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Lead screw whip, is it dangerous?

Discussion in 'CNC Mills/Routers' started by Andreas Bockert, Nov 11, 2017.

  1. Andreas Bockert

    Andreas Bockert Journeyman
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    Hi

    I'm working on a Sphinx style CNC machine with a 1000x1000 footprint.

    Those of you who have made a similar machine, do you experience a lot of lead screw whipping? I'm running it at about 160ipm (4000 mm/m) and the screws are whipping a lot.

    Is whipping lead screws dangerous? I.e. can I break the screws? Or will it simply effect accuracy.

    I'm considering converting to a design with screws under tension but that would mean I have to disassemble the entire machine...
     
  2. Joe Santarsiero

    Joe Santarsiero OB addict
    Staff Member Moderator Builder

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    I wouldn't say it's dangerous if everything is secured. It's certainly not desirable, but a little whip from time to time isn't a big issue. If you have a screw that always looks like a jump rope then you should probably consider upgrading or lube it and try to pull it in tension first like you mentioned. Other than rpm, moving a heavy load, lack of lube, and/or taking too deep a cut can induce some whip at various lengths too.
     
  3. Flash22

    Flash22 Veteran
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    I run the 1m actuator, The anti backlash nut does reduce the whip, with my rebuild I am using a standard nut and the anti backlash nut, hopefully that will do the trick

    I did look at going up to a 10 or 12mm leadscrew but I cant justify the cost atm
     
  4. Scotty Orr

    Scotty Orr Veteran
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    I ran into this with my 1 meter lead screw. You can eliminate (most of) it by relieving the compression on the lead screw. Do this by loosening the lock collar at the end opposite the stepper, then just hold it against the end cap just enough to keep the bearing in place (don't crack the end cap screws while doing this - that's how the compression got there in the first place). Find a new position on the lead screw (rotate collar 90 degrees for example) to retighten the grub screw.

    Note: the compression was introduced in order to "force" the bearing and collar on the stepper end into place. Once the stepper is installed, that will hold that end in place. Caveat: the flexible coupler needs to not be compressed (it can act like a spring), so you might need to make an adjustment there as well.
     
  5. Andreas Bockert

    Andreas Bockert Journeyman
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    @Scotty Orr I released the compression on one of the lead screws and it reduced the whip significantly. At least to the point where I don’t fear that it will self-destruct.
     

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