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Tips For Inserting Barrel Arbor Into Mainspring

Don

By Don
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Don Super WRT Addict

Don

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Last night I was finally successful in hand winding a mainspring into a barrel. I thought the tough part was over...until I tried to insert the arbor into the spring. I tried several different approaches and could not get the arbor to fit inside the inner coil. Then disaster struck and the barrel went one direction and the arbor another, into the void.

Any tips for getting the arbor into the mainspring?

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Geo Distinguished Member

Geo

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Hi Don,

I usually use tweezers to hold the arbour by the square and gently press it into the centre coil of the spring while turning the arbour against the direction of the coil. If you have a pin chuck yo could use this instead of using tweezers, it may give you better control. Do this with the barrel resting on a plate or anvil with a hole in it to allow the other end of the arbour to enter when it protrudes through the barrel wall as it is fitted. Then place the cover on and snap it in place.

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anilv Distinguished Member

anilv

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Hi Don,

 

To add to what Geo said,

 

Flatten a piece of Rodico onto your workbench. Using the handle of your oiler make a divot in it. Then fix the barrel/spring into the rodico (so that it doesn't move) with the end of the inner coil nearest to you and the hole in the midle over the divot you made. Oil the inner part of the barrel where the arbor will contact. Next hold the arbor with your tweezers and get the edge furthest from you into the coil. Using a needle/oiler work the coil around the arbor while applying downward pressure on it with the tweezers. The end of the arbor will sit in the divot.

If the replacement spring is correctly sized to the arbor you don't really need the oiler but in most cases I find the inner coil of the spring is slightly undersized.

 

 

There's actually a tool for this... 'google barrel arbor holder'. Pin vise works but its jaws may leave marks on a bearing surface.

 

And to top it off... theres also a tool to close the barrel lid ...... sheer luxury!

 

bonus tip... for the arbor to fly off you must have been holding the arbor tightly... whenever you do so, curl your free hand around the movement so that it is oppositeyour tweezers. Something you have to consciously do in the beginning but once you make a habit of it you'll find youself spending less time with your nose to your workroom floor.

 

Anil

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Don Super WRT Addict

Don

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Thanks for the advice, guys. I have a couple of pin vises, so I'll try those. Anil, the Rodico idea is perfect, as I don't have a staking/riveting block. But I do have a barrel closer, when I get to that point.

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  • 3 months later...
chadders1966 WRT Addict

chadders1966

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Bob,

Reviving an old thread to ask if you ever worked out an answer to your question? I got a bunch of pin vices lately, and mixed in was a barrel arbor holder. I've used it and it was great, so much easier with it. I now want to get some more, but they cost a lot. I'm just wondering which are the most useful.

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bobm12 Distinguished Member

bobm12

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Hi chadders,

 

nope, I haven't gotten the answer yet but hope and patience is the last thing a watchmaker loses! :)  I was just thinking, maybe the one you have is the answer to this question, since you already found uses for it. May I ask what size it is? In my mind, I'm willing to start with one like yours and work my way into the other ones as need arises...right now I haven't venture into the expense fearing I make the wrong choice.

 

Cheers,

 

Bob

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chadders1966 WRT Addict

chadders1966

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It's quite tricky to measure. I think it closes to 0.5mm, but unlike others I've seen the closure is not circular but oval. This means it can actually hold arbors up to about 1.5mm without marking. However I don't think it would be as secure as the ones with a circular grip. Hope that makes sense.

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bobm12 Distinguished Member

bobm12

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Thanks, I'll check on the different ones offered by...you guessed, Bergeon. Then I'll try the closest one. I got a couple of ETA movements and Seikos I will try it first (just to see how they "grab") and get back to you with a report.

 

Cheers,

 

Bob

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