I just finished setting up a Chinese Router and was doing my first test cut.  It was a simple Rectangle with square outside corners.  I sue V carve pro and the G code seems to be fine but 3 of the 4 corners were rounded.  Anyone have any ideas?

Thanks
Rickh

You are running in CV mode, and Mach3 is rounding the corners in order to try and maintain constant velocity. The slower your acceleration, the more rounding you'll see. One thing you can do is go to General Config, and set Stop CV on Angles to 89, and enable it.

That worked.  I am new to Mach 3 - my previous CNC had proprietary control software and not so many variables to deal with.  Would it also be a good idea to increase the acceleration?

Thanks for the quick response!

If your machine can handle it, higher acceleration is usually desirable.

Unfortunately, one more issue if you don't mind.  The x and y axis do not seem to hold their calibration settings.  I thought they were calibrated perfectly, then I cut a simple square and one side is almost .125 larger than the other.  Re-calibrated and once again one side is slightly larger than the other.  I first used a standard tape measure to calibrate at several different distances and then after that was dialed in I used a dial indicator for fine tuning. 

Thanks in advance!