Bell-Matic Stem Removal

Written by john demerceau
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Bell-Matic Stem Removal
Mechanical watch movements like the Seiko Bell-Matic movement are based on gears and levers. (Comstock Images/Comstock/Getty Images)

The vintage Seiko Bell-Matic series of alarm watches featured a precision self-winding mechanical movement. While watches based on this movement have long since been superseded by Seiko quartz watches, Bell-Matic models remain in demand among collectors. The 4006-A movement found in the Bell-Matic watches was designed with an eye toward quality and accuracy, and it was also noted for its ease of assembly and disassembly. For example, all you need to do to remove the stem of your Bell-Matic vintage watch is to push a lever. Once you remove the stem, you can take the entire movement out for maintenance or repair.

Skill level:
Easy

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Things you need

  • Jeweller's screwdriver
  • Jeweller's vice with watch case holder bracket
  • Seiko screw-back case opener
  • Jeweller's awl

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Instructions

  1. 1

    Remove the watch band by inserting a jeweller's screwdriver into one side of each spring-loaded pin located at the top and bottom of the watch case so the pin pops out and allows you to remove the band. Set the pins and band aside, or pop the pins back into the case, if you wish.

  2. 2

    Insert your watch case holder into your vice and tighten the vice turn-screw until the holder is secure between the jaws of the vice. Turn your Seiko Bell-Matic watch so the back faces upward and insert the watch into the case holder.

  3. 3

    Open the case by lining up the prongs of the Seiko case-back opener blade with the indentations in the case cover. Turn the opener toward you until you fully unscrew the case cover from the threads in the back of the watch. Set the cover aside.

  4. 4

    Gently lift out the gasket above the internal threads of the watch case.

  5. 5

    Remove the case spring located between the edge of the case and the movement by pressing down on it gently until it dislodges from inside the case and pops out of place. Lift it up and out of the case and put it aside.

  6. 6

    Remove the bell button below the winding stem by inserting a thin jeweller's screwdriver and pressing down on the pusher bar behind the button.

  7. 7

    Locate the setting lever axle. It is a small cylindrical piece of metal with a small ferrule at its end that is found behind the stem and under a small, angular bracket (yoke) that holds a lever (setting lever).

  8. 8

    Insert the tip of your jeweller's awl and press down on the ferrule so it disengages from the yoke bracket. Unscrew the stem by turning it toward you until you are able to pull it out and remove it. You can now turn the case over and slip the entire movement out for service, cleaning or lubrication.

Tips and warnings

  • You can use any adjustable screw-case opening wrench instead of the Seiko case opener; make sure to set or select the wrench prongs or bits that properly fit the indentations in the back of the case.

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