[danielcoyle]

Hello

I have been using straight fluted cutting bits predominantly until now. I now have work that would definitely benefit from switching over to a more effective spiral bit type. I understand that spiral bits cut "better" than straight fluted bits and that, generally, more flutes is better but I don't REALLY understand this. Before I start buying two or three fluted spiral cut end mills for my wood working I want to know as much as I can about which is right for me. Does anyone have some time to spare or a good link to send me to?

[ger21]

and that, generally, more flutes is better

Actually, for wood, more flutes are not better. You'll almost always want to use 2 flute bits, unless your cutting plastics or aluminum, where 1 flute bits are often a better choice.
Three flute bits can be used for wood with very high feedrates, but few smaller machines are can use them effectively.

What will you be using them for?

[danielcoyle]

. Thanks. I have a larger machine. Its a four by 8 with a 6 horsepower spindle that maxes out at about 18,000 rpm. I want to use the mill to cut plywood sheets and strand board sheets. Until now I've really been in the business of carving. So, I'm not very familiar with common processing of sheets and boards like this.

[ger21]

You want to use a compression spiral. Plywood is hard and abrasive, so I'd look at a chipbreaker compression spiral.
Vortex Tool: Two Flute Upcut & Downcut Spiral (with chipbreakers) - Series 3400
Vortex Tool: Xtreme Performance Compression Spirals w/Chipbreakers - Series 3400XP

I'd try a 3/8", and start around 400ipm at maybe 14,000-15,000 rpm.

[SignsOfHa]

Forgive me if you know this, but compression is good because you get a clean edge from the down spiral, and the bottom up spiral keeps it from cramming everything on the floor of the cut. Yes, they're expensive, but so is your time.