Primaterra

This chair is my first. It’s been created from a chesnut log about 60cm long and 20 to 25 cm diameter. This normally allows the assembly of two chairs.

First, you have to split the log in half, and then each half in half againto obtain two planks with the central parts and two narrower parts from the outside.

One of the wide pieces will be used for the seat, and one of the narrow ones for the back. The holes for the legs must be drilled at a diameter over 25mm through the seat. The center of these holes must be about 5cm from the edge of the board, and 10 cm from the end. Drill the holes so that the legs will be inclined to the outside, to give the chair better stability.

Then, drill the mortise to insert the back. I did it with a chainsaw, but it is possible to use a dril and then a saw or chisel. Shape the tenon on the back so that it just fits the mortise. The back can be locked in place using either a wooden pin or, as I did, forcing it in with a mallet.

The next step is to shape the tenons on the legs. This is done with a sharp knife, or you can start with the axe and finish with the knife. Check the fit often, as it is rather difficult to add wood back on. When the fit is good, insert the leg in the seat in the chosen position, and mark the position of the wedge on the end grain of the tenon.

The wedge must be inserted in a saw cut at the center of the tenon perpendicularly to the grain of the seat, otherwise the wood may (or most likely will) split as the wedge is forced in. When the line is drawn on the end grain, remove the leg and saw on that line for about half the thickness of the seat.

Of course, you have to repeat these steps four times... You then have to prepare the wedges. It is preferable to use well seasoned oak heartwood for these. Cleave a piece about 5mm thick and the width of the tenon andwhittle it down to a sharp edge at one end.

After you have put the legs in the seat, the wedges are driven in with the mallet, which locks the legs solidly in place. Your chair is then finished! To make it more comfortable, you can dig the seat with a gouge to make it conform to human anatomy.