I have disassembled an old dining chair. It had loose joints and had become a little rickety, so I plan to glue it back together and refinish the wood.
While I have it apart, I am using its parts as templates to build several new chairs. It is entirely constructed with doweled joints. I expected mortise and tenon joinery. On my new chairs, should I maintain the doweled joints or plan for mortise and tenons? Is there a disadvantage to the doweled joints?
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The downside is that dowel joints get loose and become a little rickety.
Go M&T if you can..
Given that the glue tolerance on both dowel and m&t is the same, what accounts for the greater loosening of the dowel joint?
Two things:
1: Long grain to long grain glue surface is maximized in M&T, on a dowel it is limited.
2: A dowel distorts seasonally, expanding (compressing itself) and then receding inside the drilled mortise. Eventually this results in a loose fit. It is worst in chairs because using them stresses the joints when they are both loose and compressed, hastening the process.
MJ, Harvey, and others—a question about what seems to me a further advantage of M&T over dowels, albeit related to what’s been described already.
Without any experimental data to support my belief, I think it’s true that because a M&T joint (if it’s not a loose tenon joint) has only one side of the joint that can be subject to differential movement/compression/expansion (the non-problem side being that from which the tenon arises in continuity from the piece), there’s probably going to be about half the overall joint loosening/movement over time. This, combined with the much-increased long grain-to-long grain glue surface area of a decent-sized M&T joint over a doweled joint, should, I think, explain the much greater longevity of M&T joints in this kind of work.
So, the question: What do you kind and knowledgeable folks think?
I wouldn't use dowels as joinery for any amount of money. They will always, always fall apart. Mortise and tenon is far superior.
MJ is right. There was an article in FWW long ago that demonstrated the problems with dowel joints.
The glue of choice for re-gluing the original chair is gap-filling epoxy (from the hardware store.) Anything else won't last, at least in my experience. When making a new chair with M&T joints, yellow glue will work fine, altho I sometimes use long set epoxy on complicated glue-ups (of all sorts) to give me more time before the glue sets up. Yellow glue can stick the pieces at the almost together point, whereas epoxy acts as a lubricant till it sets well. When using long set epoxy, don't remove the clamps till the next day, even if it seems to have set up. There is a story there...
Thanks for the tips guys. I appreciate the help.
Harvey—I agree with your description of the advantages of epoxy in repairs of this type, but there remains the question—what about future repairs? I suppose that an epoxy-repaired joint, well done, is very much more unlikely to come undone in the future than, say, a hide-glue-repaired joint, but the hide glue advocates constantly crow about the ability to release those joints (often with much hard work that goes undescribed, esp. with regard to M&T joints, I think) and more readily repair them.
There’s a part of me that likes the idea of facilitating future repairs, especially in highly-valued pieces, but the practical side of me thinks that the epoxy path is, generally speaking, going to be more suitable/satisfactory in the greater proportion of instances.
Thoughts?
I think the "Old Masters" whose furniture survived long enough to be considered classic examples in whatever style chose the best adhesives they could at the time they were working. I'm pretty sure they built it well enough to last without considering that someone might have to fix it 100 years later and without ever being glad that the glue was "reversable".
If they had titebond, CA, polyurethane, and epoxy they would have used it all without apology.
I cannot help but think you’re almost certainly correct. That said, I like to think about “the next guy” occasionally, too. It’s nice to be able to fix a well-loved chair. Or table, or whatever.
I too would use M&T joins, mostly because I don't own a Domino, and without one, the effort of making slip tenons exceeds the benefit.
I rather like the M&T joint too - it's easy enough to get right, very forgiving of error and is somehow both 'real' woodworking yet not so much trouble that it gets in the way of making things happen.
Most chairs will loosen over time, being as they are, subjected to substantial dynamic forces. Even really good ones can become a bit rocky - dowels just tend to fall apart faster.
Mortise and tenon it is.
Chairs are tough. Outside of going the Windsor route using green (er) legs with dry stretchers and aprons, M & T for me. I have repaired our kitchen chairs when the stretchers came loose. I pried them apart, found some unknown glue, with pin nails for some unknown reason in each joint!! Nothing like using a straight pin to make a joint strong, right?
I cleaned up the glue, cut slots in the stretchers, fox wedged them, and put everything back together. And hope they live longer than I will because I don't want to fix them again.
Neighbor had loose arms on a dining room chair that was held together with a screw. Good design should not depend on using a single screw to hold a lever arm secure. I could only use different screws to 'fix' them and hope no one wiggles the arms loose again.
And don't call me when they fail.
About 3+ decades ago when my daughter was in kindergarten her teacher had a rocking chair in the class she would use for story time. Many of the joints were loose and it was quickly becoming a problem. I offered to fix it which led me to try a “new to me” product called Chair Doctor that I purchased at Lee Valley. It flows almost like water and causes the joint to swell and once dry locks the joint again. For the next few years I would inquire occasionally if the rocking chair joints were coming loose again and fortunately for me and the teacher the fix was still working. The best part was that it required no disassembly. The glue is injected into the joint with a fine tip hollow metal needle, for lack of a better word. When necessary, you can drill an almost invisible 1/16” hole to give the glue a better pathway.
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