Tid-Bit 10 - Adjusting Pallets
The Graham deadbeat escapement is found in a wide variety of clocks, including most of the Vienna Regulators and Precision Regulators seen in my shop. With time the escapements pallet faces become grooved from sliding across the tip of the escape-wheel teeth. Over the centuries this grooving can convert a deadbeat escapement to a recoil escapement. Interestingly, when this happens the clock often continues to run, perhaps a tad fast, but run none the less.
While hardened pallets wear at a slower rate than softer pallets, eventually they all develop grooves, unless of course one is lucky enough to own a clock with jeweled pallets. My methods for dressing grooved pallets are discussed in a previous Technical Tid Bit (see the April 2010 Bulletin, page 191 for Tech Tid-Bit 4).
Figure 6 – Initial Lock on Deadbeat Face
Given my inability to readily measure the amount of lock, I set it by looking at a pallet through a 10 power microscope, allowing me to estimate the initial lock as I slowly move the crutch from one side to the other. As an aside – I typically polish the plates on the mechanisms I restore to a fairly bright, reflective finish. I find that it is easier, when looking from above the mechanism, to see the pallets by looking at the reflection in the plates rather than actually looking directly at the pallets. Looking from above allows me to see one of the two pallets’ degree of lock. Seeing the other pallet requires turning the mechanism on its side, making the other pallet face is then visible.
If the initial lock is not right – what do you do? Before grinding pallets, or making any adjustments I first measure the width of the anchor - Figure 7 shows how I measure the distance on a single-piece Viennese anchor with a caliper.
