Endmill Options upcut vs downcut

[DIYAudioGuy (Justin DIY)]

I have found that when using an upcut endmill to cut plywood I get long plywood “hairs” that clog up the dust boot, but with a down cut endmill I get tear out in the plywood (I am cutting dados and rabbets in the plywood, see pic).

Does anybody have any experience with combination upcut/downcut bits? I think the correct term is compression bits? Does carbide create sell them?

[WillAdams (William Adams (Carbide 3D))]

I’ve had good success in plywood w/ a #251.

Compression tools require that one get a toolpath sufficiently deep to engage the upper flutes which have the downcut geometry.

[CullenS (Cullen Simpson)]

I have used compression bits on plywood and had very good results with them.

[Woodcrafter (John Matteson)]

I’ve also had good results with compression bits.

Here’s a fairly recent post (Oct 2024) discussing them that might be helpful.

Understanding setup of compression bit

I want to cut a shape out of a board that is 3/4" thick. I am considering a compression bit to do this. Let’s say for example this one: My small understanding is that the initial cut has to go deep enough to get past the 7/32" tip of the bit (which is upcut) to be effective at reducing tearout. How do I set that up? Do I make my depth of pass 7/32" (roughly 5.6mm), that seems like a LOT. I guess I’m not sure how to properly use it