Router Technique
Flattening a Benchtop

by jefbur, Jeff Burstable
July 2004

jefbur, Jeff Burstable
I was handed down a nice workbench from my father-in-law who is also an avid woodworker.   Unfortunatley the top of it is no longer flat, and has a pretty bad bow in it.   Due to the large size I am not sure how to tackle this to make it flat again.

Any suggestions?

Do I just break out the belt sander and to the best I can with that?

Go to ebay and pick up a #5 or #6 plane.   It will make quick work of the bow in the table.   then refinish the top and bottom to prevent it from moving again.

Edwin Hackleman:
I might also add to doghouse's comments that be careful that all nails or metal of any sort be removed before planing.   Over time, these get covered up with about anything you can imagine.   It might be best to sand lightly first to expose any embeded foreign objects.   Then plane. That could save your knives.

Another possibility is a power planer.   I have personally never used one of these, but I hear that they work.

This may be overkill, but I saw a show on TV (David Marks???) where they made a dead-flat frame on the outside of the bench for the router to rest on.   You would use a straight bit on the router to flatten the top of the table.   The frame allowed the router to be supported at a single heights and moved in two directions (x- and y-planes).   It would take a lot of time and make a "mell of a hess", but you'd get that top perfectly flat.

Frankly, it seems like more work than I'd be interested in doing.   At this time, I don't need a dead-flat benchtop, but it's another option.

I know the Woodworkers Source here in Tucson has a 18" Drum sander that will do 36" wide stock and depending on the type of wood it should cost about 15 or 20 dollars to have it sanded flat.   It might be worth some time to call around and see if that type of sevrice is available in your area.

jefbur, Jeff Burstable
Well due to the width of the table I was not able to get a hand planer to work for me, however the good news is I came up with a jig.

With my router and alot of time and patience, I was able to get the top perfectly flat.

I screwed a piece of wood onto each side of that table.

Then, I built a bridge like jig for the router to ride on.

The feet of the jig sit on the wood that is screwed to the side of the table.

I set the router to the lowest spot of the table, then just routed off the high spots.

I was concerned about sagging, but it didnt at all.

I used 3/4 ply for the jig, and I was careful not to push down hard.

Using 2 layers of 3/4 ply would probably be fine if you are concerned.

I did blow through 3 router bits in the process, so yes, it does eat them up, or at least the brand I have.

It did leave little ridge lines which were easily removed with my handheld belt sander.

I'll try and get a couple of pics up later tonight of the jig setup and the end result.

I didnt even notice that post before you guys mentioned it.

Sheesh, that is exacty what I did, could have saved myself alot of time if I wasn't so blind.

Here are a few pics:

Jig setup:

Overall pic of redone top:

Now the entire top needs to be finished, any suggestions for a durable finish?

The top is Oak if that makes a difference.

I'd go for poly/BLO.   It will keep glue & stuff from sticking & can be renewed without a lot of work.   Might think about a sacraficial top of hardboard, too.

What kind of construction was required to keep the bridge from sagging in use under the weight of the router and your pushing?

I have been considering doing the same thing but worry about that.

Did one bit stay sharp through the entire process or did you have to use several?

Looks like you used a jig something like the David Marks one described in my early post.

Would love to see pictures if you got 'em.

Congrats on the bench.   Has your FIL seen it?   Bet he'd be a little jealous seeing his bench lookin' like new.

Mark Gunter:
Good job of jigging up, Jeff, and good job on the top.

If it were mine, I'd seriously consider a plain oil finish, and maintain it as needed every few months.

If you think you might do alot of damage to it, you can always use a hardboard skin on it and change the hardboard when it gets ratty.

Remember, that when using an oil finish on Oak, you don't really want to flood the wood, as the large Oak pores can absorb the oil deeply enough into the wood that the internal oil may never cure - and meanwhile, the pores will bleed out for quite a spell.   So, oil on Oak works fine for me if you apply it conservatively.

Good luck with the "new" bench

Joe Lyddon:
That makes very good sense!

Hey, is it OK with you if I saved parts of this thread & pictures for my web site under Router Techniques??

I will be adding this technique to my website...

... working on it...

Have fun,

Email: jefbur, Jeff Burstable

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