Monday, January 4, 2010

Battari Shōgi 5

This is the fifth in a series detailing the construction of a folding bench for a Japanese merchant's house, or machi-ya. Previous installments are linked to in the 'Blog Archive' to the right of the page.

Next step is to mortise for the two tenons that come through at each corner of the frame. As usual, I drilled out these mortises, which are 0.5" square, using a 10mm brad point drill, and as usual, the Wenge caused the drill to get reeeaaaally hot. After the holes were through, finally, I set to work chopping the mortises square using a paring block and a 10mm bench chisel:


A little further along:


Not the easiest wood to work with the hand tools, this Wenge, though it can in fact be chopped and pared. I finished cleaning out the mortises using a hollow chisel bit. I couldn't locate my bottle of camellia oil, so I grabbed a little vegetable oil to lube the cut:


A plastic faced hammer drives the chisel so as to not damage the upper end of the chisel:


Success as the bit is worked fully through (it took a few tries from each end to clear it):


The mortises end up about 0.007" fat from the target as a result, however I can adjust for that when I do the tenons.

Next step is the trench for the mechi, which is a stub tenon at the root of the double tenons. I used a 90˚ reference clamped to the stick, and my plunge trim router:


The completed trench required a small amount of clean-up at each end, using a 2-bu, or 6mm chisel:


Mortise one is complete, 3 to go:


Another view:


No need to show the same procedure for the other three mortises. Another issue: one of my long rails had a defect on the backside with a little area that the planer had missed. I chose to leave it as I didn't want to bring the stick down below dimension.

If the bench was always in the down position after installation, I might have chosen to leave it be with the defect, but since it would be possibly exposed to view when the bench was folded up, and because part of the skipped section was inconveniently situated at a corner joint, I elected to patch it. It's an area about 7" long and is low by about 1/16" (1mm) in the worst spot:


The patch piece is fairly close in grain match, though not perfect:


I trimmed it to shape, an irregular polygon, using a ryoba (on rip) saw and a trim plane:


I clamped the patch in place and then knifed out around it:


The result of the knifing:


Then followed some freehand routing with my trim router, taking the mortise down about 0.125", the patch being 0.135" thick:


That's my self-imposed 15-picture limit for today - I ask the reader to return next time if they want to see how this patching job turns out. Hopefully not in the firewood pile.

Thanks for dropping by today! --> Go to part 6

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