Where did my Alignment go wrong? MCOSMOS

Qualityy Keith

Registered
Hello all. My first post here. Very well to meet you all. I have an inquiry about a CMM program I made.

Its basically a cylindrical piece with a flange. A thru hole as well as a threaded hole. The drawing has the flange as Datum A. The front of the part is a plane and is Datum B. The threaded hole is located on Datum B. The thru hole is located on the shaft. The holes are referenced back to the Datums.
I made my program in MCOSMOS. I aligned plane, circle, circle. Like on the drawing. (Please see pic for reference. ) The part sits on CMM as the picture. Looking down from up above.

I measured my Datums. I used the threaded hole as a made up Datum C. I first measured the plane, Datum B. Then I measured the origin which is the threaded hole Datum C. Then finally Datum A which is the OD of the flange. I aligned Datum B plane to the YZ Plane. Origin the threaded hole Datum C. Then I aligned Datum A as point through axis. I believe in the Z. But cannot recall for sure.

I made some rotations to align my coordinate system. Repeated steps for my CNC mode. Went along programming with no issues. Everything was picked up and measurements were reporting back and measuring correctly based on my coordinates.
However, when I went back to execute the program there were some funky rotations with my alignment going on. They were rotating 15 degress etc...I didn't understand what was happening.

I believe it is my alignment. Anyone offer up what I did, am doing wrong? Should I only be rotating my coordinate system AFTER all datum features are measured? Thanks for reading and offering some insight.
 

Matt Swartwood

Starting to get Involved
Your picture unfortunately did not attach to your post. It's difficult to mentally picture what you are dealing with.
 
One tip that has helped me a lot: After each call to an alignment command of any sort, turn CNC Off and put in a Programmable stop, then using the joysticks watch if your coordinate directions still match your intention. You will need to turn CNC on again at each stop to continue through the alignment routine. Let us know if that helps.
 
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