Inaccurate Dimensions

[Notselrach]

I use Rhino4 for creating a DXF, cut2d for creating gcode and mach3 for cutting the pattern.  Circles i cut are consistently too small - an 11 5/16 Circles comes out
10 7/8.  X,Y axes are calibrated and equal.  I am using a .25 end mill and I have it set to cut on the inside of the circle.  Where do I look to correct this problem?  Is is stepover?

[ger21]

Is everything cut too small. or just circles?

Can you post the .dxf and g-code for a simple circle?

As a guess, since your off by about 2 times the bit diameter, I'd say you're doing something wrong in Cut2D. Sounds like your cutting a pocket? If so, do you have an allowance set?

[Graham Waterworth]

If you cut a circle 5 21/32 dia what is the error?

Graham