I recently had a very old English chain fusee pocket watch come in. The watch needed a new balance staff because of a broken pivot. Due to parts not being available, I had to make one with my lathe.
Here is the lathe that I use. It is an 8mm G. Boley watchmakers lathe with a variable speed motor.
Before we can start on the new staff, the old balance staff must be measured so we know what size to make the new staff. I measure and draw a rough sketch.
Next, I use 2mm blue steel and mount it in a lathe collet. This is how our balance staff will begin its life.
I start to turn the steel down to size in the different sections.
More turning on the lathe.
We can see that the staff is starting to take shape.
Now we are really getting somewhere. The first pivot has been turned and the undercut has been turned so that it can be riveted onto the balance.
Once the one ended has been completed, the other end must be turned. We need to turn the staff in one sitting otherwise the workpiece won’t be true.
More shots of the balance staff.
More shots of it starting to take shape.
A few more.
I now start to turn the bottom pivot.
It’s crucial to go very slow and carefully at this point.
The pivot is almost there. A few more turns and it will be ready to part off.
Once parted off, the pivots are cut to size to make sure it fits between the plates. I will then mount it on the balance and polish the pivots.
Here is the staff next to a Canadian 10 cent coin for scale.