Niagara saw set

[Lee Schierer]

Has anyone ever heard of a Niagara saw set? This one most likely belonged to my Grandfather who sharpened saws. The only markings are the word Niagara on the moveable handle and the numbers 5-, 5, 7, 8, 11, 12, 10, 8. The numbers are on the circular disk. I'm not sure what the numbers are for. It mabe for the number of teeth per inch of the saw being set or the angle of the amount of set. There is a flat adjacent to each of the numbers that is angled. The 7 has been use the most judging by the amount of wear.

Here are a few photos:
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