Monthly Archives: September 2015

Cantilevered Conoid Chair

I finished my Conoid Chair last weekend. This was a very satisfying project to do. After I completed the electrical and table saw upgrade in my shop I wanted to build something special on my new saw. I immediately decided this was the one. I started it back in mid-June and plugged away at it slowly. So overall I would say it was not a huge investment in time from a single board of wood to a finished chair. Maybe 60 hours. And if you were doing a set of them, the amount of time could be greatly reduced per chair.

This will be a bit of a long post as I didn’t post anything while I was doing it. So today I will post it all in one go. You can also get my drawings done for the chair. Basically there are none to be found on the internet. I drew them based on pictures on the net and chairs in my house.

This is my first attempt at this chair so it is basically a work in progress. That is to say the angles and sculpting can always be tweeked a little here and there. Currently this chair (and my drawings) are 81º on the back and the seat is a 4º rise. (So it is not 90º to the back. If it were it would have a 9º rise.) Some of the pictures of the chair on the net show quite a recline so maybe 80º or even 79º would work well. Also the dimensioned stock I used was a little bulkier than my drawings. I think my finished product could be a little more trim than it is but overall it looks good proportionately.

The bridle joints have to be perfect to work well, especially since it is on an offset angle. Here I am showing the back legs on the two feet set at 81º.

Close up of the bridle joint. I trimmed this stock down after this photo.

Before gluing the legs to the feet I trimmed back the front, leading edge of the legs on the table saw using a stop block so I could finish the curved cut on the band-saw. You have to be careful of where you place your stop block when doing it on a table saw. Because (the circular blade) what you see on top as you push your stock through and what you can’t see below have very different cutting positions.

Here you can see the basic profile of the feet and legs. Look closely at the left end of the leg lying on its side. You can’t see it fully but it is tapered on the back edge from the top, down to 10mm above where the seat joins the back leg.

Now that I have the feet and legs roughly complete I can move on to the seat. The stock I was using was 60mm thick so I had to do a lot of planing to flatten it and get it down to 50mm.

Hard work but somebodies gotta do it.

After I got the seat stock down to thickness I could begin on the joinery. For this bridle joint I cut a matching angle (81º) on the back edge of the seat and set up the seat with a supporting back on my table saw to cut the shouldered joint. The legs were done with a jig, router, and brass template guide. Sorry no picture was taken. Again I have to stress that the joint has to be perfect to work well. Any play in this joint is unacceptable. The reason why it is shouldered is because it is not a through joint.

Here is a close up of the joint in all its glory.

Nice fit. there will be no pins or wedges to hold it together, which is why it needs to be a perfect mating surface.

Now I am on to making a template for the sculpting. I am using French curves and a steel rule for this.

It was a big, heavy piece of bubinga.

With the chair dry assembled I slipped the seat template over the legs to draw the pattern and use it as a cutting template. Not shown in any photos but for the seat sculpting I not only used hand planes but employed a hand grinder with an Arbortech attachment. To get the curved line established I simply followed the template with my Arbortech power plane.

That is a lot of hogging out to do.

Getting there.

The bottom of the seat. Notice the fluted surface I left just behind the joint. A little added support as the bridle joint butts up against it. And it looks kind of cool I thought.

First full dry assembly.

At this point the seat, legs, and feat are glued up and I am now fitting the top rail. The joinery for this is a wedged mortise and tenon. Wedged tenons are a bit nerve racking because you can’t test them. And if they fail (wedge breaks, doesn’t seat properly, etc) while going together they can be a heck of a thing to pull apart.

The top rail is now sized, cut and fit correctly.

There are eight spindles I turned on my lathe. I am using Monarch Birch, native to Japan. One thing to note when gluing up is the angle. In order to get good pressure down onto the joint you will need to use wedges otherwise you will get lifting on one side of the joint.

After all the hand sanding was done I applied shellac to finish it. I love shellac. It is a little old-time but it is so nice to work with. For years I used oil based tung and linseed, and poly urethane’s for finishing. But they take too long to cure and smell noxious for many days. Shellac on the other hand smells fruity, is 100% natural, and it dries when the ethanol evaporates. I just mix the amount I need and am done in a day.

A majestic chair.

I have always loved the design of this chair. And I gotta say it looks great beside my dining table.

You can get a bitmap of drawings for this chair from the link below. But be aware that the dimensions for the stock are smaller. I think I ended up using 40mm for the feet and 45mm for the legs, 50mm for the seat tapered down to 35mm. Whatever you feel you can get away with while maintaining a proportionately elegant look.

Conoid Chair

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