Hello all. In programming a part with a oval keyway in the OD to run on a Mazak 18-MSY mark 2 with a Maztrol T Plus control.

I'm using the MGV milling function, trying to cut a .408" wide slot with a .313" endmill. My slot looks 95% complete, but one end of the slot has an incomplete radius. Instead of a full radius blending smoothly into the long straight walls, one corner has a distinctive blend mark from a smaller radius. If I were programming in EIA, I would think that I inadvertantly turned tool comp off too early, because the endmill seems to be pulling too tight a turn going into the last corner of the slot. The resultant radius measures about .360", which is not the tool or the programmed part geometery.

My process parameters are as follows:

MODE: MGV OUT
Mode #: 3-0
GRV-WID: 0.408
DEPTH: 1.08 (through the part)
FINISH: .010
RV: 120
FV: 180
R-FR 1: 0.0008
R-FR 2: 0.0005
R-TOOL: 9
F-TOOL: 9

SEQ:1
SPT-R: 0.535
SPT-O: -90.0
SPT-Z: 0.625
FPT-Z: 0.640
ROUGH: .001

Any idea why this slot is not comming out oval? I'd program it as a MMP (Manual Milling Process), but I only have +/-.0025 on the slot width, and then the operator would need to edit the program to size the slot instead of comping the tool diameter. I'd like to avoid that. Any help would be apreciated.