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

This Tech Tip Video from Canadian Measurement - Metrology shows the procedure used to calibrate a star probe in PC-DMIS. In addition to recommended settings, tips to avoid unexpected probe hits are also covered in this video.
Hey there and welcome back to my tutorial series. Today we'll be talking about star probes. So, in an earlier tutorial, I showed you how to build the star probe. Today, I'll show you how to calibrate it. I often get this request so I thought I'd make a video and show you how it's done. It's actually quite easy. The first thing I want to do is have a look at our probe build. So, over here on the active tip list you can see we have five tips, five active tips. So, it's important to know the tip assignment and I did review this in the previous video so I'll just go over it now again. You can see tip one is pointing down in the Z minus, tip two is X plus, tip three Y plus, tip four pointing to the left, it is X minus, and tip five is Y minus pointing to the operator. Okay, so as we calibrate you'll see each tip calibrate in order from one through five. You can change the order but in this case we'll keep it simple and just go one through five. So later when I play the calibration, I'll explain which tip is being calibrated at which time.
Okay, so let's just go into our calibration settings. There's a few things I need to explain here. The first thing I want to explain is what's called The System Mode and that's this area here where you see manual DCC, manual plus DCC and DCC plus DCC. So, the setting I recommend is DCC plus DCC. So what that will do is enable sample hits prior to the probe calibration routine. So the purpose of that is to locate the center point of the sphere exactly so that all the hits are evenly distributed in that pre-hit retract distance, in this case 2.54 millimeters. So because we have to eyeball the squareness of our star probe build, this helps us to avoid mishits and crashes.
Okay, so the next setting we need to look at is the calibration mode. So I have it set on default so the default mode will distribute my five hits around the equator and finishing on the North Pole. So my five hits will be four around the equator and our final hit on the top at the North Pole. So that works well for this build and we'll just stick with that. So again, when I run the calibration, you'll see how that is implemented. Okay, so that's about it, pretty simple settings. So, let's close this, cancel and I'll just click okay.
All right, so let's run the calibration and then I'll just talk you through it throughout the routine. Okay, so I'm all set up here and this is tip one and here's our four sample hits. So, after the fourth hit, it will start the calibration routine. So, this is the hits around the equator. This is star dangle zero, four hits you can see them perfectly, evenly spaced and finish at the top. So, here's tip two pointing to the right and our four sample hits again, number four and right to the equator. So, nicely, evenly spaced out. And the last hit, so it does its clearance moves, goes to tip three and this is the one pointing to the back of the machine. So, based on that orientation, it will go to the equator and notice how it avoids the shank because we've told the software that the shank is pointing straight up so it won't crash into it. Finish at the North Pole, two clearance moves and tip four. So, it's the exact same routine for all five tips and calibrate it in numerical order.
Okay, so that's the end of tip four, two clearance moves and tip five pointing towards us. So, this will give you a good view of how equally spaced that pre-hit retract distance is based on the sampling that we've just done. So, you can see there they're nicely, evenly spaced. If we didn't have DCC plus DCC, this might be a problem. Okay, so that's the end of that and we're done. So, that's how you calibrate a star probe. Well, I hope you found this useful. Thanks for joining me and we'll see you next time.
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