Runout to A - B

[[Me...]]

Attached is a capture of a section of the print and part that has a .001 to -A- - -B- runout and I'm consistently getting it out of tolerance. I usually do not have issues measuring or getting the results accurately with this type of dimension but this part seems to be giving me some grief. The machining process is questionable do to the fact that they index in between maching -A- & then the -B- side. I noticed that the bore with the runout in question is off .0008 in "Z" and around .0003 in "Y". The program repeats and I'm confident in my base alignment, scan & evaluation settings so I figured I would see what you pros think is best in this situation.

How would any of you align this part in terms of the Base Alignment?

What should the evaluation settings be for a stepped cylinder?

[[Ri...]]

I would use the Stepped-Cylinder for A-B as your spatial in the Base Alignment.

Regarding evaluation settings, that depends on you. Is this a functional check or process control?

On your Ø.9848, are you using a Cylinder or Circles?

On Datum A, and Datum B, how many circle paths?

What sensor are you using?

[[Me...]]

XXT RDS Sensor

I measured Circles because they're fairly short, the cookbook settings basiclly for both diameters...

It is a functional check as well.

[[Er...]]

Oh god no, do not use a steped cylinder in your base alignment. But use it as datum for you run out.

[[Ri...]]

Eric,

What issues have you seen with using it in the Base Alignment? I've only used it a couple of times with no issues.

If you are that concerned, poor man it with a 3d line from A & B.

[[Er...]]

Random collisions and sublime angle errors.
Sometimes if works fine, then suddenly, without remeasuring the non cnc base alignment, toutching fixture, or anything else that could skrew things up it tries to transport thru the part. Everytime before I figured out why, was a "Wtf just happened moment?!" of biblical proportion.

Sometimes Ive got small spacial angular deviation that doesnt make sense.
Never took the time to figure out why this happened. But replacing it with a line or one cylinder fixes it.
But as a datum for evaluation, it works Great.

It could have Been a version specific error thats fixed now. But Im not going to try it again. Here, the love story of Steped cylinder and base alignments is over.

[[Me...]]

I do not have it in my Base Alignment currently, tried it before but I constructed a 3D line instead of using the Stepped Cylinder, I get the same results for the runout no matter what I try.

[[Me...]]

I had our other CMM guy check the same dimension the same exact way on a Brown & Sharp with PCDMIS on it and he got it within .0002...

The only issue I have with that machine measuring it is that the two datums that were scanned but he does not scan when he calibrates the probes.

[[Ri...]]

It's possibly just your probe qualification then.

Setup a ring gauge in the same plane that you are measuring your part. Measure the ID of the gauge with both probes that you are using, and look at the difference.

[[Me...]]

I figured out what was going wrong.

Sorry for wasting everyone's time but the issue was that I had copied and pasted the program from a previous OP and the Base Alignment was not correct.