Max velocity

My small machine can't handle 120 ipm velocity. I have to keel dragging the slider back to between 60 and 70 ipm. How do I make a change in MyMill.ini to set max velocity that works for me?
 

Doesn't really answer my question but did figure it out in those sections. Don't understand the relationship between 2.00 and 120 ipm. With some trial and error settled in on a setting of 1.34. Gives me 81 ipm. If I go higher the steppers over step. In reality I don't need .0005 resolution so could change from 1/2 step to full step. I just make wood gear clock parts and plastic repair parts. .001 resolution would be fine.

Thanks for the info.
My little machine began it's life as a circuit board router. The engineers couldn't get it to work. Kept breaking the cutters. Z was two stage solenoid. The engineers weren't mechanical so it got stuffed in storage. I eventually got slated for the dumpster. I intercepted it , resigned Z to stepper drive. Made several other changes before finally putting it to use.
I'm retired so it's mostly for hobby projects and repair projects.