Using my newly shop-made tenon jig, I was able to make double tenons.  I made a set-up board with mortises to evaluate the fit for the outside of the two tenons and for the completed tenons.   I also used my ½” & ¾” shims for the four needed TS set-ups.  I was pleased with the fit.  Then I experimented to determine if I wanted square end tenons or round end tenons.  Since I made the mortises with a router, I will have round end tenons.  If I had used a mortising machine, I would have elected to have square end mortises.  With some practice, the production double tenon pieces had a good fit into their respective mating part.  40 tenons done, 20 more to go.

Thanks for looking.   Danl

 

 

Well done! Getting double tenons to fit properly into double mortises is always (for me) a tedious task. You made it look easy.

Dali Lama say:  if it is worth tenoning, it is worth tenoning twice!

 

nice technique, nice piece too.  like the figures on the oak.

i also see you are a fan of blue tape and Sharpie - to keep track of what piece is what.

1 hour ago, DAB said:

i also see you are a fan of blue tape and Sharpie - to keep track of what piece is what.

Yes, I need to keep notes and the blue tape helps.  I have learned the hard way to not let the tape be in place to long especially when on a plywood panel.  Soon, I will move the tape to the inside of the nightstand.   Danl

Well done Dan!  Your time spent on the fixture has already paid back dividends in both time and quality.

Great progress. You ended up with some beautiful white oak.

Dan that is nice work ! Double tenons are difficult to say the least. Lots of prep but the end results are excellent. I like the overall design of the table too. Doesn’t get any more solid than that. 
Paul

I've played around with double or 2x2 tenon arrays several time for the last decade or so helping students.  My working theory is that so long as the individual tenons aren't so small and weak enough to fail then they have more total surface area for glue than a single tenon. They also reduce the weakness of the mortise side by leaving a bridge between the mortises. I cheat of course as I use a CNC for both side of the joints, but the theory stands no matter how they are made.   The desk I'm using at this moment has 4x4 cedar legs with a 3x5 tenon area into a butcherblock top: https://4dfurniture.blogspot.com/2016/05/simple-desk-design-tenon-array-joint.html  

A book stand I made for the college library has two posts tenoning into the slanted top with a 1x4 through dogbone tenon array.: https://4dfurniture.blogspot.com/2020/02/a-rare-book-display-stand.html.  The dogbone shape also has a little more surface for glue than a simpler rectangle would.  

I also found I could push the tenons closer to the perimeter of the stretcher/post/leg for better resistance to racking.  In simple table designs where there is not much racking or twisting force to expect more simple joinery (single tenons) is easily enough to hold the parts together. 

 

4D