router table flatness

[keith ouellette]

If the router table is not flat could that cause the cope section of the cut on a matched set of rail and stile bits to be off a little?
Everything else is tight but there is a little space at the cope.
I thought it might cause the piece to go through on a tilt and make the cut loose.

[Charles McCracken]

Keith,

That's a possibility. The stile could span a low area and the rail ride low through it. Can you post a picture of the joint?

[glenn bradley]

Cutting rail and stile pieces that fit poorly is what led me to put a straight edge on my RT once upon a time. That's when I found out the 1 1/2" thick laminated MDF will still sag is there is an unsupported span of 22" :mad:. My now well supported RT does a great job. A very small problem as you describe will result in an unacceptable joint.

Also, holding the piece by hand against a miter gauge or a backer block is not a good method of control unless you've got a really strong grip. Use a small clamp or make yourself a sled. You'll be happier.

[Greg Cole]

I too have a premade RT top that I don't like to say how far it sags.... :mad:
Even with the 1" x 1" angle iron supports, it's still not flat enough for routing on long pieces. If I'm doing small things, it's ok... but anything over @ 18" or so and I'll see the vairiance in cut-profile etc due to the sag.
Another "one of those days" projects is a build my own... or the Bench Dog cast iron style. Sadly, the RT top I have now is a common brand of the 1 1/2" phenolic coated and I had better rail n stile joints using the Bosch table top Borg bought RT (which I gave to a neighbor when I bought the "better" one).
I have a 24" x 48" piece of 1" thick phenolic coated BB ply that I bought thinking maybe I'd use it for a top.... if you haven't seen 1" BB ply, you'll have to do a double take when you start counting the layers... like 22 of them.

Greg

[Jim Becker]

Yes, any time you are doing a "matched set" deviations in the work surface can affect the quality of the joint. One way to help compensate is to be sure to use feather boards to hold the material down on the table and flat to the fence so that the material is always in the exact same position as it moves through the cut.

[George Bregar]

Yes, any time you are doing a "matched set" deviations in the work surface can affect the quality of the joint. One way to help compensate is to be sure to use feather boards to hold the material down on the table and flat to the fence so that the material is always in the exact same position as it moves through the cut. Which is critical even if the surface is flat, as the stock may not quite be.

[Jim Becker]

Which is critical even if the surface is flat, as the stock may not quite be.

You're correct, George. I should have mentioned that, too. Chalk that up to delayed action from the morning latté......

[James Hart]

Several years ago, with my first home-built router table, I used a Rousseau router table plate. I immediately noticed that it seemed the wood was tilting up as it approached the bit, then down after it passed. It was slight but enough that you could see it.

I picked up the package and read the back, 'all Rousseau router table plates are milled with a small crown in the center to ensure consistent depth of cut.'

I can't say whether this is still the case, but that one is long gone.

Jim