from geometry to physics

The most exciting part of any build for me is working out the joinery. I know this isn’t the most complex piece of furniture in the world, but when I was thinking through how this was going to come together there were a few things I had to consider.

  1. Weight – a cabinet of this size, even in white pine, has enough weight to make mounting the paramount concern.
  2. Gravity – The joints holding the tops and bottoms to the sides have to either resist or work with gravity
  3. Assembly – how would this all go together to create a final product

To answer the first question I immediately went to the french cleat idea. The idea is simple and elegant and will hold all manner of heavy things securely to the wall. To top that all off, as long as the wall cleat is securely attached, weight just helps it hold better. Gravity is your friend.

And now that we’ve made friends with gravity I felt it was high time to exploit that friendship. Dovetailing the top and bottom (Tails on the sides) means again that gravity can only help the joints hold together.

Assembly has been the most fun part of the design to work out. The first hurdle was the back.

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I salvaged some nice beaded tongue and groove board from the dumpster of a new local barbecue joint.  While, I can (and have) made this sort of back by hand, the opportunity to “recycle” these scraps and incorporate a bit of local color made it a perfect match for this project.

A few months ago (about the time I bought this wood) Anne of All Trades was Instagramming a saw till build for Mark over at Bad Axe Toolworks. Her solution for attaching the back seemed elegant and frankly it worked out the one problem I couldn’t figure out at the time. She had grooves cut in the sides and top into which the boards slid. They were held in place by two battens across the back. One of these was the french cleat and I think the other was just a batten. After sliding them into place, each one was finish nailed in at the bottom to hold the whole thing together.

The grooves were run first by striking lines with my marking gauge and then clearing them out with my shoulder plane. I made sure to use the same gauge settings across the board (from the back edge) so that the groove matched up all the way around. The bottom will be shortened 1.5″ from the back to leave clearance for the back to slide in.

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The only thing left for me to work out was how the french cleat could be securely connected to the carcase in order for it to work properly.

I know some would say that glue and screws would do the job, but where’s the fun in that?

I decided to attach the bottom batten by simple nailed lap joint, but the cleat had to be better. Mortise and tenons to start. The cleat would be tenoned into the sides, but I also wanted to secure it to the top board to avoid any kind of bending out. I settled on adding a “tongue” to the top of the cleat and lining that up with a “groove” in the top piece. This way the cleat is secured on three sides and held in place by the forces exerted upon it by gravity.

Win-win.

The joinery on the cleat itself looks like this:
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The joint for that looks a little something like this:
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And when it’s assembled, the boards just slide in, voila!
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I still need to dovetail the bottom and work out a few more joints before assembly, but I’m happy with how this is coming together.

 

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