probe cal

[willydog]

for a global machine and a ph10mq probe head if i calibrate tip 0 and run parts, then later if i calibrate other probe orientations without calibrating tip 0 will they be valid calibrations. we run a variety of parts and each 1 has very lengthy cal. routines. i don't want to cal tip 0 and all other probes for a particular part and blow out the calibrations for previously calibrated parts.

[Wes Cisco]

what I was told

My understanding is that it is best practice to always calibrate A0B0 then any other angles. So if you need A90B0 & A90B-90 to start with you would calibrate A0B0, A90B0, & A90B-90 in that order. Then later when you need A90B180, you would calibrate A0B0 & A90B180 in that order. Your calibrations for A90B0 & A90B-90 would still be valid. A calibration stays until you unscrew somepart of the tip/probe build or have a crash. There have been many discussion about how often a calibration should be done if neither of the above have happened. I recalibrate if a tip angle I am going to use has not been calibrated in the last 7 days, others say from once a shift to once a month or more. HTH

[CGoode]

If you calibrate Probe and Stylus X at position A0B0. Then Calibrate Probe and Stylus X at position A90B0. You do not need to recalibrate when you go back to postion A0B0 with Probe and Stylus X. If you change either the probe or stylus the yes.

[Hilton Roberts]

Generally a program has several tool orientations in it and once those positions are calibrated for a particular part, you are good to go.

H

[Matthew D. Hoedeman]

I think that ALL calibrated tips are related BACK to the 0,0 tip (if it is in the probe file) and that when you re-calibrate 0,0, then you HAVE to re-calibrate the rest. So, if you calibrate 0,0 and 90,-90 and 90,90, then go back and calibrate 0,0 and 90,0, then the 90,-90 and 90,90 are no longer in relationship to the NEW 0,0 calibrated position. That is why it asks that question about 0,0 when you do a calibration. Once it is calibrated and as long as the tool does not move, do not calibrate it again unless you calibrate ALL of them. You can add new tips by calibrating just the new tips.

[Wes Cisco]

Really?

Matt, you said I think, does anyone know which way is correct for sure? TIA

[Jonathan S]

I always "mark all" and calibrate all tips for that program if I haven't done it recently or I have unscrewed the probe. Better safe than sorry.

[Jeffrey Lovely]

Had a manager ask me while calibrating tips
Is that necessary
almost lost it !!!

[Hilton Roberts]

Would that be the same manager that wants you to run balls to the wall and wonder why parts check bad? Would that be the manager that does not know to do your job but feels somehow qualified to tell you how to do yours? Calibration.....we don' need no stinking calibration...takes too much time...and time is MONEY..

H

[J Temmen]

The only thing all probe angles have in common is their relationship to the cal. sphere, once you calibrate the angles you need you can recal any or all at any time as long as the sphere has not moved. When you rehome however you will need to re-find the sphere to add any more angles, this is usually done with A0B0 only because it's the easiest one to hit normal to probe.

[Matthew D. Hoedeman]

Myself, I take no chances. If I am programming a part, I calibrate the tips I think I'll need. I leave the tool in place. Then, if I need to add a tip, I will add it and calibrate just it. BUT, before I go and actually make a report foa checked part, I will delete the angles I didn't use and calibrate ALL the tips, THEN i will check a part. There are too many possible problems that can bite you with the tip calibration. I remember a time when there was a minimum of 4 different angles that had to be defined to calibrate the probes. How many of you remember that? AND, it really does make sense since your tip SHOULD describe a sphere as it indexes from one position to another and 4 is the minimum number of 'points' required to make a sphere. Is it just strange that those numbers match? HOW did they change the 'program' to get it to calibrate, correctly, with less angles (tip positions) than are needed to create the sphere that the tip should inscribe as it rotates? ALWAYS REMEMBER, C-Y-A!!!

Oh, BTW, I do not have 'single' part runs, so the extra time for the 'first' part involved with the tip calibrations is NOTHING to worry about, as far as I am concerned.

[Wes Cisco]

Thanks Matt

I agree about CYA all the way.

[Snaggy]

While we are on the calibration thing, I work in a sub contract engineering firm, as such I never know what parts are going to land on the cmm for me to check. So I don't have to keep adding probe angles and because I have to move the sphere, I calibrate 5 probe set ups in 360 positions each (i.e every 15 degrees). Question is how often should I recalibrate them assuming I don't crash?

[Jeffrey Lovely]

No thats the quality engineer !!!

[Matthew D. Hoedeman]

As long as you don't crash, even something as 'light' as just un-seating the probe, you should NOT have to re-calibrate EVER. However, that will make EVERYONE a little jittery about your calibrations. I would say no more often than once a week. Talk to Hilton, he can give you some excellent ideas on how to track your probe to see how often you should recalibrate.