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IndustryArena Forum > MetalWorking Machines > Tormach Personal CNC Mill > .007" egg-shaped holes while circle-milling
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  1. #1
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    .007" egg-shaped holes while circle-milling

    I'm getting about .007" egg-shaped holes while trying to circle mill.
    It appears to be happening in the X Axis.
    Does this sound like a backlash issue, and what needs adjusting?

  2. #2
    Community Moderator Jim Dawson's Avatar
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    Re: .007" egg-shaped holes while circle-milling

    It does sound like a backlash issue. The normal causes are: 1) loose motor coupling, 2) thrust bearing adjustment, 3) worn ball nut/screw.
    Jim Dawson
    Sandy, Oregon, USA

  3. #3
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    Re: .007" egg-shaped holes while circle-milling

    0.007" that's like 0.17 ish in mm. That's a lot for it to be a backlash problem alone.
    Sounds like something is loose or needs a lot of adjustment.

  4. #4
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    Re: .007" egg-shaped holes while circle-milling

    Which axis has the correct size for the diameter ? .... that is the axis that doesn't have a problem.
    Are there flats where the axis changes direction ?

    As Daz says, check all items that are on that axis, I've seen bodgy work where some builder used pointed set screws instead of keys on drive mechanisms.

  5. #5
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    Re: .007" egg-shaped holes while circle-milling

    Y axis is correct, X axis is over-sized .007".
    I'm guessing it's the Thrust-Bearings.

  6. #6

    Re: .007" egg-shaped holes while circle-milling

    Not on a Tormach, but the last time I had an issue like this the ballnut was loose in the carriage. Easy fix.

  7. #7
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    Quote Originally Posted by RussMachine View Post
    I'm getting about .007" egg-shaped holes while trying to circle mill.
    It appears to be happening in the X Axis.
    Does this sound like a backlash issue, and what needs adjusting?
    Check the play between the ball nut halves in the X axis. They have a spacer between them to preload them. Put in enough shim to take out the slop.

  8. #8
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    Re: .007" egg-shaped holes while circle-milling

    Quote Originally Posted by bfnt77 View Post
    Check the play between the ball nut halves in the X axis. They have a spacer between them to preload them. Put in enough shim to take out the slop.
    I did this on my Y axis ball nut,it worked well. I am thinking offset keys that hold the two halves together, then a spacer shim wouldnt be needed, I just have to get up the "want to" to get it done.The parts I make arent that critical.
    mike sr

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