At the beginning of each of my shifts, I calibrate my stylus to 0.001 mm. 80% of the time I only use it in position a0 b0. And when it shows 0.002 (or even 0.003) I start wiping everything in the world until it is 0.001. Sometimes it takes a long time. How do you solve this problem?
jjewell Aerospace/defense (AKA fighter jet parts, not NASA but still supersonic). Now, if you are just going to say things like "uncertainty" "accuracy" ,"and "repeatability" with no proof (facts, studies, hard numbers) then don't even reply. I am interested in this subject for sure but you are losing my interest with every comment. I'm not trying to be a d*** about it but give me something to look into. So far you haven't given me anything.
A-machine-insp I calibrate before every part as well for the same reason
jjewell Idk what you are going on about? you are a demi-guru on here and a member since 2006. I hope that you calibrate your probes..
I don't think you understood what A-machine-insp was saying. I don't think that he was saying he needs .001 micron deviation. He was just pointing out that calibrating before running is good enough as long as it doesn't fail the cal.
Maybe you work in oil and gas with loose tolerances or you work at a forge and don't notice a difference but for me I am doing | TP | .002 | A | B | C | at complex angles.
I pretty much calibrate every time I go to a different program unless it is just A0B0 and that is sufficient unless I am doing something special
I'm surprised that none here asked a question about the probe type... ? TP2 or LSPX is not the same...
Calibrating before each part allows taking into account the relative dispacement of the artifact from the scales, because of the temperature changing...
If the measurement lasts a little time, this parameter can be forgotten. But sometimes, the part stays a long time on the granite, so it can be important to re-calibrate.
This is also the case after a little collision, or after a tip changing when you're looking for a hight accuracy, even if the uncertainty won't go under some µm, remove the max of causes will help...
A stddev on a LSPX1 L50 D5 bigger than 0.5 µm calibrated by 25 hits just shows that there's a dust on the artifact / tip. So a cleaning can be a good idea !
The same value of stddev on 5 hits and on 25 hits doesn't mean the same thing at all...
The statistical extent on different radii of the tip with 1 µm stddev can give 4 or more µm of sphericity of the tip.
Just my opinion...
Good point on the probe type. I am using a Renishaw SP25-M. It obviously scan calibrates all angles not previously calibrated. When I am calibrating probes/angles I have used before, I have it set to 13 points on 3 levels. For tight tolerance parts, I will run the scan calibration even if the probe/angle has been previously calibrated. And yes, I use a master probe. As long as the probe/cal sphere is clean, I get .0000 stddev.
dear friends, some of you wrote 13 and some of you write 25 strokes. Where do our talk about? Can you share a flagged image?
Using a prime number for things will force the software to take it's data and come to an absolute mathematical calculation instead of giving it the opportunity to round like it could with an even number. Due to this best practice, I qualify my master with 13 hits & my slave probes get 11 hits. In my programs, datums will get 7, 11, or 17 hits (depending on the geometry). Measured features will get 5, 7, or 11 hits (depending upon geometry).
I agree. The only time I deviate is on smaller circles when using the TP20 probes. I usually do 6 hits on those to negate positional error from the tri-lobe that we get with the TP20s.
Interesting, I use all TP20s and have never heard this before. Can you please expand upon this a little bit more? How does 6 hits eliminate the tri-lobing effect for smaller circles?
