Sunday, 17 August 2014

The sella curulis: the final touch

The finished sella curulis when folded.

With all the separate pieces of the sella curulis finished, there was one thing left to do: join all the parts and make the chair out of it! First, all the wooden parts were finished with linseed oil. Then I added some metal chair sliders to the feet. These sliders allow for easy movement of a chair over a floor surface, but more important they lifted the feet a few mm above the ground. As the gilding of the claws also went partly under the feet, this would protect the gold from being scratched away.

The metal chair slides have three metal pins that are driven into the wood. You cannot hit the slides with a metal hammer as this will dent your sliding surface.

Two views of the chair slides on the feet of the sella curulis.

The parts of the sella curulis are joined with mortise-tenon joints. These are in turn fixed with wooden pins. The pins were also made from pear using the 6 mm hole in the dowel plate. For each mortise-tenon for the rail two short pins were needed (8 in total), but for the X tenon really long dowels were needed, around 9 cm long. Using pins is generally enough to fix a joint, and normally I do not use glue for these joints. But this time I wanted to be sure it stayed fixed, so I added a 2-component wood glue to the joints. After the glue had dried, the holes for the pins were drilled and they were driven in. 

Left: The clamped and glued sella curulis. Right: The glue was applied very carefully in the mortises.

Above left: The long pins for the X mortise. The other photos show the pinning process of the seating rail. The chair was upside down and rested on blocks covered with towels to protect the gilding of the eagle heads.

The holes for the pins of the X mortise were already pre-drilled on a drill press, because the margin to drill the hole in the mortise and tenon was very tight. A slight deviation in the angle of a hand-held drill could compromise the folding capability of the chair. The pre-drilled holes served as a guide to drill the hole through the X tenon after glueing. When making 6 mm pins, the holes are made slightly smaller (5.8-5.9 mm), so they pins will stay fixed. For a 9 cm long pin this is not feasible, as the pin will likely break during the repeated hitting with a hammer. The pin has to go into the hole more easily, so also here a 6 mm hole was used with a little drop of glue to keep the pin in.

Left: the pre-drilled hole in the X mortise. Right: the pin in its place.

The pin driven in. You can see that the head of the pin is staring to split due to the repeated hammering. The eagle heads rest on towels for protection.

Yes, it is finished!

 Two more photos of the finished sella curulis.

Finishing the medieval folding chair also meant that I had to clean up all the mess  in the workshop. 
In the upper left corner you can see another project on its way.

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