Monday, June 8, 2015

Engineering solution?

To get around the issue of the grain running in the wrong direction on the connector of my modified Tage Frid-style stool, my idea is to make the connector piece essentially out of hardwood plywood. I created the plywood with ¼” thick plies of cherry in an alternating perpendicular orientation. This way, potentially, the wood on the sides of the connector piece will have a substantial amount of end grain to connect to.

I made the plywood, cleaned it up a bit on the jointer and planer, and cut the sides with a 15 degree bevel. This bevel establishes the splay angle of the legs. To complicate matters, the leg will also be joined at another angle that will establish the rake, making this a compound angle dovetail. (The splay angle is side to side; the rake is front to back). I used the test leg I cut for my first test since it already had the tenon that will form the vertical tail of the dovetail. The trick to cutting angled dovetails is to not think about the fact that they are angled dovetails. Just mark everything clearly and cut to the lines.

I was a little nervous when I tapped the dovetail together because this is where it broke in my last test. The fit was a bit too tight and I had to do more pounding than tapping to put it together. The joint survived the pounding without a budge. Now that it was together, I had to try to break the wood. I wrenched it around, simulating the wracking force chair legs have to endure. Nothing moved; no cracks anywhere. I put the leg securely in my vise and got out my hammer. I bashed it in all directions and still it didn’t move. Finally, I climbed up on the bench and put all my body weight on the joint. There was a bit of creaking, but I think that was me and not the wood.

I’m satisfied now that this plywood method will hold. Not only does it provide end grain for the dovetail but each layer bolsters the other layers against movement. I’m considering adding another ply of cherry going side to side on the underside just between the two leg joints and adding a small stretcher a few inches down from the seat, which will serve two purposes -- fortifying the two legs and serving as a handle to move the stool. Also, I feel like the tenon can be a touch wider, so i’ll incorporate that as well. All in all, I’m happy enough to go forward.

Wednesday, June 3, 2015

Engineering Problem

I love a good engineering problem. I think my favorite thing about woodworking is that it’s the intersection of engineering and creativity. I’m working on a design for some barstools based on the Tage Frid three-legged stool. The problem is that the seat height needs to be about 28” and I’m afraid sitting on a three-legged stool that high would make it top heavy. The last thing I’d ever want is someone falling off of one of these stools. Frid swore by the design of the third leg in the back. I’ve made a couple of those stools now, and I agree that it’s fine when you are sitting at a low height. People aren’t used to having one leg in the back, so when they shift around expecting the seat to be solid, they could topple over.

The second problem is that I’ve seen examples of people making the Tage Frid stool with slight variations and they never look right. The proportions are critical to this design. They make the design. So how do I add another leg in the back without messing with the proportions? I did drawings where I widened the connector between the seat and back to accommodate two legs joined with through tenons. They looked awful. I found that no matter how great the rest of the stool looked, my eye always went right to the connector, which called attention to itself because it was so out of proportion to the rest of the stool. My proposed solution is to join the legs on the sides of the connectors with vertical dovetails.

So. The other problem is the grain direction of the connector. The grain needs to run straight from the dovetails on the back to the tenon on the front. If you make a hole on the side, you leave a section of short grain which is vulnerable to breaking. Indeed, on my first test run, the back chunk of the connector broke immediately. This is a critical area of the stool, so that part of the connector needs to be strong.

My idea for mounting the legs in that spot with a dovetail is to make the connector out of laminated perpendicular plies. It would be like plywood, except this would be hardwood plywood. This is a compromise, as most design decisions are. My hope is that the plies will adhere well and strengthen each other. Time to do some tests.

Friday, November 21, 2014

Tage Frid Three-legged Stool

I just finished a series of posts on the Craftsy woodworking blog about building a Tage Frid inspired three-legged stool. It was a challenging build from start to finish. These posts detail the whole process. My version is made of Ambrosia maple.

Craftsy posts:

Wednesday, September 10, 2014

Robotic Furniture

This article introduces the Roombot, a robot that assembles itself into different pieces of furniture -- Transformers-style. The inventors describe it as the "future of furniture." Why am I not worried?

Thursday, August 21, 2014

Libby Schrum in the New York Times

I’m happy to report that friend-of-Furnitude Libby Schrum got a great feature on her bench 'Siblings' in the Home and Garden section of today's New York Times.  Nice ink, Libby!  See my post on her work here.

Tuesday, July 29, 2014

Craftsy Post on Spoonmaking

Here’s my new Craftsy post about my first foray into making a wooden spoon. I’m not sure it was wise to write a post about my first effort but I tried to illustrate my learning process. Spoonmaking seems to be huge right now. Here's a link to the #spoonmaking tag on Instagram. Crazy! I'll do a post on spoonmakers soon. I love that people are making all kinds of stuff. 

Saturday, July 26, 2014

Jeff Miller Chairmaking Class

Jeff Miller, one of the great furniture makers working today, is teaching a class in Nashville soon for the Cumberland Furniture Guild. If you are in the area, there are still a couple places left in the class. Click here to register. The class will be on August 9 in Spring Hill, Tn.

Jeff is as good a designer as he is a maker, so I’m happy to be able to take the class from him myself. I'm eager to hear his thoughts on approaching chair design. Here is Jeff’s website. And here is a post I wrote about him back in 2008. His arch table is still one of my favorites.

Here is a video about Jeff from the Highland Woodworker. Enjoy.