Just4Fun":20o7o5zo said:
What advantage do they have over a bevel edge chisel? Or was it a cost issue, with a cheaper-to-make square edge considered "good enough" for rough work?
From what I have read about methods of manufacturing and from other discussions, I'd put it like this:
Back when all chisels were hand made, the default, simplest shape was rectangular in cross section. This had the fewest steps in making, so was cheaper. It would also be nice and strong.
Making the bevel edge style needed more skilled forging, to shape the bevels, then extra grinding, to finish them straight and even. The saving in materials was insignificant.
The extra cost was only justifiable where the work required it or the shape was handier, ie in cabinet making, not in carpentry or joinery.
When chisel manufacturing was mechanised, a pair of shaped dies were used, in drop forging. Making a bevel along each edge was a bit easier than making a rectangular section, so this became the norm. With the improved steel then available, there was no longer a disadvantage from reduced strength. In any case, the finished shape was a bit chunkier than some of the old chisels.
These chisels were made so economically that they outsold the rectangular section ones and became the normal pattern.
