis column. Price is $405 for the complete
      > unit. I think I'll pass.
      >
      > Daniel J. Statman, Statman Designs
      > www.statmandesigns.com
      > dan.statman@...
      >
      > ----- Original Message -----
      > From: "RichD" <cmsteam@...>
      > To: <SherlineCNC@yahoogroups.com>
      > Sent: Saturday, January 03, 2004 7:54 PM
      > Subject: Re: [SherlineCNC] Z-axis ballscrew (again!)
      >
      > > jchrisj7734,
      > > I have mentioned several trimes before that there is a ballscrew
      > > available that will fit **in** the column with similar pitch as far as
      > > I can determine. Should be easy to retrofit.
      > > No one else has picked up on it that I know of.
      > > On my 5400, I have replaced the bronze nut with a delrin nut and steel
      > > carrier assembly out of shear curiosity (and to save $$).
      > > After many loooong runs, the backlash is still ~.001"
      > > and I think that's flex or shift in the entire head assembly from moving
      > > 10 pounds of motor, etc.
      > > Plastic has the advantage that some variation in pitch and wear can be
      > > accomodated without adverse effect. I still use the old screw.
      > > Previous mention of this, it seems, is interested either.
      > > RichD
      > >
    • jmorrphd2
      List Members: There is more than just the backlash problem with the Z-axis on the Sherline. The axis is also not rigid enough and it is too sticky for fine
      Message 2 of 20 , Jan 12, 2004
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        List Members:
        There is more than just the backlash problem with the Z-axis on
        the Sherline. The axis is also not rigid enough and it is too
        "sticky" for fine movement. I've had problems using larger, 1/4
        and 3/8" end mills when milling steel. The whole axis, motor and
        all, will twist and chatter.
        Replacing the leadscrew with a ball screw is only a partial
        solution to the Z-axis problem. The motor/spindle assembly has
        its center of gravity offset from the spindle and this leads to
        some torque against the way of the Z-axis.
        The whole Z-axis needs a redesign or needs to be remade with
        different materials for more demanding users. A ball screw is
        only a bandaid.
        Regarding the cost of the ball screw, this is about right for a
        Class 3 ball screw. I've had similar quotes for 12 and 16 mm
        ball screws ranging from $550 (for quantities of 5) to $1250. This
        is just for the screw and does not include the fixed bearings on
        either end of the screw. These bearings with blocks are on the order
        of $150 to $250 each.
        An 8 mm ball screw is too delicate to bear the weight of the
        motor/spindle assembly and its attendent friction. Although the
        specs seem to indicate that it could support this weight, the screw
        itself may buckle due to its small diameter.
        I would agree with Dan, I would not want to pay $405 for a bandaid
        either. -Jim


        --- In SherlineCNC@yahoogroups.com, "Statman Designs, LLC"
        <titanium@c...> wrote:
        > To all interested parties. I just got my e-mail quote for the
        ballscrew
        > that just fits the Sherline Z-axis column. Price is $405 for the
        complete
        > unit. I think I'll pass.
        >
        > Daniel J. Statman, Statman Designs
        > www.statmandesigns.com
        > dan.statman@r...
        >
        >
        > ----- Original Message -----
        > From: "RichD" <cmsteam@s...>
        > To: <SherlineCNC@yahoogroups.com>
        > Sent: Saturday, January 03, 2004 7:54 PM
        > Subject: Re: [SherlineCNC] Z-axis ballscrew (again!)
        >
        >
        > > jchrisj7734,
        > > I have mentioned several trimes before that there is a ballscrew
        > > available that will fit **in** the column with similar pitch as
        far as
        > > I can determine. Should be easy to retrofit.
        > > No one else has picked up on it that I know of.
        > > On my 5400, I have replaced the bronze nut with a delrin nut and
        steel
        > > carrier assembly out of shear curiosity (and to save $$).
        > > After many loooong runs, the backlash is still ~.001"
        > > and I think that's flex or shift in the entire head assembly from
        moving
        > > 10 pounds of motor, etc.
        > > Plastic has the advantage that some variation in pitch and wear
        can be
        > > accomodated without adverse effect. I still use the old screw.
        > > Previous mention of this, it seems, is interested either.
        > > RichD
      • RichD
        Jim, I pretty much agree with you. The cost and the uncertainty just kept me from pursuing it. Again, my delrin Z nut assembly has performed perfectly for many
        Message 3 of 20 , Jan 12, 2004
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          Jim,
          I pretty much agree with you. The cost and the uncertainty just
          kept me from pursuing it.
          Again, my delrin Z nut assembly has performed perfectly for many hours
          of engraving use (multitudes of Z moves) and 3D contouring.
          I am interested in the double slide arangement discussed earlier
          where the spindle motor drive is carried by a parallel column.
          I have all the parts on hand except a drive belt.
          RichD

          jmorrphd2 wrote:
          >
          > List Members:
          > There is more than just the backlash problem with the Z-axis on
          > the Sherline. The axis is also not rigid enough and it is too
          > "sticky" for fine movement. I've had problems using larger, 1/4
          > and 3/8" end mills when milling steel. The whole axis, motor and
          > all, will twist and chatter.
          > Replacing the leadscrew with a ball screw is only a partial
          > solution to the Z-axis problem. The motor/spindle assembly has
          > its center of gravity offset from the spindle and this leads to
          > some torque against the way of the Z-axis.
          > The whole Z-axis needs a redesign or needs to be remade with
          > different materials for more demanding users. A ball screw is
          > only a bandaid.
          > Regarding the cost of the ball screw, this is about right for a
          > Class 3 ball screw. I've had similar quotes for 12 and 16 mm
          > ball screws ranging from $550 (for quantities of 5) to $1250. This
          > is just for the screw and does not include the fixed bearings on
          > either end of the screw. These bearings with blocks are on the order
          > of $150 to $250 each.
          > An 8 mm ball screw is too delicate to bear the weight of the
          > motor/spindle assembly and its attendent friction. Although the
          > specs seem to indicate that it could support this weight, the screw
          > itself may buckle due to its small diameter.
          > I would agree with Dan, I would not want to pay $405 for a bandaid
          > either. -Jim
        • Statman Designs, LLC
          I think the most economical thing to do is purchase a complete Z-axis with ballscrew on eBay. It looks like it would be real easy to build a bracket to mount
          Message 4 of 20 , Jan 12, 2004
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            I think the most economical thing to do is purchase a complete Z-axis with
            ballscrew on eBay. It looks like it would be real easy to build a bracket
            to mount it to the X-Y table base, and to built a mount for the headstock.
            Here is a complete ballscrew slide with motor and controller for $199
            opening bid. there are three of these listed by the same seller, so I am
            pretty sure they will go for the minimum bid.

            http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2586623506

            The only problem with this method is that you cannot rely on always finding
            the exact component if you want to build multiple machines. Also if
            something breaks you are a bit screwed, but we are all professional
            machinist, so we can fix it right up, ;-).

            Daniel J. Statman, Statman Designs
            www.statmandesigns.com
            dan.statman@...

            ----- Original Message -----
            From: "RichD" <cmsteam@...>
            To: <SherlineCNC@yahoogroups.com>
            Sent: Monday, January 12, 2004 11:23 PM
            Subject: Re: [SherlineCNC] Re: Z-axis ballscrew (again!)


            > Jim,
            > I pretty much agree with you. The cost and the uncertainty just
            > kept me from pursuing it.
            > Again, my delrin Z nut assembly has performed perfectly for many hours
            > of engraving use (multitudes of Z moves) and 3D contouring.
            > I am interested in the double slide arangement discussed earlier
            > where the spindle motor drive is carried by a parallel column.
            > I have all the parts on hand except a drive belt.
            > RichD
            >
          • wyverndudejfg
            Hey! I m intrigued! After what has seemed to me to be really not that much use, my Z-Axis developed enough backlash to be a problem (I d guess about 0.007 or
            Message 5 of 20 , Feb 19, 2004
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              Hey! I'm intrigued!

              After what has seemed to me to be really not that much use, my Z-Axis
              developed enough backlash to be a problem (I'd guess about 0.007 or
              so).

              I (sort of) solved this by adjusting the nut crooked. There's two
              setscrews on
              each side of the bolt that secures it to the carriage; I just
              adjusted one of them in, and one of them out. I had to play with it
              a bit to simultaneously take up the play without binding, and keep
              the nut centered on the leadscrew, but it wasn't that bad... but it
              was a far more 'temporary' fix than I anticipated.

              After about maybe 2 hours runtime (and VERY little of that up/down),
              it seems I have the play back again. I can keep tilting it; then
              when that runs out of room, I can tilt it in the other direction, but
              after awhile...

              It sounds like the ultimate solution will be the Z-Axis backlash kit,
              but $35 seems a bit much -you'd think Sherline would give us a break
              when the kits' very existence is an admission that there was a design
              weakness... they could've MADE some PR points (by disseminating them
              at zero or minimal cost) instead of losing some... I'm sure the Taig
              contingent are hooting over this one...


              The delrin nut doesn't *seem* like it should work, but your
              experience seems to prove otherwise. It sounds like it was easy
              enough to do, so I'd be willing to give this a try -my question is,
              how did you cut the threads?








              > On my 5400, I have replaced the bronze nut with a delrin nut and
              steel
              > carrier assembly out of shear curiosity (and to save $$).
              > After many loooong runs, the backlash is still ~.001"
              > and I think that's flex or shift in the entire head assembly from
              moving
              > 10 pounds of motor, etc.
              > Plastic has the advantage that some variation in pitch and wear can
              be
              > accomodated without adverse effect. I still use the old screw.
              > Previous mention of this, it seems, is interested either.
              > RichD
              >
            • RichD
              BryceA, I tried the slotted and squeezed nut trick. Lasted 1 day. Phooey! When engraving wide areas for stand up letters, the background needs to be left
              Message 6 of 20 , Feb 19, 2004
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                BryceA,
                I tried the slotted and squeezed nut trick. Lasted 1 day. Phooey!
                When engraving wide areas for stand up letters, the background
                needs to be left **flaaaaaat** to look good.
                I tried several versions of antibacklash nut systems suggested by
                searches of patents, etc. All became more trouble than they were
                worth. Due to the Sherline screw being small and in a cramped space,
                I decided to try the direct approach. No metal nut. Just a delrin
                replacement held securely with a carrier shaped like the old saddle
                nut. With many hours of use (with the old screw, BTW), the performance
                has been great. No change in the apparent backlash (more likly slide
                shift) of .001 and consistant to this day. The lube oil typicaly turned
                brown quickly with the bronze nut with little use. Now the oil only shows
                a slight darkening after many hours.
                3/8-20LH taps are available if you search long enough for many $$.
                I made my own to a tight spec and the carrier design allows additional
                squeeze to zero out any play easily.
                My brass or bronze engraved plates are beauty now.
                RichD

                wyverndudejfg wrote:
                >
                > Hey! I'm intrigued!
                >
                > After what has seemed to me to be really not that much use, my Z-Axis
                > developed enough backlash to be a problem (I'd guess about 0.007 or
                > so).
                >
                > I (sort of) solved this by adjusting the nut crooked. There's two
                > setscrews on
                > each side of the bolt that secures it to the carriage; I just
                > adjusted one of them in, and one of them out. I had to play with it
                > a bit to simultaneously take up the play without binding, and keep
                > the nut centered on the leadscrew, but it wasn't that bad... but it
                > was a far more 'temporary' fix than I anticipated.
                >
                > After about maybe 2 hours runtime (and VERY little of that up/down),
                > it seems I have the play back again. I can keep tilting it; then
                > when that runs out of room, I can tilt it in the other direction, but
                > after awhile...
                >
                > It sounds like the ultimate solution will be the Z-Axis backlash kit,
                > but $35 seems a bit much -you'd think Sherline would give us a break
                > when the kits' very existence is an admission that there was a design
                > weakness... they could've MADE some PR points (by disseminating them
                > at zero or minimal cost) instead of losing some... I'm sure the Taig
                > contingent are hooting over this one...
                >
                > The delrin nut doesn't *seem* like it should work, but your
                > experience seems to prove otherwise. It sounds like it was easy
                > enough to do, so I'd be willing to give this a try -my question is,
                > how did you cut the threads?
                >
              • Alan Marconett KM6VV
                Hi Rich, Delrin saddle nut? Sounds interesting! Maybe you could sell a few. I d be interested. I did find a source of LH taps and dies, but not in the
                Message 7 of 20 , Feb 20, 2004
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                  Hi Rich,

                  Delrin saddle nut? Sounds interesting! Maybe you could sell a few.
                  I'd be interested. I did find a source of LH taps and dies, but not in
                  the 1/4-20 size. Probably in MSC.

                  I received a PSME (Precision Scale Model Engineering) catalog a short
                  time ago. Great stuff!

                  http://www.psmeScale.com

                  Alan KM6VV

                  RichD wrote:
                  >
                  > BryceA,
                  > I tried the slotted and squeezed nut trick. Lasted 1 day. Phooey!
                  > When engraving wide areas for stand up letters, the background
                  > needs to be left **flaaaaaat** to look good.
                  > I tried several versions of antibacklash nut systems suggested by
                  > searches of patents, etc. All became more trouble than they were
                  > worth. Due to the Sherline screw being small and in a cramped space,
                  > I decided to try the direct approach. No metal nut. Just a delrin
                  > replacement held securely with a carrier shaped like the old saddle
                  > nut. With many hours of use (with the old screw, BTW), the performance
                  > has been great. No change in the apparent backlash (more likly slide
                  > shift) of .001 and consistant to this day. The lube oil typicaly turned
                  > brown quickly with the bronze nut with little use. Now the oil only shows
                  > a slight darkening after many hours.
                  > 3/8-20LH taps are available if you search long enough for many $$.
                  > I made my own to a tight spec and the carrier design allows additional
                  > squeeze to zero out any play easily.
                  > My brass or bronze engraved plates are beauty now.
                  > RichD
                  >
                  > wyverndudejfg wrote:
                  > >
                  > > Hey! I'm intrigued!
                  > >
                  > > After what has seemed to me to be really not that much use, my Z-Axis
                  > > developed enough backlash to be a problem (I'd guess about 0.007 or
                  > > so).
                  > >
                  > > I (sort of) solved this by adjusting the nut crooked. There's two
                  > > setscrews on
                  > > each side of the bolt that secures it to the carriage; I just
                  > > adjusted one of them in, and one of them out. I had to play with it
                  > > a bit to simultaneously take up the play without binding, and keep
                  > > the nut centered on the leadscrew, but it wasn't that bad... but it
                  > > was a far more 'temporary' fix than I anticipated.
                  > >
                  > > After about maybe 2 hours runtime (and VERY little of that up/down),
                  > > it seems I have the play back again. I can keep tilting it; then
                  > > when that runs out of room, I can tilt it in the other direction, but
                  > > after awhile...
                  > >
                  > > It sounds like the ultimate solution will be the Z-Axis backlash kit,
                  > > but $35 seems a bit much -you'd think Sherline would give us a break
                  > > when the kits' very existence is an admission that there was a design
                  > > weakness... they could've MADE some PR points (by disseminating them
                  > > at zero or minimal cost) instead of losing some... I'm sure the Taig
                  > > contingent are hooting over this one...
                  > >
                  > > The delrin nut doesn't *seem* like it should work, but your
                  > > experience seems to prove otherwise. It sounds like it was easy
                  > > enough to do, so I'd be willing to give this a try -my question is,
                  > > how did you cut the threads?
                • RichD
                  Hi Alan, The Sherline Z axis leadsrew is 3/8-20 LH. Taps are very hard to find and then you want H1 or less oversize. While waiting for quotes I made my own. I
                  Message 8 of 20 , Feb 20, 2004
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                    Hi Alan,
                    The Sherline Z axis leadsrew is 3/8-20 LH. Taps are very hard to find
                    and then you want H1 or less oversize. While waiting for quotes I made
                    my own.
                    I am getting ready to produce a run of nut carriers (steel saddle) and
                    nuts. I may sell a few. We'll see. I have a modified design in mind.
                    RichD

                    Alan Marconett KM6VV wrote:
                    >
                    > Hi Rich,
                    >
                    > Delrin saddle nut? Sounds interesting! Maybe you could sell a few.
                    > I'd be interested. I did find a source of LH taps and dies, but not in
                    > the 1/4-20 size. Probably in MSC.
                    >
                    > I received a PSME (Precision Scale Model Engineering) catalog a short
                    > time ago. Great stuff!
                    >
                    > http://www.psmeScale.com
                    >
                    > Alan KM6VV
                    >
                    > RichD wrote:
                    > >
                    > > BryceA,
                    > > I tried the slotted and squeezed nut trick. Lasted 1 day. Phooey!
                    > > When engraving wide areas for stand up letters, the background
                    > > needs to be left **flaaaaaat** to look good.
                    > > I tried several versions of antibacklash nut systems suggested by
                    > > searches of patents, etc. All became more trouble than they were
                    > > worth. Due to the Sherline screw being small and in a cramped space,
                    > > I decided to try the direct approach. No metal nut. Just a delrin
                    > > replacement held securely with a carrier shaped like the old saddle
                    > > nut. With many hours of use (with the old screw, BTW), the performance
                    > > has been great. No change in the apparent backlash (more likly slide
                    > > shift) of .001 and consistant to this day. The lube oil typicaly turned
                    > > brown quickly with the bronze nut with little use. Now the oil only shows
                    > > a slight darkening after many hours.
                    > > 3/8-20LH taps are available if you search long enough for many $$.
                    > > I made my own to a tight spec and the carrier design allows additional
                    > > squeeze to zero out any play easily.
                    > > My brass or bronze engraved plates are beauty now.
                    > > RichD
                  • Alan Marconett KM6VV
                    Hi Rich, Thanks for catching my mistake! They would be even HARDER to find!. Now you re talking about steel saddles? Alan KM6VV
                    Message 9 of 20 , Feb 20, 2004
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                      Hi Rich,

                      Thanks for catching my mistake! They would be even HARDER to find!.

                      Now you're talking about steel saddles?

                      Alan KM6VV

                      RichD wrote:
                      >
                      > Hi Alan,
                      > The Sherline Z axis leadsrew is 3/8-20 LH. Taps are very hard to find
                      > and then you want H1 or less oversize. While waiting for quotes I made
                      > my own.
                      > I am getting ready to produce a run of nut carriers (steel saddle) and
                      > nuts. I may sell a few. We'll see. I have a modified design in mind.
                      > RichD
                      >
                      > Alan Marconett KM6VV wrote:
                      > >
                      > > Hi Rich,
                      > >
                      > > Delrin saddle nut? Sounds interesting! Maybe you could sell a few.
                      > > I'd be interested. I did find a source of LH taps and dies, but not in
                      > > the 1/4-20 size. Probably in MSC.
                      > >
                      > > I received a PSME (Precision Scale Model Engineering) catalog a short
                      > > time ago. Great stuff!
                      > >
                      > > http://www.psmeScale.com
                      > >
                      > > Alan KM6VV
                      > >
                    • RichD
                      Alan, The nut is carried by a saddle similar in shape to the stock bronze unit. It could be made of aluminum, brass, steel, whatever. It does not touch the
                      Message 10 of 20 , Feb 20, 2004
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                        Alan,
                        The nut is carried by a saddle similar in shape to the stock bronze unit.
                        It could be made of aluminum, brass, steel, whatever. It does not touch the
                        leadscrew. Only holds the Delrin nut cartridge rididly and provides the
                        adjustment for fit and backlash as needed in future.
                        This can be used on a slightly worn screw, as I have been doing, with
                        perfect performance.
                        Swapping to the new nut is no diff than a new bronze nut.
                        There is a slight loss of Z movement on the prototype, but that will be
                        minimized on the new version. Im trying to preserve the original nut length.
                        RichD

                        Alan Marconett KM6VV wrote:
                        >
                        > Hi Rich,
                        >
                        > Thanks for catching my mistake! They would be even HARDER to find!.
                        >
                        > Now you're talking about steel saddles?
                        >
                        > Alan KM6VV
                        >
                        > RichD wrote:
                        > >
                        > > Hi Alan,
                        > > The Sherline Z axis leadsrew is 3/8-20 LH. Taps are very hard to find
                        > > and then you want H1 or less oversize. While waiting for quotes I made
                        > > my own.
                        > > I am getting ready to produce a run of nut carriers (steel saddle) and
                        > > nuts. I may sell a few. We'll see. I have a modified design in mind.
                        > > RichD
                      • Alan Marconett KM6VV
                        Hi Rich, OK, I see that now. It s now just a holder. Sounds very good. Alan KM6VV
                        Message 11 of 20 , Feb 20, 2004
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                          Hi Rich,

                          OK, I see that now. It's now just a holder. Sounds very good.

                          Alan KM6VV

                          RichD wrote:
                          >
                          > Alan,
                          > The nut is carried by a saddle similar in shape to the stock bronze unit.
                          > It could be made of aluminum, brass, steel, whatever. It does not touch the
                          > leadscrew. Only holds the Delrin nut cartridge rididly and provides the
                          > adjustment for fit and backlash as needed in future.
                          > This can be used on a slightly worn screw, as I have been doing, with
                          > perfect performance.
                          > Swapping to the new nut is no diff than a new bronze nut.
                          > There is a slight loss of Z movement on the prototype, but that will be
                          > minimized on the new version. Im trying to preserve the original nut length.
                          > RichD
                          >
                          > Alan Marconett KM6VV wrote:
                          > >
                          > > Hi Rich,
                          > >
                          > > Thanks for catching my mistake! They would be even HARDER to find!.
                          > >
                          > > Now you're talking about steel saddles?
                          > >
                          > > Alan KM6VV
                          > >
                          > > RichD wrote:
                          > > >
                          > > > Hi Alan,
                          > > > The Sherline Z axis leadsrew is 3/8-20 LH. Taps are very hard to find
                          > > > and then you want H1 or less oversize. While waiting for quotes I made
                          > > > my own.
                          > > > I am getting ready to produce a run of nut carriers (steel saddle) and
                          > > > nuts. I may sell a few. We'll see. I have a modified design in mind.
                          > > > RichD
                          >
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