Flattening Workbenches and Wide Boards With A Router

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174 – Flattening Workbenches and Wide Boards with a Router

The traditional method for flattening a workbench is to use hand planes and winding sticks. While some folks truly relish this labor of love, others prefer to delegate this grunt work to power tools. The power tool method is very similar to the action of a CNC machine. A router is placed inside a sled that rides along two parallel rails that are attached to the sides of the bench. The router sled is very easy to make from scrap 3/4″ plywood. The rails can be made from 2×6 construction-grade lumber. Cheap and simple!

Here are two options for router bits. They have the same specs (1 3/4″, 2-flute straight bits) but the Freud will save you a few bucks:
Amana — 45453 – //amzn.to/2AV03Uk
Freud — 12-194 – //amzn.to/2EAN38o

Perhaps one of the best parts about this jig is that you can re-use it for other things. Have an end grain cutting board that needs flattening, but you don’t want to send it through your planer? Have an oddly-shaped natural edge slab that is just too large for your tools? Both situations can be handled with a setup like this. And if you plan on using it a lot, you can get as elaborate as you want with the design of the jig. The version I show you here is stripped down to the absolute basics.

This video is an excerpt from the recent Split-Top Roubo Workbench Guild Build. Join the Guild today to see the entire set of videos and build your own lifetime workbench!


Robert B. says:

I had to flatten a buddy's 2×4" bench that he made from an old house that burnt down. He thought he did it right but ended up with a 1/4" twist after three weeks sitting in his shop. So I told him that we had to remove a 1/2" before it's flat. So some time ago I had made a jig from 1.5" gas pipe and welded adjustable footings. It will accommodate a 6'x12' table with the extensions. Once together it's a tank. The first thing I do is inquire if the table is ever going to be moved. Then I see if shims can take out the twist. It not and cutting is the only answer then I set it up my jig around the table using Irwin levels. I had two router slide boxes I made out of aluminum channeling. Their tolerances were perfect. Plus they traveled down the pipe on bearings. The problem is that its too easy to move around so I have to clamp it after every pass. But once I'm done, we flipped his freaking heavy table and ate the other side. All he had to do was smooth it with a low setting planer and sand it. Net time I saw it it was awesome.

The Builder's Cave says:

What kind of countersink bit is that?

Brian Mullaney says:

Just wanted you to know I used your method and wound up with a dead flat surface. Flat as a pancake. I couldn't be happier. Thanks for the great video. Something I added that helped was stop blocks on either end of the bottom side of the sled. This kept the sled from sliding off the rails.

I added a spacer between the rails and the bench top which let me route all the way to the edge. Final change was I used pre primed MDF from Home Depot for the rails. The primed surface is nice and slick for the sled and factory MDF edges are dead straight.

Again great video, this method works folks.

Michel Hébert says:

What if you seal the rails with epoxy, wouldn't it be stable?

Yuval Davidi says:

why not use an electric hand planer?

Lee Ninde says:

try using dental floss. cheap, strong, disposable, easier to tension, less likely to weigh down, easier to store, and easier to see the "kiss".

Arsath Sally says:

Can we not use a leveler for the rails instead of the strings/cords?

Vajna & Vajna Dental says:

Nice shirt man 😀

Vlad Malik says:

Very nice and thorough! Thanks for going over every step.

Symore Butts says:

Ummm? Overkill much? I do meth and don't obsess that much. Great video.

Steve's Woodworking says:

I just used this method on my new Roubo workbench top. I was having a terrible time with the hand plane tearing out the wood. This method did the trick. I had a bit of anxiety when doing it, but it all worked great! I did glue on a couple of stop blocks on the bottom of the sled on each end, so it wouldn't accidentally fall off the side board and dig into my top. Thanks!

Alistair N says:

Any reason you can't just use a spirit level to make the pieces of construction lumber parallel? i.e. Level one side, then level across from the end of one to the same end of the other, then level along the other, then go around and check all four positions are level as a sanity check? Or was this business with the string to make the exercise cheaper?

Andrew Eberhardt says:

The string logic is flawed…

Imagine the string is just barely touching. Now raise one corner 2 inches, and lower the other corner 2 inches. The string is still barely touching, but the boards are clearly not parallel.

wighus says:

My favorite part was to see Duggee! 🙂

Greg Brooks says:

do you need a plunge router to do this or can you use a fixed router.

Ron Hochhalter says:

I received the Freud bit you suggested and I'm ready to start this project. My top is a commercial grade restaurant cutting board I received from a friend. Finished off the edges with a piece of Poplar sandwiched between the hardwood cutting board and a piece of red oak on the outer edge. The reasoner doing this is to accommodate for the end vise without cutting into the top. Hopefully I can make the jig so it completes the cut all the way out to the edges. Thanks for this helpful video on how to level the side boards.

Charles Elkins says:

Good Explanation

Robert W. says:

Hey buddy, do you have plans for this bench? If so, where can I buy them/what's the price? Thanks🤘

Sean Baker says:

What kind of plywood is the sled made out of in this video?

PG Tips says:

Fantastic example, great job.

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