I am trying to cut out a 5 foot circle from 3/4 material using a 1/4 inch bit in two passes. I imported a dxf file from my customer into part wizard. I created a tool path to profile outside, in two passes. In the simulation, the correct tool path is followed on the first pass. On the second pass, it deviates slightly, which will result in something that is not really round. It seems to be moving off of the original tool path by about 1/8 inch. It is not doing this all the way around the part, just about 1/3 of the circumference. There is individual detail inside the circle as well, but these are separate tool paths and they appear to be correct.

Does anyone have any suggestions of what I might look for to fix this? Thanks.

Greg