Need Help! Z axis is not staying steady


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Thread: Z axis is not staying steady

  1. #1
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    Default Z axis is not staying steady

    Running some repetitive grooves with sharp corners as shown in image of intended results. By the end of the cuts, I have lost about 0.1" Z height. The actual lost height is about 0.95", give or take 0.01.
    There are 4,800 lines of code in this, if it matters. I reran the code generator (V-Carve 7.0) and sequenced the vectors from left to right, bottom to top, with a few slips where I missed a couple. Anyhow, it is clear that the leftmost part is fine, and the Z drops by the end. Why?
    I replaced the Z-axis stepper this morning with a double stack unit, to ensure I had the power to lift the router and staging. Moves smoothly. It did before though.
    Larken recently sent me a new controller chip saying the old one had been found to have a bug. Maybe this is buggy too? It is too repeatable!
    I would consider buying a new controller card. Looks like one can be had for $35.00 (ZTW 5 Axis Mach3 Control Break Out Board). You can pay more, but what is the point?

    Rocko

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    Attached Thumbnails Attached Thumbnails Z axis is not staying steady-intended-result2-jpg   Z axis is not staying steady-result2-jpg  


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    Quote Originally Posted by rocko View Post
    Running some repetitive grooves with sharp corners as shown in image of intended results. By the end of the cuts, I have lost about 0.1" Z height. The actual lost height is about 0.95", give or take 0.01.
    There are 4,800 lines of code in this, if it matters. I reran the code generator (V-Carve 7.0) and sequenced the vectors from left to right, bottom to top, with a few slips where I missed a couple. Anyhow, it is clear that the leftmost part is fine, and the Z drops by the end. Why?
    I replaced the Z-axis stepper this morning with a double stack unit, to ensure I had the power to lift the router and staging. Moves smoothly. It did before though.
    Larken recently sent me a new controller chip saying the old one had been found to have a bug. Maybe this is buggy too? It is too repeatable!
    I would consider buying a new controller card. Looks like one can be had for $35.00 (ZTW 5 Axis Mach3 Control Break Out Board). You can pay more, but what is the point?

    Rocko
    Something definetly is out of wack. Could your z axis coupling be slipping? It happened to me once and the router would start cutting deeper and deeper. also, I can't figure why the bottom of the letters are flat if you are using a V carve tool, unless the tool is flat bottomed. Make sure your tool selection matches your actual tool. Could you have some "open" vectors, although the preview looks good.
    Good luck, these can be hard to get a handle on.

    Mike



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    Friday, I took apart the Z axis. It was easy, really. Only required taking the tool holder off, then 2 screws for the traveler where it attaches to the Z stage. After that, the Z stage comes off from the bottom down the rails. I then took off the Z stepper and took out the Z screw and nut holder (traveler). The nut is nylon and nests snugly inside the Z traveler. I cleaned the screw and nut, using acetone. There was lots of black gunk on it, but it seems really smooth and tight still. I reassembled it all and ran some cuts. Still got the same problem. I could change out the Z linear bearings, in case they are getting a set from all the up and down in a small range, but it still seems like a non-mechanical problem. I have the old chip Larken told me to change out, and will put that back in and test run again.
    Hoping,
    Rocko



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Z axis is not staying steady
Z axis is not staying steady