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Discussion Starter #1
I'm in the process of making a router table. I've seen reference to "dead flat" in this Forum as the desired spec. for router tables. My latent machinist genes (Father, Grandfather, Great-Grandfather) tell me there has to be a tolerance involved in the definition of "dead flat."

So, I'm looking at my bench top as an assembly surface for the router table top. I have previously routed it flat(?) using the "sled" procedure described elsewhere on this site.

The router table top will be about 32" x 24". I've placed a precision straight edge (flat to 0.00064") over various locations on the portion of the bench top where I would assemble the table top. I couldn't get a 0.01" feeler gage under the straight edge at any point on the top. Didn't try thinner gages - just used the first one I grabbed.

I also tensioned some 6# test monofilament line across the diagonals of the potential assembly area. The diagonals are 42" long. One line was slightly above the other. Hard to see (at least for these tired old eyes), but I was able to determine that putting a 0.025" feeler gage under one side of the bottom diagonal line would raise it so it just kissed the top line.

So, my question is: Is this portion of my bench top "flat" enough to assemble my router table? My alternative is a portion of our kitchen's granite counter top. However, this will require some skillful negotiations and possibly some major concessions on my part :)
 

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crosseyed & dyslexic
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I think your work table is plenty flat enough, even though I think most guys were referring to "dead flat" was the actual router table top. That is most important. Using material that is stout and flat is number one. I used 1" mdf laminated to a 1/2" mdf then used plastic laminate on both sides to maintain flatness. I don't know what kind of router you are planning on using but my PC 7518 weighs a lot!
I'm glad I didn't skimp on the top.

Good luck!:thumbsup:
 

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Machinist flat is much flatter then for woodworking. You don't want it dipping so it throws the cut off. I'm sure your table will be flat enough if you have machinist background.

As mentioned make it strong enough not to flex or sag with the router in it.:thumbsup:
 

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Discussion Starter #4
I think your work table is plenty flat enough, even though I think most guys were referring to "dead flat" was the actual router table top. That is most important. Using material that is stout and flat is number one. I used 1" mdf laminated to a 1/2" mdf then used plastic laminate on both sides to maintain flatness. I don't know what kind of router you are planning on using but my PC 7518 weighs a lot!
I'm glad I didn't skimp on the top.

Good luck!:thumbsup:
My thinking was that the flatness of the surface on which I assemble the table top will govern the flatness I achieve in the final product.
 

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Make sure the insert flatness is carried over from the table.... No good getting a flat table if the insert isn't up to the job...

Sent to y'all offen' a iPad thing......
 

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In my experience with plastics, I had to have metal tools that had a tolerance of .0045".

In wood working, I can cut a piece of factory built laminated MDF and I'm fine for a router table.

Different industries equal different tolerances.

Curtis
 
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