Disassembly Bulova 10BUC Disassembly

Discussion in 'Watch Repair' started by Paul Raposo, Mar 6, 2020.

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  1. Paul Raposo

    Paul Raposo Registered User

    Nov 4, 2005
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    Hey all.

    I have this Bulova Surfmaster with a 10BUC movement (Based on the AS 1200).

    I want to replace the mainspring but I'm not sure how to proceed with the disassembly.

    Do I remove the bridge that holds the sweep second hand gear and then remove the gear, or is there another step before this?

    bulova_surfmaster 017.JPG bulova_surfmaster 018.JPG bulova_surfmaster 019.JPG
     
  2. glenhead

    glenhead Registered User
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    Nov 15, 2009
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    There's not another required step, no. I tend to let the power down and remove the balance assembly before I start working on watches, but removing the sweep second pinion and arbor first will be fine.

    Glen
     
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  3. Paul Raposo

    Paul Raposo Registered User

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    Thank you Glen.

    Does the gear just lift up, or is it on the pinion with pressure?
     
  4. Skutt50

    Skutt50 Registered User

    Mar 14, 2008
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    If I remember correctly the gear is pressed on. Careful when removing. It is easy to break the arbor.
    There is a special tool for this. It looks similar to a hands remover but the tip of the tool is made a bit different.
     
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  5. Paul Raposo

    Paul Raposo Registered User

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    Thanks much for this tip Skutt50. I may have to think about holding off and letting my watchmaker have a look at it.
     
  6. roughbarked

    roughbarked Registered User

    Dec 2, 2016
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    Two hand lifting levers can be used if one is skilled enough. Protection to stop scratches on the plate is required. I was taught to use two screwdrivers of the same size and twist them in opposite directions to keep the wheel coming off straight. Any deviation from straight up lift, will result in bent or broken pivot.
     
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  7. Paul Raposo

    Paul Raposo Registered User

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    That's how I remove hands. I never had any luck using those Presto or Bergeon plunger style tools.
     
  8. glenhead

    glenhead Registered User
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    Nov 15, 2009
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    I didn't interpret your question as "how do I remove the indirect drive wheel", I thought you were asking how to remove the second-hand arbor. Sorry!

    I use a Presto #3 wheel remover. You don't have to spend $80 for an Almighty Bergeon (all hail, genuflect genuflect), you can get one of the $15-20 versions that are currently showing on eBay. It's dismayingly easy to bend the third-wheel arbor when you remove the indirect drive wheel. Once it's bent, it's danged difficult to get it straightened so the wheel is true in the flat. Indirect drive wheels are why I own two Presto #3 removers. Maybe I could have gotten better at removing them with twinned screwdrivers or other methods, but the Presto just works.

    Glen
     
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  9. Paul Raposo

    Paul Raposo Registered User

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    That's ok Glen, I didn't articulate very well what I meant. Not using the correct names for the parts didn't help either. Now I know what the parts are called :)

    Admittedly I only used a Bergeon plunger style hand remover four times over 20 years ago and each time I either damaged the hands or dial. I should have practiced on a cheap watch before using it on something nicer.
     
  10. Al J

    Al J Registered User

    Jul 21, 2009
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    Paul,

    I would never use the Bergeon plunger style tools for hands - I always use levers as they give far better control. But for removing pressed on drive wheels, the Presto style wheel removers are what I use. There are two styles, one for an odd number of spokes, and one for an even number of spokes on the wheel. Most wheels have an odd number of spokes like yours, and for that you would need the blue handled Presto #3. I have polished the tips to ensure that they don't create any marks on the bridge, and in all the years I have been using these, I've never damaged anything with them.

    Using other methods can lead to bridge damage, like this...

    Hacked%20bridge_zpsspuixqst.jpg

    Or this...

    Drive%20wheel_zps3unx8hg0.jpg

    Both on Speedmasters for the chronograph drive wheels, which use the same concept as the indirect sweep seconds.

    Keep in mind that if a wheel had been pressed on too far, it may be very difficult to remove, and in extreme cases other methods may need to be used to remove the wheel.

    Generally this is not a task I would recommend people do on their own.

    Cheers, Al
     
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  11. Paul Raposo

    Paul Raposo Registered User

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    Thanks for this tip about the different tools based on the number of spokes. Something that would not have occurred to me.

    Normally I'm curious enough to give a new task a go, but this movement is in really nice condition and I'd like to keep it that way rather than blunder through an attempt.
     
  12. roughbarked

    roughbarked Registered User

    Dec 2, 2016
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    In that case stick with your gut feeling and take it to your preferred watch repairer.
     
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