Wednesday, June 25, 2008

Shinto Bench

On and off for the past 3+ weeks, when I haven't been working on the new sofa, I've been working on what I have dubbed the Shinto Bench.

It was finally decided by the powers that be, that we (meaning the Design Team, aka me) need to have actually produced something. Since 2 of the 6 benches are for customers, they have been jumped up to the top of the priority list, and I have been working on them solidly for the past week.

They are a simple bench that echo the lines (in my eye at least) of Shinto Shrines and Temples. Simple in looks, and basic construction techniques, but actually turned out to be quite involved.

All of the tenons were through tenons, where the tenon penetrates through the legs and seat. The seat tenons will be flushed up, and have a wedge of ebony, while the stretcher tenons are left proud and are keyed with more ebony.

The mortises in this case were better served to be square, made with a hollow chisel mortiser. The hollow chisel, a sharp chisel blade on 4 sides, with a drill bit in the center, echoes the construction technique of yore, where they would drill out the waste wood first, and then come back and square everything up with a chisel. The hollow chisel mortiser does take some getting used to; making sure that everything is lined up just so, cutting just over halfway through, and then flipping, and cutting from the opposite side, leaving you with a clean surface.

To complicate all of this, the legs are splayed in both directions, necessitating the tenons going into the seat to be cut in with compound angles, which seemed simpler than cutting the mortise other than straight. The leg mortises were cut with only one angle, so the tenons could be straight with only an angled shoulder.

Then the tenons were cut by hand, with a tablesaw and dado blade, then mortised in the tenon to allow for the key. The seat was cut with our CNC router, with required a bit of tricky programming of what turned out to be 1/4 of a sine wave. Fortunately, I laid this problem to one of our showroom guys, who happens to have a background in engineering and a love of calculus, and he set me up with the equation I needed.

It was only after everything was cut and finished (for 6 benches) that I could clean one up enough to dry fit, and hope I was accurate enough for it to go together.

Fortunately, the dry fit went fine. Unfortunately, it is not easy making sure each tenon fits into each mortise. There is a lot of sanding of tenon faces, and paring of mortise cheeks until the proper fit is found.

I am pleased that it is all coming together, and that I've had the opportunity to experiment with non-traditional wood. The long cherry bench was requested as Artistic Sapwood cherry, where I was to select an interesting board with sapwood, and sort of bookmatch it into a seat. It may be a bit hard to see in the photo, but the sapwood runs down the middle of the seat, lightening in the center where we cut down into the heart. It was to be a bit rustic. I followed through with that same thought for the other customer's bench, in walnut. In this case, there was more sapwood, so the only heart left on the bench is in the 4 corners.

Too bad I didn't think to make one for myself, I do really like them. I just don't want to ever have to make them again for any reason.

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