Called wood pins or pegs, dowels are lengths of hardwood with an important role to play in simple carpentry. They can be a decorative part of joints made with them, or be there for strength alone. Few tools are needed but the secret of success lies in using them accurately.
There are two basic ways in which you can use dowels in woodworking joints. You can drive a dowel through such joints as a half lap instead of using a nail or screw, or you can use them to make joints in their own right by drilling holes in one piece of wood, glueing in dowels, and then slotting these into corresponding holes in the second piece.
The dowel joint proper is used mostly in furniture making where it provides a neat joint of great strength without intricate cutting and without the need for unsightly reinforcement. Dowels can also be used to repair furniture.
In any joint, the size of the dowel is very important. Use a small one in a big joint and it won’t have sufficient strength; use one that’s too large and the holes you drill to accommodate it will weaken the wood. Ideally you should choose dowels which are no more than one third the thickness of the timber into which they will be fixed.
The thickness of the wood must be con-sidered, too, for the dowels must have sufficient space between them and at each side otherwise when they’re hit home or pushed into their corresponding holes the wood will split. So follow the carpenter’s ‘one third rule’ and mark the width as well as the thickness into three (ie, a 9mm/3/sin dowel will need at least the same amount on both sides of it). And don’t forget that planed wood can be up to 5mm less all round than the dimensions you ordered, and three into this size might not give you enough room for a successful joint.
Types of joints
There are different types of dowel joint. The simplest and easiest to make is the dowel joint in which the dowel peg passes right through one piece of timber and into the other, sometimes passing through this as well if it’s thin enough. Because in either case the ends of the dowels show, they are often used as a decorative feature of the article you’re making.
If you don’t want the ends of the dowels to be seen, you must make a joint. Inject adhesive onto the dowel before tapping it into place with a mallet — you can use a hammer but you should protect the dowel with a block of wood. You should also apply adhesive to the meeting faces of the timber.
The glued joints should be cramped until the adhesive has set.
With through joints and halving joints, you now saw off the bulk of the protruding dowel and use a block plane to trim the end flush. You can use an ordinary plane for this, but it must be set for a very fine cut. Smooth off any remaining roughness with glasspaper.
If using dowel pellets, hit them into place over the countersunk screws (with the ones you’ve cut yourself make sure the grain follows that of the wood). Plane off excess after the adhesive has dried.
RULES FOR DRILLING HOLES.
– make them the same diameter as the dowels
– they should be a little deeper than the dowel’s length
– slightly countersink these where the pieces of wood meet TIP: DOWELLING JIG
With a drill use a dowelling jig so the holes will be straight and square.
WHAT CAN GO WRONG?
The most common problems are:.
– the dowels being too tight. Forcing the joint together causes the wood to split – so always check the fit first.
– the joint being forced out of alignment because the holes were drilled out of line with one another- always check the alignment before finally applying the adhesive
MITRED DOWEL JOINTS.
– use a mitre box for accuracy.
– place mitred pieces together in a cramp and mark them at the same time
– the dowel at the outer corner should be shorter than the one at the inner corner