Jump to content

Loose pinion

dnhb
 Share

Recommended Posts

dnhb WRT Addict

dnhb

Posted
Posted

I have a Waltham key-wound pocket watch, small seconds: 20640806 on base plate & 640 80 6 on top plate. The pinion shown in the photo of the rear of the top plate - driven by the barrel - is loose & doesn't turn the main (first ?) wheel on the same arbour. The other photo shows the arbour on the dial side which appears to have a clip of some sort around it. I'd be grateful for advice as to how to proceed to rectify this problem.

20250514_125902.jpg

20250514_130004.jpg

mbwatch Super WRT Addict

mbwatch

Posted
Posted (edited)

Remove the cannon pinion from the dial side first. The "clip" you describe is sort of a metal tab some American companies designed their cannon pinions with in order to make it easier to tighten friction. If that is the problem, the solution is as simple as gently squeezing the tab with tweezers to bend it ever so slightly inward, while supporting the inside of the cannon pinion if possible (it may be harder to support inside since it does not have an open tip as a hollow tube)

The cannon pinion should just pull straight off of the arbor on the dial side if you pull it straight up with tweezers. There's no jewel in danger of breaking and the arbor is thick so there isn't much risk of breaking the arbor.

But when you are describing that the center wheel's pinion is not turning the arbor, is the pinion firmly attached to the center wheel? If you remove the center wheel and hold onto the rim of the wheel, does the pinion turn independently of the rest of the wheel? It should not. 

I'm not sure if this was the case on older Waltham, but the pinion may be threaded onto the center wheel arbor and they are often loose. This was a safety mechanism for a broken mainspring and may just need to be tightened back down. I can't remember for sure, but these might be a reverse (left) thread instead of normal right.

And does the entire arbor turn independently of the wheel? Also should not.

Edited by mbwatch
  • Like 1
  • Thanks 1
dnhb WRT Addict

dnhb

Posted
  • Author
Posted
3 hours ago, mbwatch said:

Remove the cannon pinion from the dial side first. The "clip" you describe is sort of a metal tab some American companies designed their cannon pinions with in order to make it easier to tighten friction. If that is the problem, the solution is as simple as gently squeezing the tab with tweezers to bend it ever so slightly inward, while supporting the inside of the cannon pinion if possible (it may be harder to support inside since it does not have an open tip as a hollow tube)

The cannon pinion should just pull straight off of the arbor on the dial side if you pull it straight up with tweezers. There's no jewel in danger of breaking and the arbor is thick so there isn't much risk of breaking the arbor.

But when you are describing that the center wheel's pinion is not turning the arbor, is the pinion firmly attached to the center wheel? If you remove the center wheel and hold onto the rim of the wheel, does the pinion turn independently of the rest of the wheel? It should not. 

I'm not sure if this was the case on older Waltham, but the pinion may be threaded onto the center wheel arbor and they are often loose. This was a safety mechanism for a broken mainspring and may just need to be tightened back down. I can't remember for sure, but these might be a reverse (left) thread instead of normal right.

And does the entire arbor turn independently of the wheel? Also should not.

Thanks for the prompt response. I apologise for not stating the issue more clearly. The problem is that - what I now know I should have called - the centre wheel is not being turned by the pinion (which is driven by the barrel) with which it shares the arbour (1st photo above). The pinion & arbour are indeed reverse threaded but the arbour (the 'screw') is clearly damaged ('rounded' rather than 'sharp' threads) with swarf evident. When the pinion is screwed on there is only enough connection to prevent the pinion being lifted off but not enough to stop it turning on the arbour. Is a (reversible) repair (threadlocker?) possible in the short term while a replacement centre wheel assembly is sought so that the viability otherwise of the watch can be established?

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Restore formatting

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
 Share
Go to topic listing


  • Recently Browsing

    • No registered users viewing this page.

  • Topics

  • Posts

    • AndyGSi
      Reusing mainsprings in an automatic and slipping

      By AndyGSi · Posted

      The 3930 is just the reference from GR who make these springs and the X after signifies it's for a auto. So from a google search. 1.45 is the height 7.0 is the size of barrel this will fit from the washer 0.075 is the thickness which is where the strength comes from 240 is the length which equate to running time The critical part is the strength. If you fit a stronger one i.e. 0.085 then the potential is the watch would run faster, especially as these are newer materials. Obviously the height is also significant and you can't fit a higher spring in the barrel, but going down 0.05mm won't make a difference.
    • JohnL
      Reusing mainsprings in an automatic and slipping

      By JohnL · Posted

      Andy, thank you again for all your help. You are a true gent. I removed the winding stem in order to pop it into the case so I could play with the movement more easily while the dial and hands were still in place, but it appears the setting lever spring has sprung. So, unfortunately I need to address that before looking at anything else.  If I might be so bold: I presume (given I know what everything else is) that the 3930 is the power rating? How do you know what a suitable rating is for a watch, how do you know 3591 (assuming that's the power) is correct for the Slava 2427? I just know it's 1.5 mm wide, 0.06mm thick (assuming my measurements were correct) and fits in a 7.0mm barrel. The magic art of knowing whether a thicker or less wide spring would be suitable is eluding me, the maths didn't turn out as I thought they would. Again, thank your for all your help thus far. 
    • AndyGSi
      Reusing mainsprings in an automatic and slipping

      By AndyGSi · Posted

      I've found with Russian watches they don't stick to the Swiss numbering system. The problem with the mainspring is that as this is a dual barrel system they're very small compared to most automatics. If you look on Cousins the weakest 1.45mm high spring is 0.085mm which could be too powerful for this movement and is also designed for a 7.5mm barrel. If you then look at the GR Catalogue and work back from the GR3930X, this is the first auto with correct power rating. Although you'd probably have to go back further to this one to make sure it fits.    
    • TimepieceTinkerer
      Title: ETA 2836-2 Not Ticking After Pallet Fork Replacement – Need Assistance

      By TimepieceTinkerer · Posted

      Hi all, I’m currently working on an ETA 2836-2 movement. I replaced the pallet fork with a new one (ETA2801710, sourced from CousinsUK). After full reassembly and lubrication, I’ve encountered a strange issue: The movement is fully wound and has power. When I fit the balance assembly, the movement does not tick at all—completely dead. When I remove the balance, the gear train suddenly releases and spins freely, indicating power was present. The pallet fork just “floats” without snapping side to side—almost as if it isn’t even there. No interaction with the escape wheel is visible at that point. However: Before fitting the balance, I checked the pallet fork manually — it was working as it should, clearly interacting with the escape wheel. I’ve inspected the pallet bridge jewel (where the pallet fork sits) and everything looks normal. No signs of misalignment or obstruction. I’ve rechecked everything I can think of and I’m completely out of ideas. Has anyone seen this behaviour before? Any suggestions would be greatly appreciated. Thanks in advance! TT
    • dnhb
      Loose pinion

      By dnhb · Posted

      Thanks for the prompt response. I apologise for not stating the issue more clearly. The problem is that - what I now know I should have called - the centre wheel is not being turned by the pinion (which is driven by the barrel) with which it shares the arbour (1st photo above). The pinion & arbour are indeed reverse threaded but the arbour (the 'screw') is clearly damaged ('rounded' rather than 'sharp' threads) with swarf evident. When the pinion is screwed on there is only enough connection to prevent the pinion being lifted off but not enough to stop it turning on the arbour. Is a (reversible) repair (threadlocker?) possible in the short term while a replacement centre wheel assembly is sought so that the viability otherwise of the watch can be established?
×
×
  • Create New...