Clutchcargo

I picked up a large lock miter router bit to miter together some columns into 5/4 pvc. This will be my first project using a router. This bit is difficult to set up because it's basically just trial and error until you get it right. My question is, what speed should this bit be turning at?

Tippy

The speed of a router bit is a fxn of its diameter. The guideline I use is not to exceed a tip speed of about 75 mph. You can go up to 100 mph if you feel the application really calls for it. So, a 3" bit will run 8000 rpm (roughly 71 mph) and a .5" bit will run the full 22,000 rpm of the router (roughly 33 mph).

Anyways, this is just a guidline I use. Routers and their bits are designed to run at high rpm's, as opposed to shaper cutters. So you can be a little north of my 75 mph threshold to get a little cleaner cut. However, as I said, I don't exceed 100 mph, it can lead to bit failure.

TexasTimbers

Trial and error is it with a miter lock bit. At least that has been my experience. As to the RPM all I know is mine works best at the #3 setting on my big Porter Cable. At least for most woods.

But Tippy sounds like he knows what he is talking about I'd take his advice. I never thought about converting RPM to MPH.

Okay I just looked at my router and the #3 setting is 16,000.

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Clutchcargo

It seems like 8000 RPM is far to slow, it causes the workpiece to chatter\. I find that 16-20000 seems to work better. I'm cutting 5/4 PVC boards.