Reply by LD100

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Posted on Centering router's bit when router is in a lift?

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9 posts in 199 days

#1 posted 01-05-2021 04:45 PM

Hello all. First, I want to express my thanks for all of your thoughtful responses.

I agree with much of what has been said. It doesn’t matter if the bit is offset from the insert in a router table unless bushings are involved. Bushings don’t directly attach to bits like bearings do, so in this case bit to insert coaxial alignment is important. (Hence the use of centering cones on hand held routers.)

The Leigh RTJ400 is exactly the jig I had in mind that triggered this thread. This particular jig is for router tables only, and you move the jig (and the work piece), not the router. The guide bushing is attached to the table insert and it is elliptical. Because it’s elliptical, by rotating it judiciously one can actually tune the fit of the joint (loose vs tight). However, if the bit isn’t centered on the insert, the jig won’t work as expected. All your tails will be shifted. Which direction and how much they are shifted depends on the offset error in your particular router table.

For those interested here is an old video discussing this jig. (in the video, it’s mentioned that the jig includes a DVD! What’s that?)

When installing my Porter Cable router into my table, I observed that when I rotated the router body, or even simply removed it and put it back in, a slightly different offset error would result. I found this a bit maddening because it was seemingly random. Your tips and comments are all helpful here and dead on.

If I can get my router centered to my satisfaction and lock it in place, I will be happy leaving the Porter Cable permanently in place and call it good.

I purposely did not mention my particular equipment because I was looking for general information. I did not want to start a discussion about “this brand vs that brand” since my purchase is a done deal for now. My lift is a SawStop lift, and I chose this lift because I like the design of the lift mechanism and it’s preconfigured for my saw. The clamp mechanism on it is simple, which I like, but the alignment between this clamp mechanism and the table seems entirely dependent upon SawStop’s component accuracy or perhaps a factory alignment step. There is no mention of a way to adjust the clamp position. I have reached out to SawStop to inquire but no answer yet.

The router clamp has a 4.2 inch diameter. It is aluminum and is held in position by three fasteners (see arrows). I don’t know if the fasteners are locating (e.g. precision shoulder screws) or if the clamp is simply jig-located in the factory and the fasteners locked down.

SawStop includes collars for 3.25 inch and 3.50 inch diameter routers. The manual is vague in my opinion, saying that “if your router is significantly smaller, use a collar.” The clamp is not designed for routers larger than 4.2 inches, and the manual fails to mention that if your router isn’t exactly either 3.25” or 3.50” their included collars are not going to work. The aluminum clamp flexes when tightened but it is not designed to flex much. With the provided sizes they are covering “most routers” out in the world, although I have read complaints about router compatibility with this lift and SawStop’s failure to make this crystal clear up front to shoppers.

One thought I had was that I could loosen the three bolts, reposition the clamp, and re-tighten. I would not do this without express guidance from SawStop. (I don’t want to lose a factory alignment and then create a nightmare for myself.)

My background is mechanical engineering and I regularly work closely with tool and die makers. Thanks again for all of your advice.

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