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Unable to calibrate 2mm ball probe

mushking
I'm fairly new to running a CMM and I'm having an issue that I'm not sure how to fix. Every time I try to calibrate the 2mm ball probe that I typically use (and have used almost daily for the past couple months), it just refuses to calibrate automatically.

When I say that the sphere I calibrate to hasn't moved, the probe goes off to one side and can't seem to find the sphere. When I say that it has moved, I take my hit on the sphere and the probe either stops short of the sphere or crashes into it. I can get it to calibrate manually, but that isn't really feasible in the long term.

The thing that is especially confusing to me is that using other probes, I don't have any issues calibrating. For some reason, it's just the 2mm ball.

Also, I'm using PC-DMIS version 3.125 on a Brown & Sharpe Xcel 9.12.9.

Any help would be greatly appreciated!
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  • Things not mentioned include:

    1) Check to see how far THEO and MEAS is in the results file for that probe... if calibration error is encountered and the difference is big, check the 'reset to theo before calibration' box and it will likely calibrate
    2) That old probe file that worked, this does not mean your probe file was corrupt at all, it might have just had the above issue and the old file had meas values closer to theo and it worked.
    3) For your master probe, THEO and MEAS values must always be exactly the same for x,y,z values... if there is any difference at all it is error. A small difference in diameter offset is expected.
    4) If theo and measured values are the issue it can also work to increase prehits in the measure window... but better to reset to theo.
    5) It is best to use a dedicated master probe, never measure with it only set the ball. If you do measure with your master tip and want to re-calibrate it... tell pcdmis the ball moved even if you did not move the ball and calibrate only that tip not along with other tips/angles, then you must recal everything to be certain. If the master tip gets bent in use then only doing this will correct it and maintain other tip correlations to it.
    6) If the machine was homed after the last time the ball was moved, consider it invalid and tell pcdmis the ball has moved. You will always need to use the master to set sphere location after machine was homed, every time you home it the ball location is lost so to speak

    NEVER CALIBRATE THE MASTER TIP WHILE SAYING THE BALL DID NOT MOVE. Never recal the master tip and say the ball did not move, you need to lie to pcdmis and say the ball moved for the master tip even if you did not move it
Reply
  • Things not mentioned include:

    1) Check to see how far THEO and MEAS is in the results file for that probe... if calibration error is encountered and the difference is big, check the 'reset to theo before calibration' box and it will likely calibrate
    2) That old probe file that worked, this does not mean your probe file was corrupt at all, it might have just had the above issue and the old file had meas values closer to theo and it worked.
    3) For your master probe, THEO and MEAS values must always be exactly the same for x,y,z values... if there is any difference at all it is error. A small difference in diameter offset is expected.
    4) If theo and measured values are the issue it can also work to increase prehits in the measure window... but better to reset to theo.
    5) It is best to use a dedicated master probe, never measure with it only set the ball. If you do measure with your master tip and want to re-calibrate it... tell pcdmis the ball moved even if you did not move the ball and calibrate only that tip not along with other tips/angles, then you must recal everything to be certain. If the master tip gets bent in use then only doing this will correct it and maintain other tip correlations to it.
    6) If the machine was homed after the last time the ball was moved, consider it invalid and tell pcdmis the ball has moved. You will always need to use the master to set sphere location after machine was homed, every time you home it the ball location is lost so to speak

    NEVER CALIBRATE THE MASTER TIP WHILE SAYING THE BALL DID NOT MOVE. Never recal the master tip and say the ball did not move, you need to lie to pcdmis and say the ball moved for the master tip even if you did not move it
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