Pendulum Period
This is my first clock (SP5B 2.0) and is currently breaking in. Before I write anything else, I want to publicly thank Steve for sharing his talent and passion for clocks with us. The print and build process was so enjoyable and the design remarkable. Steve's attention to detail in the assembly notes was at a level of detail I've never seen before and was obviously a engineer's labor of love. Thank you, Steve!
My clock has now run for 2 days straight and is keeping decent time! At first I had some stoppage and decided to let the entire gear train run for multiple cycles with the pallet removed and 3 lbs of weight. I swear that the gear noise softened as they ran through the cycles. Is that possible? When I put the pallet back on, the escapement wouldn't turn freely with 5 lbs and I discovered that the escapement assembly set screws were not allowing for proper meshing with the other gears and creating friction against the frame. Once I adjusted the alignment, everything started to work.
My question has to do with the period of the pendulum. Mine takes 37 seconds to make 30 cycles or 1.2 seconds per cycle. Should it be a 1.0 second period? And if so, wouldn't that be a good way to achieve the best accuracy?
Thanks for the kind words. A lot of effort goes into optimizing a clock for 3D printing.
The horizontal form factor of this clock stacks gears on a single arbor that can be a bit sensitive, as you found out. Once it is adjusted, the clock should run great.
Regarding pendulum length, many old clocks have a 2 second period with 1 second in each direction. This often used two gear pairs with 60:8 and 64:8 ratios followed by a 30 tooth escapement and a 39" pendulum. I believe that a 39" pendulum is disproportionately long in a small clock.
All of my clocks have shorter pendulums. This requires different gear tooth counts. For example, gear ratios of 36:8, 36:8, 36:8 and a 25 tooth escapement has a 24.5" pendulum beating 4556 times per hour. In the days of hand cut gears, the 39" example has 170 teeth to cut, while the 24.5" pendulum only has 157 total teeth and an additional arbor. With a 3D printer, the total number of teeth is an insignificant factor. I select gear ratios that allow a good overall balance. There is no difference in accuracy of a 39" pendulum compared to a 24.5" pendulum.