What spiral bit for a downdraft router table?

[tim walker]

I see up cutting, down cutting, and even have seen combos spiral bits. I will be using mine for cutting plywood using a temp[late on a downdraft router table. Does it make a difference if plywood or solid wood which to choose? I have read somewhere that one causes more tearout than the other but don't remember which does what. TIA

[Mel Fulks]

Tim, you don’t say what you are trying to do. The fastest cutting bit is a 1/2 “ diameter single flute .

[Robert Engel]

Depends which side the template is on. Want to draw toward template.

[Mike Gresham]

Tim, In my experience, up and down spiral bits do not differ amount of tear out, but in where the tear out is most likely to occur. Up spiral is most likely to cause tear out on the surface closest to the router. Down spiral is most likely to cause tear out on the surface farther most from the router.

[Wes Grass]

Grooves or pockets, down cut.
Profiling, compression bit.

Solid wood, deep pockets, up cut.

[tim walker]

Sorry was out of pocket. My first project will be using a template to cut out large areas 16" x 4-1/2" in plywood like Ron Paulk does. I have seen vids of people using a handheld router to do this but seems much easier with a template on a router table. Since some of these sections will be as long as 7', I think it best to have the template on top. In the future will be doing dados in both ply and solid wood. 459475