Dowels were not always the choice of furniture craftsmen because of the difficulty in manufacturing them in a pre-industrial revolution environment since dowels, to be useful, must be perfectly round and completely uniform in large numbers. The most common joint prior to 1830 was the mortise and tenon joint, a tongue on one piece of wood (the tenon) that fits into a slot (the mortise) that was drilled or carved into the other piece of wood. It was sometimes even further secured by the use of a peg that pierced both pieces of wood. (see illustration). However, this peg should not be confused with the modern dowel since it was different in both form and function. The peg was generally hand carved and was often purposefully irregular to give it gripping power. It was not the main element of the joint but was only there as part of the supporting cast and most mortise and tenon joints do not have a peg.
In pre-Civil War construction, dowels came into use very early with the advent of machinery. What most machines do well is convert energy into circular motion and dowels are a natural adaptation of this trait, a round wooden pin produced to fit in a round hole and each one the same as the last. Early dowels were made of maple and were smooth with no ridges. Typical 18th century furniture construction used 7/16 inch dowels in virtually all joints and this technique was the norm through the turn of the 20th century.
Early in the 20th century, with increasing factory production and the advent of resin glues, the venerable hundred-year-old dowel underwent several major changes. The main ingredient of the dowel went from maple to birch, it added spirals for better glue distribution within the hole and its size was reduced from 7/16- to 3/8-inch in diameter. With the exception of using grooves instead of spirals to facilitate installation with a pneumatic “dowel gun,” the current dowel has remained unchanged this century and little change is foreseen. Of course there are other size dowels and they are manufactured from almost any wood available, most commonly oak, walnut, maple and cherry but these are primarily for custom work and special situations. The norm in manufactured furniture is birch, 3/8-inch in diameter by 1 1/2 to 2 inches in length.
The most common malady of a dowel joint is just plain old being loose. In this case, open the joint carefully with a mallet, inspect the dowels to make sure they are not cracked, scrape or drill old glue out of the holes using an 11/32 drill bit (1/32 smaller than the hole), scrape old glue off the faces of the joint using a flat chisel and use a small rasp to gently remove old glue from the dowels. Once the joint has been cleared of old glue, apply fresh glue in the holes, on the dowels and on the faces and clamp the joint securely, cleaning up excess glue with a wet rag. That was easy.
Dealing with a cracked or broken dowel is slightly more difficult. If the dowel is merely cracked you might be tempted to just reglue and let it go – but don’t. You’ll end up fixing it twice. If it is cracked or broken off it must be replaced. Removal of the broken piece is usually the most difficult part here. Try to pull it out if possible. If it was poorly constructed to start with and has little glue you might get lucky and remove the whole thing intact, not likely but possible. You also might try inserting a screw into the face of the dowel and pulling on the screw with a claw hammer. Again the chance of success is very small but give it a shot. If that fails you must drill it out. Cut the dowel flush with the face of the joint. Don’t try to drill through a protruding stub. If at all possible put the piece in a vice or in the jaws of your Workmate to free both hands for using the drill. Use a new, very sharp 3/8 bit and let the bit do the work. In other words don’t pressure the drill, let the bit pull in.
If you are unsure of exactly which way the dowel runs in order to drill it, remember that the dowel is almost always at a 90-degree angle to the face of the joint. The faces are the things that are cut on angles with dowels installed on the square. Be very careful when you drill and you can feel the difference if you are not drilling straight. The grain of the dowel is running in the same direction as your drill bit. The grain of the main piece runs in a different direction and you can feel it if you wander. You will also feel the end of the old dowel when you hit bottom since there usually is a bit of air and old glue at the end of the dowel. You will hear the slight “crunch” of the dried glue as your bit cuts it. While drilling, check your work frequently to make sure you are lined up with the old dowel and make directional corrections as you go. Trial and error and experience are the best tools here but patience goes a long way too. Don’t get discouraged. If you miss the hole badly and end up with a sloppy fit, just drill it out to the next size commonly available dowel and continue on.
Dowel sizing can be a real problem because like lumber, dowels aren’t always the size claimed. For example, most long birch dowels commonly carried in hardware stores are undersized by 1/64 to as much as a 1/16 of an inch. That doesn’t sound like much but even 1/64 under will make a sloppy joint. If you must buy long dowels, measure them with calipers first and if necessary, buy a drill to match the size of the dowel. Long dowels from oak, maple or walnut are generally true size and the 1 1/2 and 2 inch spiral or grooved manufactured dowels are always right so if you have access to them, even if you have to buy in quantity, you are better off. Besides, this won’t be the last thing you ever repair.
His book “How To Be a Furniture Detective” is available for $18.95 plus $3 S&H. Also available is Fred and Gail Taylor’s DVD, “Identification of Older & Antique Furniture,” ($17 + $3 S&H) and a bound compilation of the first 60 columns of “Common Sense Antiques by Fred Taylor” ($25 + $3 S&H). For more information call 800-387-6377, fax 352-563-2916 or email@example.com.
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