Mandrel for wheel cutting

I wish to cut multiple copies of the same size wheel in one go, so that I have spares in case of in inevitable mistake, and also so that I may end up with most of the parts for more than one watch with little additional effort. This means making up a mandrel to hold multiple wheel blanks for the wheel cutting process, instead of just using a superglue arbor for a single wheel.

The design of my wheels, with circular cutouts rather than the traditional spokes, means a slightly different design of mandrel to what may be seen being used on YouTube by an Isle of Man watchmaker. Mine will have five pegs to locate in the five cutouts in the wheel, with (at least) two approaches for producing the pegs: from a length of brass bar turned to the diameter of the cutout; milled directly into the end of the mandrel. Each peg will be drilled to pass a screw, with a thread tapped into the body of the mandrel. There will be a cap that fits over the end of the mandrel, recessed so that the pegs fit inside a lip, and with five screw holes so that it can clamp the wheel blanks in place.

Starting with the first approach, I turned some 5mm brass bar down to 3.95mm to fit the 4mm cutouts. This was then centre-drilled and drilled to 2mm, so that I can use M2 screws to hold a cap into the end.


And parted off. It is tempting to set up the capstan to make this process quick but since I’m only making ten, five for each of two different wheel cutout sizes, I don’t think it’s worth the time.