Problem with radius cutting?

[jamesigi]

Hi,

I've recently just put together a 4 axis hot wire machine for cutting foam shapes out. And on a specific design that I've been trying to cut all corners come out radius except one. Whenever my machine goes to cut the same corner it ends up stepping up the cut and creating a niple before completing the cut.

I've tried to include some picture of the cut i desire and the cut i'm receiving.

For other info:
Im drafting on Autocad 2006 and converting in CadWorks 3.0
All radius edges are at 1/4" and 1/2" except the very top (or peak) of the shape which ive set at 2"

I'm justr curious as to why im getting the top cut wrong.

Also the correct foam shape picture is a screen shot from the .dat file i get after converting my cad drawing in CadWorks 3.0