Problems cutting circles

[curtisturner]

I am running Mach 3 on a cnc router I built.

AC Srevo's , built like a tank.

I am running into a problem where I can not find a likeable solution
If I have some g-code that cuts a circle it cuts it real sloppy(out of shape), I have been able to make them perfect by slowing down the feedrate.

And like wise when I cut a square it rounds all the corners (almost like a circle) until I set the feedrate way down.

Is there any way to tell Mach 3 to use exact cuts.

It seems as though the interpolation is shreading the shapes unless slowed way down.

Any help would be great.

BTW this is not a problem with the router chunking it is not even being taxxed and it is making beatiful cuts.

Thanks
Curtis

[ger21]

The square with rounded corners is from being in Constant Velocity mode. Switching to Exact Stop mode will give you sharp corners.

As for the circles, I'm not sure. How fast is the PC your using?

[phillip]

Check your back lash on the x and y.
Mine had .004 and looked real bad and ruff. When the bit is cutting a good size chip, it may move more because of the extra backlash. After i took out the backlash problem solved.