Onehanded (my left hand held the camera AND tried to press the limbs of the tool together...) use of the Ingold Fraise, a very rare tool used to correct the profile of horological wheel teeth. The cutter is driven to and fro by means of a horsehair bow, while the wheel to be modified is pressed into contact with it. Both are supported between dead centres in the body of the tool.

This Ingold Fraise is missing two cutters, but is otherwise in very good condition. I believe the tool was made in the first quarter to the mid1800s. It is much easier to use, and leaves a better finish, than the more usual Topping or RoundingUp tool. Studies done during Ingold's lifetime suggested that the power requirements alone in a watch or clock after finishing the wheel teeth with his Fraise were reduced by about a quarter (ie 25% less power was required to drive the same piece of clockwork after using the Ingold Fraise on the teeth).

There is not much published information in English about the use of this tool. George Daniels gives a brief description of it in 'Watchmaking', as does Malcolm WIld in his seminal 'Wheel and Pinion Cutting in Horology', but other than that, it's largely a question of Suck it and See.