How to Plane Rough Lumber

Learn the basics of flattening rough-sawn wood

Expand your woodworking skills and get access to a wide range of domestic and imported wood for your furniture projects by learning to flatten and plane rough-sawn lumber.

By the DIY experts of The Family Handyman Magazine

The flattening process

If you’re an aspiring woodworker who wishes to move on to more advanced projects, there’s only one path. That’s learning how to flatten rough-sawn wood. Continuing to buy S4S (smooth all four sides) at the home center will limit your project portfolio for two reasons. First, you’re stuck with 3/4-in.-thick stock. Advanced woodworking calls for a myriad of thicknesses only available in rough-sawn form. Second, by flattening dry, rough-sawn wood, you’ll end up with boards that are perfectly flat, straight and true, which is rare with store-bought boards.

It takes an investment to flatten wood, though. You can’t pull this off without a jointer, surface planer and table saw. You could spend a ton of money on a jointer, but a basic 6-in. jointer will do most everything you’ll need; prices start at about $400. If you’re only doing small projects, you can get away with a 4-in. jointer for less money, but you won’t be able to flatten wider boards. Surface planers start at about $350. But you won’t get good results with either tool unless you keep them equipped with sharp knives. As for the table saw, any type will work fine, including portables.

Woodworkers all have their own system for flattening wood, some of which are pretty complex. This is one simple method that’ll get you started. As you get comfortable with flattening, you’re sure to develop your own.

Jointer Smarts

  • Be persnickety and square the fence to the bed before any jointing. That’s the only way to ensure square sides.
  • A rust-free polished bed and fence will give you much better results.
  • When you’re jointing edges, move the fence every dozen or so passes to spread the wear over the entire edge of each knife.

Jointer
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From rough-sawn to flat, straight and true

It’s simple, fast and rewarding to turn gnarly, cupped and twisted rough-sawn lumber into beautiful furniture-grade wood. Here are the basic steps.

Finding Rough-Sawn Lumber

If you have a hardwood retailer or woodworking supplier near you, that’s great. If not, you can shop online. Many rural woodworkers, including pros, buy all their wood online. Search for “hardwood suppliers” to find many sources.

Board thicknesses are always listed as “X/4.” A 4/4 board is 4 by 1/4 in., or 1 in. Always get 1/4 in. thicker than the finished thickness you’re after. For example, if you need a 1-in.-thick final thickness, you should order a 5/4 board. Select widths that are 1/2 in. or so wider than the finished width.

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Dealing with tear-out

If you have tear-out or chatter during jointing, swing the board around and send the other end through first. If the tear-out is still there after the side is flat, let it go and send that side through the planer after the other side has been flattened.The planer gives a smoother cut than the jointer. If that doesn’t do it, you’ll just have to sand your way out of the jam.

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

  • Safety glasses
  • Square
  • Tape measure
  • Table saw

You'll also need a jointer and a surface planer.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

  • Rough-sawn lumber