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Hexagon wont help me, so now i ask you for help

pcdmisstudent
Hi guys & girls & friends & family.

I have a bigboy problem with my CMM, or well, rather a problem with the relationship between our 6 tips in our rack.
I've called hexagon support and they couldnt bring any help (also the good guy at support wasnt available today)
So now i want my friends (you guys) to help me! Cos i know some of you have the best knowledge n experience of this stuff!!
And... i cant wait for the other hexagon guy to help me, cos we have a big measuring error now..

So...I have two programs for checking our tips: a short & a long one.

Short one: I place a calibrated ring on our fixture plate. I measure & align to it with the master tip (with the rings top plane as Primary/Z-orgin and a circle with XY orgin).
Then it swaps to A0B0 for the next tip in our rack and measures the ring with a circle to evaluate Diameter, XY, Z(using a vector point on the face of ring) and also roundness to check for wear/dirt. I repeat this for all the other tips in the rack.
I get a big deviation in XY between the tips (0.05mm in X, 0.05mm in Y) and <0.01mm in Z. (I'll post the PDF report named "ring check")

The long check program uses the calibration sphere, where i use the same principle. Bolt the sphere to the fixture plate, Measure the sphere with mastertip A0B0 and align to it. Switch to another angle for the same tip and evaluate diameter/XYZ. Then swap to the next tip in the rack which measures the sphere and evaluates diameter/XYZ.
And I get the same big deviation in XY as in the ring check program. (Ive posted PDF report called "sphere check")

I have used these check programs for a long time and they've worked good so far.

So now....How do i get all the tips to show 0 in deviation (or at least <0.005mm per axis)?

Ive tried so far:

1. I ran our whole autocalibration program for all tips (which i also havent made any changes to) with good results, low STD, normal diameter deviation and the master XYZ is "perfect".
( ill post PDF report called "Autocalibration").

2. "Manually" calibrated the tips for the check program, i.e. I go into probe utlities for the first tip in our rack & calibrate A0B0 (master tip) saying "yes , sphere has moved". Then I go into the probe dialog for the 2nd tip in the rack and only calibrate A0B0 saying "no sphere hasnt moved". Ive done this for all tips in the check program with good results in the calibration results. But still bad results in the check program.

3. Ive reseted all tips to nominal and ran the autocalibration program again with good cal. results (But bad "check" results).

4. Ive inspected all tips for damage & cleaned them from dirt (also cleaned sphere/ring)

5. Played around with the calibration parameters for the tips, number of points & levels. And i acctually got sucess from this for the 2nd tip (Which you can see in the reports).
But i dont know why it worked, because it change anything for the other tips.

The only other thing i can think of that i havent tried is deleting the all probe files & build up new ones (If they became corrupt for some reason).

Anyone else has any ideas?
Just ask if u want more info, i can post code of the programs and show calibration settings etc...





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  • Ok guys. I deleted the probe files and rebuilt them.
    I thoroughly cleaned all scales, tips, sphere & modules.
    Created an short autocalibration pogram with only a couple of angles and with cnc+cnc, 13 hits, 3 levels for each tip.

    After the calibration i ran the sphere check program, and they were all ALMOST good., some of my troublesome tips still gets halfbad deviation in XY (my disc & 0.5mm tip).
    Seems like i solved.....no........WE solved it
    I upload the results from the sphere check.
    Attached Files
Reply




  • Ok guys. I deleted the probe files and rebuilt them.
    I thoroughly cleaned all scales, tips, sphere & modules.
    Created an short autocalibration pogram with only a couple of angles and with cnc+cnc, 13 hits, 3 levels for each tip.

    After the calibration i ran the sphere check program, and they were all ALMOST good., some of my troublesome tips still gets halfbad deviation in XY (my disc & 0.5mm tip).
    Seems like i solved.....no........WE solved it
    I upload the results from the sphere check.
    Attached Files
Children
  • in reply to pcdmisstudent
    I think the reason behind the weird measurements were a result from us recently getting an offline seat.
    And when i installed it and started programming it, i built our probe setup as it is. The probes on the online computer is acctually wrong. Theres a tesa-star head instead of our new HH-AS8-T5 (Didnt have to change em because they would be the same dimensions).

    Some tips were also a bit different from reality, our tip1/master is a diameter 2 ruby with lenght 30mm 1.5mm stem. It used to be a 2 ruby with a 20mm 1mm stem and then a 10mm long and 3mm diameter extension.

    It didnt make any difference in our measurements since they were nearly identical and corrected itself during calibration. But Im just guessing that when i imported the first program written offline (with new tips), the probe files on CMM computer became corrupt or something(?)
    not sure, just a theory.

    But it seems reasonable, because 09/25 our first offline program were run in the CMM, and the day after, the results from the check program were bad.
  • in reply to pcdmisstudent
    I do 24 hits and 3 levels for my calibration routines. I had issues with calibration deviations in the past and more hits have consistently given me better results. Calibrations take more time but the end justifies the means in my opinion.
  • in reply to pcdmisstudent
    What probe you have?
    I ve never had any problem with calibration deviation, this was some odd problem where calibration results were good, but practical measurement results were bad
    Ive touchtrigger probe tp200, and we used 7 points for years, with no issues. Ive then experimented abit, but it doesnt seem (according to me) to make a big difference between using 25pts as Hexagon recommends nor 7, or 9 etc..Wish i kinda had time to make a "real" study about it.

    Now i only picked 13 hits/3 levels for this new autocalibration because it seemed like a lot of people here on the forum use that number
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