hammers aren't just for nails

Carpenters in Japan use several different hammers, each designed for a specific purpose, such as hammering nails, adjusting planes, and striking chisels.

Unlike framing hammers, a traditional Japanese hammer does not have a nail puller, but is flat on one face and slightly curved (convex) on the other. To pull out nails, carpenters use a separate nail puller.

what's kigoroshi-men?

The flat face of a hammer is used for most of the hammering and the curved side called a “kigoroshi-men” is used for the last blow. The kigoroshi-men is designed to drive a nail into the wood without damaging the surrounding surface.

assembling without glue

Also, furniture makers use the kigoroshi-men to temporarily compress a tenon to fit it into its mortise. After assembly, the wood gradually expands to its original size for a tight fit.

In this process the kigoroshi-men can dent the wood without tearing its fibers, but the edges of the flat face of the hammer will tear the fiber and the wood will not expand even if water is applied.