Quote:
Originally Posted by Cory
What machine, specifically is this?
If I were running 3/16" HSS I would run it at 200 SFM or so and .0015 chipload, which works out to 4266 RPM and 12.8 IPM. You would have to adjust from this point based on whether you had flood/mist/no coolant.
I would take .090 depths of cut, so 3 passes of .083", plus a finish pass.
Carbide would definitely be a more forgiving option, but that cutter in carbide wants to run at a MINIMUM of 17,000 RPM, so you're not going to get much advantage out of it other than rigidity.
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It's a converted bridgeport (of mine) with ball screws from an older CNC, stepper motors, and a Mach 3 controller that an older mentor put together for us. Now that I've checked, I've realized that I don't have 3/16th carbide bit, so I'm just going to use the HSS for now. If bad things happen, we can make the part bigger and use the 0.25" end mill. We've got plenty of spare aluminum.
I currently have two plans (all at max rpm of 4400 ish, and 3 IPM plunge)
1- Cory's 3x 0.090 deep cuts with a finish pass with 12.8 IPM
2- Jared's 0.125 deep cuts with a slower speed of 8 IPM with an optional finish pass at 12.8 if the tool deflection/machine sloppiness is significant
We're also going to try to see how accurate it really is. Right now, I'm doing the bearing holes undersize, then reaming the hole to press-fit, but for fun, I'll try doing a bearing hole with a 0.01 width finishing cut and a bigger 0.25" HSS end mill to see if I can get accurate enough.