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My First 400 Day Clock Service

imk

Registered User
Nov 11, 2022
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I have been given a Kern & Sohne Bentima 400 Day clcok that look exactly like the one in the below link:

When I received it the main spring was almost fully wound but the clock didn't run, so I gave it the extra quarter turn and it ran for a few days then stopped.
I gave it another quarter turn and same again, so I have fully released the main spring and have given it a couple of turns and it seems to be running ok.

Hence, as it has stood for years in a loft I think the main spring has glued up and the clock basically needs a good service.
So question what oil's to use on this type of clock please?

Many thanks in advance IMK
 

KurtinSA

NAWCC Member
Nov 24, 2014
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San Antonio, TX
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Welcome, IMK! Lots of thoughts on this, but generally you should try to find a synthetic oil and one of low viscosity. A good place to start is say Mobil1 0W5 or the like. Not sure what you have over there. The spring will need a good clean to get all of the old oil and varnish off of it. Then oil just a bit...you don't want to soak it in oil as that creates its own set of problems. You will need a main spring winding tool in order to easily and safely get the spring in/out of the barrel.

Let us know what you find when you get the spring out!

Kurt
 

imk

Registered User
Nov 11, 2022
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0
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Hello Kurt and many thanks for the reply.
I had a look at couple of videos re removing main spring and spring winding jig etc.
It doesn't look rocket science and I think i can use the key harbor in my lathe operated by hand.
Then fashion something to hold other end of spring while winding it.

As far as Mobil 1 0W5 is concerned I couldn't find any reference to it on the web either in UK or USA.
Hence I'll have a hunt for an alternative low viscosity synthetic oils
Many thanks imk
 

Dells

NAWCC Member
Oct 18, 2019
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In the cotswolds UK
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Hello Kurt and many thanks for the reply.
I had a look at couple of videos re removing main spring and spring winding jig etc.
It doesn't look rocket science and I think i can use the key harbor in my lathe operated by hand.
Then fashion something to hold other end of spring while winding it.

As far as Mobil 1 0W5 is concerned I couldn't find any reference to it on the web either in UK or USA.
Hence I'll have a hunt for an alternative low viscosity synthetic oils
Many thanks imk
Hi imk
I am in UK and I use Mobil 1 0W5 only because it’s what I use in my car so what ever you use in your car and as long as it’s fully synthetic and low viscosity it will be fine.
Dell
 

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