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Excerpted from The Complete Illustrated Guide to Furniture & Cabinet Construction Assembling Cases Get it right the first time with the right tools and the proper clamps and clamping technique When you're ready to assemble your furniture, you usually have only one shot to get it right. Once the glue is spread, there's no turning back. Glue up a cabinet out of square, and you'll pay dearly later in the construction process because your error will accumulate so that fitting subsequent parts becomes a nightmare. To get it right the first time, it's vital to have the right assembly tools on hand and to use the proper clamps and clamping technique. After all, who hasn't glued together what was a perfectly fitted miter, only to find the joint slipping out of alignment as you placed pressure on the joint? Learning and practicing the correct approach to assembly will save you untold hours of frustration. The dry run One of the best techniques I've come to learn about assembly (and learned it the hard way, meaning I had to make many mistakes first) is to always -- and I mean always -- do a dry run of any assembly. This means assembling all the parts without glue. Make sure you use all the necessary clamps you'll need and check to see that you can confidently close all the joints. In effect, you're practicing the entire assembly sequence. And 9 times out of 10, you'll discover during a dry run that something is missing or you need more clamps in a specific area to bring an assembly together. Or perhaps you'll need to rethink the glue-up process and break the assembly sequence down into smaller, more manageable parts. It may take more time, but investing in a dry run is well worth avoiding the horror of applying glue, only to find that you can't quite put the parts together as planned. Assembly tools and jigs There are innumerable jigs and tricks used in assembly. All are aimed at making the process of putting together multiple parts easier, more accurate, and ultimately less frustrating. There's nothing worse than spreading glue only to find you don't have the right tools or setup ready to go. Here are some essential assembly aids that make glue-ups go a lot smoother.
It's vital to square up a case or opening immediately after assembly--before the glue dries. One way to check for square is to read the diagonal measurements from outside corner to outside corner with a tape measure. When the two measurements are equal, the opening is square. But clamps often get in the way, it's practically impossible to get a reading on the back of the case, and reading the outside corners won't tell you whether the inside of a deep case is square. A more accurate method is to use a pinch rod.
As an aid to assembling a case square, cut a piece of plywood to the exact width of the case opening, making sure adjacent edges are square. Before you clamp the case joints, clamp the board inside the case, lining up one edge of the board with the case sides. Voila! No more twisted or out-of-square openings. Shims and blocks align parts It's a good idea to keep on hand a variety of shims and blocks in varying thicknesses, from playing cards, squares of plastic laminate, and strips of leather to 1/4-in.-, 1/2-in.-, and 3/4-in.-thick blocks of wood. These spacers help align or position parts during glue-up, and they're great for protecting the surface of your work. In the photo at right, small squares of MDF align the clamp heads over the center of the joint, while plastic shims prevent the pipes from dinging the surface.
Gluing up assemblies often means having to get underneath the work to attach clamps or other parts. The simplest answer is to raise the entire assembly on blocks of wood. But finding stock thick enough can be a pain. Just as strong, and easier to make, are sets of riser blocks made from 3/4-in. plywood glued and nailed together. Blocks about 5 in. high by 2 ft. long are sufficient for almost all your glue-ups.
Like blocks, cauls made from scrap material can prevent dings in your work. More important, cauls distribute more clamping pressure across a joint, allowing you to use far fewer clamps when gluing up. For broad gluing surfaces, use bowed clamping cauls. For narrow joints, scrap plywood or leftover sticks of wood work fine. The trick to getting the cauls to stay where you want them until you add the clamps is to tape them temporarily in place.
In many cases, you don't need to bother clamping dovetail joints, especially on small box constructions, such as a drawer. To assemble and fully seat the joints without damaging the pins, tap over the joint with a wedged-shaped block of dense wood. The shape of the block allows you to position it over the joint regardless of the size of the tail. [ next ]
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