Flattening Wide Boards
You don’t need monster machinery to flatten monster boards.
By Dave Munkittrick
Big, wide boards make my heart race with anticipation. Panels and tabletops are so pleasing to look at when they’re made from a single board. Absent are jarring grain patterns and color changes caused by multiple board glue-ups. And I avoid the hassle of trying to match boards for a uniform, pleasing appearance.
I used to shy away from these beautiful wide boards because I thought I needed an aircraft carrier-sized jointer to flatten them. Over the years, I’ve learned a few tricks that allow me to take advantage of what a wide board has to offer—even in a small shop.
Don’t limit your woodworking to boards that fit on your jointer or planer. Here are four tried-and-true techniques to tackle any size board with confidence.
Power-Plane by Hand
For really wide boards, you’ll have to abandon stationary machines. A handheld power planer is the key to this technique. First, you need a flat surface larger than the board. Shim the board under the high spots so it won’t rock. A cupped board should be set convex side up at first to prevent rocking. Mark all four edges of a wide board with a marking gauge to indicate its high spots (Photo 1). The gauge is just a 2-in.-thick block with a 5/8-in. dowel set in a hole. Power-plane the board down to the marks (Photo 2). Use a set of winding sticks to fine-tune the flatness (Photo 3).
Big, thick planks are best flattened in stages. You don’t want to remove all the wood at once. That’s because removing wood releases tension, causing the board to slightly change its original shape. Remove about 75 percent of the wood you need to take off the first side. Then flip the board and remove another 75 percent. Let the wood sit for a day or two on stickers. Then re-mark and finish flattening the board.
If you’re lucky enough to have access to a widebelt sanding machine, you can get the finishsanding done there. For the rest of us, a belt sander, a random-orbit sander (preferably a 6-in. model) and elbow grease will finish smoothing the board.
1. Flatten big slabs of wood in several steps. Place the board on a flat surface and add shims to steady the board. Use a shop-made marking gauge to transfer the flat surface onto the edge of the board.
2. Plane the high spots down to the line using a handheld power planer. First use a lumber crayon to mark the high areas. Skew the planer so the heel rides on the previously cut surface. Cut with the grain to avoid tearout. Check your progress frequently with a straightedge.
3. Fine-tune the flatness of your board using winding sticks. When the two end sticks are parallel, run a third stick back and forth between the two to check for high areas in the middle. Mark any high spots and remove them with light cuts. Check your work frequently
Joint & Hand-Plane
There’s no need to cut an inch or two off a board’s width so it’ll fit your jointer. Instead, remove the jointer’s guard and make a full-width pass (Photo 1). Then handplane the remainder (Photo 2). Now the board is ready for the planer. You may have to repeat the steps to get the whole length of the board flat.
Removing the jointer guard is no casual thing; you must take precautions! Clamp an acrylic guard to the fence to keep your hands clear of the cutterhead. And always, always use a pair of push blocks.
1. You can flatten a board that’s slightly wider than your jointer by removing the guard. It’s just like cutting a giant rabbet: The uncut portion rides over the rabbeting ledge on your jointer. Caution: Secure a temporary acrylic guard over the cutterhead.
2. Hand-plane the uncut strip of wood flush. Skew the plane so its heel rides on the jointed surface of the board. A power hand planer will also do the job.
Rip, Joint & Reglue
If the board is more than 2 in. wider than your jointer, hand-planing is a chore. Try this technique instead: Joint an edge of the board and then rip it on the bandsaw (Photo 1). Joint and plane each board separately; then glue them back together (Photo 2).
To minimize grain interruption at the joint, it’s important to avoid cutting through cathedral patterns. They’re hard to align when the board is reassembled. Follow the straight grain and your joint will be almost invisible.
1. Rip a wide board into jointer-sized pieces on the bandsaw. Make sure the board has one straight edge to go against the fence. Make the cut where the grain runs straight on the board. That way, the joint will be less visible when the board is glued back together.
2. Glue the board together again after it has been jointed and planed. Leave the board a little thick so it can be planed to finish thickness after the glue dries. Shifting the boards a bit may help blend the grain and hide the joint.
Turn Your Planer into a Jointer
Build a sled to hold a wide board steady through the planer (see photo, right). Fasten a stop at the front of the sled to keep the rollers from pulling the board through without the sled. Add a backerboard to prevent kickbacks. Shim under the high spots to prevent the planer rollers from flattening out the board before it’s cut. You’ll find it’s best to position a cupped board concave side up because it’s easier to shim around the perimeter than the middle of a board.
Joint a really wide board with your planer using a shop-made sled. Support the board on the sled with shims and double-faced tape. After you joint one side, remove the board from the sled and plane the second side normally. The sled is simply a piece of 3/4-in. sheet stock. Stops and a backerboard are fastened to the ends to hold the board on the sled.
Flattening Wide Boards
A huge, wide board makes a stunning tabletop. If it won‘t fit through your planer, flattening that board can be a lot of hard work. You could use a belt sander, but it’s much easier to use your router. To get started, you’ll need a large, flat surface, such as a big workbench or a hollow-core door. Lay the board on the bench and place shims underneath the board so it won’t rock. Next, mill two guide boards about 1-ft. longer than your workpiece. Screw or clamp them to the bench top an equal distance apart. Make a sliding carriage for your router from two 1-in. by 1-in. pieces of aluminum angle, and fasten them to two cleats. Install a large-diameter bit in your router and you’re ready to go. Slide the router back and forth on the carriage, then advance the carriage down the length of the board.
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