Pendulum knocking
  • So, I was one of the lucky ones who got the tick first try. I ascribe this success to extensive multi-step polishing: 150 grit multi-purpose sandpaper to thin, then 220, then 600 ebony... then coarse steel wool, then fine steel wool, and finally polishing using the red polishing compound and a cloth wheel. For ALL of the arbors, but extra special care on the pendulum and escapement arbors. I also took special care not to directly touch the polished metal after polishing (to avoid deposition of moisture or other stuff that could increase oxidation.

    However, I may have been too good, because now my pendula swing widely enough to hit the frame in the middle. They don't hit all the time, but they will hit for about a minute at a time a few times an hour.

    I tried reducing the drive weight, but that just resulted in the clock running slightly slower.

    What factors influence the pendulum swing amplitude? Which of them are best to adjust to reduce that amplitude while minimally affecting timekeeping?
  • When the Sextus is working as it should there is very little space between bob and frame on the inward swing, so it really does not need a lot to cause some knocking.

    If it is just the one bob that connects with the frame this will be caused by one of the connectors not being glued at 90 DEG to the pendulum, so that the Pendula do not swing synchronously.
    If it is both then congratulations on getting such a healthy amplitude.
    I am presuming that you have already balanced the pendula using the counterweights and that they hang vertical, in order to stop the bob from hitting the frame just push the counterweights in causing the pendula to hang with the lower bob pointing slightly outwards, just keep adjusting until the bob stops hitting the frame.
    Doing this makes no difference to the timing.
  • Awesome, thanks for the prompt reply. Trying now.