We have two of the Puma 240-M's in our shop. One has a gantry loader and the other does not. We are making a part with a small threaded hole in the centre and 6 straight thru holes around it on a 4" pitch circle. The perimeter holes are 3/4" and are cut using a 1/4" end mill. The part comes out with oval perimeter holes. It almost appears like a backlash problem but both machines are doing the same thing and I'm not sure where to begin correcting the problem.
The funny thing is the machine can drill holes accurately on a similar pitch circle, but cannot seem to machine a hole out with out producing an oval.
Has anyone seen this before? Any help would be much appreciated.