Cutting 1-3/4 inch Oak

[catbourger]

Does anyone have experience with the Amana 46328 compression bit (or equiv). It's a 1/2 inch diameter 1-5/8" cutting length, 3-1/2 OAL bit. Amana tech support recommended I start with 18,000 rpm, 320 inches/minute, with pass depth of 1/2 inch. Does this sound right for oak?

Karl

[srwtlc]

It all depends. What is it that you'll be cutting, small parts with short cuts and lots of corners or large parts with long continuous cuts and few corners. What do you have for a machine and are you using a spindle or router? The chip load, for a 2 flute, at those settings is on the conservative side, but the higher RPM could overheat the tool if you have parts of the cut that will cause the machine to slow down often. Keep in mind also, that on the second and third passes, the downcut portion of the bit will keep chips in the kerf and not cool the bit as well so at 18000, it may overheat it.

Depending on what you have and are doing, you could run at a lower RPM and lower feedrate. Do your profile passes at a heavier chipload with a small amount oversize and then a finish pass at a bit higher RPM and slower feedrate to clean it up.

[catbourger]

Thanks Scott. I have PRS Alpha, with 4 hp spindle. Typically my pieces are about 7 inches wide by 36 inches long. There are pocket cuts as well, but these are 1/4 or 3/8 bit cuts, and I have them under control. I have been using end mills, but I would like to improve the cut and have the bits last longer.

[srwtlc]

Karl, I have the same setup and cut a fair amount of 4/4 red oak. I generally use 0.375" compression bits and run anywhere from 12000 to 14000 and 4-5 ips for a 0.375/pass profile cut. If I need a clean finish cut, I'll leave 0.018-0.020 on the profile and follow up with a full depth pass a bit higher RPM and slower feedrate (1-1.5ips).

I think that 18000 at 5.33 ips is going to heat up the tool a bit much unless your toolpath has minimal slow down areas. If that's the case, you could run faster at that RPM, but will need firm holddown to keep the vibration down. PRS and 4hp can do it, but the cut quality will likely suffer. We don't have the mass of the big iron machines.

Use the Chipload calculator (TL) to find a chipload/RPM/feedrate that works for you and keeps the tool cooler throughout the cut.

[catbourger]

Scott,

Up to now I have used the same feed rate and spindle speed as you have. I will start from there and go up or down as necessary.

Thanks for your help.