Expert: Harold Williamson - 12/14/2009

Question
I have a Hermle movement in a grandfather clock that is labeled 1151-050H and also has the markings 94cm/60 that has been scratched out (possibly by the last person adjusting the clock??).  Anyway, I have taken the movement apart, cleaned it, reassembled it, oiled it, and reinstalled it and it runs about 5 minutes fast per hour!  Have the pendulum adjusted as far down as is possible (to the end of the knurled nut)  It also ran fast when I took it apart to clean it.  When it ticks, it has a very short swing.  My question is, it appears the pendulum has been cut down in length by somebody for some reason.  Not even sure it is the original pendulum.  However, it is a brass lyre pendulum and is currently 42-1/2" from the very top end down to the bottom of the nut. Has what appears to be a 6-1/2" bob on it. The case will allow for up to 48" pendulum in length.  My question is, do I need to get a longer pendulum than what I have to get the movement to slow down and if so, can you direct me to what length as well as to the gettin' place?  thanks.  Murrel Petry,   Washington state.  

Answer
Hello Murrel,

First of all is the ball actually coming down with the regulator nut?

Then you mention that it has a short swing and that could mean that the verge is not setting deep enough into the escape wheel to give the pend. overswing past the point of tick.  That would make it run fast.  Adjusting the depth should be done without the weight hanging.  Mark where the verge adjustment plate is now so you will have a reference point to go back to.  This adjustment is trial and error so be careful when rehanging the weight so it wont spin the escape wheel if you have the verge too far away from it.  Have good light and a visor to see close to your work.  These adjustments are usually done by a clocksmith but it sounds like you have your ducks in a row.

Another reason for a short swing is loss of power up the train and that could be bushing wear/slop in the pivots.  That is a whole different animal. A lyre pend. takes more power than a stick pend.  If you want to make up a dummy stick pend and try to find the length have at it but the short swing tells the tale of depthing problems.

Let me know how it works out.

Harold