Why is it necessary to adjust Japanese chisels?

Adjusting your Japanese chisel according to its use.

Japanese chisels, called nomi, are tools that require a series of adjustments before being used. For all new chisels, fine sharpening is to be expected, as well as adjusting the hoop. In Japan, it is always up to the buyer of the tool to finalize and adapt it to their own usage; it is a philosophy of the tool...

First of all, you must prepare the handle of the nomi. You can start by removing the varnish from the nomi. To do this, use a solvent such as acetone or a paint stripper. Once the varnish has been thoroughly removed, clean it with a cloth soaked in acetone. This operation is preferable because the feel of the wood is much more pleasant than that of a varnish.

In Japan, there is no orthodoxy regarding the shape of tools, so you can completely modify the nomi handle according to your needs (width, length). The Japanese most often refine the handles that are mass-produced and a bit too wide.

Japanese chisel: adjusting the hoop / Katsura-otochi.

It is essential to correctly adjust the hoop, or katsura in Japanese. It is that thick ring at the top of the handle. Indeed, on Japanese chisels (nomi), this hoop is thick and plays a very important role. It serves both to prevent the wood from splitting and also to center your strikes. It can be chrome-plated, blued, or hammered depending on its manufacture. But it always has a specific shape on the inside. The ring tapers more on one side than the other; the handle must protrude from this side.

First, you must clean the inside of the hoop with a file and abrasive to remove any defects that would hinder the passage of the handle. Next, you must compress the top of the handle / tsuka, not carve it to reduce it. You must first compress it with a hammer on an anvil or a piece of hardwood so that the hoop can allow 2mm of the handle to protrude. To do this, you must strike the hoop with force so that it compresses the handle.

Finally, simply dampen the end of the wooden handle slightly and strike it concentrically with a hammer (using its edge) so as to push the wood out around the hoop. The goal of this operation is to create a small dome to center your strikes.

Adjust your Japanese chisel regularly.

This operation will need to be repeated each time the small dome becomes damaged. This will most often be the case for heavy-duty chisels like damekiri, tataki nomi, mokumachi nomi, hiramachi nomi, or anaya nomi.