Gone With the Wind:
Charles Mak demonstrates a simple technique to help you achieve maximum yield from the most stubborn boards with just a couple of sticks and a hand plane.
Charles Mak demonstrates a simple technique to help you achieve maximum yield from the most stubborn boards with just a couple of sticks and a hand plane
Even if you use machines to prepare rough timber – as I usually do – knowing how to dress stock by hand can be very useful. When a deformed board or assembly (like a door or carcase) is too big or too small for a machine, your hand skills are what you can count on.
In preparing a rough board, the first task is to dress one side flat in length, flat in width and out of wind. Among the various deformities, twist is usually the most challenging to deal with, and that’s why the general advice is to avoid buying twisted boards. Another strategy for twisted boards is to rough size them closer to their final widths and lengths before you flatten them as some of the defects – cup, bow or twist – are removed in the sizing process.
Although any twisted board can be flattened, before you start, you should check to ensure it will yield the desired thickness after the twist is removed. In the sidebar, you can find out how to do that.
After being flattened, a twisted board can become too thin for your particular project
Spotting twist
To test for twist, you can press on the diagonal corners of a board on a flat surface to see if or how much it rocks. However, to accurately pin point the high spots, you need a pair of winding sticks. Winding sticks make a narrow board appear wider and make the twist easier to see. I have made several pairs of winding sticks and generally use a pair that is about at least 30cm longer than the width of the workpiece.
To use the winding sticks, first place a stick across each end of the board, at right angles to the length of the board and parallel to one another. Sight down so the winding sticks align at one end. Look across the other end of the front stick to see how the edges line up. If the other ends misalign, the board is twisted. Mark the diagonal pair of high corners on the board. Then, reposition one of the sticks and repeat the sighting to check the entire board.
For a long workpiece, some woodworkers use three winding sticks. After removing the high corners at the ends, they run a third stick back and forth between the two end sticks to look for other high spots in the middle.
Centre the winding sticks on the board and sight at about an arm’s length away from one of the sticks
Mark the first high corner and then the diagonal corner which is also a high spot
Keeping one of the sticks constant, run the second stick back and forth to find other high areas
Salvage twisted boards
To get an idea of how thin a twisted board will become after it is flattened, follow these steps that American furniture maker Ric Hanisch uses:
1. Place a winding stick at each end of the board
2. Shim up one of the sticks until both sticks are parallel
3. The vertical distance made by the shim at the edge of the board is the amount of twist
4. The twisted board, when flattened, will lose its thickness by the twist on both faces.
The gap on the wedge shows how much material is to be removed at the diagonal high corners
Holding the work
To knock down the high spots, hold the workpiece down firmly so it does not rock. For smaller boards,
I go with the vice, but for long or wide pieces, I select a face where the board will rock the least and secure it on the bench. A word of caution however, it’s easy to introduce a false reading when securing the workpiece between a tail vise and bench dog as long or thin boards can easily distort under pressure
from both ends.
For a board too big for the vice, I cramp it to a bench with shims placed underneath the high corners
Choosing the plane
For a small workpiece or mildly twisted surface, you can flatten it with just a smoother or jack from start to finish. However, if a lot of material is to be removed, a scrub plane is a better choice at the start. You can also hog off bulk waste with a toothed blade or a cambered blade set in the wide throat of a smoother and finish the job with a jack plane.
You can retrofit a smoother with a cambered blade to use it as a scrub plane
Removing the twist
Flattening a deformed board of any size is all about removing the high areas; the trick is to know how – with as little trial and error as possible. I start by knocking off the high corners with a hefty cut to form two small flat spots. Take care to remove equal amounts from the opposite corners if you want to salvage as thick a board as it can be.
As the high corners come down, I lighten up on the cuts and make two types of strokes: diagonal and across the board, trying to extend the flats towards the centre. When the board gets relatively flat across,
I reset the plane for a shallow cut and plane with the grain for the final strokes. Finally, confirm the surface is out of wind with the winding sticks.
Practise this technique on mildly twisted boards first to develop a sense of where and how much to plane, while building your confidence. The hand-planed face is now the reference surface for thicknessing the reverse side. Do you now face plane the reverse face (and every other board that comes into your shop) also by hand, or with a machine? It is a question that only someone who has the hand skills gets to ponder about!
Plane down the two high diagonal spots and check the work often to avoid taking too much material from one spot
Enlarge the flats by making alternating diagonal cross strokes and inward from the edge to avoid break-out
In finish-planing, loosen up the grip and make the final, long strokes with the grain
Sighting a dark edge against a light background allows easier reading
