How to cut this piece?

[Andy Sowers]

I'm working on the wood-geared clock I spoke previously of... specifically, the frame which holds all the gears and what-not.

Ran into a detail on the plans which I'm considering modifying. The plans call for butt-joints for the angled pieces (shaded in blue below):

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What I'm thinking is to use half-lap joinery instead. But there inlies the difficulty. I would need to precisely cut these pieces to exactly match the curve along the top cross member and again along the bottom to match the vertical frame. But then I'd also need to exactly mill the backs of the frame to recieve these support structures...

If it these were meeting at right angles, i think I could do it no problem, but handling the curves and the arbitary angle at the bottom is throwing me for a bit of a loop...

Suggestions on how to cut this? Should I be using a different joint?

Thanks in advance...
Andy

[Danny Thompson]

Make the lap square (straight across) rather than curved?

[David DeCristoforo]

The "best" way would be to make some router templates. A little experimentation will be required. You could easily set something up to hold the pieces and guide a rabbeting bit set to one half the stock thickness. It would seem to me that, with all of the precise milling involved in the making of a clock, this is going to be the least of your concerns....

[Lee Schierer]

I would glue up the rough form using half lap joints as you have suggested, before doing the detailed cutting and then use a scroll saw to cut the details. Then you only have to be concerned about the joint fit with straight lines. I don't think the straight lines will be noticeable in the final piece and even if they are does it really matter.

[John Schreiber]

If the plans say to do it with butt joints, I'd suspect that is the best way. It could be that differential expansion and contraction is figured into the design and you could mess that up. Unless you know of a problem, it's probably strong enough as designed.

If you do want to make it stronger, I'd square up the angles, that should make it doable. If you want to keep the pretty curves, I'd suggest creating some jigs and a lot of experimentation to get it just right.