Expert: Kenneth Saunders - 2/10/2009

Question
QUESTION: I have several old wall clocks of which most keep irregular time. They are all more than 50 years old. What I mean is that when I wind them up they run slightly fast for 2 days or so then start to slow down such that by the 6th or 7th day they are running anything from 10 to 30 or even 40 minutes late. Obviously the mainsprings have set. I have some practical knowledge of clock repair and have stripped down and reassembled a few of them. Most people I have spoken with are wary of fitting a new (modern) mainspring, saying that it will damage the gear teeth. What I want to know is can something be done to improve the mainspring ? Is it possible to sort of re-condition the mainspring ?

ANSWER: not possible to re-condition.

I would replace the springs

if typical American clocks I would use these (but without knowing exactly which movement you have the sizes may be different.

http://www.timesavers.com/catalogmain2.asp?ProductID=18790&submit1=Search

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QUESTION: Unfortunately I am not in the US of A. So if I can get a mainspring what should I be looking for ? What I have is a mix of Seikosha, Kienzle, GB clocks. Some have open springs, some have springs inside a barrel. Thank you once again.

Answer
replace the spring with the exact same or slightly thinner if available --I would not worry about modern springs causing problems for your clocks.

There are many suppliers - do not know your location so cannot suggest anything without more info.

here is a list:

ftp://atmos-man.com/main/matclock.mcc