Detailed description of the spur wheel tool
The wheels in the set have 12 and 20 teeth respectively.
The body of the spur wheel is a circle with eight finger fitters around the outside. The body width is about six millimetres. From this inside circle the ‘negative’ teeth are pointing towards the centre.
After tracing the inner contour, the spaces between the teeth are in fact the positive teeth around the outside of the spur wheel.
Pushpin markers are located in the top surface of the body.