I was told at the PCDMIS training that anything under 0.015" STD DEV is ok. Where is everyone's max at? What is a good STD DEV to stay under? 0.015" seems high to me.
Calibration - STD DEV
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I would say MM, NOT INCHES ("). Nowayinhell would I accept 0.015" for the STD DEV for ANYTHING. You can basically double that value to get any of the 'shape' items, ROUNDNESS, SPHERE, FLAT, STRAIGHT, etc. (at least, it will be DANG close). So, I guess it depends on WHAT that STD DEV is for? CAlibration results? NO WAY! Alignment features on a fixture? NO WAY! A measured feature of a part, well, that will depend on the tolerance of the part.sigpic
Originally posted by AndersII've got one from September 2006 (bug ticket) which has finally been fixed in 2013.Comment
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That has to be MM. and that is a little high for MM for simple probes.
Although, how many of their trainers have real world experience?Comment
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On a Discovery, 5 microns on a good probe, and up to 17 microns on a bad probe.
Good= within the Renishaw guidelines of module
Bad = Not within the guidelines of the module
Star probe - forget them....Comment
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I have my calibration STD DEV set to give me a warning if it is greater than 0.010mm (0.0004"). Only EVER happens if I miss a piece of crap on teh tool or tip.sigpic
Originally posted by AndersII've got one from September 2006 (bug ticket) which has finally been fixed in 2013.Comment
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First time I've heard anyone else say that. Now I don't feel so bad. I get a big ration here for refusing to use one. everyone whose seen a picture of a CMM sees one of those being used so they think I should use it. There is one guy here that insists I use it instead of tip rotations (he is a Ziess guy). I still refuse. I don't know why that is the most requested thing here in a plant full of people that don't know jack about CMMs. They have their place but that place is not with most of today's hardware and certainly not with most of our tolerances that is for sure.
Craig<internet bumper sticker goes here>Comment
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First time I've heard anyone else say that. Now I don't feel so bad. I get a big ration here for refusing to use one. everyone whose seen a picture of a CMM sees one of those being used so they think I should use it. There is one guy here that insists I use it instead of tip rotations (he is a Ziess guy). I still refuse. I don't know why that is the most requested thing here in a plant full of people that don't know jack about CMMs. They have their place but that place is not with most of today's hardware and certainly not with most of our tolerances that is for sure.
CraigComment
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What-you-talking-about, eh? This machine is 20 (or more) years old and yes, I check sheet metal. The machine (factory) specs are +/-0.0007" (linear, repeat, sqaure, etc., and I am still within them) and I use 1/2 of my machine spec as a limit for my calibration STD DEV. What gives? What does sheet metal have to do with that, huh?!
sigpic
Originally posted by AndersII've got one from September 2006 (bug ticket) which has finally been fixed in 2013.Comment
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Ya know, I never even look at the results of the calibration. IF it calibrates within the set tolerances (0.0004" STD DEV and 0.002" size) I never even bother, I just go on with what I am doing. If it pops-up a warning, then I will double check what I have done and do it over.sigpic
Originally posted by AndersII've got one from September 2006 (bug ticket) which has finally been fixed in 2013.Comment
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What-you-talking-about, eh? This machine is 20 (or more) years old and yes, I check sheet metal. The machine (factory) specs are +/-0.0007" (linear, repeat, sqaure, etc., and I am still within them) and I use 1/2 of my machine spec as a limit for my calibration STD DEV. What gives? What does sheet metal have to do with that, huh?!
j/k
What is the tightest tolerance on your worst sheet metal part?
Last edited by cmmguy; 12-19-2006, 11:45 AM.Comment
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