Adding a 'pin' to a regulator 'boot'

[dnhb]

I recently learned that regulator 'boots' can usually be rotated to allow the insertion/removal of the hairspring. This has lead me to look further into this sub-system & I am currently trying to see if I can replace the missing pin opposite a boot on a broken regulator arm. I have managed - with the boot rotated through 90° (it's back in its original position in the attached photo) - to drill a hole to accept the thinnest brass wire I have to hand (~0.3mm) and would like to learn what should be used to secure the pin - e.g. would Thread Locker provide sufficient durability? Also, how critical is the internal distance between pin & boot: more generally, are there any 'rules of thumb' which apply to such subsystems?

[watchweasol]

Hi. I believe that cousins at one time supplied pinsreads for insertion. Have a look through their catalogue.

The distance is critical as in the fact that the spring beats between the boot and the pin so the larger the gap the longer the travel. This would have an effect on on the rate.

[tomh207]

@dnhb I was reading something on this in the past couple of days, maybe it will help.

Tom

[praezis]

54 minutes ago, dnhb said:

I have managed - with the boot rotated through 90° (it's back in its original position in the attached photo) - to drill a hole to accept the thinnest brass wire I have to hand (~0.3mm) and would like to learn what should be used to secure the pin

Maybe 0.3 is already a bit too much. I would drill 0.2 or what the diameter of the old pin is.

Put in a tapered pin for hairsprings, tap till tight and cut to length, polish the head.

Frank

[dnhb]

10 hours ago, tomh207 said:

@dnhb I was reading something on this in the past couple of days, maybe it will help.

Tom

Thank you very much, Tom. That is very helpful.

10 hours ago, praezis said:

Maybe 0.3 is already a bit too much. I would drill 0.2 or what the diameter of the old pin is.

Put in a tapered pin for hairsprings, tap till tight and cut to length, polish the head.

Frank

Thank you, Frank. I couldn't reliably measure the old pin diameter but as I implied this is really an exercise in learning the theory & also practicing working on such miniscule parts.

A propos the latter, I'll try tapering the pin into a smaller inner hole but my understanding is that the top of the pin is often folded over to lie something like the spring's thickness above the near part of the boot. In what cases can the pin just be "cut to length" if, by that, you mean the height of the boot?

[praezis]

1 hour ago, dnhb said:

In what cases can the pin just be "cut to length" if, by that, you mean the height of the boot?

Yes, the pin will be longer than the boot, shorten it to correct length so the boot can be closed.

Frank

[dnhb]

23 hours ago, praezis said:

Yes, the pin will be longer than the boot, shorten it to correct length so the boot can be closed.

Frank

Apologies for going on about this issue, but I've seen instances in which the boot is not thus "closed" i.e. the top of the pin is not folded over. What determines which of the two pin designs should be used?

[Neverenoughwatches]

33 minutes ago, dnhb said:

Apologies for going on about this issue, but I've seen instances in which the boot is not thus "closed" i.e. the top of the pin is not folded over. What determines which of the two pin designs should be used?

Perhaps a sketch from you might help to understand what you have seen. Sometimes on cheap movements there is not even a boot, the pin comes down from the regulator arm and then bent back up to form a loop for the hairspring to fit between. In this case the loop has to be undone or the hairspring undone from the stud holder to be fitted.  The important thing is that the hairspring cannot slip free from between whatever is holding it at its regulation or active point . The pin/pins/boot should be smooth inside so that the hairspring can bump cleanly between them and also not catch when the regulator arm is moved whilst adjusting the rate. So what determines which design is quality of manufacture and convenience of maintenance. 

[dnhb]

17 hours ago, Neverenoughwatches said:

Perhaps a sketch from you might help to understand what you have seen. Sometimes on cheap movements there is not even a boot, the pin comes down from the regulator arm and then bent back up to form a loop for the hairspring to fit between. In this case the loop has to be undone or the hairspring undone from the stud holder to be fitted.  The important thing is that the hairspring cannot slip free from between whatever is holding it at its regulation or active point . The pin/pins/boot should be smooth inside so that the hairspring can bump cleanly between them and also not catch when the regulator arm is moved whilst adjusting the rate. So what determines which design is quality of manufacture and convenience of maintenance. 

Thanks for your comprehensive response, NeW. I've seen the simple wire loop version on a small clock & a boot alongside a pin of the same height on a few timepieces. I'd assumed the closed boot approach might be more important in watches to prevent the balance spring 'escaping' due to shocks.

Having spent a few hours  fashioning a pin to close the boot on my 'test piece' regulator arm,  I'm concluding that Watchweasol's idea of buying one from e.g. Cousins would make a lot of sense in the case of an actual repair!

[Neverenoughwatches]

3 hours ago, dnhb said:

Thanks for your comprehensive response, NeW. I've seen the simple wire loop version on a small clock & a boot alongside a pin of the same height on a few timepieces. I'd assumed the closed boot approach might be more important in watches to prevent the balance spring 'escaping' due to shocks.

Having spent a few hours  fashioning a pin to close the boot on my 'test piece' regulator arm,  I'm concluding that Watchweasol's idea of buying one from e.g. Cousins would make a lot of sense in the case of an actual repair!

An original replacement is always best, providing the design was good to begin with.