Tid-Bit 4 - The Joys of Pallets
Those of you that know me are aware that my true love in the horological world is regulators, both Viennese and Precision regulators. There are many reasons for this affection, but one that stands out is the ability of these clocks to keep time rather, well, precisely. Many factors contribute to their precision, but a significant one is the use of a dead beat escapement. While invented by Richard Towneley, and first used by Thomas Tompion in 1675, George Graham popularized the escapement in 1715 and is generally credited with its development.
The “Graham Dead Beat Escapement” offers two significant improvement over the anchor escapement: (1) The pendulum is not being constantly being pushed by an escape wheel tooth throughout its cycle, thus allowing the pendulum to move freely during most of its swing. This significantly improves the pendulums isochronism. (2) The escapement does not push the escape wheel backward (commonly called “recoil”) during part of its cycle. This reduces wear in the clocks gears, and improves the accuracy of the mechanism.
This shot shows a face that is roughly 50% resurfaced. Amazing to see how rough the pallet was before I started resurfacing - even though it looked great through moderate magnification. Note too the residual groove from where the escape wheel teeth had worn a track across the pallet. The residual groove is now only visible at the right hand side of the pallet face - about a quarter of the way up the edge. By the time I had ground the face square to the edges of the arm all traces of the groove were gone. I use the technique described in this Tid Bit to resurface pallets that are excessively grooved.
Thiscloseupoftheimpulsefaceshowspalletwhenitisabouthalfwayground.Interestiingtoseehowroughwasbeforegrinding.NotealsothatIhaveremovedmostgroovewhereescapewheelteethwornface.
