Thread: joints for chairs

Thanks guys appreciate your responses to my question.

Originally Posted by IanW

So you would entertain loose tenons too, WW (in the 'right' circumstances)? I'm not sure there would be such an advantage in using epoxy for the rail part - I'm yet to be convinced tha it is going to be around as long as HG, and it is just as prone to failure as any other glue - the mere fact it needs mixing gives room for errors & less-than ideal quality. May as well use the same glue each side, IMO, and retain the removeability factor. Neither glue is weaker than the wood, when properly applied, after all........

I'm not so deaf to new ideas, so yes I would give loose tennons a try in the 'right' circumstances. I'm damned if I can imagine what the right circumstances would be though!

I restored a large set of eighteenth century mahogany chairs that had previously been restored in the 1940s or '50's by a very reputable London firm. Several of the chair rails had given up the ghost, but in fairness to the restorers, they decided to extend the life of the original rails for as long as feasibly possible. They had fitted loose mahogany tennons to several of the rails, but by the time the chairs came to me, the loose tennons had failed (they were wobbling in the rails and the mortices). The only thing holding them together was the upholstery.

Not having used 'poxy glue (in woodworking), I can't comment on it to any extent, so I bow to your superior knowledge of it. My thinking was, if using a loose tennon, would be to have the rail/tennon joint made permanent and then use horse sauce on the actual mortice and tennon joint.

For the seat and back, I wanted to have a solid form fitted surface. My first thoughts were to make a frame in which the supports for the seat and the back are cut to have curvature, and a thin 3/8 inch thick ply would be glued into the frame. The second idea was to just make a formed plywood out of three pieces of 1/4 inch oak.

What are your thoughts? How would the 3/8's inch oak ply hold to the frame over time?

Originally Posted by IanW

Lignum - as I said, loose tenons should be as good as the 'regular' kind, all things being equal. In your case, properly done by a skilled person, all things are more likely to be equal...
,

Forgot to add, i also include some nice corner blocks.

Originally Posted by Woodwould

I'm not so deaf to new ideas, so yes I would give loose tennons a try in the 'right' circumstances. I'm damned if I can imagine what the right circumstances would be though!

Just stirring, mildly, WW!

Originally Posted by Woodwould

Not having used 'poxy glue (in woodworking), I can't comment on it to any extent, so I bow to your superior knowledge of it. My thinking was, if using a loose tennon, would be to have the rail/tennon joint made permanent and then use horse sauce on the actual mortice and tennon joint.

I doubt my knowledge of 'poxy is all that s'perior WW, though I (shamefacedly) confess to splashing a good deal of it around in my more callow days (& my old dad was determined to make Araldite very rich, for a while there). I wasn't being hypercritical, just wondering out loud if there would be any material advantage in the approach you described. When a stressed joint failed, it would be the weaker part that let go, & since the 'rail' joint is embedded in long grain, it's likely to survive the visissitudes much better than the stile joint, which is embedded in cross-grain. So you would be very unlikely to have to worry too much about the rail side, ever....(?)

Just an opinion,

Originally Posted by Lignum

Forgot to add, i also include some nice corner blocks.

Cheat!

Originally Posted by IanW

When a stressed joint failed, it would be the weaker part that let go, & since the 'rail' joint is embedded in long grain, it's likely to survive the visissitudes much better than the stile joint, which is embedded in cross-grain.

Good point.

One side of a traditional tenon is still a lose tenon, so the chance of that failing is similar to a double sided lose tenon. I have made lose tenon (the other, other way) chairs back in the early 90`s and havnt had complaints.

Dowells are crap, never touch them.

Originally Posted by Lignum

Dowells are crap, never touch them.

Now THAT I will heartly agree with.

The number of dowelled things I've tried to fix over the years... One of them I remember vividly - a set of basket-case Blackwood chairs. Literally - they were brought to me as a flat-pack in a couple of laundry baskets (& not an Ikea spanner in sight!). Well I put in oversize dowells where I could, then glued & screwed in some really hefty corner blocks. Sent them back to the owner with no gaurantees, but they stood up well for a good many years until I lost track of them. I love corner blocks too!

Now I'm going home - with all this 'puter chatting it's taken me twice as long as usual to finish what I was doing!

Originally Posted by Lignum

One side of a traditional tenon is still a lose tenon, so the chance of that failing is similar to a double sided lose tenon. I have made lose tenon (the other, other way) chairs back in the early 90`s and havnt had complaints.

Dowells are crap, never touch them.

ummmm, didn't you have a double doweller at one stage?

Originally Posted by echnidna

ummmm, didn't you have a double doweller at one stage?

Yep $49 GMC and it fell apart in a month, I dont even know where it is. when i clean up and find it, you can have it for spares

I think that the best of modern glues are stronger than hide glues, but nevertheless, I've had most types of glue fail under extreme circumstances - usually extreme variations in humidity. For this reason, it's reasonable to assume that sometime, your chair is going to need to be repaired, and if it has to be disassembled, hide glue is best. Also, it will stick to itself, unlike many other glues.
As far as floating tenons go, I've used them to repair chairs where dowels have failed, but wouldn't use them on a new one. As WW says, it's just another place where a failure can occur, and the top of the rail above the floating tenon is a weak point.
At some point in its life, someone will try to rock back on every chair, which puts a huge strain on the leg/rail junction. You can help mitigate this by raking the legs back. This makes it harder to rock back, and also balances the force of someone leaning on the backrest. However, a chair needs to be carefully designed if you are going to use this technique, or it will look weird.

Originally Posted by AlexS

As WW says, it's just another place where a failure can occur, and the top of the rail above the floating tenon is a weak point.

If the amount of stock at the top is to thin thats fair, but thicker stock and good corner blocks their wont be a problem. Every join one day will fail, and i cant understand why a certain section of the woodworking community are so anti lose tenon.

Just add corner blocks and stir

Lignin, if I were you, I'd invest in some clamps; that chair is never going to survive with loose joints like those!