Kumiko is a beautiful Japanese technique developed in 600-700 AD that involves assembling thin wooden pieces without the use of nails. Pieces are grooved, punched and mortised before being individually fitted using a plane, saw, chisel and other tools for fine adjustments. Steve Rothwell has been doing Kumiko for quite some time and joined us in the shop to show us his techniques.
Steve’s work is full of cross-halving joints, all of them hand-cut. He cuts a small slot, only .004” of an inch narrower than the material he’s working with, and friction fits the parts together.
Gotta know the angle
Parts that butt together internally have angles cut on the ends that match the internal angles of the work. Steve finesses the angles with a hand plane and shop-made jig, again working in very small fractions of an inch and fractions of angles to get the fit right.
Some of Steve’s panels have bowed parts in them. He creates these by steam bending the parts, in addition to cutting angles on the ends of the bowed parts that allow them to seat in the frame.
Producing the pieces
Steve mentions hand ripping the thin pieces he needs, then talks about switching to a table saw for the cuts. Another approach would be to use the Bridge City hand plane with skids that allows planing parts to uniform thickness or sanding the parts to thickness with a drum sander.