A suggestion for better Tool Grinding by Peter Goodwin.
The double ended bench grinder provides an easy solution for regrinding tools of all sorts. Its drawback is that dry grinding heats the tool and can easily burn (soften) the cutting edge.
Frequent dipping of the tool in water is the recommended practice to cool the steel. A problem with this method is that the thin edge cools quickly and contracts before the main body of the tool.This can initiate minute cracks along the cutting edge.
A better method is to use an aerosol spray can of plumber’s pipe freezer.
Direct the jet at the tool away from the thin cutting edge and apply for a few seconds.
Cooling the body of the tool first prevents cracks forming. This method is very quick, clean and dry, and no residue is left on the tool. If you continue there is now less risk of burning because grinding starts with the tool at well below room temperature.
A few words of warning:-
- Do not point the spray directly at your fingers as this could result in frostbite.
- Wear gloves, as the tool can be very cold to hold.
- Do not spray the grinding wheel as the thermal shock could crack the wheel.