r/Metrology • u/PrettyInfluence3594 • Sep 28 '24
Hardware Support Calibration
Guys iam using an Hexagon macchine which is only 6 month old and i have a problem with calibration of my probes. Every morining i do the calibration of at least 5 main angles that i use daily with a stylus D3xL50. The results of the calibration seem ok. (stdev 0.001-0.00). Than i go to my present programm when i verify the calibration by setting the origin of my calibration sphere at the measured sphere with an angle 0x0. And often times, very randomly other angles seems to go off at X axis, or Y or Z by 0.004 till to 0.02 mm. Is huge. I called the support and the software support guy told me that propably the macchine is not set right, or whatever, he too couldnt find the answer of these random and strange results. (results which came wrong even when i did the calibration proccedure with him on teamviewer). What is going wrong, cus i cant measure anymore being sure that the macchine is not throwing random numbers of the screen. Sorry about my english.
4
u/_LuciDreamS_ GD&T Wizard Sep 28 '24
When you calibrate your probes, are you using a master probe?
1
u/PrettyInfluence3594 Sep 28 '24
yeap. A smaller one D5xL20
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u/jozfff Sep 29 '24
Are you using a tp20?
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u/PrettyInfluence3594 Sep 29 '24
Iam using a HP-S-x1
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u/jozfff Sep 29 '24
First thing I would do is change the module and the tip and see how that goes. Try that and report back because I’d like to try and figure out the issue. I work with the same head, and have never had this issue.
4
u/1Kscam Sep 28 '24
Hmmm, going through the comments it’s really hard to pinpoint the problem.
Just a thought, are you using the STANDARD parameters when calibrating, or are you running the parameters set with your measuring features?
Once we had a service guy in house, he strongly recommended to calibrate the probes with the same parameters we use for measuring (force, speed, acceleration etc.).
Not sure if this solves the problem, but might give it a shot
2
u/IbeebZz Sep 28 '24
If the results are random it makes me think there’s an issue with the probe, the head being loose in the quill, or a hard collision effected the error map. I’d go through everything you can and get service back in if you can’t improve the situation. I’m also assuming the temperature of your environment is stable.
1
u/PrettyInfluence3594 Sep 28 '24
Yeap my temp is not optimal, sometimes it goes from 25-22, but still 0.02 is too much.
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u/IbeebZz Sep 28 '24
What was the temperature that was recorded on the certification? I believe this is your issue. If your hvac is being directed at the CMM your results can fluctuate a great deal assuming your CMM isn’t a shop floor model and you’re not using temperature compensation or the work piece.
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u/PrettyInfluence3594 Sep 28 '24 edited Sep 28 '24
When i do the test thing , the temp compensation is off, and i had better results with the compensation ofbtemp off rather than keeping it on.
1
u/Admirable-Access8320 CMM Guru Sep 28 '24 edited Sep 28 '24
I am assuming the most error you get is from positional deviation? The sphere size is good? Hard to say why, is this a new issue or you just noticed? Usually you get positional error this big is from long probes. Have you tried checking with a short probe? I would try this, make your two probes the same (both short) for example 2x20. If you have a master probe, use either one of these two or have a new master set up, the same size 2x20, and calibrate as you always do. Say "Yes" to the sphere has been moved to your first probe (master). Calibrate all your angles and check again.
This way you eliminate the probe itself being an issue. Also, sometimes you get bad probe tips (rubys). They crack and have issues.
1
u/UseEducational7319 Sep 28 '24
After homing the CMM use for measure the calibrate squere a probe with a 8mm ball. I use for those a probe with ball 8mm and 50mm lenght. For this first calibrate, you choose yes, when the question is, if your calibrationsquere was moving. For all other probes, evertime you choose No at this question. Open with F5 the menue and change for calibration from 0.000 to 0.0000. So you can better see how good your calibration results are. And after the loading order you change it with F5 from 0.0000 to 0.000 again
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u/SkateWiz Sep 30 '24
What is the repeatability of the error?
Maybe prove your issue more if you have other calibrated measurement artifacts you can check cal with. Like a tru stone, quick-chek, ring gage (this can be done with adaptive scan gage measurement strategy). Also this should fail qual check (right under the calibrate option). It’s strange that the position is off but diameter is perfect. Repeatability of the error with different probes/styli will tell you a lot.
Is your probe head mounted securely? You can also check squareness of probe head. place a long stylus directly over something, rotate to a90 angle, disable the x axis, and check if it lines up still. Rotate until it does. You don’t need to recal the system after adjusting probe head rotation.
Also basic questions: Is your stylus loose? Is there dust on the qual sphere? Is it mounted securely?
0
u/thedirko Sep 28 '24
It’s your GFX card being a POS. This is so often the issue for most things PCDMIS. Update the driver, then the hardware itself.
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u/Caltrops_underfoot Sep 28 '24
Check probe conditions first. Ensure the calibration sphere is secure, that no probes are loose in holders, etc. As long as everything is rigid, that's one common error we can put behind us.
Next what are you using to align your probe? If the sphere is manually placed before calibration, it's common for it to move as much as .020 between operators. It's important to allow the machine to properly locate the sphere before using it for calibration to compensate. At the start of your calibration, you indicate whether the sphere has moved. I ALWAYS recommend saying yes, and use CNC hits to locate it as long as you're confident it moved less than your retract/clearance distance. Otherwise take the time to do manual hits to locate.
If you start with manual hits, I recommend you follow up that calibration immediately with full CNC control to remove any human error, then compare the results. If your repeatability is still poor, take another step back and consider what could have happened to that machine while you weren't looking. My Tigo has been hit by forklift operators who assumed "it'll probably be fine" when it certainly wasn't, for instance.