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There's Plenty of Power in a Simple Incline

By Percy Blandford

Koatbuilding presents some very challenging clamping problems. There never seems to be enough clamps; and even when there arc, they usually don't have sufficient capacity for the job at hand. As a result, boatbuilders arc always improvising different ways to apply pressure with what's at hand, using a combination of wedges, struts, and ropes. I've found that many of these improvised solutions are also useful for woodworking.

By a long margin, wedges arc my most valuable clamping tools. In my workshop, I use them most often in edge-gluing operations, but they're also handy for making other types of clamps. Before describing how to make these tools, however, let's take a closer look at the wedges themselves.

Wedge Theory

Wedges can be any size, depending on the scale of the project, but it's important not to make clamping wedges too steep. Steep wedges are difficult to drive and prone to slipping. As a rule, I don't use wedges any steeper than l-in-4 (1-

Shop-made solution. Working side-by-side with its metal equivalent, this simple but effective wooden beam clamp relies on wedges to exert clamping pressure.

in. rise over 4 in. of length). Wedges with a l-in-5 pitch arc good for general purpose clamping. (Sec Fig. 1.)

Single wedges arc good, hut double wedges are better. A pair of shallow opposing wedges driven against each other—1 call them "folding wedges"— will exert substantial pressure with less risk of shifting the workpiccc. (Sec Fig. 2.) I use folding wedges when gluing a narrow wood lip to a wider board, and in other situations where it's important to prevent parts from shifting.

If you elect to use wedges singly, resist the temptation to drive the wedge against a dowel or bolt. Instead, let the wedge work against a scrap block that pivots on a screw or bolt. (Sec Fig. 2.) The block can pivot to bear against a broader area of the wedge, helping to distribute clamping pressure more evenly. As with any clamping operation, it's important to cushion the workpiccc with a scrap of wood at each wedge (or folding wedge) location.

Wedge-Based Clamps

Apart from the low-cost appeal, the nice thing about clamping with wedges is the flexibility you have. All you need are boards long enough to hold the work, wedges, pads, and stops for the wedges to work against. Using these ingredients, you can assemble a shop-made clamp that will do the same work as a store-bought pipe or bar clamp. In situations where you need to keep cdgc-glucd boards from buckling, use a double-beam clamp as shown in Fig. 3. Narrow wedges can be driven between the workpiccc and the clamp boards to keep the gluc-up flat.

In situations where clamping pressure needs to be applied near the middle of a wide workpiccc, you can construct your own deep-throat clamp. (Sec Fig. 4.) This clamp consists of a machine bolt, a large wedge, and two stout clamp arms, each with a foot or caul at either end. Pressure can be applied in two ways: by driving die wedge in against the outer feet, or by tightening the bolt. Locate the bolt near the centers of the arms to get the best balance between clamping force and throat capacity. A

PERCY W. BLANDFORD is a woodworker and writer; he lives in central England.

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Wood Working for Amateur Craftsman

Wood Working for Amateur Craftsman

THIS book is one of the series of Handbooks on industrial subjects being published by the Popular Mechanics Company. Like Popular Mechanics Magazine, and like the other books in this series, it is written so you can understand it. The purpose of Popular Mechanics Handbooks is to supply a growing demand for high-class, up-to-date and accurate text-books, suitable for home study as well as for class use, on all mechanical subjects. The textand illustrations, in each instance, have been prepared expressly for this series by well known experts, and revised by the editor of Popular Mechanics.

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