Making a dial (part 1), making a forming die

Making a dial (part 1), making a forming die

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:

curvature of the watch 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,

cutting the brass from stock,

then centre the square in the four-jaw independent chuck:

centring the square in a 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

positioning the graver bit with plenty of clearance,

then I gradually cut the brass to a circle,

circle is cut but needs deburring.

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,

cutting the face flat.

Now the circle is cut

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

cutting the ellipsoid shape.

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

change of position of 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!

 

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