Abstract
Commercial hack saw having been quenched entirely, it is very brittle and becomes useless by breakage rather than wear.
So we tried to harden only the teeth of hack saw by oxy-town gas which we could obtain easily. We succeded in manufacturing a non-breakable saw.
The tests show;
1) Both sharpness and life are nearly equal to the commercial hack saw.
2) The amount of bending in the plane of the saw owing to the hardening remains within the specification of JIS.
