Hi, hopefully someone might have a suggestion with my issue.  I have cut many flat parts without issue but recently just cut 2 3D patterns in tooling board.  Both had the same issue. The issue I'm having is from the top edge of the part to the side, it should be a sharp edge but it ended up with about a 1/16" radius on the edge.  The radius is consistent around the whole part.  All other dimensions are good on the finished part. Here is a like to a picture of the part.  http://i1148.photobucket.com/albums/o567/jon8949/CNC/IMG_20150114_184916668_HDR_zpsf47a663b.jpg

The 3D Rhino data file has the part with a sharp edge and I run Visual Mill for my CAM software.  During my simulation in Visual Mill it also shows a sharp edge.  I'm not sure if there is a setting in Mach3 that could be causing my issue.  I'm running a Gecko G540.

Any help would be appreciated.  Thanks, Jon

Maybe your acceleration / decelaration settings in motor tuning?

Mach3's CV mode is rounding the edges. Faster acceleration/lower feedrates may help, or playing with the "Stop CV on angles" setting.

Thank you both for the info.  I'll check that out tomorrow on the machine.