Here is my build of SP7: https://www.youtube.com/watch?v=pgtvyV1DrsI. Another excellent design.
A few notes:
I am using the active pawl from Hoppy's mods and the original static pawl. I found Hoppy's pawl more reliable, but his static pawl put too much weight on the ratchet wheel and cause it to miss some ticks. I still have work to do on the static pawl selection.
I made the pendulum shims thicker. I think the issue here is that I printed the base and frame with a 0.6mm nozzle and 0.4mm layers to reduce print time, and consequently the feet sit fractionally higher.
The pendulum mechanism had the number 5668 on it, ordered from ebay. I believe it is the same circuit with SMD transistors. I also tried one labelled 12888. It did not work well, and it seems to have less power. The circuit is quite different: it uses only a single transistor. The battery cover won't sit quite flush with the 5668, so I added some stick-on feet to make the base sit better.
The minutes hand was too loose and so I tweaked the STL.
Not yet tuned! I take inspiration from a video by the curator of clocks of the British Museum, who talked about clocks that you bring out to show off on special occasions rather than using them as regular timepieces.
Thanks for the advice that might help other builders. I should see if Hoppy would like the new pawls added into the MMF release.
I print almost everything with a 0.4mm nozzle and 0.2mm layer heights. Many of the newer printers seem to be drifting towards 0.6mm nozzles. There are a few component widths in the designs that are specifically tuned for a certain number of perimeters with a 0.4mm nozzle. Arachne fixes a lot of things so exact widths or nozzle size are less important.
I was surprised to find so few different pendulum mechanisms. It appears that there are other types.
I have been noticing loose hands in some of my designs as well. Different nozzles and printer speeds make a big difference. The newer designs are getting released with multiple center hole sizes.
My clock collection is a bit like the British Museum. I don't have enough wall space to keep them all running. There is usually an easy build clock, the newest crazy gear wall clock, and sometimes my first design. The living room has a large silent desk clock with a solid dial that is easy to read and a crazy gear desk clock.
One other change I forgot to mention. The clutch slipped at first so the minute hand didn't go round. I made the small spacers thicker with a slight improvement. The change which really helped was to roughen up the gear 5 spacer and the surfaces it comes into contact with using coarse sandpaper, to add a bit more friction.