straight extrusion cuts becomes steps?

[nicanor76]

I'm doing test cuts on my finished CNC, still learning how to use the CAM program (MasterCam X2), so am a total newbie to CNC. I programmed (through Rhino) to do two series of circular extrusion cuts, one inside the other. But when I cut it in insulation foam, the straight cuts ends up becoming stairways (and oblonged oval instead of a circle because of this stairway problem).

I haven't really fine tuned my newly finished machine yet. But still, I don't see the reason why it would go back to the entry point in a different location after each depth cut. Any ideas? I attached a pict of the end result.

[grahamshere]

Are using mach3, looks like you hav'nt set up you steps per right, your losing steps.

[nicanor76]

ya, using Mach3. Also haven't done much one fine tuning yet. I guess I should do that before doing any more test cuts. Is there a list of things newbies should check through Mach3, in case I miss any and get frustrated down the line.

Thanks