Task at hand: Make a top for this cover using thin Luan. I thought finger joints would work to keep it sturdy, and to not require cleats on the inside. BTW, this is a cover for my CNC controller so looks is not a priority to me on this one.
The top is cut to fit, but just barely oversized:
Place the top under the carcase, keeping track of mating edges:
Slide the carcase back:
Then tilt it up so the mating edges are aligned. I used double sided tape to secure it:
Take it to the scrollsaw and arbitrarilly cut fingers. I say ‘arbitrary’ because I did this by eye. You might want to at least get the count right(unlike I did) to make it symetrical. The length of the cut is equal to the thickness of the material you are using.
You can see how the two edges line up perfectly, even if you have variable-spaced fingers:
Remove the waste using a Rip blade(because it has flat-top teeth) in the TS. Set the height to the thickness of the material you are using. In my case, this is done for all four sides of the carcase AND the lid. Note also the backer to prevent tearout in this short cut.
A test fit came out perfectly… Well, except for that one missing finger I (wrongly) ajusted for.
You can see that I adjusted my scrollsaw & TS cuts so the pins would be slightly proud for sanding purposes:
Glue it up and pin it in place while the glue dries. The pin nails are easily removed once dry.
You can see an adjacent corner after it is sanded flush with the surface. Also note the irregular finger spacing you can easily achieve.
No, I’m sure I’m not the first to come up with this method. I thought about what I needed, and it seemed to be an acceptable solution.
-- Backer boards, stop blocks, build oversized, and never buy a hand plane--