Marco Gilardetti wrote:
Honestly, I think it's a bit pretending. Belonging to the "I know better than you peasants do" serie.
If the teeth might be bent and permanently damaged by simply pulling the file back, goodness only knows what might happen to them by pushing them forward.
Has anyone ever damaged the teeth of a saw by pulling it back perhaps?
So I'll continue to use my files in both directions without any concern at all.
I do see your point. However, if you consider the geometry of a single file, (or saw), tooth, you will note its "buttress" form. Pushing the file forward, the cutting edge is well supported by the buttress. However, stroking backwards, that same cutting edge is now at peril of breaking away, or folding over, due its lack of support/bracing. In metal working, a carbide tool bit will perform well all day long when used as directed. However, in the case of a lathe for example, if the machine is stopped while the tool is still cutting, then reversed while tool pressure is still exerted on the workpiece, the carbide edge quite often will chip off.
Besides, exerting force on the backstroke while filing or sawing is wasteful of effort, at the very least, since no real cutting action occurs then anyway. I was always in awe of my father, who could use a handsaw extensively and never seem to exert himself in the least. He explained that my fatigue was due to wasting my efforts by applying down force to the saw while on the backstroke.