Router RPM versus Bit Diameter

I am fortunate to have a Bosch 1617evs variable speed plunger router. For some reason I never utilized its variable speed capability. In my younger days as a machinist, I recall numerous charts and reference material which would allow machines to be adjusted for RPM and optimum feed rates taking into account various materials being machined.

Based upon my previous metal working experience I decided to use the speed adjusting capability and see how it worked. My routers speed adjustment is graduated in numbers from 1 to 6, 1 being equal to 8000 RPM and 6 equal to 25,000 RPM. My experience has been very favorable. As a general rule the smaller the bit diameter the higher the RPM. I use 1/2 inch straight slot bits frequently and running them at 16,500/20,000 RPM works very well. The bits seem to last longer, produce a better finish and the noise factor is significantly reduced. Some recently purchased, inexpensive, two flute HSS end mills seem to work a lot better, and hopefully will last longer between sharpening.

Here is some info about routers which includes a chart of router bit speeds based on the diameter of the bit: http://www.rockler.com/articles/router-bit-basics.cfm

Google "Router bit speed charts" and you will find a number of charts.

I flipped the switch the wrong way when I started up a 2 1/4" cove bit, 5 1/4" in diameter. Started at 22,000 RPM.

I "KNOW" why they put speed controls on these thing. Sounded like an air raid siren, scared the begezes out of me.

I use a simple rule of thumb. Starting at half inch at 22,000, I knock it down a speed for every half inch after that.

Larry

Many better bits come with recommended speeds on the packaging but, the link Howard pointed you to should cover things close enough. Here's another example: