Drawboring

Drawboring is a simple and fundamental skill that will radically transform your joinery. The few extra steps it requires will virtually eliminate gaps in a mortise-and-tenon joint – even if the wood still needs to reach equilibrium with its environment. Plus, drawboring reduces clamping and the need for a perfect fit.Drawboring is one of is one of the simple reasons that so much antique furniture survives today, some of it as sound as the day it was made.

What is drawboring? It’s a technique that greatly strengthens a mortise-and-tenon joint, transforming it from a joint that relies on glue adhesion into a joint that has a permanent and mechanical interlock. In essence, you bore a hole through both walls of your mortise. Then you bore a separate hole through the tenon, but this hole is closer to the shoulder of the tenon. Then you assemble the joint and drive a stout peg through the offset holes. The peg draws the joint tight.

Drawboring offers several advantages compared to a standard glued mortise and tenon:

• The joint will remain tight. A common problem with mortise-and-tenon joints is that the joint can open up and develop an ugly gap at the shoulder. Sometimes this is caused by the wood shrinking as it reaches equilibrium with a new environment (such as your living room with its forced-air heat). Sometimes this gap is caused by simple seasonal expansion and contraction, especially with woods that tend to move a lot,
such as flat-sawn oak. The peg in a drawbored joint keeps the tenon in tension against the mortise during almost any shrinkage.

• The joint can be assembled without clamps. Drawboring is excellent for unusual clamping situations. Driving the peg through the joint closes it and clamps are generally not needed. Chairmakers use drawboring to join odd-shaped pieces at odd angles. It’s also an excellent technique when your clamps aren’t long enough. Or when you don’t have enough clamps. Drawboring also allows you to assemble a project one piece
at a time if need be.

• The joint can be assembled without glue. There is good evidence that drawboring allowed early joiners to assemble their wares without any glue. This is handy today when you’re joining resinous woods (such as teak) that resist modern glues or when you’re assembling joints that will be exposed to the weather, which will allow water to get into them and destroy the adhesive.

• The joint doesn’t have to be perfect. The mechanical interlock of drawboring means that your ...

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