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September 30, 2012 at 12:03 am #48383
So I’m working on a tiny Lucien Piccard LP38 movement – trying to unscrew the screw of the ratchet wheel (winding wheel) – the screw head came off leaving the screw inside the barrel. So I have another LP38 I thought I’d swap the barrel with the screw – same story – the head broke off (I’m turning counter-clockwise just like the rest of the watches). I tried 5 small ladies movements after that (I have a lot of old unneeded junk movements) and all 5 the screw head came off leaving the screw inside – 6th one it worked. I’ve done a bunch of Russian small ladies watches recently – no problem. Swiss movements – the head of the screw breaks. Question: Is it me? Anyone else had this problem unscrewing the screw that holds winding wheel in place? And most important – how do you remove the broken screw from the barrel (actually it’s inside the barrel arbor pivot)?
Any ideas?September 30, 2012 at 8:17 am #52258david pierceParticipant
The winding gears usually have a left hand thread. This will be a relitavely small screw with a large head. Always make sure of the direction required before attempting to unscrew these large headed screws. These screws usually unscrew in a clockwise direction. Before attempthing to remove the stud you still must have this information. If you have access to a drill press or a lathe get a small milling cutter and mill a flat on the top of the broken stud. Then select either a left or right hand drill bit that will drill in the direction that unscrews the broken part. You may have to make your own drill bit to do this. Put a few drops of liquid wrench or diesel fuel on the stud to allow it to soak in around the threads. Drill it out in the direction that unscrews it and keep your fingers crossed.
DavidSeptember 30, 2012 at 8:51 am #52259
Hi David. Unfortunately (for me) I think you are soooooo right. Yes, they are large headed screws and when you say relatively small – no, they are EXTREMELY small and trying to drill out the broken screw using your methods, I do not have equipment, presicion or a drill bit that small.
Now as far as left handed screw goes, that’s just unfair – I’ve done quite a few mens watches by now (put apart, clean, oil, put together) – the first thing I do is I turn that same large headed ratchet wheel screw CLOCKWISE a bit to release the clicker to unwind the mainspring – care to comment on that? If the screw is left handed, how are we supposed to unwind the mainspring? Doable but on most watches it is setup correctly (unscrewing is couter-clockwise)
Furthermore, manufacture is supposed to add one or two parallel lines on the screw head as a sign that it’s a left handed screw – they don’t! So how am I supposed to know what kind of screw is it? Getting specs and paperwork on these old movements will not happen.
I just ordered another LP38 movement from eBay – so the right thing I guess is to try lightly in both directions and hope that it’ll budge right away.
And by the way, the transmision wheel next to the ratchet wheel is also UNMARKED left handed – I tried it – it unscrews in clockwise direction.
WHY DO THEY DO THIS TO US??????????????????????
😮September 30, 2012 at 9:43 am #52260Bob TascioneModerator
The left handed screw is usually on the crown wheel and breaks off in the brass plate. These can usually either be worked back out or dissolved out with a alum solution. One thing to note though is Not All left handed screws have the 3 slots or any other markings to identify them! You’re right..it’s not fair!
I’m not sure what movement is used as the LP 38 but the LP 37 is a Font (FHF) and I believe it does use a left handed screw on a large crown wheel. I’m not positive about that though. Lucian also used ETA etc. movements. I’ll try to find a link to a LP 37 pic if there is one and will post it up here so you can check to see if it’s a similar movement. Also if you have a Bestfit catalog you can identify it through setting mech pics.
I’ll be back with more info if I can find some for you.
Also…don’t sweat it. We’ve ALL BEEN THERE!
Take care for now,
BobSeptember 30, 2012 at 3:37 pm #52261david pierceParticipant
I just reread your post. To push the gear to clear the click use a bamboo kabob stick that can be picked up at almost any grocery store. Push the sharp end of the stick against the gear tooth. NEVER turn the gear with the screw. I hope no one instructed you to to use the screw for this. It is only designed to hold the gear in place while the watch is running. The reason for the left hand thread is to prevent it from coming loose as the gear turns.
DavidSeptember 30, 2012 at 6:17 pm #52262Bob TascioneModerator
One thing that may help you determine what type of thread you have is that the screw in the winding gear will usually tighten in the direction that the gear turns when winding. So if it turns clockwise then you should have a RH thread…counter clockwise LH thread. I don’t know if this is always the case but just something that I noticed over time. I think I covered this a little in the watch course. I’ll check to see where (if I did in fact cover it) and will post up here.
EDIT: If you go to the Watch course – Video 1 Part 2 then below in the quick navigation menu click on ‘Remv, Bridges’ you’ll find that I mention this when showing the screw with vertical lines.
EDIT: Also found the Lucien Piccard 37 (FHF 59-21) (I was wrong…no large crown wheel, looks like it uses A RIGHT HAND thread on the winding arbor though) at http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&ranfft&118&2uswk&Lucien_Piccard_37
As I mentioned in an earlier post these left hand screws are usually found on the crown wheel and not the winding/ratchet gear. These crown wheels usually turn in a counter clockwise direction. Here’s a pic of a movement using a large crown wheel http://www.ranfft.de/cgi-bin/bidfun-db.cgi?10&1archimedeshop&b118&2uswk&Longines_6972
These screws thread into the brass plate and when a break occurs they can often be picked back out or an alum solution can be used to dissolve the steel screw out without damaging the brass.
Hope this helps EdwardnyOctober 1, 2012 at 8:47 am #52263c.kellyParticipant
I saw this post yesterday but didn’t jump in because I wasn’t familar with that model watch. After looking at the link I would have to agree that the ratchet wheel screw is a right-handed thread. Now the crown wheel screw should be a reverse thread. I am pretty sure the reason watch companies did this was they intended the screws to be tightened in the direction the wheels moved when winding the watch. If they tightened otherwise then the friction of the wheels moving while winding could cause them to become loose and fall out. I think Edward hit it right when he mentioned he had to turn the ratchet wheel clockwise to disengage the click. That says to me that the screw should have loosened going in the other direction. Also if you tightened going the other way I think you might risk breaking a tooth or even the click itself especially on these smaller wristwatches. Have no idea what would have caused them to break inside the arbor unless they had rusted in place or someone used lock-tite. Just thought I would throw my opinion into the conversation.
Charles KOctober 2, 2012 at 5:53 pm #52264vanhooglesnortParticipant
I broke one off in a barrel arbor and was able to remove it quite easily (to my surprise). I secured the barrel arbor in a pin vise. This allowed me to put a lot of downward force on a course stone and twist the screw’s shank (in the proper direction) right out of the arbor. Not sure it will work every time but it worked great once!October 15, 2012 at 12:58 pm #52265
Well, after all said and done, you were all correct – I received my new (old dead) LP38 movement (from ebay, of course) – and yes, it was a left hand screw with no markings – it unscrewed in the correct direction quite effortlessly – put it apart, washed it, put it together, oiled it and it’s ticking quite happily…
Thanks all for your input!
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