I cast a pair of rotors for a 1/3 scale blower and used Alibre to draw a sample of a half a rotor. I downloaded a copy of Freemill and generated the G code and was able to cut a sample in ABS. I machined both directions, XY and YZ since there is no roughing cut program in Freemill and milled a pair of rotors to test. I mounted a casting and ran on the XY plane and ended up with the correct profile, but when I loaded the YZ program the tool starts correctly by skimming the surface, but then lowers slightly in Z with each subsequent pass and starts to machine a tapered shape. The DRO's show the same readout as the G code program, but if I stop and return to zero the Z axis I get a reading that represents the amount the tool plunged beyond what was programmed and what the DRO indicated.
Any thoughts?
I re-tuned all three axis and they were accurate.