To measure a Hermle clock pendulum, start at the very top of the movement. Continue all the way down to the bottom of the rating nut on the pendulum. The CM number will only be accurate to the pendulum length if the bob diameter is small.
How do you measure the drop of a pendulum?
The drop is the length of the pendulum from the hand shaft all the way down to the bottom of the pendulum rating nut threads. It is a different way of measuring the pendulum length then the German made way. Both ways are based on the smallest bob diameter bob.
How much should you adjust the length of the pendulum?
2.03 hours fast per day. The pendulum length as tested was 19 cm. L=22.35 cm. The pendulum needs to be lengthened to 22.35 cm.
Alternative Methods to Determine the Correct Pendulum Length for a Clock.