new build z axis not flat and screw to long

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This topic contains 2 replies, has 3 voices, and was last updated by  Ryan 1 week, 2 days ago.

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  • #109587

    Mark B
    Participant

    It’s been a long time since a bought my MPCNC here (Nov?). Finally have had some summer vacation time where the kids schedule and mine lined up to do the build (or at least start). I have two questions:

    I loosened and tightened several times the z-axis assembly. The z rails are not entirely flat. I’m checking them on the edge of a glass table as shown in the instructions. I’m wondering how accurate this needs to be. putting three sheets of notebook paper under the end of one rail removes the rocking. My cheap, digital, Harbor Freight calipers show equal gaps between the mounts. My best guess is that the holes are far enough off (handheld drill) that when I push down to make them flat it deforms the metal and springs back slightly even after tightening. Do I need to disassemble and make the rails again?

    Second issue – my lead screw is too long. Not sure if I calculated wrong now, or when ordering, or just forgot what I did. If I need to go back and redo the z-axis, I guess I might make it longer. If not, I’m thinking I’ll just cut the lead screw to the bottom of the z-rails (hack saw/angle grinder). Anything I should be cautious of there? Cut the top or bottom? Round the end slightly? Or should I go back to the calculations and remake the assembly?

    Thanks

     

    #109592

    Barry
    Participant

    Cut the end that goes into the coupler.  Rounding the end or at least taking off the burr is a good idea as well.

    1 user thanked author for this post.
    #109674

    Ryan
    Keymaster

    The Z rails can almost be twisted by hand to get them perfect (unless you actually have bent rails). Get is as close as you can before you get too irritated with it and then call it good!

    1 user thanked author for this post.
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