Seth Thomas mainsprings, “set” ?

Alan Flowers

New User
Apr 30, 2016
4
1
3
Country
How can you tell if a mainspring is set or too weak AFTER it is out of the clock?
 

tracerjack

Registered User
Jun 6, 2016
1,874
289
83
Lodi, CA
Country
Region
From my limited experience you can only tell for sure if you put it back after everything is clean and repaired and see if it powers the movement. I’ve personally had many springs that didn’t expand in a lively manner when unwound, but worked fine.
 

Dick Feldman

Registered User
Sep 1, 2000
2,646
249
63
Colorado, usa
Country
Region
I would ask what the background for your concern.
This subject comes up every so often and then goes into obscurity for as long as memories last.
My feelings are that main springs and escapements are zeroed in on because they are what is visible. I also feel both are most times victims rather than the cause of problems in clock movements.
I feel the most common cause of clocks not being reliable is low power in the train. Low power due to friction due to wear. That wear occurs in the pivot holes in the plates. New main springs and adjustment of escapements is seldom a long lasting fix for movements.
So—I believe the first approach to clock repair should include diagnosing and solving that wear.
As a partial answer to your question. Main springs seldom go bad. Main springs break and come unhooked as well as a number of other maladies. Many/most main spring problems are the result of click assembly failure. There is a lot of power stored and one should be sure that power can be properly restrained, every time the click assembly works.
I have mentioned before that this board is populated by repair people of all levels. The same is true of U Tube videos, etc. Many of the current myths of clock repair are innocently spread by novices to the trade.
Clean, oil and adjust are not bad for clock movements but are mostly preventative rather than being curative. Those processes being basic and necessary are part of that set of myths.
I would appreciate hearing your situation and the cause for your concern over main springs.
A photo or six would also be helpful.
Best,
Dick
 
  • Like
Reactions: disciple_dan

Bruce Alexander

Sponsor
NAWCC Brass Member
Feb 22, 2010
7,610
872
113
Hanover, PA
www.testoftimeclocks.com
Country
Region
A "set" mainspring should be one of the last things you consider as a possible cause for poor performance. Even if your mainsprings are set, they will likely provide adequate power to the gear train for a significant portion of the movements designed run time. For example, if you are working on an 8-day movement, set springs will likely provide 4 or 5 days (for example) of good operation before their torque curve peters out. If you have a way to measure the spring's torque, you could plot out a curve and get some idea of how quickly the power/torque falls off as the spring unwinds, but without some real world references, you won't be able to determine if the spring is too "tired" (another description of "set") to get the job done.

There are general rules of thumb. If the spring expands less than 2 to 2 1/2 times the diameter of the barrel, it may be set. If there are many coils spanning the inner and outer coils, the spring may be set. Neither of these general guidelines are sufficient evidence, by themselves, to seriously consider replacing the spring(s).

Here is a link to a recent Thread which touches upon these concepts: https://mb.nawcc.org/threads/chime-spring-for-waterbury-mantel-clock.180762/#post-1476387. The original poster StuartG, reinstalled his original mainspring. Hopefully he'll find the time to let us know how things have worked out so far.

Good luck with your project and welcome to the NAWCC's Forums Alan.

Regards,

Bruce
 

Darrmann39

NAWCC Member
Dec 6, 2020
412
61
28
54
Country
A "set" mainspring should be one of the last things you consider as a possible cause for poor performance. Even if your mainsprings are set, they will likely provide adequate power to the gear train for a significant portion of the movements designed run time. For example, if you are working on an 8-day movement, set springs will likely provide 4 or 5 days (for example) of good operation before their torque curve peters out. If you have a way to measure the spring's torque, you could plot out a curve and get some idea of how quickly the power/torque falls off as the spring unwinds, but without some real world references, you won't be able to determine if the spring is too "tired" (another description of "set") to get the job done.

There are general rules of thumb. If the spring expands less than 2 to 2 1/2 times the diameter of the barrel, it may be set. If there are many coils spanning the inner and outer coils, the spring may be set. Neither of these general guidelines are sufficient evidence, by themselves, to seriously consider replacing the spring(s).

Here is a link to a recent Thread which touches upon these concepts: https://mb.nawcc.org/threads/chime-spring-for-waterbury-mantel-clock.180762/#post-1476387. The original poster StuartG, reinstalled his original mainspring. Hopefully he'll find the time to let us know how things have worked out so far.

Good luck with your project and welcome to the NAWCC's Forums Alan.

Regards,

Bruce
I have a superior 8 day clock that runs absolutley fine for 5 days, i wind all my clocks on Sunday morning and by Thursday it's stopped. As long as I wind it every five days it never stops. Wouldn't that be a sign of a set mainspring

20210504_154009.jpg
 

wow

NAWCC Member
Jun 24, 2008
5,432
613
113
76
Pineville, La. (central La.)
Country
Region
I have a superior 8 day clock that runs absolutley fine for 5 days, i wind all my clocks on Sunday morning and by Thursday it's stopped. As long as I wind it every five days it never stops. Wouldn't that be a sign of a set mainspring?
Not necessarily. It may be a sign of wear in the time train. Older mainsprings were made of quality material and most new ones are not. When a clock wears and the pivots wear the holes in the plates enough to cause the wheels not to mesh properly, the clock will not run as long as it did before the wear. Usually, as others have stated, the problem is not in the mainsprings.
 
Last edited by a moderator:

Willie X

Registered User
Feb 9, 2008
14,776
1,741
113
No, I have a similar Ansonia "Extra" with the original wrought iron main-springs. It will do 10 days any time you want to try it.

Short runs are almost always caused by trouble within the train. The list of problems is a long one. Now, if you have a main-spring that's only 3 feet long, thar's yer problem. :oops:

Willie X
 
  • Like
Reactions: Darrmann39

Darrmann39

NAWCC Member
Dec 6, 2020
412
61
28
54
Country
No, I have a similar Ansonia "Extra" with the original wrought iron main-springs. It will do 10 days any time you want to try it.

Short runs are almost always caused by trouble within the train. The list of problems is a long one. Now, if you have a main-spring that's only 3 feet long, thar's yer problem. :oops:

Willie X
Thanks, it ran when I got it and without taking it out of the case looked pretty clean. But the 5 day run confused me. I didn't figure it would run for that long if or had wear problems. Shows I'm still way way green at this.
I'll have to tear it down and take a closer look and figure out what it is .
 

Bruce Alexander

Sponsor
NAWCC Brass Member
Feb 22, 2010
7,610
872
113
Hanover, PA
www.testoftimeclocks.com
Country
Region
Wouldn't that be a sign of a set mainspring
Personally I think that it could be, but by itself that is not definitive.
If you've ruled out other causes, I think you can consider a set mainspring as a possible cause of a short run, but again, it should be one of the last things you should consider and there should be other indications as well. I've begun to actually measure the torque output of a suspect mainspring. So far I've seen that the few clocks I've tested in this manner have far more power than they need so even when there's a pretty steep fall off of the so-called torque curve, the beats per hour rate doesn't seem to be too adversely affected. Recoil escapements will likely be more affected by a drop in torque.

I'm not familiar with a "Superior" clock, but I've been told that many American clock manufacturers overpowered their clocks to reduce warranty work and to ensure that they were able to power through the break down of natural lubricants used in their day (at least for a little while).

So I guess I'm saying that you shouldn't overlook the possibility of a set mainspring if it looks to be set, but I think it should be discovered through the process of elimination. My hope is that by measuring the torque curve of suspect springs, I may be able to decide earlier in the process whether I should replace a "tired" mainspring or not.

I fully realize that some folks with more experience are more conservative on this topic, and I've become more conservative but while I still may be a little wet behind the ears, I have seen through testing that mainsprings can and do become set and that their acquired drop in torque can be sufficient enough to affect the movement's performance. Here's a link to a graph that I plotted out about four years ago: https://mb.nawcc.org/threads/can-mainsprings-be-rejuvenated.144741/post-1130731 The entire thread has interesting viewpoints.

You also mentioned that it "looked pretty clean". Without knowing it's recent service history, the only useful thing about a movement looking pretty clean is that you should be able to spot wear a little better.

Something else to consider, open loop-end springs are far less likely to be significantly "set". Barreled hole-end springs are the only type of spring I've seen with set torque curve issues.

Until you're ready to service the movement, just wind it twice per week. Try to keep it operating in the middle of the spring's torque curves. Don't wind it up as tight as you can, but rewind it before it starts to slow down. There's nothing wrong with that approach if the movement is truly clean. If you can detect no dirt of abrasives in the pivot holes, you can also re-oil the movement, but that's a bit of a crap shoot if you don't know the recent service history.

Regards,

Bruce
 
  • Like
Reactions: Darrmann39

Willie X

Registered User
Feb 9, 2008
14,776
1,741
113
Do you have David Goodman's book? Dr. Goodman and I had the same way of thinking about trouble-shooting a clock.
To fix a clock you need to figure out what's wrong with it and that is best done before you take it apart. The list can be long or short but you need to know how to look for and find the problems first and then learn how to best address the problem area/s.

Sounds overly simple but it's a lot deeper than you may think.

Willie X
 
  • Like
Reactions: Darrmann39

bruce linde

ADMIN / MODERATOR
NAWCC Member
Donor
Nov 13, 2011
9,127
1,473
113
oakland, ca.
clockhappy.com
Country
Region
If every individual gear between the plates spins like a greased pig sliding down an icy downhill ramp, and the fully serviced and reassembled gears together also spin like said pig when you apply the lightest pressure to the great wheel…. then only minimal power will be needed… be it weight or spring driven.
 
  • Like
Reactions: Darrmann39

shutterbug

Moderator
Staff member
NAWCC Member
Oct 19, 2005
47,369
2,131
113
North Carolina
Country
Region
When you get the movement out of the case, let the mainsprings down and then rock the great (or second) wheel back and forth with your thumb while watching the pivots in each wheel, front and back. I think you'll find at least some of them bouncing back and forth in their holes. That's what wear looks like, and is the evidence you need that the movement will require "surgery" ;)
 
  • Like
Reactions: Darrmann39

Alan Flowers

New User
Apr 30, 2016
4
1
3
Country
I would ask what the background for your concern.
This subject comes up every so often and then goes into obscurity for as long as memories last.
My feelings are that main springs and escapements are zeroed in on because they are what is visible. I also feel both are most times victims rather than the cause of problems in clock movements.
I feel the most common cause of clocks not being reliable is low power in the train. Low power due to friction due to wear. That wear occurs in the pivot holes in the plates. New main springs and adjustment of escapements is seldom a long lasting fix for movements.
So—I believe the first approach to clock repair should include diagnosing and solving that wear.
As a partial answer to your question. Main springs seldom go bad. Main springs break and come unhooked as well as a number of other maladies. Many/most main spring problems are the result of click assembly failure. There is a lot of power stored and one should be sure that power can be properly restrained, every time the click assembly works.
I have mentioned before that this board is populated by repair people of all levels. The same is true of U Tube videos, etc. Many of the current myths of clock repair are innocently spread by novices to the trade.
Clean, oil and adjust are not bad for clock movements but are mostly preventative rather than being curative. Those processes being basic and necessary are part of that set of myths.
I would appreciate hearing your situation and the cause for your concern over main springs.
A photo or six would also be helpful.
Best,
Dick
This is my 1st attempt at Clock restoration. So I don’t know what 100+ year old springs should look like. It’s a Seth Thomas 89 C. They’re clean, no rust. I had expected them to play out more than they did. Thanks for your comments.

Al Flowers

EE77FBFD-2F09-4E31-AF55-BED4D86DCCF4.jpeg
 

Willie X

Registered User
Feb 9, 2008
14,776
1,741
113
Those springs are fine. You will have to look elsewhere for your problem/s. It's not unusual for a clock to have many small problems.

I'm assuming the springs have been pulled out, cleaned up good, and lubed. Look up 'servicing mainsorings'.

Willie X
 
  • Like
Reactions: Bruce Alexander

Darrmann39

NAWCC Member
Dec 6, 2020
412
61
28
54
Country
Do you have David Goodman's book? Dr. Goodman and I had the same way of thinking about trouble-shooting a clock.
To fix a clock you need to figure out what's wrong with it and that is best done before you take it apart. The list can be long or short but you need to know how to look for and find the problems first and then learn how to best address the problem area/s.

Sounds overly simple but it's a lot deeper than you may think.

Willie X
Thanks, just the sort of book I've been looking for

20210804_152827.jpg
 

Forum statistics

Threads
168,196
Messages
1,466,879
Members
48,161
Latest member
Bruce bic
Encyclopedia Pages
1,060
Total wiki contributions
2,955
Last update
-