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What equipment do you have for GD&T on ID grooves?


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Our manual CMM has died. It was a machinist favorite inspection equipment for spot checking characteristics, especially for ID grooves, specifically GD&T like runout, position, concentricity, etc. I have been tasked to find inspection equipment to replace it, but a manual CMM is hard to come by these days. I either need to find a CMM to use thin custom made disc probes, or another type of equipment capable to do the same. I'm looking for something use to setup and use, accurate and reliable. All ideas are appreciated. Below is an example of a valve we machine and inspect.

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Depending on the tolerances, you could either use a very thin disc probe or possibly an "L" shaped probe with a small stylus and have a few rotations about the A axis (depending on your machine setup) with a long stylus that's probably 75mm long with a 0.3 ruby sticking out the side, protruding appx. 1/4" perpendicular from the main stem of the stylus when the sensor is in the down position. That particular stylus is kind of a one-trick horse for us; we use it for one part number and discs usually suffice for the rest. We've purchased Ø25mm discs and had our tool room grind them down to a suitable thickness when needed.

My gripe about using discs is Calypso doesn't "truly" have a way to calibrate a disc probe using the reference sphere ***Someone please correct me if I'm wrong here*** which is beyond me. The bend map is going to reflect that of the stylus system you copied to create the disc "template". But if done correctly and you aren't working four decimal places out it's pretty reliable.
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What sensor are you using when using the disc probe? I have a XXT TL3 and it was my understanding you can't get the disc probes to work. A question was asked if we could purchase a Duramax CMM, and have it used manually when needed. Could Disc probes be used manually with the Duramax CMM? I do like the idea of already having familiar software.
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A roundness tester can check that pretty well. You'll have to change tips between truing the A cylinder and checking the groove, but it's doable. You can also check the cylindricity of the A bore.
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That is our setup as well. They outline the steps to "qualify" a disc in the advanced training manual, which I will try to find. To "paraphrase" though, basically what they suggest is to take a stylus system with similar hardware (extensions and such) with similar lengths, to best simulate the amount of bending and deflection that will take place during measurements. An example would be a 12mm disc on a 50mm ceramic extension that we use, where I just made a copy of a 2mm ruby with 50mm extension, and manually modified the geometry of the probe in the stylus system manager. I would then use a calibrated, precision ring gage, make a quick bullsh*t program using a freshly qualified ruby to make a base alignment and then measure the ID with the ring gage. I would assign a ±.0001" tolerance in the X,Y, and diameter and modify the geometry accordingly, getting as close to 0 deviation as possible. Getting the Z height correct can be a bit tricky; if you touch the top of the ring with the bottom of the disc it's going to think you are using a 12mm spherical ruby and making contact on the bottom of it, so you subtract half the diameter, then add half the thickness of the disc to get your Z height to get your "ball center". It sounds convoluted, and it kind of is, but once you do it a few times it's not bad for simple down Z- qualifications.

That's until you have an RDS holder and need to qualify discs at compound angles... that's really a lot of fun when you need to start messing with vectors.... 😠

I'll see if I can't find the manual and I'll screenshot it and post it for you. It'll probably be a lot clearer than my trying to regurgitate it from memory.
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