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

[transatlantic]

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.

But if it was a tight joint, and glued properly, it's one piece so to speak?

 

[Sheffield Tony]

Looking at that last set of photos, if you put a sideways pressure on the top of the table, the top of the dovetail serves as a wedge trying to split the top of the leg.

 

[MikeG.]

........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.

One of the most sophisticated and developed joints in British oak framing is the joint between floor joists and a bridging joist (the big beam that runs along the middle of the ceiling in a cottage or farmhouse). The resulting joint, bare faced tenons on the centreline of the depth of the bridging joist with a diminishing haunch, took hundreds of years to be fully developed and there were presumably hundreds of failures and deaths even in getting that far. Anything like the joint in the OP would weaken a plate significantly, meaning that the plate would have to be massively increased in size to compensate.

 

[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.

But if it was a tight joint, and glued properly, it's one piece so to speak?

Over time, you never know how the glue will fare. I'm not sure you can rely on the joint
alone in this case, as you could on a traditional pinned M/T.

 

[Doug71]

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.

But if it was a tight joint, and glued properly, it's one piece so to speak?

Over time, you never know how the glue will fare. I'm not sure you can rely on the joint
alone in this case, as you could on a traditional pinned M/T.

Yeah I always drawbore my dovetails in this situation, belt and braces 8)

 

[Sgian Dubh]

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.

Not a bad choice at all for three legged tables, even if used on just one leg to allow final assembly. The alternative to sliding dovetails, tapered or not, would be M&Ts that need to be sloppy so that all parts can be wriggled together - not a great option, or an adaption of the M&T in the form of a bridle joint so that each rail can be slipped into place individually, also probably not a good technical choice. Webbing clamps could be one method to apply pressure, for the M&T type variants, and even for the sliding dovetail if required. Slainte.

 

[D_W]

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.

Partially, but also to create tension on a joint so that it doesn't open with seasonal movement (something we probably don't see now due to the abundance of cheap glue slathered on the entire tenon).

 

[Max Power]

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.

Not a bad choice at all for three legged tables, even if used on just one leg to allow final assembly. The alternative to sliding dovetails, tapered or not, would be M&Ts that need to be sloppy so that all parts can be wriggled together - not a great option, or an adaption of the M&T in the form of a bridle joint so that each rail can be slipped into place individually, also probably not a good technical choice. Webbing clamps could be one method to apply pressure, for the M&T type variants, and even for the sliding dovetail if required. Slainte.

Always knowledgeable interesting replies from you Richard, having spent forty years doing all sorts of wood work both in a professional capacity and as a hobby, yours are some of the posts I most enjoy reading.