Slightly simpler than Andy’s version, just use the profile of the portion you want to leave, do an outside contour, make the first pass with as much offset as you want/need to cover the whole part and make successive passes with less stock left until you make one final pass with no stock left. In this case you can probably just do two passes, first leaving .020” stock, then the final cleanup pass.
See attached dxf…..
On Mar 29, 2015, at 7:06 PM, email@example.com (firstname.lastname@example.org) [sheetcam] <email@example.com (firstname.lastname@example.org)> wrote:
I have a cylinder on one end of which I want to leave a raised area that is the full width of the circle and 3mm wide. It will be 2.5mm high. See attached dxf. I want to put this on end in a V-block and use a 1/2" end mill to simply cut down 2.5mm.
I have tried all manner of operations (contour, facing, pocketing) in combination with dividing the lines into various contours (just the two horizontal lines, the half-circles as contours, etc) but can't for the life of me get a tool path that will cut this. The closest I get is cutting the raised area by making the two center lines separate contours and doing profile with outside offset . But then the outer part of the circle will have to be cut manually as the cutter can't reach the edge, I just can't get the cutter to go out there. How is one supposed to do something like this?