Shortening a loop end mainspring

dad1891

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I have a 1929 Plymouth mantel clock that needs a new mainspring. I was not able to locate the proper length spring, so I purchased a spring that was approx. 20" longer than the original. I have two questions:

1. The original spring had a formed loop that was riveted to the end of the spring, whereas the replacement spring has the end folded over and riveted.
003.jpg 004.jpg

Is it better to use the formed loop assembly from the old spring, or anneal and form a loop? Do you guys have any neat tricks for forming loops?

2. I have looked at the catalogs from several clock suppliers and haven't seen rivets that seem to be suitable. Where do you get your rivets and the tools necessary to peen the end?

Thanks for the help!
 

dickstorer

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Good Morning Dave,

I doubt if there is a "better" way. Easier, probably. I have always used the old loop and either made a new rivet or if you're really in a hurry, anneal the new spring, punch a new hole, and use a small machine screw and a nut. If you use a screw and nut the end of the screw could be peened a bit to keep it from coming loose. The rivets that come with new clicks/click springs work pretty good, also.
 
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shutterbug

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You'll have to cut the spring, anneal the end, punch the hole and rivet.
 

R. Croswell

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I find it easier to reuse the original end. I am concerned as to why you can't find a suitable spring for your Plymouth mantel clock. The ones I have seen use a pretty standard spring. 20 inches is an awful lot to remove from a spring. Can you show us a picture of your clock movement and provide the dimensions of the spring you removed and the dimensions of the spring you purchased before you cut 20" off of it.

RC
 

Jay Fortner

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Either way is totally acceptable. The one piece spring is a little stronger as the load is carried by the spring leaf not just the rivet. Not that I've ever seen a rivet break but I have seen them almost about to fall out. You will have to anneal either way.
 

Randy Beckett

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While doing some test recently with some long Korean springs, there was a lot of cutting them off a little at a time, trying different lengths. I just started reattaching the loop, by punching a new hole and connecting it with a 1/8" pop rivet, then hammering it down. It was only meant to be temporary, as I searched for the optimum length, but I can't pull or pry it off, and have to drill it out to remove it. I don't think it would ever come loose on it's own.
 

R. Croswell

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While doing some test recently with some long Korean springs, there was a lot of cutting them off a little at a time, trying different lengths. I just started reattaching the loop, by punching a new hole and connecting it with a 1/8" pop rivet, then hammering it down. It was only meant to be temporary, as I searched for the optimum length, but I can't pull or pry it off, and have to drill it out to remove it. I don't think it would ever come loose on it's own.
If you used a steel pop rivet I'm pretty sure it will hold. Not so sure how long an aluminum one might hold but would take a long long time for the sharp edge of the spring steel to slice through it especially is the pull piece remained in place.

RC
 

Randy Beckett

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If you used a steel pop rivet I'm pretty sure it will hold. Not so sure how long an aluminum one might hold but would take a long long time for the sharp edge of the spring steel to slice through it especially is the pull piece remained in place.

RC
I did use aluminum, just because that's all I had. Steel would have to be a better choice, and just as fast and easy.
 

lpbp

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I would be interested to know what the length of the old one was, the extra length may not have been a problem.
 

dad1891

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I would be interested to know what the length of the old one was, the extra length may not have been a problem.
Original .018 X 11/16 X 72
Replacement .016 X 11/16 X 96

Original spring is way too strong. This clock is a relative rarity in the fact that the movement has very, very little wear from the date it was manufactured. It has the cheaper version of the ST 89. I'm changing the spring to improve the longevity, since I plan to keep it for a while. Unfortunately, there is not enough room for the longer spring.
 
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dad1891

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Jay, you make a good point about the folded over method having more strength. I'll have a go at making some loops with the scrap material. If that doesn't work out, I can always fall back to the original loop.

Until I saw the replies, I didn't even think about pop rivets. I would be apprehensive about aluminum, but steel would probably work OK. As it turns out, back in the dark ages I needed some 3/32" rivets and found them at McMaster in Monel. Lb for lb, they are the toughest rivets I have ever seen. Have almost thrown them out several times when I was cleaning house, but I finally found a use for 'em.

Thanks for the replies.
 

Jay Fortner

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I may be wrong but ST 89's ran .0165 X 108 on the time side and .014 on the strike side. I had one once that came with .018's on both sides and it kept terrible time and the strike went off like an AK without the rate reducer. I changed them out for .0165 and .014 by 96's.

Form the loop around a #3 phillips screwdriver shank.

I just looked up the mainspring chart and it says 3/4" X .017" X 120" which seems a bit long to me.
 
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dad1891

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Gee, I didn't think that anyone would spend the time to look up the correct springs. Here's a pic of the movement.

016.JPG

The only thing stamped on the back is 6-39, which is presumably the manufacture date. The plates are 3-1/8 x 4-7/8 and .056" thick.
 

dad1891

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Hmm,that's not an 89,what gave me the idea it was? Are there any other numbers on it?
I guess that may have been me. :whistle:

Nothing else on the plates. The instructions stapled inside the back door say that it is either a 4300, 4500 or 4600 Plymouth movement.
 

bangster

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Either way is totally acceptable. The one piece spring is a little stronger as the load is carried by the spring leaf not just the rivet. Not that I've ever seen a rivet break but I have seen them almost about to fall out. You will have to anneal either way.
A properly peened rivet won't fall out.
 

dad1891

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The last Plymouth I serviced had what was essentially a an 89-L qtr. striker movement. The movement currently being discussed looks a lot newer. Perhaps it be a replacement movement, maybe Asian?

RC
I'm pretty sure that it isn't a replacement movement. Here's a link to an article written on the exact same clock with exactly the same movement. The limited research I have done indicates that this movement was made by ST from 1930 until they stopped making movements in the 50's and sold under the Plymouth name as a lower cost clock than those branded ST.

Apparently these were pretty common as I can find a couple on fleabay right now, but they generally have not been well taken care of.
 

shutterbug

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Hmm,that's not an 89,what gave me the idea it was?
Maybe this, from post #12
It has the cheaper version of the ST 89.
I just finished one of those! That rack tail is about the cheapest thing I've run across yet!
I have it recorded as an A200-053, ST. Early 1900's.
 
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R. Croswell

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I'm pretty sure that it isn't a replacement movement. Here's a link to an article written on the exact same clock with exactly the same movement. The limited research I have done indicates that this movement was made by ST from 1930 until they stopped making movements in the 50's and sold under the Plymouth name as a lower cost clock than those branded ST.

Apparently these were pretty common as I can find a couple on fleabay right now, but they generally have not been well taken care of.
Interesting information. Apparently variations of the ST #89 were used in earlier models while later (1930s, 40's and on to the end) used different movements. I see both types of movement in Plymouth clocks on "fleabay" right now with the more modern looking cases having movements like yours. There must not have been a huge number made or one would expect to see a correct spring available.

RC
 

doug sinclair

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I have formed loop ends on mainsprings using a method I devised. It uses a modified silversmith's draw tongs, and a steel dowel. The method as shown requires a lot of heat in order to assure and end won't crack once formed. Re-using the original hook is easier. image.jpg image.jpg image.jpg
 

dad1891

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I have formed loop ends on mainsprings using a method I devised. It uses a modified silversmith's draw tongs, and a steel dowel. The method as shown requires a lot of heat in order to assure and end won't crack once formed. Re-using the original hook is easier.
Doug, that looks slick. Strangely enough, I have a pair of those tongs that I inherited from my grandfather. Unfortunately, I use the heck out of them working on sheet metal and I can't bring myself to modify 'em.
 

callnursepj1

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Installed a suspension spring in one of these never found any train data but it seems to run well around 10535 BPH
 

callnursepj1

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Calculated values for this movement are 10536.96 BPH with a pendulum length of 116.05 cm. Center wheel teeth = 56 ,Third wheel teeth=56 pinion=10 ,Fourth wheel teeth = 56 pinion=10 ,Escape wheel teeth=30 pinion=10.
 

shutterbug

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A 10537 beat movement would require a pendulum somewhere in the 4.5" range. You probably meant 116.05mm, which would be 4.569 inches.
 

R. Croswell

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Calculated values for this movement are 10536.96 BPH with a pendulum length of 116.05 cm. Center wheel teeth = 56 ,Third wheel teeth=56 pinion=10 ,Fourth wheel teeth = 56 pinion=10 ,Escape wheel teeth=30 pinion=10.
The figures calculate out to be 11.6 cm (116 mm) or 4.57 in. as Shutterbug indicated. Remember the pinion on the center shaft when is NOT used in the calculation. I believe that may have been the problem.

RC
 

Willie X

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That's not anything akin to an ST-89. I have tried for years to figure out exactly what they were and when they were made. Best I can figure is that they were produced by General Time and covered most of the gap from the time S-T folded (c1930) until GT started using Hermle movements (c1957). The late S-T 89 movements are seen in Plymoth clocks until at least 1933 and were mounted with a black Phillips screws in the usual manner. After then the GT movements were mounted with a smaller longer philips screw which went through a rubber grommet encircled in the movement foot.
The GT movements are somewhat difficult to repair and require a stronger but shorter spring. I wouldn't cut that new spring untill I installed it to see if it will work. Once installed, if it has enough power, you may find that it will work OK at its present length. Certainly it could be 8" longer than the old (thicker) spring and still fit in the same space as the old one.
My two, Willie X
 

callnursepj1

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IMG_4906[1].jpg This clock used black Phillips screws with "hour hands" that were cut down to use as washers, has anyone ever seen this before:???:? It would appear to have been done at the factory. Had problems with the raised portion of the strike snail contacting the inside of the case causing the hands to stay in one spot, back set clearance issues between the movement and case due to the washers? Yes, I did replace the springs way too strong caused excessive arbor bushing wear, original spring end loops were stamped with ST logo I used cut down (-16") 11/16" .0165" 96" springs.
 

Willie X

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Yes, the rubber grommets have deterioated and been removed. When they were removed a make-do washer was added. It should have a flat washer (#8) or two between the case and foot and another one in place of the wire terminal you have now. This will restore the correct position in the case. As it is now your hand shaft is probably a little far from the dial.
Or, you could search out the correct rubber grommets ...
Willie X
 

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