Saturday, May 28, 2016

A Ming-Inspired Cabinet (58)

The upper compartment of these cabinets are guarded by a pair of sliding doors. These doors will have bubinga frames, shedua back panels, and a special type of latticework in the Matsu-kawa-bishi pattern.

Matsu-kawa is pine bark, and hishi/~bishi means diamond. It’s a pattern thought to resemble a chunk of pine bark, and is composed of three overlapping diamonds, or lozenges if you prefer, one large and two small:

If the form can be tiled over a larger area, thereby a pattern such as this can be obtained:

There are countless variations on the theme.

Matsu-kawa-bishi  is a popular design motif, seen in many Japanese arts and crafts, including textiles, pottery, and even as an architectural roof tile ornament. Here it is incorporated into a tsuba:

This pattern is infrequently used for shōji lattice (kumiko) as well, and it was seeing a few examples of screen doors with this pattern that led to my interest in making it a part of this cabinet project.

Just drawing out the pattern of sloping zig-zag kumiko was challenging enough, and making the pieces and cutting the joinery has also been keeping me quite preoccupied of late.

Here’s how the upper sliding doors are intended to look once complete:

Making slender sticks with a zig-zagged form, if you want the parts to be predictably uniform - which certainly facilitates the joinery work - will require jigging and fixturing whether working with hand or power tools. In my case, I have that Zimmermann pattern making mill, and that was the go-to choice. If I didn’t have the mill, I would have found another way, but, well, I’m glad I have the mill!

Once I had the design work complete to the required level of detail, I jointed, re-sawed, planed and dimensioned some blanks about 3" thick and 8" wide. These were then processed on the mill into boards which had a staircase-like form on two sides.

Here, I’m cleaning up milling marks on the completed blank:

Notice that the blank sits atop a MDF support jig which was also cut so as to mirror the stepped pattern. This jig provided support and positioning when milling the backside of the blanks.

I later re-sawed those stepped blanks into oversized zig-zagged-form strips, and then planed these strips, the kumiko, to size.

Just getting to the point of having the kumiko in hand and ready to join required many days of standing in front of the mill, moving the tables back and forth, in and out. During that process the mill went down for a day when one of the gib bars self-tightened slightly and make the y-travel extremely tight after hundreds of movements. At first I though that the lead screw’s bronze threaded nuts had gotten choked with dust, however I later determined that the gib had moved. A day was lost as a result, the mill partially disassembled and reassembled, and some hours of sleep were lost too! I do know the mill better as a result.

With the FZ-5V back up and running, I set to work preparing a fixture for cutting lap joints. This is where a pattern mill with a large rotary table really comes in handy.

Here’s the first cut completed:

And then the other is done similarly:

There was a fair amount of head-scratching, calculator work, and pre-planning which went into those two zig-zagged cuts. They must cross each other in the dead center of the rotary table. It took me three tries to get it right.

Here’s (most of) the kumiko after finish planing:

Another view - I feel the mill gave me excellent results in terms of repeatability, as these alignments show:

Packing the kumiko together like that would make for an interesting pattern to use in other areas perhaps. Another time.

I had about 6~8 sticks which came out bowed after resawing, however a few of them were usable when cut into shorter segments.

Making minor thickness adjustments to the ‘steps’ was accomplished by plane, card scraper, and a small hardwood block with affixed #220 sandpaper:

On the mill table, I prepared some cross-wise slots for the purposed of indexing. In the next photo I’m milling half laps in one of the kumiko:

These cuts were made in a series of half a dozen steps to preclude blow out. All positioning was made using the DRO.

Proof of concept was attained a short while later:

Toward the later part of the afternoon, a pile of parts was steadily mounting:

There are 72 sticks altogether, and 240 half laps to cut. It’s very repetitive work, but one has to pay attention at each and every step so as to get good results and not to mess up any parts, so it is mentally tiring. 'Auto pilot’ doesn’t help much.

Another stick, another round of laps:

The rotary table’s vernier scale allows precision to 0.25˚, which helped me feel confident when setting table position to the required 21.79˚ angulation. I’m milling the laps which slope one direction first, and then will rotate to the table to complete all the laps which slope the other way.

I’m thinking that another full day in the shop should see me through the rest of the half laps. Hah - nothing like a little optimism! After that, there are joints at the perimeter of the lattice panel to cut, and some small tenons to be formed so the lattice can be connected to the surrounding frame. These matsukawabishi pattern lattice doors are one of the points of focus in the overall design, a pleasant surprise to discover (I hope) when opening the cabinet, and I am striving, as always, for clean execution and high precision in my work. So far so good, and more than a week so far has been soaked up attending to my new second wife, Ms. Zimmerman.

All for this time-  thanks for visiting the Carpentry Way.

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