A six-sided tresoor for castle Hernen: part 1

We have recently started with a new large project involving a six-sided tresoor (dressoir or cupboard) for castle Hernen in the Netherlands. These dressoirs started to appear in the 15th century and remained popular throughout the next century. As castle Hernen is focussed on the medieval as well as the  early renaissance period, this furniture piece is a perfect choice as fits both these periods. The tresoor will be loosely based on the one that is on display at Château Langeais in France (shown in a previous blogpost). We decided to make our tresoor six-sided in order to make it a bit more challenging to make. And indeed, this already appeared to be the case when we started working on the frame.

The 15th century six-sided dressoir at castle Langeais, France.

The vertical posts 

The basis of the frame of the tresoor consist of 5 cm square thick vertical posts. However, four of the vertical posts are not square but have a 45 degree angle, due to the fact that the dressoir is six-sided. These four posts have a pentagon-like shape, and the initial thickness of these posts therefore had to be much larger than the 5 cm.

Initially we planned to use recycled industrial 10 cm square oak posts, but these showed too much cracks and contained woodworm, and basically were useless. Luckily, a visit to the timber trade at castle Terhorst in Loenen, the Netherlands yielded a perfect plank. However, in total it was a bit large: 6 m long, 60 cm wide and 8 cm thick, and weighing around 260 kg. The plank was cut at the timber trade in 2 parts by chainsaw and these were lifted onto my car with a forklift truck. At home we had to use four people to lift each individual piece from the car. 

 Left: the two planks on top of the car at the timber trade at Castle Terhorst. Right: the thickness of the planks is more or less similar to the width of my foot.

In front of the workshop, I used a circular saw to cut the plank into more lighter weight/user-friendly parts. However, the maximum cut of the circular sawblade appeared not to be deep enough for the 8 cm, so the plank had to be turned over and sawn from both sides.

 

It was necessary to make a sawcut from both sides in order to make the complete cut. The two parts were first cut in half, then one quart was cut lengthwise in half. This produced almost flat pieces of timber that needed only a few strokes with the jointer-planer machine.

A similar problem appeared when we wanted to cut the 45 degree angle with the saw table. Setting the saw at an angle automatically reduces the cutting depth, and so no complete saw cut could be made. Also, it was impossible to set the angle for the backside of the post with the saw table. As a result we had to do it by hand, i.e. the medieval way.

The pieces of timber were still heavy - around 30 kg and needed support for the sawtable (I only had one roller stand for the other end of the saw table). A provisional support was made using a Black-and-Decker Workmate and a plank set to the height of the sawtable.

Completing the 45 angle by chisel

The 'waste' of the incompletely cut 45 degree angle was cleared from the post with a chisel. First the length of the 'waste' was sawn into smaller pieces, which were broken of the post using the chisel. The 45 degree angle was then planed flat.

 

Sawing the 45 degree angle 'waste' into smaller pieces with a frame saw at castle Hernen. 

Photo copyright Ton Rothengatter.

Breaking the parts from the incomplete 45 degree angle with a chisel. Right photo copyright by Ton Rothengatter.

Planing the post flat with a medieval type plane with a toat at castle Hernen. The post is held with a double screw vise, while the complete vise and post were kept in place on the workbench using my weight. Right photo copyright by Ton Rothengatter.

Comparing the frame saw, draw-knife and Roubo saw

We first started to saw the back angle of first post with a frame saw. The sawblade of a frame saw can be turned making it possible to saw along the length of the post. However, the unequal weight distribution of the saw made it difficult for us to saw in a straight line. Sawing also proceeded slowly due to the fact that the teeth of the sawblade were set for cross-cutting.

Left: Two wooden clamps and a double screw vise were use to hold a post at a vertical psoition. Right: Some additional stability was procided by Bram, while his father was using the frame saw.

We then decided to try a draw knife to remove the wood to the correct angle for the second post. This proceeded relatively fast, however more work was necessary afterwards to flatten the back with a plane. Finally, we used  a small pit saw (or Roubo saw) for the third post. We needed to construct this saw first, as shown in the previous post. The Roubo saw worked fast and produced a far more straight line than the frame saw or the draw knife. The weight of the Roubo saw is well balanced and equally distributed to both sides of the blade. In conclusion, the Roubo or medieval pit saw performed best to cut the angle of the vertical posts. 

The roubo saw at work on the third post in our workshop. The post was secured with several clamps to the workbench.

The backside of all the posts were finally planed to flatness and the correct angle. The third post was then cut in 2 smaller parts for the front of the tresoor.

Left: Planing the backside of the posts flat with a plane. Right: The differnt parts of the frame; the four pentagon shaped posts are in the middle.