Joinery for wall-mounted box/cabinet

[trimbleepic]

Hi!

So, I'm planning on making an open faced cabinet (no door) to hang on my wall in my workshop (5 sided box). I plan to attach a French cleat to the back to attach to the wall.

The two weight bearing surfaces will be the top and the bottom shelves. Obviously the top rests upon the vertical sides, so I would expect it could be simply butt-jointed to the two vertical walls... (or any other of many options)

...but what is the best way to attach the bottom to the two vertical walls? It is essentially hanging from the three verticals (two sides and the back) I'm not ready for dove-tails, and I don't want to rely on screws to bear the weight. I was thinking a rabbet on either side of the bottom into dado's on two verticals... But, if I use plywood for the project, is it safe to put weight onto dados(of plywood)? could the plies eventually fall apart? What is the best way to attach the bottom if I use ply?

[rivendale34]

The simplest, most common and over all best (in my opinion) would be a simple dado. That way there is a bottom shoulder to hold the bottom shelf up. It doesn't have to be ver far from the bottom edge of the sides, 1/2 an inch would do. You can dado across the back if you want, but it's not that necessary unless you expect it to be holding a lot of weight. Screws on the back and a strip of hardwood across the front or under the bottom shelf will provide support to prevent sagging. Marc posted a short article on the homepage about supporting a shelf just a few days ago.

I'd suggest a rabbeting the sides to join the top however. If you're like me, you may not plan on putting anything on top, but you will anyways.