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Lead Screw Lapping — Parallax Forums

Lead Screw Lapping

idbruceidbruce Posts: 6,197
edited 2012-08-12 05:35 in Robotics
Hello Everyone

I was wondering if anyone has some experience with lead screw lapping. I really do not want to create a special jig for this purpose, so I am looking for ideas. I was thinking of a dedicated lead nut for this purpose, as demonstrated in this video.

Bruce

Comments

  • $WMc%$WMc% Posts: 1,884
    edited 2012-08-09 20:43
    The whole purpose of lapping is to fine tune the nut to the shaft.
    '
    This has to be done as an assy.
    '
    Its matching the nut to the shaft
    '
    So...NO
    '
    The screw and nut should be one assy. after honing.....They should be together for life after the honeing/lapping
  • idbruceidbruce Posts: 6,197
    edited 2012-08-10 03:03
    Walt

    I do not completely believe that theory. If that is the case, then all lead nuts should be created with a tap that was created from the threads of the lead screw, and then the lead screw and nut should be lapped or honed together as an assembly.

    However I do believe that once a nut is used with a particular lead screw, it should then become an inseparable set.

    Bruce
  • Paul K.Paul K. Posts: 150
    edited 2012-08-12 02:55
    In the video they are lapping the screw to a nut that they have made which they don't show you. What he calls the "nut" in the video is actually lapping the screw. It stays on the machine as every screw put on there is lapped to its dimensions.

    The screws are oversized, nuts undersized when made. Lapping brings them to the tight tolerance that tapping/threading can't.

    Its actually better to buy a precision ball nut and screw setup. Its not lapped but precision ground. Trying to build a jig wont help, you'll still have slop. You don't make something like this with a jig.
  • idbruceidbruce Posts: 6,197
    edited 2012-08-12 05:35
    @Paul

    I realize that there are many options where lead screws and nuts are concerned, because I have been studying them and pricing them for several years. Ball screws are definitely out of the equation in this particular instance, because I am attempting to build a very low cost machine.

    Considering that I do not work for Tiag or have taken a tour of their plant, I cannot actually agree or disagree with what you said, but in my particular instance, I just want to remove microscopic burrs to create a smoother running lead screw. In any type of screw driven drive, there will always be backlash (slop), otherwise the screw would be unable to turn due to friction. Instead of having out-of-the-box accuracy that can be achieved with ball screws, my goal is to make a smooth running lead screw and then make the backlash minimal through adjustment. In my opinion, the accuracy of the pitch of the screw will ultimately determine the precision of a drive, not by the amount of backlash that can be minimized through adjustment.

    Bruce
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