Flattening a Workbench or Big Slab

The setup of the rails and carriage

The setup of the rails and carriage

Side by side passes along the length of the bench top. About 1/16” deep

Side by side passes along the length of the bench top. About 1/16” deep

A new surface emerging!

A new surface emerging!

Cabinet scraping to further clean up the surface

Cabinet scraping to further clean up the surface

Shiny and flat!

Shiny and flat!

Shop Tip

Flattening a Workbench or Big Slab

This summer we put some time and effort into flattening our workbenches which also served to refresh the surface of each one. Here are some photos of how we did it.

We clamped two straight pieces of poplar to the front and back of the bench top, an equal distance and slightly above the top surface so that the two were parallel with each other. Then we made a carriage longer than the distance between the two poplar rails by about 12”. This carriage was made a little wider than the base of the DeWalt router that we would use for the work. The carriage essentially is a tray that slides across the top of the two poplar rails and that allows the router to slide along it side to side.

The router sits in the carriage, then travels a little more than the length of the bench. The cutter that was used was a wide 1 1/4” straight carbide-tipped bit. Starting from one end, we took shallow, side-by-side passes the length of the bench until we had shaved the entire surface. Our benches get a lot of use, so some had deeper scars or had developed a little twist over the years. Taking off 1/16” flattened most of the benches. A couple of them needed just a little more taken off. There were little tweaks to the setup once we got started, for instance the duct tape on the router was needed to help the dust collector perform a little better.

Once the routing was finished, we refined the surfaces a little further with a cabinet scraper or long bench plane. This whole process was pretty simple to set up and works great for flattening any large plank that’s too wide for machines or just too awkward and heavy to handle, like the benches.

I should mention - I say “we” casually, William did all the work. It was a big, noisy, dusty job. I (Craig) led the emotional support team and documented the process. Well done William! The benches look so shiny and new that we’ve taken to wearing sunglasses in the shop.