Expert: Michael Radi - 5/12/2010

Question
I bought a key wound mechanical clock movement off e-bay for a project i'm doing. The pendulum that came with the movement is a lot shorter than I was expecting and its virtually useless in my clock. Is there a way I can use a longer pendulum on this movement? I don't want to have to buy a different movement as it is non-refundable.

Any advice is appreciated.

Answer
Here is the really important thing, the pendulum length determines the timekeeping of the clock movement. If your movement keeps time with the current pendulum, putting a longer pendulum on it will slow it down.
Have you tested the movement to see if it keeps proper time with that pendulum?