Hairspring regulating pin

[nriddell]

Hi - This is my first post on the forum but I have been an observer for nearly two years now. The reason I am coming out of the woodwork is to triple check that I have identified the correct course of action for a watch that I am working on just now. I apologise for any incorrect terminology that I use, but I have included a picture for reference to aid with any identification.

In summary, the regulator pin (the "post" that the hairspring sits between, as opposed to the regulator boot) has broken. I need to remove the rivet on the other side of the regulator, but would the forum be able to confirm that I will require the item listed in Cousins catalogue as item S37391? Item S37391 looks to be tapered and does not have a head which I am assuming is more suitable on the basis that the taper can be used to accommodate different styles of regulator. 

I read in another post on this form that item S37393 (hairspring pin with head) was required, however I do not think this will be correct as the current pin does not have a head like the one shown against item S37393.

Help and assistance is greatly appreciated.

Thanks

[dadistic]

I bought the S37391 pins, these are brass taper pins that are used to attach a hairspring to a collet.   S37393 is likely close to what you are looking for, but given the variety of regulators that exist, my guess is that you won't find an exact replacement in that assortment. I've never replaced just the pin on a regulator, so I'm not completely sure what might work.

It might help if you told us what watch movement this is for? 

[nriddell]

Hi David - I have never had to replace a collet and so I am not sure how the pin would be used to connect the hairspring to the collet. In answer to your question, the movement is an ST (AS) 1686 (link below to the movement details).

http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&&2uswk&AS_1686

Thanks again

[StuartBaker104]

The parts you need would be s37393. Whilst this is an assortment of 100 with different sizes, it is unlikely you will find an exact match here, so you would need to modify to suit. These are straight pins with a larger diameter head that sits inside the regulator arm. The pin has to sit parallel to the boot, so easier to start with a straight pin than a tapered one. It's also important that the pin doesn't touch the first free coil of the hairspring.

However, if I were you, I would take the time to find out that an AS 1686 uses the same regulator as an ST 1686 or 1786, and you can buy the complete regulator arm. Note that there are two types depending on whether you have an adjustable stud carrier.

I have replaced one of these pins in the past and it's a really fiddly job unless you have just the right tools.

[nriddell]

Thanks for your tips and reply, Stuart. I had identified that there was a relationship between the movements that you mentioned based on the ranfft.de link that I had provided in my second post but when I reviewed the availability of the balance the price was £20 which is more than I had planned to spend. On that basis, I was going to attempt the replacement of the regulator as a learning exercise. Worse comes to worse I can plump for the replacement balance or try a source a full movement which will probably be cheaper. I'll look to get the S37393 part that you confirmed.

Thanks again for the tips.

[StuartBaker104]

It's not the balance you need, it's the regulator. Only £6 unless you have an adjustable stud carrier in which case £10

 

[nriddell]

6 minutes ago, StuartBaker104 said:

It's not the balance you need, it's the regulator. Only £6 unless you have an adjustable stud carrier in which case £10

 

Good spot - I had only seen the complete balance. Very kind to point me in the right direction.

[StuartBaker104]

No problem. The complete balance doesn't include the regulator.  It's just the balance wheel and hairspring.