PC-DMIS Disc Probe Calibration | CMM Tech Tips - CMMXYZ

This Tech Tip Video from Canadian Measurement - Metrology shows the procedure used to calibrate a disc probe in PC-DMIS. Disc probes are useful when measuring internal grooves in deep bores.
Hey there, so today we're going to be talking about disk probes. More specifically, how to calibrate them. Building them is pretty simple, but calibrating you need to remember quite a few things, so we'll run through that in just a moment.
So the advantage of a disc probe is that we can measure internal grooves, like an O-ring grove or something like that. And they're actually pretty accurate, because I did one the other day, and the results came out pretty good when I measured a ring gauge.
Okay, so let's look at the build. So you can see the description of my tip on the bottom there. It's a 6 millimeter by 10 millimeter disk, so we're looking for the word disk at the end of it. So once we complete our build, we're ready to calibrate.
Here's the calibration settings I used for this particular calibration. I set the number of hits to 24, create retract to three millimeters, move speed to 60% and touch speed at 2%. So I wanted to have a large number of hits because what we'll do, is separate those on three levels beginning at start angle negative 10 and ending at positive 10. So we'll go slightly below the equator then it'll go to the equator, then it'll finish at 10 degrees above the equator with 8 hits on each level. So it's nicely, evenly spaced out, lots of hits so we'll get a really good sizing of that six millimeter disk.
One of the most important things to remember when calibrating a disk probe, is that we need to have that qualification tool picked up with another probe so we can answer the question, has the qualification tool moved? We'll have to say "No," because we can't sample the top of that qualification tool with a disk probe, it just won't work. So we need to say, "No," and we also have to have the system mode set to DCC alone, not DCC plus DCC. Because if we had it on DCC plus DCC, it would want to sample the top of that sphere. So very important, set it to DCC and it'll go straight to the start angle, negative 10 degrees.
Okay, so those are the settings. So I'll run the calibration video and then just talk you through it. Okay, so all set to calibrate. So here is start angle negative 10 degrees. These will be eight hits just below the equator. Just finishing up there, so the next level should be right on the equator. So this is level two at the equator, an again it's 8 hits, I have a total of 24 hits. So eight, eight, and eight. And the last level will be level 3 at plus 10 degrees. So you can modify these a little bit, seven degrees, eight degrees, whatever you think is most appropriate. And we're done. Okay, so that's it, not too bad.
That's how to calibrate a disc probe, so the one I used is kind of small. Normally you'd use a larger one to get deep inside of a groove. But that was actually the only one I could find, so I just went with that. And sometimes you'll find that you'll have to do this a number of times to get a good calibration result. You just increase the hits, play around with the start angle, end angle, number of levels, just whatever it takes. The first time I tried this I got some pretty bad calibration results, but through a bit of trial and error I finally got it right.
Okay, so that's the end of that. I hope you found it useful. Thanks for joining me and we'll see you next time.
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