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Re: [SherlineCNC] Ball screws [Delrin Nuts]

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  • Rich Dean
    Scott, Delrin is a brand name for acetal plastic resin engineering plastic. Machines almost like 360 brass AND an almost ideal bearing material. Delrin-AF has
    Message 1 of 2 , Aug 23, 2006
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      Scott,
      Delrin is a brand name for acetal plastic resin engineering plastic.
      Machines almost like 360 brass AND an almost ideal bearing material.
      Delrin-AF has PTFE (Teflon) added making it even more useful.
      Machineablility is the same.
      See ENCO for Delrin on sale and McMaster-Carr for that and Delrin-AF.
      5/8" dia rod stock is best as the Z axis nut needs it.
      Direct replacement X/Y nuts can be made, but the better way is to do it
      a little different to secure the nuts and make adjustments easier.
      Words & music please:
      This isn't an anti-backlash nut in the true sense of the word, but
      it works and adjustments and wear will be few and far between.
      -Remove the brass nuts and setscrews from the saddle.
      -Using a well trammed mill, locate over the FRONT Y axis hole and drill
      11/32" dia to 1.250 depth. Tap 3/8-32 x .50 deep.
      This hole is VERY close to the top surface. Be careful.
      Use cutting fluid on this aluminum extrusion.
      -Do exactly the same for the X axis from the RIGHT side.
      -Make 2 brass or steel compression sleeves from 3/8 hex stock.
      OAL 5/8" and lathe threaded 3/8-32 x 17/32 length. You want a close
      fitting thread that stays snug on its own.
      A short hex head remains.
      Drill Letter F thru. Thread and hole MUST be concentric.
      -From Delrin stock--drill #8 x 1" deep and tap 1/4-20 (1 right-1 left).
      Machine to .343/.344 for a close fit in the 11/32 holes and
      cut off to .750" length. Use new SHARP taps on a guide.
      -Try on the leadscrews for fit and retap as needed for a fit where you
      can spin the nut with the fingers, but still snug.
      -Shove the new nuts into the holes, screw in the compression sleeves.
      The leadscrews should rotate easily with the sleeve just barely snug on
      the nut. Any further compression should lock it up easily. This is the
      lash adjustment.
      -Lastly, drill/tap new 10-32 setscrew holes 7/8 back from the saddle
      front face on the bottom for Y and from the left side for X (deep).
      Insert a setscrew and bed it hard into the Delrin nut several times
      then back off until the leadscrew just turns freely.
      -Lubricate with Vactra #2 way oil. You're good to go.

      I want to hear from the brave souls that do this to their poor little
      mills. It's well worth the effort.
      RichD, Atlanta


      Scott Meyer wrote:
      > Rich:
      > I need more information. Not familiar with Delrin-AF.
      > I assume the nut replaces the nut that Sherline provides with the mill?
      > Just tap a piece of DelrinAF 1/4-20 and replace the Sherline nut?
      > Guess I don't understand how that would help. Does it reduce or virtually
      > eliminate backlash for CNC?
      > I did find some DelrinAF on the web in rod form, not very expensive.
      > Scott Meyer

      > -----Original Message-----
      > From: SherlineCNC@yahoogroups.com [mailto:SherlineCNC@yahoogroups.com] On
      > Behalf Of Rich Dean
      > Sent: Wednesday, August 23, 2006 2:44 PM
      > To: SherlineCNC@yahoogroups.com
      > Subject: Re: [SherlineCNC] Ball screws
      >
      > Scott,
      > you'll pay more for mini ballscrews than the mill cost.
      > Try Delrin-AF nuts.
      > I have them on X, Y and Z. Not hard to do.
      > Dirt cheep.
      > RichD
      >
    • Ron Ginger
      Another choice is to make Moglice nuts. Moglice is an epoxy filled with moly-disulfide- very slippery stuff. You cast a nut around your screw with very little
      Message 2 of 2 , Aug 24, 2006
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        Another choice is to make Moglice nuts. Moglice is an epoxy filled with
        moly-disulfide- very slippery stuff. You cast a nut around your screw
        with very little clearance- .0001" per coat of parting wax.

        I have described this on my web site at
        http://plsntcov.8m.com/sherline.htm It has the advantage that it does
        not require any machining to your mill, but it does require mixing epoxy
        and dealing with 'gooey- sticky' stuff.

        I have used the real Moglice ( http://www.moglice.com ) product- a bit
        expensive but very good, and I have done the same thing by mixing
        graphite powder into a good brand of marine epoxy. I did both a
        Sherrline and a Prizi, one with Moglice and one with grapite- and now I
        have forgotten which machine used which product. They both seem to work
        very well.

        ron ginger
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