When to change router speeds?

[Dave Cullen]

I have 2 routers and both are electronic variable speed. I don't remember ever changing the speed setting on either of them, they're just set somewhere in the middle. What criteria do you guys use when determining the optimum speed?

[Mel Fulks]

When you use an unusually large diameter cutter is the most important ,I've used them with rosette cutters over 3 inch diameter on slowest speed. STEEL bits need slowest speed that works well. Small diameter carbide bit run at highest speed for most things but when doing something tedious in odd spaces they can be slowed to stop burning.

[Keith Hankins]

Changing speed is important as bit diameter increases. For the best answer refer to your bit manufacturer documentation (assuming not the cheep chinese crap). Google router bit speed chart and there are general based ones as well. Not say this works for all but is generally correct. Those big 2"+ bits turning at his speed very dangerous.

http://www.woodline.com/instructions/Speed-Chart.pdf

[Fred Heenie]

Two thoughts and a tip. I run a PC 7518 five speed in a table. Thought # 1. The larger router bits that I buy usually have a max speed printed on the package. # 2. The router instruction book had a speed chart printed in it. I typed, printed and laminated the typed chart one the table frame below the table top and above the router for reference.
HTH

[Al Launier]

Size of cut, geometry of bit & types of materials to be cut should dictate speed.

[glenn bradley]

I can only echo what's been said; beyond the speed setting based on bit diameter I also adjust speed for:
- burn prone woods like cherry and maple - I use lower speeds.
- template routing where some cutting against the grain cannot be avoided - I use higher speeds and light cuts.
- bits with center spurs like a double-bead bit for beaded panels - I use a slower speed even though the bit is small as the center point can burn.

Try some of the things discussed in this thread and I bet you'll notice a difference ;-)

[Dave Cullen]

Thanks for the replies. I do notice some burning with maple, even with a small bit. I'll experiment with router speed and see if I can eliminate that. It's just a knob twist.

[pat warner]

In my view, routers with 1/2" collets should see no cutters >1.5" in length and/or diameter.
And most of the time, for cut efficiency, the machine should run at the max. This applies essentially to sharp cutters. If they're not sharp I'd still run them full out, but I wouldn't take the full cut. I'd save the last 10% for a new (same geometry) cutter in a different router. The cutter in router no.2 will last 2-4x longer this way. Moreover, the final cut quality will be as good as the equipment will allow.
Now balance has to be addressed. If a cutter is out of balance, typical in tool bits>1.5" or one that has been poorly re-ground, you have to run it slower. Vibration is your enemy.
It can send you to the ER &/or destroy the work.
For those materials that char a 2 stage rout will yield a burn free cut.
Appreciate that routing has been way over hyped. It's said that routers do everything.
And in their day, with small cutters, they did well.
Now with bigger cutters and motors they don't scale. Things are not twice as good with a cutter twice as big (generally). At this point it's shaper time, the tool whose cutters have been minimized, exploited, and compromised for routing.