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vintage pocket watch mainsprings

Question

Quick question,  where to buy old but new mainsprings for old pocket/fob watches?

I'm in need of one at the moment as the arbour end snapped off, my measurements are as follows

height 1.95mm

thickness 0.24mm

approx 300 mm in length

inside diameter of barrel is 41mm

now ive hunted through cousins with no success, ive also tried putting in the exact measurements of smiths ingersoll dollar watches mainsprings but again im coming up with nothing.

anyone have any ideas please cheers

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11 answers to this question

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Ok, so for a 14mm barrel, the calculator says the mean spring thickness would be 0.17mm and length 439mm.

A 0.24 thick spring will give more power, but will have to be shorter to fit the barrel, and is only going to give you 4.5 turns, so unlikely to run for more than 20 hours or so. You aren't going to find a spring this size so you would need to cut one down to get this if you really want to.  I would be inclined to use the thinner spring which will give you the right number of turns.

Cousins search is working again now... not sure if it was me or them.

There are very few 1.95 high springs, so in the 1.9 range, GR5607 is your closest bet, assuming you need a regular hooked bridle end spring, or you could use 5616 which is slightly thicker at 0.18mm.

I would still check the barrel depth to make sure you can't fit a higher spring. If a 2.0 will comfortably fit then you could go for GR5853

 

 

 

clockboy likes this

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Bit confused, Cousin's search tool doesn't seem to be working right now, but you can see what they have here https://www.cousinsuk.com/product/upto-200mm-height

More confusing are the dimensions you have given. Is this a regular 30-40 hour lever escapement pocket watch, or an 8 day watch? A 41mm barrel is the size of a watch, and whatever the barrel size, 300mm sounds short.

You may find that you don't have the right spring fitted, and you need to work out what should be in there.  There is an excellent expanation of how to do that here http://www.vintagewatchstraps.com/blogmainsprings.php. I can't remember if it tells you but you need a spring heith with about 0.2mm clearance to the internal barrel depth.

Photos would help if you need more advice, and we all love to see them anyway.

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Ooooppps,  was meant to read 14 mm in diameter, the movement itself is a cylinder escapement, I had a thread asking the make of the movement not so long ago, I will try and copy the link into a thread  shortly to helpyou abit more ok.

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Stuart you are a star, very niceley explained and easily understandable so much so that I will use your method for future springs that I need for ancient pocket watches.

One final question, I will have I will have a look myself across the net, but would you know the correct size spring for a 16 size waltham traveller?

StuartBaker104 likes this

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Verging on a new thread here, but still pw mainspring related.

You can use the GR catalogue on Cousins site https://www.cousinsuk.com/PDF/categories/7815_GR Pages 191 - 200.pdf

but you will need the movement type which you should get from here https://pocketwatchdatabase.com/guide/company/waltham/serial-number-lookup

if that doesn't get you there then post more details, or search at NAWCC.

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Stuart many thanks my friend, your knowledge is far greater than mine,I shall have a good look this evening when I finish at the coalface, and yes it is a normal hook bridle, no fancy t bars etc on this old movement. It hasn't even got a case, I just wanted to get this old movement running again, it will probably sit in a box somewhere after this until I can source the correct size case, then knowing me it will sit with your collection.

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Stuart just to finalise this thread, I took your advice on mainspring size and it was bang on mate, fits lovely. Now I need to source a jewel for the balance as the top jewel is broken, the search goes on haha

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Posted (edited)

Well, it's not pretty, 1 due to the condition of the jewel holding area prior to work and 2 no  sietz jeweling tool in sight and 3 never done this before.

well whilst working on this old unknown ladies size 6 (34mm plate diameter) fob watch I ascertained it needed a new mainspring, help was given on sizing as I couldn't find an exact match by a very helpful forum member Stuartbaker

new mainspring fitted and then as another post in this thread mentioned I needed a replacement balance cock jewel.

i took a gamble and bought a random mix from red rooster on the bay. As luck would have it there was a few in the mix that looked like they would do the job.

so away I went and took the cock apart and started the job

 

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Edited by transporter
Attempting to upload short video
dadistic likes this

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