Why aren't 'dovetailed M/Ts' more popular?

[transatlantic]

The image below kind of shows what I mean, but without the wedge shaping, or the round bottom, and a longer tenon for more glue surface area. Seems like a good joint for joining table rails to legs, as they're self clamping for gluing up.

 

[Yojevol]

I don't think glue would be much help with this joint as just about every interface involves end grain which is notoriously poor at bonding. So the strength of the joint is relying on the dovetail only.
Brian

 

[dzj]

I think that a table leg might exert too much leverage for such a joint. Perhaps if combined with
some kind of rail-leg-rail hardware.

 

[transatlantic]

I don't think glue would be much help with this joint as just about every interface involves end grain which is notoriously poor at bonding. So the strength of the joint is relying on the dovetail only.
Brian

But it's just a M/T with slightly angled cheeks? (and one face open for it to slide in)

 

[Just4Fun]

I have used similar joints but only on rough work, not on furniture. I don't know why.

 

[That would work]

These (without the taper)are used to join beams into the sides of doghouses in yacht work which are comparatively thin.

 

[samhay]

The joint in the photo is quite commonly used to join the neck onto an acoustic guitar. It can take quite a bit of fettling.
Without the wedge shape it's 'just' a sliding dovetail isn't it?

 

[kevinlightfoot]

The orientation of the components is incorrect for a true mortice and tenon where as stated the glue area on long grain would be much greater.The strength of the pictured joint would be very poor.I don't think I would put much reliance on it in any situation I can think of.Custard would be the man or MikeG to ask for a further opinion they will probably be along shortly.

 

[That would work]

They are commonly used in traditional yacht work. To join coachroof beams into the sides of the doghouse. But without a taper. The beam is cambered.Any other yacht joiners/boat builders will remember them I'm sure.

 

[MikeG.]

Pedestal dining tables with stretcher rails instead of aprons often have the stretchers dovetailed into the top of the cross-piece on the top of the pedestals. This allows the table to be knocked-down for moving without a screwdriver or spanner.

 

[D_W]

The image below kind of shows what I mean, but without the wedge shaping, or the round bottom, and a longer tenon for more glue surface area. Seems like a good joint for joining table rails to legs, as they're self clamping for gluing up.

Lack of depth in that joint of there could be any leverage, but it's a joint that lends itself well to power tool templates whereas a mortise and tenon (before all of this exposed endgrain stuff that's also a power tool era thing) would've been more suitable for hand tools.

Mortise and tenon joints tend to be self jigging for gluing, too, if they're reasonably well made, and clamping everything hard is more of a modern thing. I'm sure plenty of mortise and tenon joints were glued with hide glue and not clamped.

As mentioned above, modern guitars often have a joint like that (or without the dovetail and just the rounded tenon, held on by a bolt instead - which is a better joint for drastically scalloped guitars that will need regular work, anyway - I could never hear the difference between a high end bolt on guitar (like a bourgeois) and one with a dovetail - nobody can. The difference for guitars is that there isn't much chance of significant levering forces. The strings do it a little bit, but not like tables and chairs get.

 

[sammy.se]

Matt estlea uses this joint in his latest tutorial, it's a small cabinet though, not a table.

Sent from my SM-G973F using Tapatalk

 

[peter-harrison]

These joints were always used for the cross-stretchers on antique chairs. I don't know why. Possibly as they could be made and glued in after all the other joints had been made and glued up, or possibly because they had a lot of resistance to being pulled apart in a narrow rail.
They do sometimes come apart, but not as often as you would think, especially given that the glue was Scotch, and houses were often damp.
They are also quite easy to re-attach as you don't need to disassemble the rest of the chair to do so.

 

[AndyT]

I'd say that for attaching table legs, M+Ts are superior, so on the whole, they are used. The need for clamping is easy to cope with - get some clamps!

Similar joints to the one shown always have been used in cabinets where a solid top fits over a frame and panel structure, or where a thin rail sits over a drawer opening.

 

[MikeG.]

I'd say that for attaching table legs, M+Ts are superior, so on the whole, they are used. The need for clamping is easy to cope with - get some clamps!.....

I'm pretty sure that draw-bore pegging as used in furniture is only a way of getting around a lack of clamps.

 

[clanger]

Matt estlea uses this joint in his latest tutorial, it's a small cabinet though, not a table.

The difference with Matt's dovetail housing in the case is that the dovetail slots in to the endgrain of the board, so there is more crossgrain to crossgrain surface area for glue. As Mike says, these joints are used more for knockdown furniture.

 

[transatlantic]

I confused matters with posting that image I think. The following image shows more what I was describing, but imagine the tails being much longer, and the angle being much less severe. Hence my analogy to a 'dovetailed Mortice and Tenon', as oppose to a sliding dovetail that is usually very small.

 

[Just4Fun]

I confused matters with posting that image I think. The following image shows more what I was describing, but imagine the tails being much longer, and the angle being much less severe.

Oh, I misunderstood what you meant. In my imagination I had the "rail" being pushed horizontally into the side of the leg/stile mid-way along the length of the stile rather than vertically from above. I would have thought the joint you mean was not uncommon.

Personally I would almost always use a simple M&T instead, but I'm sure I have seen this version a few times. I probably would not bother with it because it is a little more complex to cut than a straight M&T and I don't see any real payback for the extra effort in most projects. Of course if ultimate strength is important it may be worth the extra effort but that is rarely the case in my work.

 

[dzj]

A regular sliding dovetail might even prove to be stronger, as there's not much "meat on the bone" left
between the two adjoining mortices of the elongated version.
The morices being open-ended, aren't going to help much (strength-wise) either.

 

[worn thumbs]

Isn't the simpler answer to the original question the time that they take?In a commercial environment the cost of the time has to be passed on and in a hobby situation the cost is the time subtracted from our available productive hours in the workshop.I would suppose that were we in the position to need dozens of joints,the time taken to make jigs to speed up production would be repaid in short order.For a one off hobbyists item its harder to justify so we go with the simplest joint that does the job.As an example,the joint shown in the earliest post would adapt to fixing joists to wall plates and yet the usual solution is to nail a galvanised joist hanger in place.