[gemmiti2]

Onsrud's contacts don't seem to work at all...not even the phone system!

Anyways, I need to cut a slot into layered plywood 8"deep x 40" long. The width doesn't matter, but being that the only tool I have long enough to do it is 3/4" 4flt endmill that is 12" long!! I did the majority of it with a standard length 2flt EM and have an additional 4" to go.

Currently I am running it on a CNC router at 3000RPM(the slowest the machine goes) at 120. inches per minute. I determined through experimentation that .01" deep at a time is best, but....that's taking a really long time.

Any suggestions out there? Much appreciated.

[Phife]

Am I understanding correctly that you are trying to cut a slot in 8" thick plywood and you are only going 3000rpm at 120ipm?

If this is true, then your spindle is going too slow, you probably want at least 10000-12000rpm.

If your machine can handle the cutting forces then I would go 12000rpm and 120ipm with a 1/2" to 3/4" cutter and a 1/2" - 3/4" DOC.

These are very rough numbers but should get you started.

[ger21]

Not sure if what happens if you spin a 12" cutter at 10,000 rpm, but I'd also spin it a little faster.

One thing you can do is use a drill to remove the majority of material.

[louieatienza]

A 4-flute endmill for wood is really designed for fast cutting. Of course it depends a lot on your spindle HP

Onsud has a demo video whenre they cut 3/4" plywood with a 4 flute compression spiral bit (!) at 2800IPM(!!) in one pass (!!!)