PC-DMIS reading data from Renishaw MH8 wrist wrong for all angles but A = 0, B = 0

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  • PC-DMIS reading data from Renishaw MH8 wrist wrong for all angles but A = 0, B = 0

    I have run across a problem reading points with PC-DMIS with a Starrett CMM equiped with a Renishaw MH9 wrist. Currently using a legacy version of PC-DMIS (the 4.0 version, I believe) on an old PC using Windows XP. I am currently trying to get the CMM to read points with the probe not positioned on the perfect vertical; i.e. at all other angles except A = 0, B = 0.

    When I calibrated the Renishaw MH9 wrist at the A = 0, B = 0 position, the software reads the points in the correct position. But when I use any of the other angles I calibrated it for (B = -90, 0, 90, or 180 when A = 45 or 90) it will read it in at the WRONG location. I have noticed that when I rotate between the four different B angles while the A angle is set to 45 or 90 while moving no other part of the CMM, the graphic display would the probe rotating AROUND THE PROBE TIP rather than around the center of the MH9's hemisphere (the actual center of rotation). In addition, among these eight angles, the reading from the tip will always be at the same offset from the position of the tip as shown on the graphics display (which is already wrong): around -1.7 off in both the Y and Z coordinates, relative to the location of the tip ON THE GRAPHICS DISPLAY. So it appears that somehow there is a common error shared between all of the angled probe positions, added on top of an error where it appears to be confusing the mount point within the MH8 for the probe tip.

    How do I resolve this issue and get the CMM to work properly?
    Last edited by Prince Rilian; 02-25-2021, 06:12 AM. Reason: Misspelled "Starrett"

  • #2
    If you can revert back to 3.7 MR2 do so. My experience with 4.0, 4.1, and 4.3 was frequent Blue Screens Of Death. What you are describing I've also seen in the graphics window but it didn't affect the calibration of the tips. Set up your calibration sphere on the table. MEASURE it with rotation 0,0 (don't calibrate the tip. Just measure it). Set X, Y, and Z datums there. Rotate the the MH9 to 90,0 and measure it again. Report XYZ. If it doesn't report within couple of microns of zero (X,Y and Z), you've got a calibration problem. Check a couple of other rotations. I do this when ever I define a custom stylus configuration that isn't in the table of available extensions, adapters and styli.

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