There are a lot of different things that can go wrong with lumber. A board can be bowed, cupped, warped, or twisted. Out of all of those, twist is probably the worst one to deal with.

A bowed or cupped board can be annoying, but a twisted board is especially hard to use because it won’t sit flat. If you try to build with it as-is, that twist is going to show up somewhere in your project.

That’s why a lot of woodworkers prefer buying rough-sawn lumber and milling it themselves with a jointer and planer. But what if you already have a board that’s twisted?

I had a nice piece of poplar that I wanted to use for a project, but once I checked it, I realized it had a bad twist in it. At that point, I had two choices: throw it in the scrap pile or flatten it.

I decided to flatten it.

Why I’m Using a Planer

There’s more than one way to fix twisted wood. Traditionally, this could be done with a hand plane. Some woodworkers would use a jointer, but to do that well, you need a fairly large jointer with a long bed.

A lot of us don’t have that. I don’t have an 8-inch jointer with a long bed sitting around for boards like this.

What many woodworkers do have, though, is a planer. So for this method, I’m going to use a planer with a flat reference board underneath the twisted board.

The planer by itself won’t remove twist. If you run a twisted board straight through the planer, the rollers can press it flat as it goes through, then the board springs right back into its twisted shape afterward. That’s why we need a sled.

Setting Up the Planer Sled

To make this work, I need a good, flat board to use as a reference surface. This will act as the sled or bed underneath the twisted board.

I’m going to attach the twisted board to the flat board so the planer cuts the high spots without forcing the board flat.

To support the twisted board, I’m using a couple of wedges on both ends. These are just normal wedges, like door wedges. The goal is to stop the board from rocking.

Once the board is supported and no longer rocking, I can fasten it to the sled.

Attaching the Board

To hold the twisted board in place, I’m using hot melt glue.

I know that sounds a little crazy, but hot melt glue works well here because it holds the board securely enough for the planer, while still allowing me to take the boards apart later.

Once the twisted board is supported by the wedges and glued to the flat reference board, the whole setup is ready to go through the planer.

Flattening the First Side

The idea with the planer is simple: I’ll take as many passes as needed until the top surface of the twisted board is flat.

It’s easy to tell when I’m done because the entire surface will have been machined by the planer. In this case, the board was a little old and discolored, which actually helped. I could easily see which areas had been cut and which areas had not.

If the board didn’t have that discoloration, I would draw pencil squiggles across the surface. As the planer removes material, the pencil marks disappear. Once all the marks are gone, you know the planer has touched the whole surface.

After a few passes, the entire top surface had been planed. That told me that side was now flat and no longer twisted.

Planing the Other Side

Once the first side was flat, I removed the board from the sled.

The planer puts a lot of force on the boards while cutting, and the rollers help keep everything stable, but the hot glue still comes apart without too much trouble afterward.

After separating the boards, I checked the poplar again. The planed side no longer rocked, which meant the twist had been removed from that face.

Now the next step was to make the other side parallel to the flat side. For that, I could run the board through the planer normally, with the newly flattened face down.

I took light passes until the opposite face was cleaned up. I didn’t want to remove more material than necessary, because every pass reduces the final thickness of the board.

The Final Result

What started as a twisted, nearly unusable board became usable lumber again.

Both faces are now flat and parallel to each other. I did lose some thickness in the process, which is always something to keep in mind when flattening warped lumber.

 

This board started out as standard S4S lumber, about 3/4 inch thick. After removing the twist, it ended up a little over 5/8 inch thick.

That means I can’t use it the same way I would use a full 3/4-inch board. For example, I wouldn’t edge glue it with other 3/4-inch pieces unless I planned for that difference. But it’s still good lumber, and I can use it in the right project.

Before flattening, it was basically scrap. After flattening, it’s a usable board again.

Flattening twisted wood takes a little setup, but if the board is worth saving, this planer sled method can make a big difference. You lose some thickness, but you gain back a board that can actually be used.