Saturday, August 18, 2012

What $10 Will Get You, Part 2 - The Teardown

The next step in the restoration is to disassemble the movement for cleaning.  This is also when I have a look at all the bits and see what may need replacing.

Step one is to remove the hands.  To prevent damaging the dial, I place a piece of plastic sheet with a V cut in it over the dial.


Then I use my handy old K&D Hand Remover to pull them off the cannon pinion and hour wheel.  Since it pulls up on both sides, it won't risk bending the center wheel post.

I leave the second hand in place, then loosen the dial foot screws, and lift the dial off.

 At this point, I tried cleaning the dial.  On the left, pre-cleaning.  On the right, after soaking for about 10 minutes in Hagerty's Jewelry Cleaner.  A LITTLE better.

It's cleaned the worst of the grime, but left much of the pitting.  The corrosion has gotten below the lacquer, and I'll have to decide whether to redial - and that's if International Dial even has the right dies for this.

Back to the movement.  Before doing anything else, I let down the mainspring.  I turn the crown just enough to get the click out of the ratchet wheel teeth, then use a piece of pegwood, or tweezer tips to hold it out of the teeth while i allow the crown to spin slowly backwards agains the pressure of my index finger.

After that, the next step is to remove the balance.  Start by loosening the hairspring stud screw and pushing the stud out of the hole in the balance cock.  Then unscrew the cock screw and lift the balance cock off.  Sometimes you need to use a screwdriver to pry the cock up just a bit.

Next lift out the balance.  Now's a good time to inspect it.

The balance on a 526 of this age was a split, bimetallic balance with a blue steel hairspring.  At first glance, the hairspring looks pretty good.  Concentric, and the overcoil looks fine.  If you look closely at the right hand picture, you can see that both pivots of the balance are present - No staff replacement needed!!

Next step is to remove the two screws holding the cock dome (upper cap jewel setting) and take off the dome and the regulator.

 It's hard to see here, but there's the usual dried oil on the cap jewel - that's why we clean 'em!

Next, unscrew the pallet bridge screw and remove the bridge and the pallet.

Nothing apparently wrong with the pallet.  I check the impulse faces by holding them in tweezers and turning them till they catch the light.  Then it's easy to see any chips.

Now that the pallet is gone, you can check the freedom of the train.  I wind it a few clicks of the ratchet wheel and watch.  

Generally, unless there's a REALLY BAD problem, the train will spin.  In a dirty watch, it spin forwards and jerk to a stop.  In a clean watch, the train will spin freely, then the momentum will carry it past complete unwinding, and it will stop and spin backwards for a bit before gently coming to rest.

Next step is to remove the keyless works and dial train.

 The minute wheel clamp screws on these early 8/0s are WAY longer than they need to be!  But remove them, and the minute wheel clamp comes off, along with the clutch lever.  Now I remove the minute wheel and setting wheel, and the clutch lever spring.  Turning the movement over, I loosen the set lever screw until the set lever falls off, then pull the stem and remove the bevel pinion and clutch.

Now to remove the train.  First I remove the ratchet wheel, click, and crown wheel.  REMEMBER - the crown wheel screw is LEFT HAND THREAD!  It turns CLOCKWISE to loosen!

Here you can see the click spring.  CAREFULLY remove it - they ain't makin' any more of them!

Now remove the train bridge, and then the barrel bridge.

 Remove the train, the barrel, and the set lever screw, and you're left with just the pillar plate (I removed the lower balance cap jewel screws and setting earlier.

The last step is to pop the cap off the barrel and have a look at the mainspring.  In this case, it's a blue steel spring that's completely set.  Fortunately, I have 8/0 alloy mainsprings to replace it.
And that's it!  Now the watch is completely disassembled, ready for cleaning. 

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