Double Doweled

[Kelols]

Duane has mentioned on the forum a few times that doubled doweled joints are one sign of a potential piece of quality furniture. Of course Duane is right.

I just wanted to mention that some excellent quality furniture is made with mortise and tenon joints also. In tests of well made double doweled joints versus mortise and tenon joints, the two techniques were very close in strength. Double doweled joints are faster to make than the mortise and tenon joints but have no real advantage over the M & T joint.

The one problem I've seen with both is sloppy gluing. Surface area is very important in the gluing process along with lack of movement during drying, and when gluing is done quickly without paying attention to the surface area, or proper drying time, both DD and M&T joints can come lose. In older furniture that has been moved from a high humidity climate to a dry climate, lose glue joints are very common due to expansion and contraction.

Unfortunately most joints in furniture are hidden so it's hard to check the glue job.

[drcollie]

The Double-Doweled, Corner Blocked, screwed and glue construction applies to top-level builds for upholstery frames, mainly because no one I know of used mortise and tenon joiner on them. The key of course, is to keep a frame rigid as one a joint loosens it becomes 'wiggly'.

Mortise and Tenon is the highest form of Joinery, and I have to disagree that Doweled construction is nearly as good. What holds dowels together is glue whereas on a proper Mortise and Tenon joint its the shoulder of the tenon and the pin into the mortise. In fact, on a properly made M&T joint with a cross pin, no glue is needed at all. If the craftsman has done his work well, it can be completely strong in a dry fit. When we do beds in M&T builds there is not glue whatsoever, its the joint and a screw and nut holding it all together and it will never loosen.

If you look at chairs, every day kitchen chairs, the ones down with dowels will eventually loosen over time, as the glue will lose its bond. But a mortise and tenon chair (also a bore and wedge chair) will not, as glue is not the primary holding force in the joint. M&T joints take much more time to make and require a higher skill set, that's why you don't seem them used except in better furniture.