Can anyone help me figure out why I am breaking so many endmills? I've probably spent $100 this weekend just destroying 1/8" endmills. I'm at my wits end.

The attached job in the zip file is for SprutCam 9. I am using a Tormach 1100 (max spindle speed of 5100 rpm). My material is 6061 aluminum. I am trying to take a 1/8", 3 flute, ball nose carbide endmill and cut a 3D profile. The tool has a 1" stickout. Although the shape is double sided, I am only doing one half of the shape and leaving the rest as stock. (This was a "test" shape from another CAD program, and I was able to successfully mill it on my Taig using that program...)

Using GWizard, and taking a cut width of 0.015" and a depth of 0.050", I get a max feedrate of 70 IPM (before deflection becomes an issue). I dialed it back to 68 IPM, just to give a margin of safety. This gives a chipload of 0.001 IPT, which seems very light to me. I realize that in the CAM file, calling this a "roughing plane" is more than a bit of a joke, but I wanted to try this using just one tool, rather than worry about tool offsets and all that jazz, since this is my first time using the Tormach.

Although both GWizard and SprutCam seem to suggest this toolpath is great, it breaks my endmills. What am I doing wrong here?

Thanks in advance for your help!