Flattening a board with a router table?

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Forum topic by Brett posted 09-13-2012 10:21 PM 9295 views 0 times favorited 6 replies Add to Favorites Watch
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683 posts in 3539 days

09-13-2012 10:21 PM

A discussion on another web site about flattening boards with a hand plane gave me an idea for using a router table to flatten a board.

If you put a straight bit in the router and set its height so the bottom of the bit is exactly level with the table surface, you should be able to move a board around on top of the router table and eventually make the board flat (assuming your router table surface is flat and the board is shorter than the width of the table). The board would probably need finishing with a smoothing plane, but in theory, you should be able to flatten any board this way.

I don’t have a router table (yet) so I can’t try it myself. It might take a lot of effort, but I bet it would work.

(Note: you’re on your own as far as safety is concerned; I make no guarantees.)

-- More tools, fewer machines.

6 replies so far

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#1 posted 09-13-2012 10:26 PM


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#2 posted 09-13-2012 10:31 PM

I did this for years! Many moons ago, on another planet, (read, my first marriage), I was not allowed to buy the proper tools, even though I was making commission pieces, and professionally refinishing for years. I took a homemade router table and did exactly what you describe. If I remember, it was a Craftsman router with a straight bit, a broken light and a stripped locking nut. What fun!! Used to keep a set of locking pliers on the bench to change bits.

To be honest, the results were mixed, and overall, not too good. When a piece is say, cupped, you start off knocking off the edges. Then you come back through and maybe get another inch or two, and probably leave some lines which are actually different levels on the wood. You quickly find out that .002 on a router table part turns into a much bigger mistake on your piece.

What I finally did was to buy an electric planer from Harbor Freight and had much better results with that, after ruining a lot of wood to make it work.
Finally, I changed my life and now I have a nice planer. And that’s all I’m gonna say about that!!

-- Tsunami Guitars and Custom Woodworking, Cleveland, TN

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#3 posted 09-14-2012 05:36 PM

Google “router planing sled”

If the bit is level with the table it won’t touch the wood. If the bit is above the table it will cut but not flatten because you have no fixed reference.

-- Rick M,

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#4 posted 09-14-2012 05:46 PM

Umm… why won’t it work (at least in modified form… listen to me on this a few lines down)? wormil’s suggestion is probably a better approach though. That’s what I do to flatten slabs (well, I do it at a much larger scale). I have a wide bottom cleaning bit (mortise) that I have set up on a bridge crossing my work table. I make passes and flatten the slab out. This is just a larger scale version of what Brett is suggesting. It is very effective and saves me a ton of time compared to trying to use a #7 or 8 jointer.

The only parts you have to be sure of are keeping the board in place and making sure the router is staying referenced to one flat plane.

So, to make the OP’s idea work, you could do something like setting the router bit 1/8 or 1/4” higher than the table. Set a 1/8 or 1/4” flat piece of MDF next to it such that the board surrounds about 1/2 the router bit’s diameter. Feed the board you wish to flatten into the bit in such a way that when you “flatten” part of the board it rests on the MDF. Understand?

References to semi-related slab flattening jigs.

-- "Well, at least we can still use it as firewood... maybe." - Doss

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2202 posts in 4015 days

#5 posted 09-14-2012 06:10 PM

If the errors in the board were small enough to sink into the hole in the table, then it’d work. That’s never the case. You have to flatten large zones in the wood, which means nothing will ever fall below the table line.

The Sand Flea drum sander works on a similar principle, but only because the drum is slightly proud of the table. That works when you can push a board through in one pass, which is not possible with a small bit.

The “router sled” works well, however…just need to clean it up with a smoother.

-- jay,

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779 posts in 3121 days

#6 posted 09-14-2012 06:18 PM

Yes, the router sled will definitely require a smoother, sander, or similar to get the marks out of the board. There will be marks. No doubt about it. LOL

-- "Well, at least we can still use it as firewood... maybe." - Doss

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