[DonRotolo]

Yes. Specifically, I did the calculations for an Onsrud 63-620 (1/4" diameter) single-flute upcut bit for Aluminum, with a 1" stickout, running at 16,000 RPM and a straight-line cutting speed of 60 IPM. Under those conditions I can cut as much as 0.300 of material in a full slot. I know it sounds crazy, but it really does it. Less than 0.001" deflection. I didn't calculate the HP, but it is well under 2, maybe even less than 1.

But an Onsrud 63-760 (1/8") for polycarb with 1" stickout at 10,000 RPM and 64 IPM can only cut 0.020" deep slots. It is weird, but the thinner bit really deflects so much more compared to the 1/4" bit.

Both assume a fairly strong stream of air to blow chips out of the slot, and a vacuum system to whisk them away. For the aluminum, add mist coolant to the mix. Allowing the bit to cut chips twice is almost asking for it to shatter.

34 IPM doesn't give you the chipload you need, it is 0.0019 and Onsrud specifies 0.003-0.006. Reduce RPMs or run faster. Never any harm in taking a smaller depth of cut if .250 gets you nervous.