I've got the beginnings of a watch case but, as of yet, no dial that I'm prepared to drill a hole in. I'm not going to put a hole into the cloisonné enamel frog!
My starting point is to create domed dials, this is because enamel miniatures typically require several firings and a domed dial will minimize warping. From fitting into the watch point of view, a flat dial would be easier but in the long term a domed dial will far superior for enamelling applications.
Warping is less of a problem for cloisonné (although still an issue) since the wires and counter-enamelling give the piece a greater thickness and structure that help to control warpage. However, I found a domed surface gives more interesting light reflections, it's more difficult to bend the wires over a domed surface but I got plenty of practice when I made these set of enamel doorknobs.
I'll start this project with some copper and make a domed dial from this. First I need a die that I can use to form the copper into the dome shape. I'm following the curvature of the front watch glass for this, so I fit an ellipsoid to the glass by modelling an ellipsoid curve in blender and tweaking the paramters until it fits this profile picture of the glass:
To make the die I'm using some brass. For long-term I would use steel, or even hardened steel for very long term. But I'm experimenting, so the brass will do, so I cut the brass from stock to make a square,
then centre the square in the four-jaw independent chuck:
Then I position the cutter to take off material on the radius but with plenty of clearance with the belly of the graver bit
then I gradually cut the brass to a circle,
The circle is cut on one side but the front needs flattening and the edges could do with deburring. I can do them both be just cutting face a little,
Now the circle is cut
but I need to do the same with the other side to make the whole piece into a circle. How I wish I'd cottoned-on to using a chuck-spacer, I could have done the whole thing in one go. Also I could do with some circular brass stock and save myself shaving off the four corners!
Well, I took the piece off and re-positioned it in the four jaw chuck, then cut the same circle to match. Then I got on to cutting the ellipsoid
I found that the graver bit position was not set properly for this cut. It's fine for taking off the radius material but not for cutting the side and top. So I re-positioned the graver bit
and cut the ellipsoid.
I didn't take any photos of the finished die as I was trying to video it instead. I'll have a fiddle about and try to upload the video to YouTube and put a link in here later so watch
THIS SPACE!