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Watch Mainspring Into Barrel Problem.


cdjswiss
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I have had a tricky problem inserting a DB type mainspring into the barrel of an IWC cal 83.

The tang of the outer mainspring bridle must fit into the tiny slot at the base of the barrel.

 

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When the mainspring is pushed from the winder onto the barrel, despite all attempts to line up the tang with the slot it invariable ends up with the tang way outside the slot. With the mainspring fully unwound  nothing will shift the position of the bridle. My solution is to clamp the barrel into a Delrin support with a CuBe spring to hold the arbor in place. Then to wind up the spring from below using a recuperated pocket watch crown held in a winder. After a few winding turns the outer turn of the mainspring slips around the inside of the barrel and it is stopped in the correct position (marked by an ink spot on the ouside of the barrel) by a screwdriver blade. It can then be slipped into the slot if it has not already done so. There must be another better way - any suggestions?

 

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As a novice, I have no advice, but your solution seems very clever.  How did you build the Delrin support with a CuBe spring.  I looked up Delrin and found it's a plastic that can be formed into tubes of different outer and inner diameters.  What is a CuBe spring?  Didn't find that on the internet.  Also, sounds like you have to have three hands in order to wind the spring from the bottom, hold the Delrin support and use a screwdriver to stop the tang to make sure it slips into the slot.

Edited by DouglasSkinner
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As a novice, I have no advice, but your solution seems very clever.  How did you build the Delrin support with a CuBe spring.  I looked up Delrin and found it's a plastic that can be formed into tubes of different outer and inner diameters.  What is a CuBe spring?  Didn't find that on the internet.  Also, sounds like you have to have three hands in order to wind the spring from the bottom, hold the Delrin support and use a screwdriver to stop the tang to make sure it slips into the slot.

Copper Beryllium is not Bronze (that is copper plus tin). It is the springy material used in relays and is a good non-magnetic alternative to spring steel. Delrin is a trade name for Nylon - my bars are are labelled Delrin, but it is solid Nylon (another trade name). As to the three-hand trick; I started with the Delrin tool in an open-jaw vice clamped to the workbench. But it turned out that after winding the mainspring with two hands almost to the point of slip, I could hold the Delrin tool in the left hand between first finger and thumb and winder between second, third and fourth fingers. Then the last little quarter turn was done by rolling the Delrin tool along my thumb, while holding the screwdriver in my right hand. I probably also used my knee to ensure that the winder remained engaged with the arbor!

 

How do the IWC people do it? Any suggestions Mark?

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Thats what I always did. You know the old saying Practise makes Perfect.

OK for the T-type bridle where the tang is at the end of the mainspring. They can be hand wound fairlly easily. But the DB-type bridle with its tang 2mm from the end of the reverse-curve part of the spring is another matter. I shall continue to practice just for the hell of it, but I still wonder how it is done in Schaffhausen.

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Ah!, now I get it!  And me with a chemistry background!  I think the spring threw me because I tend to think of a helical or spiral structure.  And people use acronyms so freely nowadays (which I hate) that I'm always left guessing--acronyms seldom having much to do with their subject.

 

That notwithstanding, I think I understand better what you're doing.  Except one detail: you have a winding crown as part of the clamp.  Is that attached to a screw of some sort which fits into a threaded hole in the Delrin block?  (Sorry to be so obtuse!)

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Except one detail: you have a winding crown as part of the clamp.  Is that attached to a screw of some sort which fits into a threaded hole in the Delrin block?  (Sorry to be so obtuse!)

 

The Delrin block has a through hole, which is 2mm less than the diameter of the barrel. The winding crown passes through the Delrin block from below and its square hole engages with the square end of the barrel arbor - where the ratchet wheel normally fits. The Copper-Beryllium flat spring prevents the winding crown pushing the barrel arbor out of the barrel.

 

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I believe that at the factory, in addition to using all four fingers, thumb and knee, they hold the barrel in their teeth!

 

Ah no! In Switzerland we have an excellent apprentice scheme and it is the teeth of the apprentice that are used.

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Yes this can be tricky.

 

 

If winding in by hand I find it useful to place the T out of the hole and whilst you are winding in it will slip round (it does this naturally) and when you have several coils in then you can push the T further round until it engages the hole, then continue winding the spring in. Not easy but works well after some practice.

 

If winding in by hand then don't pull the coils to tight. And I am aware that some repairer purists may scowl at me for ever suggesting winding in a spring by hand, and they would probably be right :)

The old mainspring winders (similar to the ones clockies use) are the correct tool to use I believe - I have to say though that I have never used those, I confess that I put these ones in by hand being careful not to kink or stress the spring.

 

You can tell when a spring has been badly coiled in by hand - when you remove it it goes into a cone shape. 

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I have found that I just don't have the strength in my fingers to complete the winding by hand.  I can go so far then, the spring gets too stiff to continue feeding into the barrel.  At that point I have given up because I don't want to twist or kink the spring.  That's why this little device intrigues me--it looks simple enough that even I can build one.  Thanks again.

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Yes this can be tricky.

 

 

If winding in by hand I find it useful to place the T out of the hole and whilst you are winding in it will slip round (it does this naturally) and when you have several coils in then you can push the T further round until it engages the hole, then continue winding the spring in. Not easy but works well after some practice.

 

If winding in by hand then don't pull the coils to tight. And I am aware that some repairer purists may scowl at me for ever suggesting winding in a spring by hand, and they would probably be right :)

The old mainspring winders (similar to the ones clockies use) are the correct tool to use I believe - I have to say though that I have never used those, I confess that I put these ones in by hand being careful not to kink or stress the spring.

 

You can tell when a spring has been badly coiled in by hand - when you remove it it goes into a cone shape. 

Thanks, Mark, for this input. I shall try again by hand as you describe. My problem is that after trying previously, I found that the shape of the spring was deformed. If it goes in this wouldn't be noticed, but I did end up with considerable uneveness in the curvature of the reverse bend leading up to the bridle. It is comforting to know that there is no easy way that I missed!

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  • 7 years later...

As a hobbyist I cannot brag on any special skillset or experience regarding

pocket watch restoration or maintenance. However I think I would be remiss if I did not mention a recent experience regarding this topic.

My intended victim is a Hamilton 940 and the focus of the exercise was to replace the  balance staff. I had also noted that the mainspring was broken and I used every effort but prayer to install the new DB spring. I never successfully installed the spring.

However, I had a spares 940 and for S&G I took the barrel from the spares and a new spring

and hand-wound it in less than 10 minutes. Later I examined bother the original barrel and the "new spring" and note that there was just enough variance so to turn a common practice into a bizarre ritual. My only purpose in sharing this is to provide a bit of encouragement to like-minded hobby folk not to immediately run up the white flag when faced with a challenge. Life is a marathon not a dash.

Best Wishes,

Bruce

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7 hours ago, Stymied said:

I used every effort but prayer to install the new DB spring. I never successfully installed the spring.

Did you ask the question on the group of how should I do this?

On any type of special end Mainsprings and I words things that have protruding off the edges that need to go into holes or slots In the barrel there is an easy procedure. Yes I know it's another tool to purchase but watch repair is all about purchasing tools. You need a mainspring winder

the mainspring into the winder you leave a little bit out you do not wind it all the way and like you would normal Swiss type spring. Click a little bit sticking out to stick that into the barrel with the rest of the winder which means it all has to fit you have to pick the right diameter you rotated around until your slot lines up with the protruding part of the mainspring. You then pushed that part of the mainspring in the slot hold it in place with like the back end of a tweezer or the biggest screwdriver you have any push the spring out. The very simple procedure if you understand what you need to do.

Otherwise you can hand winding up in but that is generally frowned upon for a variety of reasons. That doesn't mean that it doesn't happen every single day right now someone on the plan is probably hand winding a mainspring it just can't have issues it's better if you could use a winder

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I just dealt with this issue a couple of days ago.  Also same thing earlier in the year.  My memory does not yield what I did earlier in the year, but a couple of days ago I did this.

Wound the spring using one of the classic winding tools.  Aligned the spring as close to the slot as I could, but, alas, I was probably off by 30 degrees.

Second try with the idea that I wanted to be off in the negative direction so that if I would the spring, it would move into the right position.  Installed the arbor.

Once the spring was in the barrel and arbor in place, I put the lid on loosely, but captured the upper tab with the slit in the lid.  Then, using a pin vise, I grasped the arbor and started winding the spring while holding the barrel lid in place.  Once making progress on winding, the lid and T was able to slip into place.

A royal pain in the @ss, but it worked.

I like @JohnR725idea of leaving  a good bit of the spring free from the winder and pressing it in place with the tab in the slot.  I will try it next time.

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