If you are building a mantel you could certainly build it with a french cleat recessed.
French cleat tool cabinet.
Then you put the wall cleat in place based on the location of the cabinet cleat.
Cut the 45 degree bevels on the strips.
Repeat the process for the accessory cleats but rip them to 2 1 2 in.
Accessories box filled with screws.
Using a hand plane or similar tool remove approximately 1 16 to 1 8 from the sharp point on both pieces.
On this cabinet i also screwed the top french cleat the one that s part of the cabinet to the wall also through the pegboard holes for even more strength.
This is so simple i m surprised it doesn t get used more often.
Then reset the saw to 45 degrees and adjust the fence to leave about a 1 8 in.
Rip the french cleat strips for the wall to 4 in.
The joint held up well but for a shelf this size it s better suited to hold smaller individual.
Flat area at the point of the bevels.
I used a hidden french cleat to hang a dovetailed wine rack that i created.
This seems to make hanging the cabinet a little easier and insures the faces of each cleat half engage cleanly.
It s simply a board that has been cut with an angle i used 45 on it s long side and attached to a surface with the angle sloping in.
Just pick some holes in the pegboard and let er rip.
So what is a french cleat.
We tested this french cleat connection and shelf using a 10 lb.
Then simply set your table saw blade to a 45 angle and rip the piece in half lengthwise.
For the tool cabinet it was easy to screw the spacer cleat to the osb wall.
The cleat is made by cutting a 5 wide piece of 3 4 plywood to fit between the two box sides.
The cabinet portion of the french cleat is glued and screwed to the top and sides of the cabinet.
If the mantel is already built and you are thinking of attaching a french cleat to it it will push the mantel away from the wall by the thickness of the cleat.
Installing the french cleat.