Learning...

[flynwill]

My learning exercise for the past few weekends has been to try and make a functional stem for an Elgin 760 movement.

The exercise is not entirely academic, I have one which I re-cased into a modern case and while I was able to get the original Elgin Crown to work it would be much better with a modern crown. To accomplish that I need a stem that fits a modern crown (0.9 x 0.225mm aka Tap 10) rather than the ~1mm x 120 TPI Elgin Thread.

I'm not done yet. I've made a lot of stems here's a few:

http://www.flynwill.com/Watches/Elgin760Recase/stemWIP3.jpg

(the bottom one is a real Elgin stem). As you can see the finish isn't great. There's another 6-10 that didn't make it this far.

Here's my setup for cutting the flats, utilizing the Sherline index block (which seems to be remarkably accurate) and a vertical milling table fitted to my lathe:

http://www.flynwill.com/Watches/Elgin760Recase/cuttingFlats.jpg

I have a screw plate that I picked up with a bunch of other watchmaker tools, but of course the Tap 10 is broken. So I invested in a single Bergeon 0.9x2.25mm Die, and fabricated a holder for it:

http://www.flynwill.com/Watches/Elgin760Recase/dieHolder.jpg

I still have a way to go before I have a part I'm willing to put into a watch, but the learning is fun. I have one that is, more or less complete, seen below, but it's still not quite right.

http://www.flynwill.com/Watches/Elgin760Recase/stemWIP2.jpg

[psfred]

This is the sort of situation where a micrometer cross-slide is a great joy -- you can turn the parts with great assurance that the sizes are exact.

It can be done by hand, but the mechanical cross-slide makes it MUCH easier....

Peter

[darrahg]

It takes effort to make staffs and also to graphically display in this thread. Thank you, DA

[tonyboy]

Amazing.........:clap: