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.
French cleat tool cabinet.
The cleat is made by cutting a 5 wide piece of 3 4 plywood to fit between the two box sides.
This seems to make hanging the cabinet a little easier and insures the faces of each cleat half engage cleanly.
The joint held up well but for a shelf this size it s better suited to hold smaller individual.
Cut the 45 degree bevels on the strips.
Flat area at the point of the bevels.
Installing the french cleat.
This is so simple i m surprised it doesn t get used more often.
It may sound fancy but a french cleat is simply a sturdy beveled support board a secret that builders and craftsmen rely on to hang heavy items such as large mirrors artworks and cabinets.
I used a hidden french cleat to hang a dovetailed wine rack that i created.
Then you put the wall cleat in place based on the location of the cabinet cleat.
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.
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.
Accessories box filled with screws.
So what is a french cleat.
If you are building a mantel you could certainly build it with a french cleat recessed.
For the tool cabinet it was easy to screw the spacer cleat to the osb wall.
Then simply set your table saw blade to a 45 angle and rip the piece in half lengthwise.
Using a hand plane or similar tool remove approximately 1 16 to 1 8 from the sharp point on both pieces.
How to build a frenchcleat wall in this video i show how i built a french cleat wall for tool st.
The other half of the board that s been cut is then attached to something be it a bracket for tool storage or the back of a cabinet for mounting on the wall.
Then reset the saw to 45 degrees and adjust the fence to leave about a 1 8 in.
Just pick some holes in the pegboard and let er rip.
Repeat the process for the accessory cleats but rip them to 2 1 2 in.