Replies

1. 
   RalphBarker | Mar 02, 2010 10:42am | #1

   I haven't built the bench in question, nor have I seen the plans. But, I'd guess that with the typical bench materials, not much spread would be required to keep the tenon in place.

2. 
   clayandnancy | Mar 02, 2010 01:36pm | #2

   I believe that he tapers the thru mortise so the wood has somewhere to spread therefore locking in the tenon

3. 
   Lataxe | Mar 02, 2010 03:03pm | #3

   J,

   You don't need to spread the tenon much in a well-fitting flared mortise to make it mechanically strong.  Eg, for a 2 inch long tenon 1" deep two wedges of 1/8" at their thick ends is more than enough.

   Also, with deep mortises there's no need to flare the whole mortise depth.  You need only flare the last inch, leaving the rest (on the side from which the tenon enters) parallel-sided.  Correspondingly, you only need wedge the last inch of the tenon that sticks through the emergent side of the mortise.  You then have a sort of Y-shaped tenon that acts like an ordinary tenon but with a big dovetail on the end.

   The splits for the wedges can be very close to the tenon ends; and it's best to make those splits follow the grain of the tenon, even if this makes one edge of the tenon near-separated from the rest of it.  Once you glue the wedges in place, those splits are "mended". 

   In fact, you could just flare the mortise and leave the tenon uncut (parallel-sided) just knocking the wedges into the gaps either side of the tenon-ends.  Once the glue has dried atween tenon and wegde you still have a flared tenon in a flared mortise.  (Unless someone can think of a reason why we shouldn't trust the glue). 

   Lataxe

1. 
   jab1 | Mar 02, 2010 04:17pm | #4

   Thanks for the advice. Not as hard as I was trying to make it.   Thanks again.