Originally Posted by Ekka

What stump grinder you got?

what engine?

What pulley sizes?

What dia cutter wheel?

I can tell you I did a lot of work in this area getting my Kanga to cut better.

Most engines will do around 3500rpm and maybe 3000rpm under load.

On a cutter wheel around 500mm dia you want the wheel doing around 1700rpm ... working on engine doing around 3200RPM

Now the Kanga was doing stupid speed, cutter wheel was way to fast and more like dust was coming off rather than chip ... also less torque.

Now the larger Rayco machines etc the cutter wheel only does around 1200rpm to 1400rpm but they are bigger dia wheels so the circumference speed is a lot higher.

There's a preferred speed, just imagine a lathe and you go too fast or too slow with the chuck. For wood the cutting speed is around 8000ft/min