I not too long ago was engaged on a late 1700s watch that was lacking a ratchet wheel for the fusee and it’s retaining screw. There was additionally some harm to the finding pin and numerous scratches on the floor the wheel would have sat on. The harm wanted repairing and the wheel and screw changing. You’ll be able to see within the drawing under the wheel could be simply 8.7mm in diameter – fairly a problem!
The very first thing to do was take a number of measurements of the present elements. The place of the ratchet clicks to determine the scale of the wheel, and the situation and dimension of the screw gap and finding pin. Utilizing a CAD drawing helped me in making some choices primarily based on the inside and outer dimension of the enamel, in addition to a tooth depend to ensure all the things appeared in proportion earlier than reducing any steel.
Taking measurements on the Hauser meant I may additionally take away the finding pin and drill a finding pin gap on the similar time. As soon as this was performed I held the fusee within the lathe to skim off the smallest quantity of fabric from the floor. I solely wished to make sure the floor was flat, so primarily eliminated the ‘peaks’ fashioned by the scratches whereas leaving the deeper grooves (not pictured right here)
When making wheels it’s not a lot additional work to make a couple of, so under you may see I’m really reducing 4. It will imply that if there are any points reducing the finding holes I gained’t have to begin from scratch! These have been minimize from some flat brass inventory barely over thickness with a central gap barely smaller than could be lastly required, then turned in a lathe to the right outer diameter.
As soon as the enamel have been minimize they might be separated for the finding holes to be drilled. Whereas setting this up, the Hauser Microscope can be utilized to examine the enamel – that they had some small burrs from the reducing course of which might be eliminated with a bristled brush, however the type was accurately.
The final activity was to make the finding pin and a screw to carry the ratchet wheel down. As peak is at a premium contained in the fusee the screw and accompanying gap must be countersunk and so I made a jig to carry the screw to make it match the outlet countersink for an ideal match. The highest of the screw head had a really slight dome, consistent with the type of the watch.
As you may see when all the things is assembled, it’s a really small wheel certainly, however appears (and most significantly, features) nice. The watch is now able to run for a couple of extra hundred years! In step with conservation apply, the wheel is engraved on the reverse with initials and a date to make it clear that this isn’t an authentic part.