This is a specialized watchmaker tool called a “Rounding Up” or “Topping” tool, likely about 100 years old, that we use on occasion to correct the teeth of watch wheels. It can also be used to cut the teeth of a new wheel when the wheel being made is first “slotted’ (cut with square slots, a predecessor to actual teeth) with a lathe/mill to contain the correct number of teeth. The value of this tool to the watch maker is determined by the variety of cutters you have to match the wheels you need to work on. When correcting teeth, it is sometimes necessary to “stretch” the wheel to expose more metal which involves the use of another tool.
