A Guide to Shinai Maintenance
The Shinai, or practice sword, was developed around 1750. It is constructed of four well-seasoned, highly polished staves of bamboo. A square piece of metal is wedged into a slot on the inside of the butt of each stave, to keep the staves aligned. A T-shaped rubber grommet seperates the tips, which are covered by the sakigawa. The nakayuki keeps the staves from spreading apart in the middle, and the tsuka serves both as handle and to bind the butt ends together. The tsuru (string) keeps the leatherpieces bound together, and indicated the blunt side of the single-edged sword the shinai represents. The guard, or tsuba, is made of either plastic or whaleskin and is held in place by a rubber grommet called the tsuba home.
Remove the tsuba and tsuba home. Untie the string at the handle. Pull off the handle. Pull off the sakigawa and nakayuki with the string. This will save you the trouble of having to untie more knot') than necessary. Hold onto the staves and mark the butt ends so you remember which is top, bottom, left and right. Then seperate them, being careful not to lose the metal square near the butt end.
This procedure should be repeated every several weeks. be sure to check your shinai before practice for any dangerous cracks or splinters in the staves! Sand the staves. When new, pay special attention to rounding the edges as shown. When old, sand away any splinters or roughness. Coat them with light oil such as gun or sewing machine oil. and let soak for at least 3 days, preferably a week. While they are soaking, check them daily and recoat them if the oil has been absorbed. New shinai are dry and need quite a lot of oil. Before reassembling, wipe away any excess oil.
Disassemble, sand and oil the staves as shown below. Repair or replace staves as necessary. Assemble the staves in the order that you marked on the butt ends; don't forget to insert the metal square to keep them aligned. Slide the tsuba (handle) over the end to keep the assembly together while you work.
Thread the tsuru (string) through the sakigawa as shown below. Leave about 2 inches, and tie a knot as shown in figures E and F.
Tie a single knot so that it end up a little bit below the first bamboo joint of the staves.
Thread the tsuru through nakayuki. Insert the tip plug, then the fit sakigawa over tip.
Tie tsuru as shown above.
Tie a loop in the tsuru as shown. The loop should be about 1Ocm from the leather loop in the handle. The string loop should be smaller than shown below; about 1cm.
Thread the tsuru through the loop in the tsuba, then back through itself as shown. Thread it back through the bottom of the leather loop and pull tight; cinch by winding around the loop a number of times and tucking through the last loop. Cut off any excess.
Tie the nakayuki as shown. Cut off any extra length.