How to grind a hand saw if it is not sharp?

First, file the sawtooth flat with a file, then use a vise to break the odd teeth to one side, and even teeth to the other side, and the two sides form an angle of about ten degrees.

If the stagger angle of the saw teeth on the saw blade is too large, the saw path should be straightened first, otherwise it is not necessary to straighten it. The way to straighten the saw road is to use two hammers, one of which is fixed on the vise of the woodworking table face up, and the other is used for correction (as shown in the figure). Pay attention when knocking, just knock back the wrong part of the sawtooth with a hammer, don't knock too much or knock the sawtooth flat!