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Thread: Itech 6090 ground up rebuild and dial-in

  1. #13
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    Default Re: Itech 6090 ground up rebuild and dial-in

    Now to re-install the Y axis lead screw. The end that is driven by the stepper motor looks like it has been free-hand ground with a bench, or worse, angle grinder. We are talking 0.5mm off round! I can only imagine they didn't have the right drive adaptor so fudged it into size. This obviously caused a fair bit of whip around.

    Not owning a suitable lathe, I improvised a means of truing it. Lead screw in V-blocks clamped to the bed of the machine; Dremel grinder bit in the spindle, worked it back and forth and around until it resembled something round and true.

    Itech 6090 ground up rebuild and dial-in-img_2556-jpg

    Not beautiful, but workable ...

    Itech 6090 ground up rebuild and dial-in-img_2554-jpg

    .. with a suitable bit of, you guessed it, shim!

    Itech 6090 ground up rebuild and dial-in-img_2555-jpg

    Last edited by loska; 12-29-2018 at 07:22 AM.


  2. #14
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    Default Re: Itech 6090 ground up rebuild and dial-in

    Finally, to re-install the Y axis lead screw. Using the machine level, I levelled the screw along its length:

    Itech 6090 ground up rebuild and dial-in-img_2560-jpg

    Shimming under the ball nut block, and re-drilling the mount points for the stepper motor and the idler bearing at the other end. Running the axis back and forward along its length allowed the sideways alignment to be checked.

    Itech 6090 ground up rebuild and dial-in-img_2561-jpg



  3. #15
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    Default Re: Itech 6090 ground up rebuild and dial-in

    Tray back on, followed by the T-slot bed, all bedded in Sikaflex to dampen vibration and seal the screws. The tray is designed to accommodate flood cooling which I have never actually used (I use mist cooling for cutting soft metals) but I may as well seal it in case.

    Prior to this I bogged up some depressed parts of the frame where the casting was under-filled, using polyester filler, then filed it back to level.

    Itech 6090 ground up rebuild and dial-in-img_2570-jpg

    All back together, time to plane the foam bed liner back to true flat!

    Itech 6090 ground up rebuild and dial-in-img_2571-jpg



  4. #16
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    Default Re: Itech 6090 ground up rebuild and dial-in

    Conclusion:

    After all, the precision achieved was:
    < 0.05mm along the Y axis
    < 0.025mm along the X axis
    < 0.02mm along the Z axis
    < 0.02mm in 100mm X-Y squareness
    < 0.02mm in 50mm X-Z squareness
    < 0.02mm in 50mm Y-Z squareness
    < 0.03mm in 90mm tram

    On reflection, the biggest improvement was probably from Z axis squareness (which was a long way out) combined with fixing the tram. This means much smoother finish without any banding, more accurately sized parts and probably less stress on tools. X/Y squareness is also important for accurate parts.

    As for flatness / straightness of the X and Y axes, given that material is clamped to the bed and probably has some flex (and the bed is planed parallel with the axes) arguably this would have less impact on overall performance. But it is nice to know everything is set up right!

    The machine is running really nicely now; for example doing very fine PCB engraving work with < 0.01mm deviation in cut depth.

    Even though the build quality out of the factory leaves a little to be desired, the materials are good enough (and the important stuff like rails and ball screws are excellent) to make a great machine for a small price.



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Itech 6090 ground up rebuild and dial-in

Itech 6090 ground up rebuild and dial-in