Hello,

The part about the height at which the french carpenter works will shed a good light on the bisaiguë. They are working down low and so a kreuzaxt would be ill-suited and has been adapted. German carpenters are working at a higher level around the height of the thigh.
The principle of chopping the mortice is unchanging regardless of the tool used within this category - bisaiguë, kreuazxt, stemmeisen - a vertical cut to sever the long grain, and then ejecting the chip. The difficulty to be grasped is in the case of the freehand action of both bisaiguë and kreuzaxt. I believe there must be some guidance mechanism involved even to the extend of pre-wasting the bulk of the material from the mortice opening.

Jon, first of all I wish you success with your application. Regarding the carpenter highlighted, I am skeptical that he knows anything.

Greetings,

Don Wagstaff