Big Bits

[crashfixer]

I have a simple question for you guys.I have just bought a new PC 3HP router for my router table and it has speed adjustment on it.My question is how to determin what speed it should be set at?I will be using a variaty of bits from a simple straight bit to panel raising bits.I assume the large bits would require the slower speeds but I just want to make certain.

[Tom Hintz]

You are right, the larger bits are designed to turn slower. There is a lot of mass, plus it is farther from the centerline of the shaft so the outboard edges are going faster yet.
I don't know exactly what speed I turn my big bits at because I just slow them down until they sound "sweet." The bigger bit sound terrible when turning too fast. It's not really a vibration, but there is something harmonic going on. When you get them slowed down the sound much better, and work great.
Your bits may have a listed speed you can find in the packaging or on the manufacturers web site. I'm sure they have a spped rating somewhere.

Tom Hintz
www.newwoodworker.com

[Fried Elliott]

See RobertM's post #11 in this thread:

http://forums.woodworking.com/dcforu...mID9/1515.html

[krethjr]

This month's American Woodworker had the following table for router bit speed settings:

0-1 24,000
1-2 18,000
2-2.5 16,000
2.5-3.5 12,000

They also stated that other factors including the rate of work piece movement, depth of cut and type of wood will effect your speed selection. BUT, for safety reasons, the bit diameter is the most important consideration.

Their other suggestion was always to try out the settings on a scrap piece first (no duh?)

Jim K

[MadMark]

Simple rule of thumb, divide the router max RPM by the bit dia in inches. So for 1" or less, use full speed. 2" half, 3" 1/3rd.

Goal here is to keep the cutting speed (radial velocity of bit) constant.