Question re gearing
  • Why are brass pins used on some of the gearing as opposed to a wooden pinion? And why not in the hands assembly?

  • There are two reasons, load and accuracy.

    The smaller the cogs the smaller the tolerances, as with any gearing system there is always a certain amount of backlash, as the cogs get smaller so does the backlash. the use of pins allows me to place them close to the pitch radius, so effectively increasing the backlash without actually increasing the cog/ pinion distance. In this respect they are a good device to enable me to increase tolerances without actually increasing backlash. Which is important when producing a kit that can and should be built with varying differences in skill. I only used them on the intermediate and escapement cogs as they need to mesh correctly to ensure that the drive force is transmitted correctly and accurately.
    As the hour hand gear train is a very low load and low accuracy one I can increase the backlash without fear of function reduction, after all it is a lot easier to sand a pinion then cut, trim, hammer in and re-trim pins. I say a low accuracy gear train as it is not important whether the hour hand actually points dead on the half hour at half past six, or whether it points a little before or after.