[sanddrag]

I realize many of you are not working on full VMCs, but I'll post my experience today nonetheless.

I had toolpaths to pocket our gearbox plate. 1/4" 6061 plate, 1/4" 3fl carbide endmill, 6000 RPM, flood coolant. At 25% stepover, and 30 IPM (what FSWizard recommends), my CAM package said it would take 16 minutes. At 10% stepover and 120 IPM (again, what FSWizard recommended), my CAM package says it will take 11 minutes. That's quite a savings. So, that's what I'm running. I should also mention, I'm feeding at 300 IPM through air on the "backstroke" of the HSM toolpath.

Now on the machine, I realize considerable time is being lost due to limits on acceleration and deceleration. I enabled the trial of the HSM parameter on the HAAS control, and saved 2 minutes and 40 seconds, with the exact same program.

I'm doing the outside contour of the plate with a 1/2" 3fl carbide, at 5500 RPM, 25% stepover, and 100 RPM, and it runs fantastic.

If your machine can do it, it seems like high feedrates with a very thin chip are the way to go, if you have the spindle speed for it.

Now, I have two questions:

Don, where are you buying your Onsrud router bits. Link?

For anyone, what feedrate should I be using when going on a helix plunge into the material with a 3 flute square corners endmill? My CAM package always puts the plunge rate at half the pocketing feed rate, but I worry and back it off a bunch, to like 20 IPM. I'm ramping down on a 3 degree helix.