Gary,
I am building a set of dining room chairs, and have attached a couple of photos of a prototype, focusing on the joinery of the bent lam apron to the rear leg. I removed the right cross brace for visibility.
My plan is to attach the rear leg with four screws through the apron into the leg. The final apron will be .750″ thick, comprised of 12 laminates. The rear leg is solid cherry. The cross brace is designed to limit flexing of the apron.
My question is: Would you recommend a different approach? My only concern is the ability of the screws to hold over the long term.
Thanks for your consideration.
Best regards, Tom Abbott
Replies
How about a half lap joint between the apron and the legs? Glue and clamp and then you wouldn't even need screws.
That is not a bad idea. My problem is that I build the back assembly first and then fit it to the apron. The task of milling two flat surfaces must deal with variations from apron to apron, and from back assembly to back assembly. So, I would have to bend the parts in most cases to get the two surfaces to pull together. I would also be concerned about trusting a cross grain glue joint for the most critical joint in the chair. But, thanks for the idea. I will mull it over to see whether those problems are solvable.Thanks, Tom.
Tom,
Well you got yourself in a pickle here. Because on the one hand you want a Thonet style round apron but you want it to last longer than 25 or 50 years. I'm thinking that may be tough as planned with screws.
It is how most of those bentwood chairs were put together. At least the ones I've seen. And they do hold for quite some time with just screws. But mortise and tenons were found in the those 2000 year old Egyptian chairs, not screws.
What to do? Well you could say that 50 years will be long enough for these things to hold together. You could say that the screw is the last century's greatest technological innovation. Witold Rybczynski did in his book, One Good Turn.
And if you like this logic then the only thing I would do differently is to run threaded inserts into the leg. Probably just two given the size of the leg. Threaded inserts use a wood screw thread into the leg with a flat head machine screw through the apron to pull things tight.
These will hold better than a regular wood or sheet metal screw.
I would put a shoulder in the leg however to rest the apron on. Just a little thing to take some strain off the screws. So 1/4" or so of shoulder cut into the leg.
I'm not crazy about the half lap idea for the reasons you gave. The only other option I see is to run some kind of loose wedged tenon through the apron and into the leg. I'd still put a shoulder into the leg to support the apron.
I hope this helps. Good luck. Gary
Gary,
Thanks for your thorough response. The threaded insert idea is a good one, one that I have used before and forgot. It has the advantage that it can be retightened if it loosens over time. I suppose that a dowel used in combination would serve the same purpose as a shoulder. I need to think through these ideas before deciding.Best regards, Tom.
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