Originally Posted by
ger21
Yes, what size bit, and what size is the pocket?
Different diameter bits require different rpm.
Feeds and Speeds in wood can be tricky. Do you want maximum tool life, or best finish? Depending on the specific material, they may be very different.
Also keep in mind that machine rigidity and power can play a huge role.
Most major router bit manufacturers list recommended feeds and speed. Onsrud has some very comprehensive charts.
But these charts are generally geared towards maximum tool life. Most hobby machines can not achieve anywhere close to these speeds.
If you are using a 1/4" bit, 21,000rpm is much higher than you should ever be running.
At 200ipm with a 1/4" bit, try 15,000 rpm.
Depending on the pocket size, you can also find that the machine never gets up to full speed, and is actually cutting much slower than the commanded feedrate.