07-11-2023, 11:18 PM
I made the Trecdimus over two years ago and since then I have had several attempts at getting it to run for any length of time. I had a number of problems which were usually down to my construction and some of the solutions I now realise were probably unnecessary. However, the three main problems that needed resolving were:
Friction. Plenty of smoothing of cogs and arbors was needed, especially with the main cog of the minute arbor and the pinion on the intermediate arbor. When the balls are loaded there’s a lot of force between these two gears and I even had to file a flat on the intermediate arbour to ensure that the pinion didn’t slip.
The pendulum limiter. I could never get the timing right and found that the pendulum bar was riding over the ringstop, the amplitude would increase and the count wheel would be advanced by two steps. The drop-weight-trigger would also further advance the count wheel when returning to its up position. The clock soon stopped. I fashioned a new grub screw for the ringstop with a spare 3mm threaded brass rod about 1cm in length and moved the ring stop so that it limited the pendulum on its left swing rather than the right. I was now able to get the clock to run for several hours.
Drop weight. With an intermittent problem it was difficult to observe what was happening, but I noticed that occasionally the drop weight made a double or even triple down/up movement and the trigger sometimes flipped over which prevented the drop weight returning to its up position. This was happening so fast that I couldn’t really see what the cause was. In the end I used a thin strip of veneer to act as a sort damper spring to help keep the trigger under control. The clock has now been running for several days and, after a bit of adjustment, running reasonably accurately. Further refinement though is still needed.
I hope this is of some use.
Friction. Plenty of smoothing of cogs and arbors was needed, especially with the main cog of the minute arbor and the pinion on the intermediate arbor. When the balls are loaded there’s a lot of force between these two gears and I even had to file a flat on the intermediate arbour to ensure that the pinion didn’t slip.
The pendulum limiter. I could never get the timing right and found that the pendulum bar was riding over the ringstop, the amplitude would increase and the count wheel would be advanced by two steps. The drop-weight-trigger would also further advance the count wheel when returning to its up position. The clock soon stopped. I fashioned a new grub screw for the ringstop with a spare 3mm threaded brass rod about 1cm in length and moved the ring stop so that it limited the pendulum on its left swing rather than the right. I was now able to get the clock to run for several hours.
Drop weight. With an intermittent problem it was difficult to observe what was happening, but I noticed that occasionally the drop weight made a double or even triple down/up movement and the trigger sometimes flipped over which prevented the drop weight returning to its up position. This was happening so fast that I couldn’t really see what the cause was. In the end I used a thin strip of veneer to act as a sort damper spring to help keep the trigger under control. The clock has now been running for several days and, after a bit of adjustment, running reasonably accurately. Further refinement though is still needed.
I hope this is of some use.