Master Watchmaker, Clockmaker and Jeweller (since 1981)
nick@clockmaker.com.au
Suite 403, Level 4, Culwulla Chambers
67 Castlereagh St. Sydney 2000 NSW Australia
Phone: (02) 9232 0500 Fax: 02 9233 2273
Do It Yourself Project: Seiko 7S26 for Novice Horologists
| Chapter 11: Practice makes perfect!
In watchmaking, practice makes perfect.
In this chapter, we will talk about concepts related to components re-assembly.
While the concepts are really simple it is important to understand them properly and to pay attention to them during assembly.
Chapter 11 is basically a set of four practical exercises.
The time has come to put your fine tools in use!
Each task focuses on the correct placement of one or more components
but the goal is not to assemble the watch as yet. Rather, the goal is to build your confidence
and skills to a level which will allow you to undertake more complex procedures later on.
Therefore, while this practice is repetitive it is essential for skill building. The more time is spent practicing, the better will be the "quality" of overall assembly.
So here are the basic concepts:
1. Most watch components - and especially wheels, balance wheel, pallet, barrel etc. are
held in place between bridges or plates.
It is absolutely essential that wheels and plates are parallel in relation to each other.
Usually the top plate is aligned to the lower or main plate with alignment pins and held with one or more screws. Therefore screws can only be tightened once the wheel's pivot is sitting correctly.
2. Because of alignment pins, it is not advisable (nor possible) to move the plate to achieve alignment. Rather, it is much easier to gently 'steer the wheel towards the jewel centre while pushing the plate down. In case of multiple wheels held under one plate, start with the wheel closest to the alignment pin.
3. Once positioned in place, the wheel must be free to rotate. Also, it must have some small amount
of end shake (axial movement). Insufficient axial movement is often the result of a bent pivot or other misalignment.
The watch will NOT function properly unless the train wheels have sufficient axial movement or end shake!
4. Axial angular movement of the wheels -
and especially of the mainspring barrel - is caused by worn pivots, arbors and plates
(or even jewels!). A new watch component will have almost no axial angular movement.
All watches older than 10 years
which have not been serviced regularly will exhibit some degree of wear.
Worn barrel arbors and bridges (or jewels) must be replaced.
5. Once again, screws can only be tightened once the wheel's pivot is sitting correctly. Let's start!
Exercise #1
Place barrel complete into the main plate as per photo.
Place the barrel and train bridge over the barrel. Make sure that
barrel arbour is aligned and protruding as shown. Insert and tighten 3 plate screws.
Check the barrel for radial and axial movement.
Disassemble and rassemble by repeating the above steps 20 times.
Excercise time: 20-30 minutes.
Exercise #2
Place the centre wheel as shown in the photo. Note the position of alignment pin.
Place centre wheel bridge, lower it gently down while ensuring that the centre weel is stiting properly.
This wheel is large and 'short' so it will sit and align itself between the plates
nicely without much 'steering'.
Check the alignment. Insert and tighten the bridge screw.
Once again, check the radial and axial movement of the centre wheel.
Disassemble and rassemble by repeating the above steps 20 times.
Exercise #3
With the centre wheel and bridge installed, place the fourth wheel as per photo.
Place the bridge and insert two screws (screw only half way down, do not tighthen).
Now rotate the movement holder upright so you can
see between the plates. While gently pushing the bridge down with your index finger,
steer the wheel into the bridge. The fourth wheel has very fine pivots, be patient and careful while steering it into the bridge jewel.
Check the end shake and check the radial rotation of the fourth wheel. Use the loupe with highest magnification and finest tip tweezers.
Tighthen the two screws and insert and tighten the third bridge screw.
Disassemble and reassemble by repeating the above steps 20 times.
Excercise time: 60 minutes.
Exercise #4
With the centre wheel and bridge installed, place the third wheel as per photo.
NOTE: the third wheel has very fine pivots.
First, insert the bottom pivot into the lower jewel. You may find this challenging because the jewel is obstructed by the wheel so it is a 'blind positioning'. It takes a bit of patience to 'find' the jewel hole. However once the pivot is inside the jewel it will 'sink in' nicely.
Place the bridge and insert two screws (screw only half way down, do not tighten).
Steer the third wheel into top jewel.
NOTE: The third wheel is completely hidden underneath the bridge. Steering must be done from the side, same way as with the fourth wheel.
WARNING: All the alignment, steering and positioning must be done with virtually
NO PRESSURE or FORCE on the wheel or pivot. If the wheel is not moving, lift the bridge and then try again.
Tighthen the two screws and insert and tighthten the third bridge screw.
Check the end shake and check the radial rotation of the third wheel.
Use the loupe with highest magnification and finest tip tweezers.
NOTE: due to the fact that top and bottom third wheel jewels have cap, the end shake is
significantly smaller than of the fourth wheel.
Disassemble and reassemble by repeating the above steps 20 times.
Excercise time: 40 minutes.
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