# Barrel spring size



## niveketak (Jun 11, 2016)

I have recently come into ownership of a French made, Westminster chime wall clock which doesn't work. The chimes and hour gongs are fine but when trying to wind the mainspring there was no resistance. Having bitten the bullet I have removed the main spring barrel and on opening it found the spring burglars have been and knicked it! I assume it had broken and someone was going to replace it and couldn't fathom out how to do it.

So am missing a main spring. I know it hooks onto the lug inside the barrel and would be 18 mm in width. What I have no idea of is how long it would be and how thick the spring itself. Cousins also quote a diameter which I am also struggling to fathom out what that means. Anyone any idea how long the spring might have been and an average thickness and also what the Diameter bit means. This is my first 3 barrel clock repair having only repaired a long case pendulum wall clock and various alarm clocks bought for peanuts.

Cheers

Kevin


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## simon2 (Dec 5, 2010)

Measure the internal diameter of the Barrel. For example. If that diameter is ( 45mm) then the strength of the spring is .45 mm.

As for the length, buy a spring that is sold to fit a 45mm Barrel. Clock mainsprings are sold , pre wound, so by buying one that will fit inside your barrel will be of the correct length. Sizes are quotes as, I.e. 18x45x45. 18 Height. X .45 Strength x 45 Diameter.

Hope this helps. If not then shout. Regards Simon.


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## niveketak (Jun 11, 2016)

simon2 said:


> Measure the internal diameter of the Barrel. For example. If that diameter is ( 45mm) then the strength of the spring is .45 mm.
> 
> As for the length, buy a spring that is sold to fit a 45mm Barrel. Clock mainsprings are sold , pre wound, so by buying one that will fit inside your barrel will be of the correct length. Sizes are quotes as, I.e. 18x45x45. 18 Height. X .45 Strength x 45 Diameter.
> 
> Hope this helps. If not then shout. Regards Simon.


 Thanks Simon but still confused. Having got the callipers out the diameter of the barrel internally is 42 mm the depth (so width of spring) is 22 mm allowing 2 or 3 mm for the cap to go back on which I assume would mean a 22x0.42x42. Cousins list the following in order Height so 22mm Thickness Length and Diameter. So having looked up the 22mm it follows with 0.4 1500 and 40. So my thinking would be that means 22 mm height 1500 mm long 0.4 mm thick and 40 mm internal barrel diameter. Does that sound right? Thanks again

Kevin


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## simon2 (Dec 5, 2010)

The correct size Mainspring for that Barrel is: 22x40x40

the strength and diameter sizes are sold in units of 5. So go for the nearest.

Regards Simon.


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## niveketak (Jun 11, 2016)

Cheers Simon


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