This depends on how you feel on historical correctness, and what period you want to represent. Documented 18th c. file knives seem to be rare. File knives in the 19th c. are much more common. In the 18th c., files were very precious, and were resharpened when they dulled, and were hand cut to start with. A very long and tedious job, in most cases, one tooth at a time. Many were soft iron, and case hardened, which would not make a good knife anyway. I have read that a file cutting machine was patented in England sometime just previous to the last quarter of the 18th c., but have seen no mentions of when they may have been imported to the colonies, or how prevalent machine made files may have been. Others, such as Mike Roberts, or Mike Ameling, would likely have much more info than I do, but even if they became available sooner than I believe, they still would have been a cherished, and expensive tool that would not be discarded lightly. They would have been re-sharpened to the point of being useless as a file, then maybe made into a knife, assuming that they were steel, rather than iron, which is another question. If you are doing 18th c., and want to be safe in your correctness, I would say no, leave no traces of teeth, but if you are into 19th c., you would probably be safe enough. Many have read Madison Grants book on primitive knives, in which he dates quite a few file knives into the 18th c. , but his dateing is very questionable to say the least. I am not saying knives were not made from files in the 18th c., only that I would think them to be rare, and not as common as some believe.
