Hello everybody. I am 'jreclocks' and live in Towcester, Northamptonshire, England.

[jreclocks]

Have spent my life in the world of communications and electronics but retirement came and interest shifted to Master Clocks. A subsequent move to a much smaller house meant my collection had to go;  hence the interest in watches.

Specifically I would like to ask if any one has experience of a quartz  Mondaine 'Stop2Go' watch circa 2015, Case 30358. Recently the crown (aka switch) came away. To screw back on one needs to remove the caseback and hold the stem. The back is held on by four M1.2x4mm slotted pan head screws of which I have only managed to unscrew one, despite  Bergeron screwdrivers, a staking set, applying acetone, easing oil and heating the sunken heads with the tip of  soldering iron.  The removed screw shows a residue on the threads and I have read in another forum that Mondaine case backs have been found glued. Have these screws been glued and if so;why? Consequently the screwheads are getting somewhat mangled and a battery replacement will soon be due

I can return it to the Sevice dept but any advice would be appreciated.

thank you

John

[Nucejoe]

Welcome to WRT forum.

[watchweasol]

Welcome to the forum John, what we need for identification is pivtures of the movement/watch.  some screws can be glued, most likley thread lock or such, probably to either secure them against falling out of to prevent tampering. As you have already used Acetone I doubt it is superglue. You might try a little lighter fuel and work the screws gently.

[jreclocks]

On 9/10/2021 at 10:11 AM, watchweasol said:

Welcome to the forum John, what we need for identification is pivtures of the movement/watch.  some screws can be glued, most likley thread lock or such, probably to either secure them against falling out of to prevent tampering. As you have already used Acetone I doubt it is superglue. You might try a little lighter fuel and work the screws gently.

 

[jreclocks]

Thank you, Watchweasol, for your response,I will forward pictures as you suggested and try lighter fuel. Glued screws begs the question

"As it is  battery driven movement how do Mondaine's Service Department free the caseback to replace them?". Surely they don't do any thing as drastic as using a screw extractor or mill the heads off! 

I still favour the targeted application of heat but worry about damaging the electronics.  

[watchweasol]

I Think the localised application of heat to the screws may yet be an option. If the case is metal would not think it would have an effect on the electronics.

[oldhippy]

Thank you for your introduction and welcome to this friendly forum.

[jreclocks]

Please find attached images of the Mondaine Stop2Go watch of which I am trying to remove the caseback by removing the four screws which we think are glued. Also note rhe notch at the edge of the case back, there is one between both pairs of lugs. To date there is no further progress. Lighter fuel and heat are the next options 

[watchweasol]

The pictures give the impression that once the screws are removed you may yet have to prise the back off to break the seal ?.  If possible clean up the screw heads with a file and use a good fitting screwdriver. Need to soften the adhesive or what ever was coating the screws first. I would proceed with the fuel first ten progress to the heat using a soldering iron with care.

[jreclocks]

Thank you for your advice but I think the damage has been done. The screw heads are such that an appropriate screwdriver will not "lock" into the slot and grip the screw despite the pressure applied, nor can I file up the the heads as they are sunken below the surface of the case back. I think I am left with only two options:-

        1.  Use a screw extractor cut for M1.2 screws but much searching has failed to find the exact one, presumably because the screws are so small.                       

        2.  Mill off the screwhead , prise off the case back and grip the protruding screw thread tight enough to unscrew it.

Do you think my first option is realistic and have you any idea from where I can obtain the correct size extractor.

I would value your further advice

Regards,

John

[jdm]

10 hours ago, jreclocks said:

The screw heads are such that an appropriate screwdriver will not "lock" into the slot and grip the screw despite the pressure applied,

Pics show wide slots, make sure your driver is dressed to be like that. You can try two shapes on the blade, first classical wedge profile, that one should not touch the bottom of the slot for maximum grip, but if the slot is shallow that is not possible, so you could try instead to shape (or even buy) a driver with parallel faces blade. In all cases apply acetone if you think the screws have been superglued. 

 

10 hours ago, jreclocks said:

1.  Use a screw extractor cut for M1.2 screws but much searching has failed to find the exact one, presumably because the screws are so small.

Exactly, no such thing exists.  A watchmaker's extractor works by grabbing from both ends.

[watchweasol]

I think you have reached the point of thinking out side the box and rigging a device to apply downward pressure whilst being able the turn the screw driver,  Ie a modifed G clamp. the main points being that the driver has to be a good fit and the watch held securely.  prior to this soak the screws with acetone as jdm recomends.

[Michael1962]

Welcome to the forum John.