Fifty-fifty chisel
The lighter and thinner bevel-edged chisel initially found favour for paring surfaces flat, and trimming fibres in the corners of joints and recesses. But the extra grinding required for bevelled edges made this a more expensive tool, so the heavier and thicker square-edged firmer chisel long remained the popular choice. Today the bevel-edged chisel is the more common type among joiners, while the thicker squareedged firmer – although better suited to heavier work like mortising – is seen less often. Even when used for paring, the bevel-edged chisel isn’t perfect because its thin edges gripped by fingers necessarily wrapped around the blade soon lead to discomfort, as is also the case when using the chisel for scribing across the grain – marking tenon shoulders, for example.
A hundred years ago (a reliable reference point for sound handtool practice) the frugal shipwright would modify a firmer by grinding edges for just the first inch of the blade to make a ‘fifty-fifty’ chisel, thereby adding the slender cutting advantages of bevelled edges without sacrificing comfort and sturdiness. Using a powered grinder the job would be done in a trice (although beware of overheating and spoiling the steel’s temper) but in the spirit of the age it’s perfectly feasible using a hand-powered grinder. Cranking the grinder while maintaining a steady angle of tilt on the blade as you also feed it back and forth on the wheel is an eective antidote to hands falling obsolete under the relentless advance of technology.