Wood-fired!

Alumni chair - shaping the stretcher joints

August 16th, 2009

My design for a chair for the Chairs of the Alumni exhibition has ’sculpted’ joints where the stretchers intersect the legs and where the middle cross stretcher intersects the two side stretchers.

I’ve just completed the two joints where the stretchers meet. This progress post shows how these were made. However, as always seems to be the case, the most interesting stages are when you forget to pick up the camera - so you might have to join the dots yourselves.

1. Mortices are cut in the middle of the two side stretchers to receive the tenons from the cross stretcher.

2. The elements are rounded in a modified router lathe leaving ample blocks of material for making the joints. (I will describe the router lathe and the process in a later post.)

This pic shows the two side stretchers in the middle and the cross stretcher that joins them at the front of the picture.

3. The tenons cannot be cut before this stage because the router lather requires mounting holes to be centred at each end. The tenons are cut to fit the mortices and then tested and tuned.

The joints can then be fitted and glued. I have no pic of the gluing setup I’m afraid but effort was made to ensure the whole structure was flat and the elements were square.

Cramping pressure was applied across the whole structure using custom-made clamping blocks that fitted the curve of the elements. Additional clamps were used to ensure the flange on each side of the joint was firmly pressed against the side stretcher.

4. The excess material is carved, filed and sanded away leaving a smooth transition between the elements.

In the next installment I will show how the legs are shaped and then glued to this stretcher assembly.

Entry Filed under: Wood