ST2 Power issues and fine tuning

[bikerclockguy]

My ST2 is losing power. After reading RC’s excellent tutorial on deadbeat escapements, I think I know what part of the problem is; the bezel around the crutch pin slot is worn. Several people mentioned that when I was trying to get it in beat, but until I read the tutorial, I underestimated the importance of a good fit. If I’m thinking correctly here, the enlarged opening in the slot that allows the crutch pin to rattle around robs the pendulum of a tiny bit of overswing with each tick-tock, until it doesn’t have enough power left to move the exit pallet off of the escape wheel. So, I ordered a new bezel, and in the meantime, I thought I would try Bruce’s suggestion of bending the crutch pin slightly, so that it rides on a different spot in the slot. That brings up something I’ve wondered about all along. The crutch has to run at an angle off of the verge arbor, in order for it to engage with the pendulum. At the point of engagement, how deep should the pin ride in the crutch slot? All the way up to the “nail head”? Slightly back? After I start the clock and the pendulum settles, mine is probably between 1/16 and 1/8” from the head of the pin being flush with the slot, but I have no idea what is correct or optimum. Also, as for the pin itself, mine is perpendicular to the crutch shaft, which makes it engage the pendulum slot at a slight angle. Is that correct, or should the end of the crutch be bent slightly so that the pin rides in the slot perpendicular to the pendulum? Also, since I have had it running, the winding drum got hung up once. I jiggled the key back and forth on the winding arbor a little and it popped loose, so I’m not sure what hung it up. It hasn’t happened since, but are there known/common issues with that setup? After it happened, I disengaged the ratchet and lowered the weight all the way down, wound it slowly, and made sure it spooled evenly in a single layer, and it did that perfectly. Just wondering if there are things that might need attention. I replaced the maintaining power spring when I went through the movement, so that is new. Thanks in advance for your suggestions.

 

[bikerclockguy]

After reading some other posts, I now know I need to adjust the crutch pin so it runs perpendicular to the pendulum shaft. I think I may have found the answer to why it's stopping as well. It ran fine with the dial off for a day and a half, so I buttoned it up. Ran all night and stopped about 10 the next morning. Pulled the dial again, hooked up my beat amplifier and it was still in beat, so I put it back together. After that, it would run in stretches from 25 minutes to an hour and a half. I read another thread from a guy who said his wouldn't run long with the minute hand on, and I think that minute/hour hand clearance is my other problem. I probably got the nut a little tighter or the hands positioned a little differently on the second dial installation. I pushed the hour hand down until I felt resistance, and it looked to be down far enough, but when I was browsing Timesavers' site while ago, I noticed they had a kit with ah hour hand bushing and a little spacer to go between the hour and minute hands. I don't need the bushing, and I don't know whether these originally had a spacer from the factory, but I'm thinking it will probably do the trick.

 

[John P]

The winding drum issue is often caused by the C shaped spring between the drum and wheel assembly. Sometimes overlooked when replacing the cable. It can slip out of position once the pin is removed.

We have 2 ST#2 clocks in our shop. One an original 1910 model and the other one is a 1976 repo.
Both had running issues similar to yours. The repo model was the worst to get going and we had the movement out several times until it now is on the 3rd week of running nonstop. The last time i had it apart, I polished all the pinions with shop made buff sticks. They are made by gluing emery paper to coffee stir sticks. The paper is pink or green. We paint the backside of the paper with wood glue and stack the whole side with the sticks. After they dry overnight, we slide them thru a razor blade placed in the vice. What you have now is about a hundred1/4 inch, thin buffs that will polish pinion leaves, escape wheels, pivots etc. We also use these to polish the brass wear plate mounted on the pendulum stick. The buff stick will fit in the slot. There are many uses for these buffs in a clock shop.

My repo #2 would run maybe 2 days or 2 hours before the polishing job and like i said it is now 3 weeks running.
I dont know if this will help your clock but it seems to have cured mine.
I just didn't know what else to do after taking it apart and checking things several times.

The original #2 issue was created by improper hanging. Most of these clocks have one or more screw holes near the bottom to insure a solid mounting to the wall. The #2's cannot wobble on the wall. Also, the doors are heavy and if one opens both of them at the same time, the clock will move sideways and is now out of beat. Check level on the sides, not the bottom.

Good luck with that
johnp

 

[bikerclockguy]

I’m zeroing in on my problem area. I spent quite a bit of time today just watching it run, and paying particular attention to the travel of the minute hand around the time track. This was in response to something I read on another thread, saying it’s critical that the minute hand not contact the hour cannon, because this will stop the clock. When I installed the hour hand this last time I paid attention to the fit and position on the cannon. I noticed it slid on with minimal force(the normal snug fit)to a certain point, and then bottomed out. At that point, the flat surface of the hour hand is flush with the cannon, and there is a slightly raised lip around the center hole on the outward facing side of the hand that sticks up just a bit. I’m guessing that’s to keep the minute hand off of the cannon? Anyway, what I observed was this: There are 6 or 7 spots around the time track where the minute hand will hang up for a second or 2. The clock can power through most of them without making a noticeable difference in pendulum overswing, but there are several of them between the 7 and 8 that are not only closer together, but “stickier” than the rest of them. The clock can power through these on a fresh starting swing of the pendulum, but if the clock is running at normal pendulum amplitude, it cannot overcome them. When I first got the beat set, I let it run for a day and a half. Ran smoothly with no issues, so I think the issues is with the geometry of the hands, rather than the escapement. Left to my own devices, I would probably polish the raised ring on the hour hand and the square boss on the back of the minute hand with some 0000 steel wool, hit them with a blow gun to get rid of any stray fibers, and then spray a light coating of dry graphite lube on both surfaces. Also, I should have mentioned above, I experimented with loosening the minute hand earlier, and the results were marginally better, but I feel like it needs to run correctly with the nut snug. I appreciate all the help so far; if I can just get past this last hurdle, I think she’ll run lIke a top!

 

[demoman3955]

sorry for your problems, but im now counting my blessings that the one i bought is now the most accurate clock i have at the moment. Its so close, that i cant tell if its gained or lost a second in 2 to 3 weeks. Its taken a while to dial it in, and i was told that it had been serviced a couple years prior to me buying it.

 

[bruce linde]

There are 6 or 7 spots around the time track where the minute hand will hang up for a second or 2. The clock can power through most of them without making a noticeable difference in pendulum overswing, but there are several of them between the 7 and 8 that are not only closer together, but “stickier” than the rest of them.

spray a light coating of dry graphite lube on both surfaces. Also, I should have mentioned above, I experimented with loosening the minute hand earlier, and the results were marginally better, but I feel like it needs to run correctly with the nut snug. I appreciate all the help so far;

first comment makes me think you need to look at the escape wheel teeth under magnification... it is far more likely that minute differences from tooth to tooth OR a worn verge or escape wheel pivot hole are causing/contributing to this problem.

second comment: no. graphite is not recommended as it's a dust that will spread over everything. much better to polish parts for smoothest interaction using 2000 grit paper and then 4000... followed by compressed air and then an alcohol clean to make sure they're spotless.

also... i don't remember if the 77 movement has the minute hand cannon with slots in the sides (i.e., pressure fits on minute hand arbor) or has solid sides and uses a tension washer underneath... but it is possible to tighten down the minute hand such that the pressure fit cannon can slide toward and touch (or graze against) the front of the front plate... or the tension washer can bind on the bottom of the cannon.

you really need to look at every possible scenario from the ground up and make sure the fundamentals are sound. by the time you get to the EW there's very little power left and the slightest wear in pivot holes or EW teeth problems can be enough to drive you crazy.

keep in mind: there is no such thing as looking too closely... multiple times.

 

[bikerclockguy]

I have some 1500-2000 paper and sanding sponges that I use for finishing gun stocks, so all set there. I think you meant hour hand cannon with the slots? I still have the dial on at the moment, but from looking at it from the outside, the cannon moves freely in and out on the minute hand shaft. Fit of the hour hand is as described above. The minute hand shaft is threaded on the end, maybe the last 3/8”. At the base of the threaded section is a square section about 1/8”, which has a flat section at the base(it’s just solid arbor shaft after that). With the hour hand fully seated on the cannon, the rounded lip around the center hole sticks up maybe 1/32” above flush. I’m not certain, but I assume that is designed to prevent the minute hand from being able to make contact with the hour cannon. The minute hand has a raised square boss on the back side; not exactly sure of the purpose for that. So… hour hand seated on cannon, square hole in minute hand fits over square section of arbor and then the nut is snugged up. I don’t know if there are supposed to be any washers or spacers in there, but I don’t think so. I found a concave washer in my parts bin, of the type that’s used with a pinned minute hand on mantel clocks, enlarged the center square with a file until it would fit the square on my minute arbor. I experimented with it, trying it as a spacer between hour and minute hands(didn’t work, just made the minute hand movement stiffen up considerably), and i also tried using it between the hand and the nut, wondering whether it would create a more even distribution of torque from the nut(didn’t make any difference). After that, I played around with backing the nut of incrementally until it was just barely holding the minute hand in place. That improved performance marginally, and it ran for a couple of hours this afternoon. I’m going to pul the dial tomorrow and give everything a second look, but the 2-hour stretch today, combined with its running for a day and a half before I put the dial and hands back on, makes me lean toward the issue being there, rather than the train or escapement. Lastly, I wanted to ask you about your suggestion to someone in another thread, to run the clock for a while with just the minute hand mounted, and the dial and hour hand off. I’m not opposed to trying that, but when I do, what kind of observations should I be making? I wasn’t clear on the purpose of that exercise. If I need to post more, I’ll add appropriate pics and videos, and thanks for your help!

 

[John P]

There should be a wooden piece behind the dial with a small screw pulling the dial down flat. Is yours missing?

 

[bikerclockguy]

There should be a wooden piece behind the dial with a small screw pulling the dial down flat. Is yours missing?

Mine has a crossbar that runs across the dial opening at the level of the seconds dial, and screws on the left and right at the 15 and 45 seconds marks. I figured that was to hold it flat there and keep the seconds bit from popping off. Other than that, it’s just the screws around the edges. I have good clearance between hands and dial though, no issues there