Stubborn Ratchet Wheel Screw

[atkin68]

First time I took one of these apart, I forced this screw and sheared it off. Now I’ve bought a parts movement to see if I can fix it, and it has the same stubborn screw. Any tips on negotiating this? Is it safe or helpful to use an automotive penetrant?

Alternatively, could I just wash the entire barrel bridge in the ultrasonic so I don’t have to deal with this screw, and then heat dry it to avoid rusting the mainspring?

BTW, this movement looks like somebody filled an ultrasonic bath with oils and soaked the whole thing for an hour. Puddles of oil everywhere.





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[straps68]

At least one of the many Mollies I've worked on was drenched in oil like that

If you wash the whole thing as is, the barrel will be filled with a mixture of grease/oil/dirt and cleaning solution. Heat drying that mess might cause some issues. If it were me, and the screw wouldn't budge, I'd open the barrel and remove the mainspring before the bath.

It should be quite safe to use wd40 or similar. Oil can't hurt metal. Good luck.

[wwwEvgeny]

Some screws has left or right direction threads. If it tough , check internet what direction has this screw in your movement. Sometimes they put 3 lines on the screw to show it is opposite unwinding direction. Carbide drills and bores , if you have skills and microscope, usually help to remove broken screws.

[atkin68]

Great advice, thank you both!

[straps68]

Some screws has left or right direction threads. If it tough , check internet what direction has this screw in your movement. Sometimes they put 3 lines on the screw to show it is opposite unwinding direction. Carbide drills and bores , if you have skills and microscope, usually help to remove broken screws.

But it is usually (e.g. in the ETA 649x) the crown wheel screw that is left hand, not the ratchet screw.

[atkin68]

Some screws has left or right direction threads. If it tough , check internet what direction has this screw in your movement. Sometimes they put 3 lines on the screw to show it is opposite unwinding direction. Carbide drills and bores , if you have skills and microscope, usually help to remove broken screws.

But it is usually (e.g. in the ETA 649x) the crown wheel screw that is left hand, not the ratchet screw.

Correct, it is the same in the 6431 - crown wheel screw is reversed.

[Yoda]

Remove the bottom of the barrel and take out the mainspring, lock the ratchet wheel and turn the barrel arbor left with a set of pliers.

[Yoda]

I looked in my cabinets and if everything goes south I can send a barrel arbor and screw for the shipping costs only.

[atkin68]

Very kind. I'll try to keep heading North and hope for the best. Thanks for the advice on the barrel [mention]Yoda[/mention] !

[Yoda]

Very kind. I'll try to keep heading North and hope for the best. Thanks for the advice on the barrel @Yoda !

I wish you the best of luck and stand by my offer.