Electric Clocks

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SP10 still is running slow

I have made 3 of these clocks and all of them run slow. For example, I set the clock at 8:30. By 11:00 it was already showing 5 min slow. This is after I modified some of the gears. The modifications I made were to the gear that mounts to the motor (gear 6). I modified the hole to fit the shaft so it cannot slip at all.

I modified gear 5-15 and 5-30 to have a 22 mm round flat friction surface and cut a groove in one of the surfaces to fit an O-ring hoping to create more friction. I am using a silk filament for the gears and I noticed they slide easily when rubbed together so there was little friction between the gears. Hence this modification. I have been checking the clock regularly and they do not seem to be slipping now,

All the gears turn…

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brauscher

6 days ago

Figured it out. Had a bad solder joint on the Shield. LED's now flashing. Will test the clock now. Thank you for your help

Flynt Moreland

9 days ago

Ready to go?

On the MyMiniFactory website for the "Electric Pendulum Clock" SP7, there is a statement:

" There have been reports that the only driver circuit available as of June 2025 is not compatible with this design. Please hold off on purchasing these plans until the design can be updated and tested with the new driver."

Is this the current status?

Also, is this mechanism on Amazon the same? It sure looks to be. :)

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Steve

Jan 01

In the past, the coiled battery connector was an indication of a useable electronic module. I am not sure if this is still true, but that does appear to be a good controller.

brauscher

22 days ago

SP 10 running slow

Is is running about 2 seconds slow per min. I know the gears for adjusting the time are NOT slipping because I glued them together for test purposes. I feel no binding when I tun the gear assembly by hand. I adjusted the pot on the driver to turn up the power to see if the motor was skipping. It is not. I have the jumper on the correct setting.

What am I missing here? Is there a way to "fine tune" the motor speed to correct this? Please help. Thank you

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Steve

Dec 18, 2025

There are only three places for the gears to slip, and you have already ruled out most of them. The motor is not skipping, and the friction clutch is not slipping. The friction clutch is after the second hand, so the second hand would still be accurate if the friction clutch was slipping. The only other place that can physically slip is the stepper motor gear slipping on the motor shaft. Make sure to rule this out.

The next most likely causes are with the electronics. A 2 second per minute error probably has the correct jumper settings, so the first thing to check is the RTC. There will be a blinking LED on the Arduino Nano if the RTC is tracking properly.

The algorithm works in one second increments. It moves the motors slightly fast or slightly slow for one second, then checks if the RTC has sent a 1Hz pulse. If it detects the pulse, then the motor switches to fast speed mode. As soon as the RTC falls behind, then the motors switch to slow speed mode, giving the RTC more time to catch up. The LED blinks every time the mode changes. The difference between fast and slow modes is not noticeable and over a long period of time the motor will track the RTC exactly.

There is no way to fine tune the algorithm. It either tracks the RTC or it doesn't. The most likely cause of not tracking is a dead, missing, or mis-wired RTC chip if you built your own board.

Is there a blinking LED on the Arduino Nano?

The serial debug monitor would provide extra information but is a lot of steps if you purchased a pre-programmed board.

dspechter

25 days ago

Time setting issues: possible interference

Hi Steve,

I am building a SP10, and I am seeing an interference issue when I try to adjust the time. It was not easy to see where it is interfering, but what appears to happen is that the little ribs on gear5_30 fall into the gear that meshes with gear5_15. I believe that is 6_25_8. I wonder if you have seen this. Possibly an error on my part. See attached video.

I have tried re-assembling a few times, and it is always there. Now I am trying out some variations on gear5_30 to eliminate this, but then I do see some slippage: while the second hand looks correct, the clock appears to run slowly. So is why I am thinking there is some slippage. I moved the shaft collar to get more spring force as a test, and that appears to be working.

I am going to try a…

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Steve

Dec 15, 2025

Hi Dave,

I am not completely sure what is happening, but it looks like gear6_25_8 is interfering with the ribs on gear5_30.

On my clock, gear6_25_8 meshes close to the front of gear5_15, so it has plenty of clearance away from the ribs on gear5_30.

Try testing for end shake on both arbors. Push gear5 backwards and pull gear6 forwards. There should only be 1-2mm of end shake on each arbor. If it is much larger than 2mm, then the gears may be moving too much and causing interference with gears they are not supposed to mesh with. See if you can move the gears around by adding spacers to prevent the interference.

Steve

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