Zaisu?

I own a kotatsu^[1] (炬燵), which is a low Japanese table covered by a blanket. An electric heater placed underneath warms the kotatsu. By sitting with the blanket draped over our legs, we manage to keep warm in winter despite the lower house temperature.

But sitting on the floor and on your legs tends to become uncomfortable after a while. Also, fully extending the legs under the table to catch more heat is difficult without something to rest your back.

The japanese Zaisu^[2] (座椅子) chair is a perfect solution. This is like an ordinary chair but without legs. But as these are rather rare here in Canada, except in specialized (and expensive) importation stores, I decided to build my own.

^[1]Kotatsu on Wikipedia
^[2]Zaisu on Wikipedia

Design

Inspired by zaisu pictures supplied by google images, in view of the limited wood working equipment I had access to, and considering the time I was willing to spend on the project, I used Solidworks to design the following chair model:

Raw material

I chose to use spruce beacuse it is easy to find.

Preparing the parts

To obtain the 1 inch thickness required for the back and the seat, I combined two planks together. Then I cut them to the final dimensions.



I used a table saw for cutting all parts, except for the triangles where I used a band saw.


To soften the seat and the back, I covered the wood with foam before stretching fabric over it. The fabric is held in place using a lot of staples, placed such that they will be hidden by the chair structure as much as possible.

Assembly

I began by assembling the chair structure using wood screws (with prior drilling to prevent cracks) and carpenter glue.


Later I installed the seat and the back using wood screws.

Result

Here is the result:


It works and I am quite satisfied with the result. I plan to build a second one in the near future, but this time the seat and the back probably won't be as thick.