For our CNC joinery project I decided to try to master CNC “dogbones”. They seemed like the ideal joint for what I’m looking to do with the CNC:

The biggest negative of dogbones, AFAIK, is that they don’t work well for joining edges. That can be solved with dowels / screws / glue.

Preparation and Setup

alt Re-using some weird scrap plywood that somewhat matches the thickness of my production plywood.

alt Quickly setting up male and female parts in VectorWorks

alt Setting up the male dogbone. I opted to have a long-side (greater than width of material) and a short-side (equal to length of material) so that I could test how sliding through the slot works in addition to the exact fit. (I figured I might want to add a middle layer for support for my wall shelf project.)

CNC Time

alt The male part is easy. I cut it first.

alt I also quickly cut female-01. I started with a tolerance of -0.02” thinking I’ll get a really snug friction fit. I quickly realize this is dumb because the tolerance should be GREATER than the original.



alt Guessing game… Ben was right about this being fairly difficult to get just right. I’m rethinking my high-level joinery goals.

CNC Reflections

alt After finally getting a decent fit, I realize the rounding on the male piece makes it so the inserted edge does not sit flush with the female piece. I somewhat expected this but chose to live with it.

alt My final cut (v4) friction fit fairly well. However, I actually prefer this non-friction fit. There’s a bit more room here, which I like and just need to learn to reinforce. But my thinking is that a slightly roomy fit means I don’t need a sledgehammer assembling or reassembling.

It fits and sits!

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