A good katana manufacturer makes sure each sword fits securely in its saya. Despite their best efforts, sometimes a sword will be loose in its sheath or become loose over time with repeated drawings,
Shimming a saya is the prefered method for tightening a katana, wakizashi or tanto in its sheath.
You will need:
- wood veneer edging
- narrow flathead screwdriver
- your sword
Step 1: Familiarize Yourself with the Saya
Start by drawing the sword and setting the blade aside in a safe place. If you look into the mouth of the saya, you will see that the width of the opening tapers. The mune (rear) side of the blade is wider and the ha (edge) side of the blade is narrow. The shim will be applied to the ha (edge) side of the saya.
There is no need to shim the entire length of the scabbard. The blade doesn't actually contact the inside of the sheath. The only point of contact should be between the habaki (the metal collar at the base of the blade) and the saya.