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Z-axis Tramming

Discussion in 'CNC Mills/Routers' started by Techvette, Oct 17, 2018.

  1. Techvette

    Techvette Journeyman
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    Any advice on methods of tramming the Z axis? Mine is custom, but it's very similar to the Z on the minimill and the c-beam machine.
     
  2. GrayUK

    GrayUK Openbuilds Team Elder
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    Mine is custom as well, and I need to build in some sort of Tramming adjustment. :)
    Maybe slots or stand-off bolts? In all Axis directions of course. :banghead:
    I also need to consider building in a good vertical and horizontal straight edge to line up on. :nailbite:
     
  3. Kevon Ritter

    Kevon Ritter Master
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    Tram X and Y first, then put a good square on the table for Z... Just a guess though.
     
  4. Techvette

    Techvette Journeyman
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    Thanks, but my question is about adding an adjustment mechanism.
     
  5. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    If your build hasn't changed since the photos you posted back in April, you've got a weak spot where the column is attached to the base so tramming may have limited impact as flexure may be in control here. I would suggest cutting some extended side plates with slightly oversize holes. That will allow you the adjustment you seek and once tightened will provide a proper hold.


    Side plates.jpg

    If you need any additional shimming, I suggest aluminum foil tape.
     
  6. Techvette

    Techvette Journeyman
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    Hi Rick,

    Thanks for the response. My post wasn't very clear - this is on my router, not the mill. C-beam long axis, big wheels to support custom carriage plates, c-beam lead-screw Z. I'll post some pics later, but it's very similar to the OX design.
     
  7. JustinTime

    JustinTime Master
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    I think that tramming the z axis is just as important as tramming the router. A perfectly square router will still not cut properly if the z axis is not square.
     
  8. Techvette

    Techvette Journeyman
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    Okay:

    This IS about tramming the Z axis. On my 1000x1250 CNC router. It is NOT related to my minimill. Hopefully this clears up the confusion.

    My Z carriage plates appear to be a little bit off. I'm going to make another set, but I was looking for ideas for an adjustment mechanism that I can incorporate into the new design.
     

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    #8 Techvette, Oct 18, 2018
    Last edited: Oct 18, 2018
  9. CNCMD

    CNCMD Veteran
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    The most important part is a fixture or method to measure the variance in the tram.

    For X axis (Left/Right) adjustments, you can just adjust through the use of the mounting corner blocks, they have the ability to shift/tram the spindle left/right.
     
  10. Techvette

    Techvette Journeyman
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    Sure - I can adjust the spindle easily. But, if the Z axis is at an angle to the gantry, it's going to move more like an escalator (at an angle) than an elevator (vertical). Even if the spindle is square to the bed, plunges will be at an angle. (Hopefully that is clear). I need a way to adjust the entire axis, not just the spindle.
     
  11. CNCMD

    CNCMD Veteran
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    I would need to see more of your machine to advise. In what I am saying you can tram the spindle left/right.

    You are talking about what I called forward/backward, and that can usually be done by loosening the C Beam that the Z Axis is attached to, and rotating that.
     
    GrayUK likes this.
  12. Techvette

    Techvette Journeyman
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    I'm talking about clockwise/counterclockwise rotation when viewing from the front of the machine. (See terrible PhotoShop art attached.)

    The X axis (horizontal in the picture) is level and square relative to the Y rails, in both the X and Y directions. There may be some pitch (rotation about X axis) on the spindle / Z axis, but what I'm concerned about at the moment is roll (rotation about the Y axis, as indicated in the image.)

    I can rotate the spindle mount clock/counterclockwise relative the the Z axis c-beam by adjusting the black router mount. What I cannot do is rotate the Z axis relative to the X axis.

    If I had used eccentric spacers on both sides of the Z, I could probably adjust those to properly align it with the carriage. But, I did not. I think I'm just going to have to make another set of plates for the Z with some slots, but I don't see that being as rigid. I was hoping someone else had already solved this. :/

    tramming.JPG
     
    #12 Techvette, Oct 23, 2018
    Last edited: Oct 23, 2018
  13. CNCMD

    CNCMD Veteran
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    How is your spindle mounted on the Z Axis?
     
  14. Techvette

    Techvette Journeyman
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    Just the 90-degree blocks connection the OB router mount to t-nuts in the c-beam. I can adjust the router mount relative to the z-axis c-beam, but I can't adjust the c-beam relative to the X axis.
     
  15. Rick 2.0

    Rick 2.0 OpenBuilds Team
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    So why not just add eccentric spacers to the upper two non eccentric wheels on the z-axis mount?
     
  16. CNCMD

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    That is exactly what I was saying above. You can loosen those 90 degree blocks and rotate the spindle in the two directions that you have made with those arrows, the roll as you called it.
     
  17. Techvette

    Techvette Journeyman
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    Yes. But if the axis is rotated, then it moves down at an angle. Even if the spindle is pointed straight down - mine is - the Z is still rotated.As the stage moves down in Z, it will be offset in X based on the Z distance moved. (Basically, the Z is aligned with the hypotenuse of a triangle who's upper interior angle is determined by how effed up my carriage plate is.)

    Squaring the spindle isn't sufficient - the axis has to be squared, as well.

    Mark's suggestion about the eccentric spacers makes sense, BUT that also means I have to make another plate with larger holes for the eccentric spacers.

    If I'm making another plate or set, I was hoping for a solution with more adjustability, like a jack screw and a pivot plate between the Z and the X carriage. I can certainly build that, but surely there is a better option. ?
     

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