Thursday, January 31, 2013

Scale Balance Model

Our next manufacturing project in class was to take a balance wheel and its staff out of a ETA 6497 movement.  Then we were to measure it, and scale it up 2x in our plans and manufacture it.

The design of the bridge and the wheel were up to us as long as we kept to general tolerances.  I decided to make an impractical iron cross balance wheel which turned out okay, but does require some final finishing.  I opted to machine the bridges out of solid chunks of brass rather than using a spacer so I got to spend some time with the mill.  The process is more time consuming but provides superior durability overall.

The only thing that remains, other than final finishing is to finish the balance staff (the axis pivot that the balance wheel pivots with).  The staff is machined out of hardened and blued steel which is more difficult to cut than untreated steel so I ordered an indexed carbide cutter which should arrive sometime tomorrow and make the turning of that part much easier.

Once I have completed this project I will post pictures of the assembled product.

Milling out the bridge plate
Finished balance wheel, bridge, plate, and cap jewel holders (without jewels)

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