Need Some Joinery Help

[riverstwo]

Hello all,
I'm working on this entryway table and have been going back and forth on the joinery for the lower shelf. The shelf is 7" wide and the grain on it and the stretcher it attaches to run in opposite directions. I think trough-mortises on the support stretchers would be the strongest but I worry about wood movement? Any ideas/help would be appreciated, thanks for looking.

 

[Henry W]

Yes that is a 'cross grain' situation, and you are always right to at least consider this.
One answer to only glue in the center 2" (?) of the mortise/tenon, and allow a bit of expansion space in the mortise (not so great in a through tenon though).

My strategy would NOT be a through tenon, but a 'hidden' or blind M/T with the mortise cut only partially into the depth of the stretcher. Then you can allow a slight wider mortise (front to back as the piece aligns in the table) and give expansion/contraction space for that shelf. Online calculators should be able to give you a number for the amount to allow. In my opinion, a hidden tenon will be plenty strong BTW - even if you decide to load that shelf with a row or two of books (or bricks!). Again you could calculate the weight bearing capacity of a 1/4" tenon 5-6" long, but I wouldn't bother.

 

[Jeff]

How thick is the stretcher (3/4")? I'd just cut a rabbet on the inside faces of the stretchers and drop the shelf into the rabbets. No mortice and tenons, and no glue needed.

 

[mdbuntyn]

I'd do something similar to what Jeff said, but instead of cutting a rabbet, I'd add a cleat to the stretcher

 

[JimD]

I would put a dado the width of the shelf across the rails of ends and put a dab of glue in the center. You probably also need to notch the shelf a little if expansion could cause it to expand into the leg.

 

[Mike Davis]

This would be an excellent place for a sliding dovetail joint.