Calibrating a 0.20 mm ruby sphere

[[Da...]]

I'm trying to calibrate a 0.20 mm ruby sphere using an 8 mm reference standard however it broke the shaft on 0.20 mm stylus. I was using the standard tensor method as well. Is there a way to adjust the force or is there something else I should be doing to calibrate the stylus?

Thank you,

Dane Hoeffer

[[Da...]]

What kind of head are you using?

[[Da...]]

Dave, we are using VAST XT. I've tried adjusting the measuring force from 200 nM to 100 nM with the same result.....a broken stylus.

[[Lo...]]

I'm interested in the answer to this issue, I have a part coming up that requires a .3 mm and was wondering about that.

[[Da...]]

First of all scanning with a .2 mm probe is not recommended. That being said, you can set the probing pressure to any amount. Even 25 mn, you don't have to stick with the pull down choices, just type in what you want. Tensor uses a high pressure hit then a low pressure hit to figure out the rigidity of the probe. The probe is breaking during the high pressure hits. You can try to reduce the setting but there is another way. Use a 6 point calibration. Calibrate at the same pressure you'll be using for the feature points. If you aren't scanning the 6 point is fine. The repeatability is pretty darn good even at very low pressures. Oh, and set the probing dynamic low too ! Oh2.... watch your clearance and retract numbers closely, if you're resorting to such small probes you are probably in close quarters. I Have broken .2mm probes by wiping them down....good luck ( order in 6 packs )

[[Da...]]

One more thing, if you are using an xxt, you don't get an infinitely settable pressure. I think you get 3 choices. Set to the lowest and add an extension. You get a mechanical advantage. It worked for me 🙄

[[Da...]]

Thanks for the info Dave. I'll give this a shot and see what we get for results.

[[Lu...]]

OK, I need it dumbed down a little farther. For both a 0.2mm sphere and a 0.3mm sphere both with carbide shanks and carbide balls, what measuring force do you use? what probing dynamic? what sphere coverage?

8mm calibration sphere, VastXT on Micura.

[[Da...]]

Ok , start with about 75 mn pressure , Probing dynamic at 50% and 180 degrees of coverage. Make sure you use 6 point calibration. Make sure you use 75 mn on the part you are checking, and use single points.

[[Lu...]]

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I'm having a some trouble with term "start with", What does "start with" mean? It almost sounds like you are saying, "Start with these settings, and when your stylus snaps, buy another one and try some smaller settings, and when your stylus snaps again, just keep snapping styli until you find a recipe that works."

75mN is actually more force than I use for any measurement in any program I write regardless of the size of the stylus, we work on very tiny flimsy plastic parts with stupidly tight tolerances, we better tools for such things on order, but the CMM is what I have to work with right now. The reason I am on this thread is because 50mN was snapping my styli, and 25mN was snapping my styli. Right now I have it set at 25mN, 10% measuring dynamic, 6 point calibration, and 5% measuring speed... I cant imagine that's very accurate... Has anyone gotten a a tiny stylus to sustainably work at forces and dynamics higher than that?