Haunched Double Twin Tennon - Mitred Vs Stub

[Jelly]

So I'm looking at starting the legs and aprons for my Table tonight,

The stock I'm joining is 2" by 4", so I'm looking at using a double twin haunched tennon, to maximise glue surface, minimise racking, and prevent breakout of the mortice.

Previously I've done tables with an L-Shaped mortice and mitred the tenons to join in the middle, but this is a very challenging proposition with 8 separate mortices to join up on each leg, and I'm thinking that it will be wholly unnecessary on top of all the other techniques applied, and stub tenons would be sufficient.

So... am I being silly and over engineering these joints, or would the approach of Apply all the Techniques! actually be worthwhile?

 

[custard]

Not really necessary. It's not a highly stressed joint, so not like it's a chair or a gate, it just needs to withstand an occasional hoover knocking against the foot of the leg.

Other furniture makers will judge the quality of your work in large part by the tightness of the glue line (inside as well as on the show face), and achieving that will almost certainly require a little tickle with a shoulder plane or chisel, multiple tenons will interfere with this scribing operation.

 

[custard]

Thinking again, why is the apron 2" thick? If it's a cabby leg then surely the leg cross section at the top (i.e. in the area of the leg/apron joint) has been cut back to something a bit less than 2"? That sounds a whisker on the heavy side.

 

[Trafalgar]

Maybe if apron is really wide a haunch is worth considering -- might arrest twist should said wide apron start to move. That's the theory at least.

 

[custard]

Agreed, I should have been clearer, a haunch is worth considering, but probably not twin or stacked tenons.

 

[Jelly]

Thinking again, why is the apron 2" thick? If it's a cabby leg then surely the leg cross section at the top (i.e. in the area of the leg/apron joint) has been cut back to something a bit less than 2"? That sounds a whisker on the heavy side.

It's following the curve of the top, cut from the solid and meets flush with the outside of the leg, It will vary between 2" thick by the legs to ¾" thick at the thinnest point about ⅓ & ⅔ from the end.

 

[G S Haydon]

Tenon with a haunch on the top. End of tenon with a miter should be kept shy of touch. No strength to be gained by end grain joint of a tenon.

 

[Jelly]

Ended up going with a single 7/16" mortice with haunch, which simplified life somewhat.

Custard: Thanks, your question whilst not intended to made me realise that one of the two tenons should be more or less useless as it would simply attach to short grain, and nothing structural, so a single tenon offset toward the back is far more logical.

As it happens it's cut back to 2" from 4" mainly to allow me to match the curves of the top and bottom more easily, they're rather bigger than the average cabriole leg, but from my full size drawings should look proportionate and striking once completed.