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Backlash error compensation

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  • Backlash error compensation

    A few weeks ago there was a post inquiring about backlash compensation with a DRO. The general consensus was that it didn't make sense, with a DRO backlash wasn't an issue.

    I was just poking around the Acu-Rite website and looked at the manual for their 200S unit.
    It does indeed have a provision for backlash compensation, for rotary encoders. That is, if the input is coming from a rotary encoder on the leadscrew, then backlash would be an issue and the 200S can compensate for it.

    But, it is indeed not applicable if one has the "normal" linear scales.
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  • #2
    Thanks for the clarification. In that earlier thread a couple of us went on to tell the original poster that the documentation must have really been referencing "tool offsets". Perhaps we were crazy. My experience with DRO's is mostly with more recent stuff and I had never had any experience with one with a *rotary* encoder. Perhaps they are old news, or just not very least not very practical as even with the ability to account for runout, you would still have to be tweaking that setting all the time as the feed nuts wear.

    You learn something new every day...maybe even something old.

    Paul Carpenter
    Mapleton, IL


    • #3
      Back in the 80's we got a new CNC machining center. Poking around the documentation and talking to the setup guy from the factory, I found they kept a leadscrew compensation table in the computer. That is, the leadscrew wasn't as perfect as the accuracy they wanted, so they measured deviation from position along the length of the travel, saved the errors, and calculated the move required for accurate positioning. Not backlash compensation, but same basic idea. It meant that the machine could be re-tested from time to time, and brought back up to snuff. Makes you wonder how sloppy the machine could mechanically get and still be compensated for before it finally fell in the ditch.
      "People will occasionally stumble over the truth, but most of the time they will pick themselves up and carry on" : Winston Churchill