I realize this is an older post. Hopefully you have found the solution. I had the same thing happening on my SP2 clock. I found that one of my gears was grossly out of balance. I had been having some trouble printing the gears with the filament I was using. If there was a lot of retractions it would tend to clog the nozzle. In this gears case it apparently had a partial clog in one area of its circumference. The material in that area had voids and was much lighter than the rest of the gear. I noticed it wasn't printed very well but it was on the back side of the gear. Since it wouldn't be visible I used it. Just like your clock I could hear the sound varying as that gear went through a full revolution. I took it out and confirmed it was badly out of balance. I added layers of CA glue to the back of the light side and drilled small holes partly into the back of the heavy side to balance it. After I reinstalled it the clock ran fine with a consistent sound. The clock ran with that gear for a long time. I eventually reprinted it while I had the clock apart to add some of the improvements Steve recently provided.

Thanks Steve, clearly I don't completely understand the physics of pendulums lol. I will try your suggestions. If I have to I will assemble a new longer pendulum. I'm very happy to hear that you released the updates to your older designs. My next step was to draw up the adjustable stand-offs. Now I won't have to struggle with threads in Fusion 360. Thank-you so much for that!

Here's my version of the pallet/pendulum update. The links between the pallet and the pendulum support are secured by 3 each 2.5mm screws. There are two 3mm screws that adjust the angle of the pendulum support in relation to the pallete. Also the pallet is secured to its shaft be 3mm screws. The pendulum support has one 3mm screw securing it to the shaft. The clock is running very well now. In fact it is running to well as in I can't slow it down. Is this due to increased energy being put into the pendulum? I have the pendulum bob as low as it can go and the clock now gains 10-15 minutes a day. I can think of a few ways to slow it down:  1. Make a new longer pendulum 2. Reduce the weight of BB's in the weight shell 3. Install the 7.5 day gearset I'm sure a longer pendulum would do it but I'd rather not have to assemble a new one if I don't have to. Do you think the reduced energy of the 7.5 day gearset would run the clock slower? I am printing the gearset now and so I guess I will find out tomorrow when they are done. I left the length of the pendulum support the same so the total pendulum length should be the same. I'd love to hear any thoughts on why it is running so much faster.

I have printed 3 SP2s. One of them was a gift for my daughter. Unfortunately, after runnng very well for a month or so at my house, it stopped soon after I hung it up at her house. I went to have a look at it and one thing I noticed was that the lower stand-offs weren't even touching the wall. Somehow I missed that when I hung it. Obviously her wall is bowed. Once I got it home I noticed that the pallet to pendulum joint was loose. I tightened it and the clock ran fine again on my wall. But the pallet/pendulum connection loosens up over time. I'm not sure why but this hasn't been a problem on the SP2 that I printed for myself. I've been thinking about how I wanted to correct these two problems for a while though I haven't gotten around to doing anything about them. Today, I was bored and decided to see if Steve has posted any new designs and I see the SP12 that directly addresses both of these problems. Being able to incorporate these into the SP2 would be a great addition. I know you are busy Steve and I totally understand that it might be awhile before these are added to the older designs. The two features are brilliantly simple. So I think for now, I will just incorporate my own version of them into my SP2s. I had a few different ideas how to fix these issues but none of them are as elegant as the SP12 improvements. Thanks for the inspiration. James Phillips

Hello Steve and Douglas Reid, I read the above thread with great interest as I am in the middle of trying something similar with my Electro Magnetic pendulum clock. I have built the SP1 and am on my third Sp2 weight driven clock. I have the SP1 in my office at work and have assembled an SP2 for me at home and one for my son in law at his business and am finishing another SP2 up right now for my 2nd daughter. They all run with an error of less than 1 minute in a week. But I have never been able to get the EMPC to run accurately. No matter what combination of pawls I tried it would always eventually advance by two teeth per swing or not advance at all. I put it aside for a while as I needed to get some other things done. (Like the SP2 I promised my daughter almost a fear ago lol). In the last few weeks I've been messing with the EMPC a bit more. I am running it from two 18650 cells through a LM2596 buck converter. I was hoping a more stable voltage would lead to a more consistent pendulum swing. At the moment I'm not concerned with battery efficiency. I am just trying to get the clock to run consistently. I had the LM2596 laying around so that is what I'm using. I hadn't even thought of a boost converter and I am not sure of the pros and cons of either one. The results so far have been mixed. I will say it is much easier to tune the clock by adjusting the input voltage which has a direct effect on the pendulum swing amplitude. A 10mv change in voltage has a noticeable effect on the pendulum swing and corresponding pawl travel distance. It leaves me wondering how this clock could ever achieve reasonable accuracy running directly on AA batteries. The clock is now running on about 2.5Vdc. The active pawl is near the top of the pendulum. Previously I was running with less voltage and the active pawl was lower. While doing so I became aware of some mechanical issues with my clock. It was running and keeping good time but then stopped. Two of the gears had slid toward each other and came into contact which locked up the clock. I installed some tiny washers where needed to space the gears. I may have installed one to many washers on one of the gears as afterwards the clock would not run at the same voltage. It seems I added some friction. I didn't feel like taking it apart again so I just increased the voltage and raised the active pawl a few notches. That is why I say I have had mixed results. One day soon I'll remove the extra washer but for now I just wanted to prove it could run consistenly. Yesterday I designed a base to hold the 18650 cells and the LM2596. The clock with its original base will just sit on top of this base and be wired to it. If this all proves successful I will probably redesign a replacement for the original base to accommodate the regulator and batteries. Douglas Reid, I am very interested in any ideas you may have concerning the electronics for this clock. I have mentioned it here before and you may already be aware of them but just in case here are a couple links showing how Dick Bipes has accomplished a similar idea using a micro-processor to regulate his electro-magnetic clock. I think his use of a cammed pendulum driving the active pawl is key. I think that arrangement alone might help this clock quite a bit. Clock Link: https://www.instructables.com/A-wood-gear-clock-with-a-unique-drive-mechanism/ Electronics Link: https://cdn.instructables.com/ORIG/FGB/5WH6/I4IXCJU9/FGB5WH6I4IXCJU9.pdf James

That is awesome. Thanks for the pic!

Very cool! I didn't even know what a Congreve clock was but I do now, I would love to see your servo tilt experiment. I am not familiar with the microcontroller that DickB used but I have some experience with the Atmega and Arduino. For me the base redesign would be the easiest part. The pendulum and pawl arrangement would probably be the next challenge and for me at least the Arduino sketch would be the hardest. Right at the moment I am committed to finishing an SP2 for my daughter. Then I have a 3D printed RC VTOL project on the list. I have so many projects. I'd like to experiment with this idea and your clock but it may be awhile before I am able to get to it.

I used CC3D silk antique gold on the gears of SP1. Its been running for 8 months so maybe it doesn't have enough run-time to develop the problem? I did use teflon dry lube liberally on the gear teeth and everywhere that moving parts made contact. For now I'll assemble SP2 as designed. I could always add bushings later if I wanted.

I have built SP1 and so far it is running strong. I just started printing parts for SP2. Would it make sense to go back to the bushings of SP1 in an attempt to avoid this friction issue? If so do you think the smaller arbor holes of SP2 could be reamed for bushings without causing other issues?