4-Leg Stool – Fabrication 3

It’s been a few weeks since the last post on the 4-leg stools, but I’m finally back and settled in after a brief New Year’s break, ready to continue.

I left things off having just finished all the chamfering, finish planing, staining and oiling of all the stool legs and stretchers. So on to assembly. For the most part there’s nothing particularly unique about the assembly process, and truthfully I forgot to take pictures of the stools being clamped up. But before the joints are all closed up one detail that is worth showing is how I sized the mortise and tenon joints.

These mortise and tenons are compression joints. I cut the tenons 1 mm wider than the mortises. Here you can see one of the mortises cut to a final width of 24 mm.

And here’s a tenon with a width of 25mm.

The thickness of the mortise and tenons is more or less matching. In the image below the tenons look slightly fatter than the mortises, but I think that’s a result of the camera angle. Thickness-wise, the fit of the mortises and tenons was snug but I could easily insert the tenons by hand.

Here’s a more clear view of the width of the tenons relative to the mortises.

When assembling joints like this the tenons will compress into the end grain of the mortises, making for a really solid connection. This is another technique that I learned from a friend here in Japan, who was taught this method at furniture making school. The whole purpose of cutting mortise and tenons like this is to make joints that won’t be coming apart easily. It’s a good method when you can’t use some sort of mechanical reinforcement like pegs or wedges.

When I first saw my friend cut and assemble joints in this way I was shocked. I thought they would be ridiculously hard to assemble, but the reality is that the tenons compress quite easily, and with modest clamp pressure the joints slide together without much struggle. I’ve cut joints like this in everything from white oak to super soft red cedar, and it’s surprising how much compression you can get away with (somewhat accidentally I cut some wide tenons for some cedar doors up to 3mm wider than their respective mortises once and everything went together).

The downside to joints like this is that they are a one shot deal. There’s no dry fitting these mortise and tenons, which means the joints need to be cut really accurately from the outset. Likewise, compression joints aren’t an option when you have to do any kind of scribing which requires the ability to assemble and disassemble a joint multiple times.

Anyhow assembly of the stools went pretty well. I had one panic moment when I realized I had one of the stretchers turned upside down, but I managed to catch it before I had the everything fully clamped. With the stool assembled you can finally see the complete structure with the splayed legs and the offset stretchers.

And here are all 4 stools assembled and stacked.

With the stools assembled the last step was weaving the Danish cord seats. I used to weave Danish cord benches for another woodworker when I was living in NY and at that time I used L-shaped hook nails tacked along the inner perimeter of the stretchers to hook the cord onto. On the plus-side using hook nails gives you the ability to work directly off a spool of cord, and overall it simplifies the weaving process making it much less labor intensive. The downside to hook nails is that they make for a slightly less finished look to the underside of the seat, and they can sometimes be felt when you reach to pick up the chair/stool/bench.

Personally I’m all for hook nails, but I’ve noticed that not many furniture makers here in Japan use them. Instead the method I see more often is to fully weave the seat, both top and bottom. Often the bottom weave is simplified, but still the cord fully wraps around the top and bottom of the seat. A fully woven seat has a really clean, finished, look to it compared to one that uses nails, and it’s really nice on the hands when handling the piece with no sharp nails sticking out. This method also has it’s downsides though. It uses about twice as much cord to fully weave a seat this way, and it takes about 3 times longer.

But that’s the method I decided to go with for these stools. Truthfully when I made a prototype version of this stool with a fully woven seat I brought it to an event for people to try out, and it was surprising to me how many people reached down and felt the underside of the seat, and commented on liking the complete weave. That was enough to sell me on the extra material and work involved.

Weaving starts with wrapping the long stretchers to form the weft of the weave. I used a thin flexible piece of mdf as a guide when wrapping the weft strands. This method effectively makes the outer strands longer so the that seat ends up with a nice curvature.

I’m not going to cover the full weaving process in detail, but for anyone who is interested I highly recommend this video:

With most woven seats splicing the cord at some point is more or less inevitable. With a fully woven seat splices can be done on the bottom side where they end up hidden from view.

Here’s one completed seat. You can see here how the curvature of the seat comes together as a result of the weft strands being longer on towards the sides of the stool.

And then there were 4.

Being new to this particular method of weaving I figured I’d be slow at first but hoped that I could pick up speed as I got a handle on the process. The first stool took me 4 1/2 hours to weave, and the rest I managed to do in about 3 1/2 – 4 hours each. Not a huge improvement in speed but every bit counts I suppose.

One area which I think I’ll simplify a bit is the bottom of the stool. On the first couple stools I wove the bottom the same as the top, alternating over and under every weft strand. This style definitely takes the most time and effort to weave.

On the last two stools I simplified the bottom weave ever so slightly by alternating over and under every two weft strands. Surprisingly that little change made things a lot simpler, so I’ll probably aim for something like this in the future.

Back in the beginning I started designing this stool with the goal of creating a 4-leg stool that would be relatively simple in design and fabrication. I wanted to keep the overall cost down so that I could make it a more affordable piece. In the end the design became slightly more complicated than what I set out to make, but I’m definitely happy with the finished result. The splayed legs and fully woven seat are not design features that are quick to execute. I may be able to improve things a little here and there in the future, but overall after this first round of 4 stools my average time per stool from start to finish was 10 hrs. Not terrible for a handmade, small batch, production run.

Thanks for reading.