Broken screw for hairspring stud - 491 cal

bbo139 · Tues. 11:34am

Hi,

So the screw snapped in the movement in the hairspring stud hole..

Any advice on how I can remove it? The movement is a 491 caliber and would like to do it my self (even tho I end up breaking the entire balance in the end.. but of course trying to avoid that 😀 )

sheepdoll · Tues. 12:37pm

Alum.

You have to remove all the steel parts from the regulator. Usually there is a U clip that holds it together.

Alum is pickling spices found in the grocers. Works great. Also good for balances.

I used it a couple days ago to remove a rusted bridge and screw from a quartz movement.

I use about 1/4 tsp in a half cup or so of water. Heating it in the microwave first. Takes a couple days to act, So I use a 7 watt bulb in an old nightlight stand to keep it warm.

bbo139 · Tues. 12:41pm

sheepdoll
Alum.

You have to remove all the steel parts from the regulator. Usually there is a U clip that holds it together.

Alum is pickling spices found in the grocers. Works great. Also good for balances.

I used it a couple days ago to remove a rusted bridge and screw from a quartz movement.

I use about 1/4 tsp in a half cup or so of water. Heating it in the microwave first. Takes a couple days to act, So I use a 7 watt bulb in an old nightlight stand to keep it warm.

But the broken stud screw keeps the hairspring locked in on the balance cock, so I need to soak the hairspring in alum as well (which I assume with affect it)

sheepdoll · Tues. 1:02pm

You have to remove the spring first. Or else sacrifice the stud what holds it to the balance. There is a impossibly small taper pin what holds the hairspring in place. You have to find it and drive it out.

Probably why I have so many watches without hairsprings. 🤣

I have sometimes used wax to keep the alum off the steel parts (when removing broken winding stems.)

Kano Sili-Kroil can sometimes loosen stuck screws, but if there is nothing to grab, something gets sacrificed. Tried drilling a screw out once, but the drill wandered into the soft metal next to it. Another time I tried a laser, but it is hard to get the focus just right.

No luck with the Burgeon tool, which just chewed up the plates as the pins are too large for these small watches.

I do like to work with rusted watches what are beyond repair.

bbo139 · Tues. 1:52pm

sheepdoll
You have to remove the spring first. Or else sacrifice the stud what holds it to the balance. There is a impossibly small taper pin what holds the hairspring in place. You have to find it and drive it out.

Probably why I have so many watches without hairsprings. 🤣

I have sometimes used wax to keep the alum off the steel parts (when removing broken winding stems.)

Kano Sili-Kroil can sometimes loosen stuck screws, but if there is nothing to grab, something gets sacrificed. Tried drilling a screw out once, but the drill wandered into the soft metal next to it. Another time I tried a laser, but it is hard to get the focus just right.

No luck with the Burgeon tool, which just chewed up the plates as the pins are too large for these small watches.

I do like to work with rusted watches what are beyond repair.

Was hoping I wouldn’t need to do screw up the balance even more 😅 but seems like that s the only way going further now

sheepdoll · Tues. 2:15pm

You could choose to sacrifice the bridge. Which is a bit easier to source these days. Split the stud with a jeweler's saw. Too bad 491 has a fixed stud since the base caliber is 500. 550 stuff has the movable stud which would make it a lot easier to sacrifice.

Balances are why I am sort of taking a break from mechanical at the moment and have gone quartz crazy. But the motor coils are just as bad as balances,

ErichKeane · Tues. 2:29pm

Thats an unfortunate situation, I think you'd have to sacrifice SOMETHING in order to make anything alum-related work. You MIGHT be able to tap the stud out despite the screw still being attached, it would gouge up the side of the stud, but perhaps not horribly?

I'm just not aware of any screw extractors that would work... that is really small.

One thing you CAN try, and it will take a LONG time: Let gravity limit where the alum goes, and put only a tiny drip of it in the screw hole at a time. It will take a little time, but could eat away a little at a time to the point that it loosens up? And hopefully if it gets to the point where it touches the stud, it only touches the little bit where the screw would touch (rather than getting onto the spring).

Archer · Tues. 2:51pm

ErichKeane
Thats an unfortunate situation, I think you'd have to sacrifice SOMETHING in order to make anything alum-related work. You MIGHT be able to tap the stud out despite the screw still being attached, it would gouge up the side of the stud, but perhaps not horribly?

I'm just not aware of any screw extractors that would work... that is really small.

One thing you CAN try, and it will take a LONG time: Let gravity limit where the alum goes, and put only a tiny drip of it in the screw hole at a time. It will take a little time, but could eat away a little at a time to the point that it loosens up? And hopefully if it gets to the point where it touches the stud, it only touches the little bit where the screw would touch (rather than getting onto the spring).

That's what I would try first...

sheepdoll · Tues. 5:02pm

I have had luck (with stems) using wax to keep the alum away from the parts you want to save. Gouda cheese wax works well for this. It can take a week or two for a stem.

The Gravity method also works for stuck dial screws, when one wants to save the dial and the parts underneath. It is really really slow though.

Broken screw for hairspring stud - 491 cal

bbo139

sheepdoll

bbo139

sheepdoll

bbo139

sheepdoll

ErichKeane

Archer

sheepdoll

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