Ducati Elite 204cc
Making a few unobtainable parts
Part 2
The rear brake light switch was in a sorry state, completely seized and the end cap nearly rusted away - I think copies are available but I decided to investigate the one I had. It more or less fell apart, allowing me to see how it was made and the end cap looked like a simple turning and filing job.
The innards were not too bad, being mostly brass, so cleaned up well. The outer casing (some sort of plastic) was stained but cleaned up with a few carefully chosen chemicals. The rubber boot was a bit hard but not split anywhere, so a few minutes being massaged with silicone grease brought it back to life.
Assembly was quite straightforward with dielectric grease applied to the centre post and spring contact blades and then the four projections seen in the second picture were bent over the casing to secure everything.
Completed, just needs the two wires attaching and fitting to the bracket - I also need to make a pull spring.
The next part was the two serrated spacing washers which fit between the headlamp and the alloy fork top brackets designed to keep the headlamp from rotating after the bolts are tightened. I counted the serrations on the lamp body and it turned out that there are 40 of them - a great number, because that is the dividing head ratio - 40:1, so one turn of the handle between each serration. I first turned the o/d, drilled down far enough to make both from a piece of 25mm dural bar. I made an adaptor years ago to attach my dividing head to the lathe using an expanding mandrel down the lathe bore which in turn is gripped by a collet on the head. with the lathe in neutral and a V tool on its side in the toolpost, the spindle can then be indexed to the next serration and the cross slide wound out to produce the cut.
This is the dividing head attached to the lathe spindle
The pieces of swarf just brush away to leave serrations which fit very well those on the headlamp. After parting off they just need the backs filing to mate up with grooves in the fork 'Ears'
Part 1 - Choke lever cover and Speedometer Bezel
Part 3 - Speedometer drive