Hi all, long time lurker, first time poster.

I believe this is the best place for this thread. I already have most of the project done and therefore have constraints I must abide by.

Some basic information about the project: I am building a desk for commission. I was given artistic freedom within an aesthetic for all details as long as the table had specific dimensions and could easily flat pack. The base is all steel and the top and shelf are solid cherry. The two leg frames are joined with two stretchers with flanges that bolt into the legs using welded threaded inserts. The shelf is mounted to the top stretcher with two bolts that thread into the steel and large rectangular steel plates set flush into the shelf, clamping it to the stretcher. The shelf is supposed to be of minimal construction and only 13 inches deep.


My problem: I have the leg frames and stretchers completed. The table top and main shelf material cut to final dimension and have started on the final bit of joinery in the project - the shelf. The shelf is only constructed of five pieces, a bottom, two sides, a back and a non structural divider. The Dimensions are (W/D/H) 36"x13"x3 1/8". I had designed dovetails to join the sides of the shelf as if I were making a standard case. I thought this would work well dealing with expansion, be strong and add a nice detail view able from the side.

In the back of my head I knew the long grain of the sides was only ~3 inches in length and that may become a problem. I thought maybe expansion would split the sides of the shelf.. But I went ahead with it anyways, not knowing a better design. Now I have cut some of the tails and accidentally partially split both of the side pieces. I've glued them back together and was thinking of going through with this design. I have plenty of extra material to make up new sides but none for a new shelf, I thought it best to ask the forum here for advice before I do something stupid and irreversible.

Above: The shelf mocked up on my (wobbly and dirty) work bench.
Above: Dovetails in shelf sides shown where i stopped after they split and i re-glued them.
Above: *upside down pic for some reason* measurement of the underside of the table surface to the top of the metal brace it will sit on top of.

I thought of a few ideas:
Standard dovetails with long grain matching the shelf - my original idea.
2. Flipping the grain orientation and doing sliding dovetails, I would have to leave material on both left/right extremities so it wouldn't break out, but not really familiar with this technique?
3. Some sort of more simple rabbit/slot/dado. This wouldn't be as pretty or strong.
4. Box joints - Meh but better than nothing.

So I propose the question:
How would you join sides and a back to this shelf so it can be a stand alone piece? I am open to almost anything at this point. I would like it to be a joinery detail if at all possible.

Thank you for reading my long post. Hopefully it wasn't too rambling and I look forward to any advice I get.