Hi Steve,
I am bringing all of my parts together and struggling a bit with my 8-day configuration build.
Main problem: my pendulum swing time is short...about 3 or 4 minutes. I cleaned out the bearings and have ABEC-3's on order. I am going to clean then again. It is odd, because they feel fine. Btw, where do I get your swing gauge for this clock? I thought you had it as a download, but I can't find it.
I can run without the pawl. It takes somewhere between 5 and 8lbs to drive it , that weight measured running as a two end hung weight. That seems high to me, based on your notes, for the 8-minute configuration, but it does run. It is touchy at 5lbs but seems solid at 8.
When I bring the pawl into the mechanism, it just stops.
The one design detail that I am finding problematic is gear3. When I screw in the M3 into the gear, the shaft cocks, and the result is that the gear wobbles. It is flat to start. I reworked it a bit on Onshape to eliminate the internal increase in diameter, and also to add an opposing screw. But it still ends up a bit wobbly. I am wondering 1) how you worked around this, and 2) whether this is close enough to the escapement to cause an issue.
Great design! Great work on your part. If you have any tips, that would be great. Thanks, Dave
Hi Steve,
Woohoo, The clock is running with 5lb single ended. I will see how this goes for awhile. Then take it apart and see if I can get that drive weight down. I dressed it up with a german face that I found on line. Still working on the hands. Also I modified the pendulum to use 4mm carbon fiber rods, 17" long. Very inexpensive upgrade if it works out. My downstairs get cold in the winter, I have noticed issues with my SP8.
Thanks!
Dave
Hi Steve,
Thanks for getting back to me!
I have a Prusa MK3S, and use Prusaslicer. Makes sense about the ABEC-3. I tried flick spinning 3 different bare bearings on 3mm shaft. Run time about 1 sec. I did some cleaning, and some selection...that made a big difference. Two stood out as much better. Just re-ran pendulum test now. Visibly livelier. Ran > 20 minutes. :)
As far as the gear 3...I am gluing it onto shaft.
Last bit, the 5 to 8 lbs in double hung mode. That is without the escapement. I will go over the debug section. I will let you know how I make out!
Thanks, Dave
Hi dspetcher,
Your clock is likely very close to running, with just a few small issues to work on.
A 3-4 minute swing time on the pendulum is quite short. I look at is as if all the kinetic energy required to make the pendulum swing will need to be restored every 3-4 minutes. If the swing time was 10 minutes, then this energy would only need to be restored every 10 minutes.
I use the cheapest bearings available on AliExpress or Amazon and they typically swing for around 15-20 minutes after cleaning. I have never found the need to use ABEC3 or higher. In fact, I don't even know if they would be any better. Higher ABEC numbers might have closer tolerances to support spinning under load at 50,000 RPM. In our use case, looser tolerances might be better, but this is just speculation on my part.
Place a clean bearing on a 3mm arbor and flick it with a finger. Some should spin for a few seconds. Pick the longest spinning ones for the pendulum. The others can be used near the weight shell. Any that are gritty or stop spinning immediately need to either be cleaned again or discarded.
The swing gauge should be in the misc subdirectory of the latest download.
When you mention 5-8lbs, are you talking about letting the gears spin without the escapement? This seems high, possibly indicating excess friction somewhere. You would have to debug each gear and gear pair on your clock to figure out where. The two most common friction sources are often gears not spinning on the arbors (drill out the center holes), or lack of end shake between the frames (reduce the height of something, usually a spacer). The debug section of the manual should have a long list of things to check.
You say the clock stops when you bring the pawl (pallet?) into the mechanism. More information is needed. The clock should run for nearly 3-4 minutes without any energy added by the escapement. If it is less than this, then the escapement may be interfering with the pallet instead of helping. Manually swing the pendulum from side to side to watch the interaction between the escapement and pallet. The escapement should start spinning quickly as the pallet tips clear the escapement. Also, the tick and tock angles should be approximately equal on each direction.
The M3 screw on gear 3 can be extremely loose. There are no forces involved other than gently holding the position on the arbor. You could glue it into position instead. Note, the screws on gear 4 are different. The friction clutch spring is trying to push the gears apart, so the screws need to be tight enough to prevent this.
btw: What printer and slicer are you using? Every gear I print usually ends up with undersized holes that need to be drilled out even when starting with slightly oversized holes in CAD. I use PrusaSlicer with Prusa MK3.5 and MK4 printers.
Steve