Measuring Outter Diameter and Inner Diameter of a group of circles

[[Ma...]]

Hey all,

so I am checking a bearing and I need to measure the total inner and outter diameter of the pads. I tried to recall them as a circle and of course just got the midpoints. How can I do this? I also tried using tangents from one to the next all the way around, then made intersection points, then made a circle with the intersection points and I go the number to be in tolerance, but I mean...is that REALLY the only way to do this? There has to be a simpler way?

I know I can do caliper measurements between the 2 pads adjacent to each other but that would be a total of 6 measurements, I really would like to just have one for outter and one for inner.

TIA!

[[To...]]

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Create a circle feature. Recall Feature Points (not Recall) from the 6 circles. Create a Diameter characteristic. Open the Diameter characteristic, click the Feature button and change the Evaluation from LSQ to Outer Tangential Element. Close.

Copy and past the Diameter characteristic, open it, click the Feature button and change the Evaluation to Inner Tangential Element. Close.

[[Ma...]]

Perfect! Thank you Tom!

[[Ma...]]

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Hey Tom, so I have a question about this. It worked for the inner, however when I evaluated as Inner Tangential, it is saying it is oversized, however when I checked it mechanically, it ended up coming within tolerance. Any idea of why? I double checked, and made sure I recalled the feature points, as well as followed everything else you suggested.

[[No...]]

First of all, when using this method, make sure to scan all the circles with a high point density. Because you want to avoid a situation like this (exaggerated):

If you still get over/undersized results, carefully check outlier elimination settings. It may either have eliminated too many points in critical spots, or it may have left too many points which are real outliers. Both can have negative effects on the results.

[[To...]]

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Did you mean "it worked for the outer"?

How far off is the result?

By "Checking it mechanically", I assume you're getting 2 point measurements. If the circles have any location deviation, that could impact your cmm result though I would expect to see a similar discrepancy on the outer tangential result, as well.

[[Ma...]]

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I did check with calipers (the tolerance is +/-.010, I know a football field) the only reason why we are using the CMM is because the customer warrants it. I did find out though that 4 of the 6 are in tolerance all the way around, and 2 of the pads are out of tolerance. (the bearing is SS and the pads are copper). I sent the part out to get reworked to make an adjustment to the pads, and just re-ran it now I am getting the outter diameter out, and the inner diameter in. I also took caliper points of each set of pads and got them all within tolerance.

Zeiss.jpg

[[Ma...]]

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I am taking points every .0005". Roughly 1500 points per pad, which is roughly .800" in diameter. I tried it with and without filters and am still getting the above result.

[[To...]]

The problem is my fault. Here's how to resolve it.

Create a circle Feature. If you're doing the OD, you'll need to flip the circle from an ID to an OD. Go into Evaluations and select Outer Tangential. Recall the Feature Points from the pattern of circles. Create your diameter characteristic.

For the inner diameter, create a circle Feature. Leave the ID/OD on ID. Go into Evaluations and select Inner Tangential. Recall the Feature Points from the pattern of circles. Create your diameter characteristic.

My original method would not let you flip OD and ID on the same circle. So creating independent features let you control the ID/OD setting. Sorry about. that.

[[Ma...]]

Yup that was the fix! Thank you, much appreciated!