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Long probe tip

We are cutting a cone inside an 8" tall cylinder. We do have a callout for the smaller ID (approx .38") , the larger is ref (approx .55") controlled be .0005" flatness, angle is 2° ±.005°, & .0005" circularity. Customer is using a custom tapered gage (I know, don't get me started Astonished ... 'not traceable, how much force is used etc. we are stuck & may tell them we cannot work that way BUT after some parts were rejected we wanted to see what we were getting so split a scrapped part lengthwise & measured that way - there is definitely a belly. Company wanted to run some tests so 4 x 100 mm carbon fiber probe with a 100mm ceramic extension - ONLY using A0B0, part is held vertically in a V block(TP 20 on Hexagon Global 575)(. I lowered movespeed to slow enough it doesn't fault out from the long probe momentum & touchspeed is at .4mm . Getting a 'repeatable' .0003-.0004" calibration with this (basically using the majority of our tolerance without toughing the part yet). Taking circles at certain heights where we know what diameter to check angle & circularity should be & for straightness taking 70 hits (over 8") per vertical line - 4 lines at 0,90,180 & 270 degrees (top front is marked by operators in machine) to check straightness & angle. Is there a better way without cutting open a part or sample ??? Not a big customer so they aren't planning to invest in different probe head etc a few hundred okay, but not worth a few thousandConfused
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  • Try to check a ring gauge. I have a small Mitutoyo one that I periodically check the CMM using its master probe. Nothing fancy in DCC mode 4 hits on the top to level & origin z & inside 4 hits to get xy origin & redo the 4 hits (0,90,180, 270) & output the size. You might get a trilobe effect but using 4 points I got close result to the gauge. See what you can get. If noting close with this kind of long probe setup just tell those genius engineers you need a million dollar CMM with fixed head for that kind of tolerance. I once had a part they threw .010 degrees on one angle. I said give me a million dollar CMM & the brand new qc lab & I will check this angle no problem. And the complaining ended right then & there.