The Swiss lever escapement dominates watchmaking, and we're learning to alter its geometry.

The pallet fork holds a pair of jewels which lock and unlock the escape wheel, powering the balance and keeping time. 

The jewels are held in place with shellac, a natural bug secretion that is used for all sorts of things—in this case, a natural replacement for superglue. Shellac melts when heated, so the stones can be finely adjusted in place with the help of a heater and depth gauge (seen above).

The pallet stones are extremely sensitive to their positioning, and must be adjusted with great precision. Just a hundredth of a millimeter too shallow or too deep in the pallet fork, and the watch will fail to run.

As with most things in watchmaking, adjusting the pallet stones is mostly a matter of being extremely careful.

Shellac can only be heated a finite number of times before it's ruined, and if it's heated for too long, it will leak out of the pallet fork and make everything messy. The key is to be delicate but swift with your tools.

Our SAWTA 2 exam will focus on hairsprings and the escapement, so we'll be practicing this extensively, moving forward.