Drawboring

The lowest shelf of the armoire housed the large drawer. The construction for this was drawbored mortice-and-tenon ends. Below is the frame prior to drawboring.

So what is drawboring? Drawboring is a form of pegging a mortice-and-tenon together so that it is held together firmly. It is more than this. A pegged joint is created by joining the two pieces and adding a dowel to the completed joint to limit movement. Drawboring, on the other hand, is the art of drawing the joint tightly together by way of a dowel through offset bored holes. This creates a very strong joint, one that is durable even without glue.

My plan was to drawbore these joints since I wanted to ensure that they did not fail, or loosen over time.

The Tools of Drawboring

You need to drill a hole. Choose your weapon – here I will use a brace. I have also used an eggbeater and a powered drill. They all work well.

The dowels are shopmade, not the type you buy in. They need to be rived so that the grain runs straight along their length for maximum strength. I plan to make my own dowels.

Lastly, in the foreground are two drawbore pins. These are tapered lengths of steel that are inserted into the overlapping holes bored into the mortice and the tenon to pull them together. This affords one the opportunity to check the fit, as well as form a temporary join.

The Mortice-and-Tenon

Below are the pieces for joining. These were made with a chisel and a tenon saw, however the procedure remains the same whatever method you use to create the joint.

I am going to do this a little more pedantically than generally in order that the steps are clearly demarcated.

Below are the measurements used:

The stretcher is 3” wide.
The centre of the tenon is 1 ½ “ from the side.
The 3/8” hole for the tenon will be ½” out from the shoulder. Allowance is made for this when determining the centre of the hole.

Use an awl to start the hole for the auger screw.

Boring the face side ...

Here you can see the exit hole. The auger bit relies on the lead screw to pull it through the wood. Once there is nothing to grip, it will stop cutting.

Now insert the bit and drill back the other way ..

And here is the final hole ..

Fit the tenon into the mortice. Since the hole is 3/8”, take a 3/8” brad point bit and use it to mark the position of the hole on the tenon cheek.

Here is the result …

Now mark the position of the hole for the cheek about 1/16” closer to the shoulder. This distance is arbitrary. It depends on the bend characteristics of the dowel. A hardwood will flex less and so you would not want to offset the holes more than neccessary. Here I am using Tasmanian Oak, the same wood as used in the frame. It has good flex.

Drill the offset hole …

The amount of offset is evident when you assemble the boards …

Now you can grab a drawbore pin and use it to pull the boards together in preparation for inserting the drawbore pin.

These drawbore pins are made by Veritas. They have tapered shafts that act as a wedge to draw the holes together and pull the boards against each other.

Insert drawbore pin and twist the handle to force the shaft deeper.

Let’s make dowels

Riven wood is wood that is carefully split along the grain. This creates a piece with greater stability.

What one does not want is to choose a board that looks like this! Use one that is straight grained.

To prepare a board for easier riving, first cut it to a smidgeon over the desired final thickness.

To split the board I simply clamp it in a vise and use a large and hefty chisel as a wedge.

Chamfer the ends in preparation for the dowel plate.

The dowel plate is from Lie-Nielsen. These come in both metric and imperial. One could simply drill a series of different sized holes through a steel plate, but LN save much time and effort, and I very much doubt that I could make one as precise as this. They write: Holes machined with 6-degree clearance taper on underside, holes are straight for the first .025" (6.35mm); so this tool can be sharpened many times without increasing the size - but at 60 Rockwell it probably won't ever need sharpening.

Begin by using a hole one size up (or closest to the riven blank you have). Drive it through the dowel plate with a mallet or hammer.

Tip: keep the dowel vertical and, depending on the straightness of the blank, use short rather than long blanks to minimise the edges catching unevenly.