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 separates the tips, which are covered by the sakigawa. The nakayui keeps the staves from spreading apart in the middle, and the tsuka serves both as handle and to bind the butt ends together. The himo (string) keeps the leather pieces 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 whale skin and is held in place by a rubber grommet called the tsuba dome.
Remove the tsuba and tsuba dome. Untie the string at the handle. Pull off the handle. Pull off the sakigawa and nakayui with the string. This will save you the trouble of having to untie more knots than necessary. Hold onto the staves and mark the butt ends so you remember which is top, bottom, left and right. Then separate 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 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.
1.Dissasemble, sand and oil the staves as shown above. Repair or replace staves as necessary. Cracks can be glued with white glue and then wrapped with packing tape. 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 handle over the end to keep the assembly together while you work.
2. Thread the string through the sakigawa as shown in figure A below; figure B is wrong and will tend to tear the leather. Leave about 2 inches, and tie a knot as shown in figures E and F.
3. Tie a loop in the string as shown. The loop should be about 10cm from the leather loop in the handle. The string loop should be smaller than shown below.; about 1/2".
4.Tie the nakayui as shown. Cut off any extra length.
*Contents are from Saskatoon Kendo Club Web Page.