Crash during Calibration

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  • Crash during Calibration

    Hello All,

    I have three CMMs running various versions of PCDMIS
    On one of these, a B&S One 7.10.7 running PC-DMIS 2015, I just tried to write a new probe file and calibrate it.
    I've done this hundreds of times without any issue, so expected the same again.

    What I did not expect was for it to crash into the qualification sphere after the first few hits. I verified that the sphere information was correct (it looked like it thought the sphere shank was in the Y- rather than Y+, thus causing it to hit with the shank of the horizontal probe).
    I then attempted to run the tip calibration again. It took three hits regularly, with me holding the jog box (thankfully) before proceeding to bump the shaft of the probe arm into the qualification sphere. Yikes!

    So I backed everything off, inspected it all for damage (thankfully none apparent, it was moving slowly), and tried running a single tip calibration, rather than a sequence.

    It took two hits, then went screaming off at absolute maximum speed towards the granite table (I had the jog box in hand, with it limited to 10% speed, so this was rather startling) before pausing and out putting an E OT Z- error (thankfully before the probe hit the table).

    I checked my scales, all the teeth used on the arms / legs for the moving pieces, everything, and can see no defects at all.

    I have since attempted a manual calibration, which it flagged as out of tolerance (despite all the results and details looking good).

    any idea why it's acting up? advice on what to do? I'm worried if I try to run it through the sequence, it will destroy something with another violent, unscripted, movement. Do I need to get Hexagon out here to look at it?


  • #2
    did you check your drawers?! lol. We've all been there.
    I presume you are using Renishaw TP20 probe system?
    If so, you might have a bad probe module. more on that later though.
    First thing you want to do is checkbox the "reset values to theoretical" within the calibration menu (bottom right near the calibrate button).
    re-execute your calibration man/dcc and make sure you check "No, cal sphere has not moved".
    take the first hit on the probe then let it do its thing. watch it CLOSELY. if you see it false-trigger, air hit, or trigger late, suspect your TP20 probe module being worn out.

    One last check you can do, prior to looking at ordering a new module, is to clean the interface between the magnets on the TP20 module and body with the renishaw cleaning goop (white silly-putty looking stuff that comes with your probe body packaging).


    • #3
      The reset values to theoretical has solve this issue for me many times. I used to have to rebuild the probe file until I found this sweet checkbox.


      • #4
        That checkbox did indeed fix the issue.
        The drawers check was indeed mandatory after an action like that.

        Why though?

        Also, you were 100% correct about the TP20; a true Guru, and thank you for your response.
        Last edited by Samex1; 10-01-2019, 05:31 PM. Reason: Forgot to say thanks


        • louisd
          louisd commented
          Editing a comment
          Your last calibration included a false hit at some point. The false hit made the location and size of the both the cal sphere, and the stylus tip inaccurate.
          Calibration protocol is find the sphere/then measure sphere for calibration (hence Man/Man, Man/DCC, and DCC/DCC options). If you had a false hit during the latter of the two operations, it uses those measured values for the next calibration as theoretical, relative to how the last calibration results outcome. It tries to match the last actual calibration.

          Clicking 'reset to theoretical' checkbox affirms that every time you calibrate, it dumps the measured data for the last calibration, and considers the cal sphere and stylus as they are theoretically defined by their respective designs within the PRB file, cal sphere definition, & master probe cal sphere origin.

        • louisd
          louisd commented
          Editing a comment
          Hold on was your "Why though?" question re: why check your drawers/undies?
          because I know a pucker moment when i read one! Lol!

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