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SP25M calibration question

Morning Fellas,

I have a calibration issue I'm hoping someone can help me with. The company I work for has an old Sheffield Discovery III in an automated cell. Fixed on the granite is a 3/4" cal. sphere that has been in the same spot for years. SP25M probe with a star stylus. Now, the star, best I can tell, is a Renishaw A-5000-7629 except the Z- tip that fixes the assembly to the stylus holder has been replaced with the center of a star body and apparently the probe file has at some point been modified somehow to reflect this change, essentially leaving me with a 4 tip star that spans 18mm's center to center.

My problem is the hard drive died on the PC and was replaced and PCDMIS was re-installed and as many files as could be scrounged up were, and were placed in the appropriate directories as best we can tell but apparently something was lost because now I am being forced to do a full calibration of this star. Best I can tell there is some sort of predetermined scan sequence that is performed during this full calibrationof the probe.
Since the span of the star and the diameter of the cal sphere are almost identical the Y+ tip is crashing into the sphere during the scan sequence of the X+ tip. I feel a simple modification of the start and end angles would resolve this BUT they are grayed out.

Is there any way to "unlock" the start and end angles so they can be modified or a way to do a standard point calibration without the scan sequence. I feel there has to be some way because apparently at some point in the past the "full" calibration was performed because up until the disc died I was able to do partial calibrations which will allow adjustment of the start and end angles.

I hope this makes some sort of sense to someone that might have the answer I seek...
Thanks-in Advance

P.S.-- the probe interface is a Renishaw PI200 and the head is a PH6M, if that info is needed...
  • Hopefully someone has a better answer for you, but I don't know of a way to select the user defined calibration mode for the SP25 to change the start angle. It is a pain because, as you have found, short star probe tips can interfere when scanning along the equator. I have also run into problems with 0.3mm styli because they shank out on a a large qualification sphere like that.

    My best suggestion is to use a smaller qualification sphere. I'm interested to hear if someone has a better option.
  • Going to laser-beam on a couple things:

    Now, the star, best I can tell, is a Renishaw A-5000-7629 except the Z- tip that fixes the assembly to the stylus holder has been replaced with the center of a star body and apparently the probe file has at some point been modified somehow to reflect this change, essentially leaving me with a 4 tip star that spans 18mm's center to center.

    the Y+ tip is crashing into the sphere during the scan sequence of the X+ tip. I feel a simple modification of the start and end angles would resolve this BUT they are grayed out.


    The Grayed out section of the 'measure probe' window... Did you forget to toggle from "Default Mode" to "User Defined"? This should be your first check.

    -In your effort to recover the drive, were you successful in recovery of the probe file(s) (PROBE_NAME.PRB and PROBE_NAME.Results)?
    -Did you by chance grab the PROBE.DAT file from the old drive? If the PROBE.DAT file was modified from it's original form as you are suggesting, that could be the root of your problem. Try to recover PROBE.DAT from old drive if you can. I believe the grayed out start/end angles is the result of your probe definition being related to that star probe definition.
    Restoring the old probe file and probe.dat will likely be the easiest path to resolve.

    -If you can't restore the files, you might want to consider manually building your probe using the "EXTEN5WAY" knuckle. That way you can modify start/end angles.
  • "User Defined" is ticked. Actually the start and end angles that are grayed out are 30* and 90* but the calibration routine is obviously not following these because it's most definitely starting at 0*.

    As for the drive, nothing from it was accessible. It died a hard death..LOL. I had previously copied the .PRB file for use at my offline seat but have yet to find any results or data files. Mostly only programs were backed up and not the PCDMIS folders themselves. Lesson learned..!!!

    May just go to a smaller cal sphere.
  • I'd contact Hexagon and put a ticket in. There might be some backend setting that needs to be switched, or a user access issue.
  • I see that the registry has a setting named ProbeQualStartAngle. I have never messed with it, but maybe changing that can force the calibration to use a different start angle?
  • I have a question... When to perform full tip calibration and when only partial? We changed our Renishaw head and the question is: is a partial tip calibration OK or not?
  • Search the forum for "Master Probe" this will answer your question