Hamilton 940 interesting pallet wear

Discussion in 'Watch Repair' started by Chris Radek, Feb 3, 2019.

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  1. Chris Radek

    Chris Radek Registered User
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    Apr 13, 2014
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    On a customer's 940, I found that after service (including the usual 941 on the pallets) it would not draw reliably in one direction. Strangely the other stone is fine. It seems like this is either from two setups, or the two divots are initial impact and bounce. Why do you think one stone and not the other?

    divots.jpg
     
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  2. DeweyC

    DeweyC Registered User
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    Feb 5, 2007
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    Good photo. Impact wear from lack of maintanence. Steel tooth gets charged with grit and the impact on the jewel actually drills into the locking surface. Could be someone changed the locks to get past the first pit (closer to arm). Replace the pallet jewel. Might also replace the EW since you cannot polish the grit out of the steel teeth without throwning out the geometry.

    As you know Chris, the locking surface must be unblemished so the unlocking is smooth and continuous. I would expect that your wear would cause loss of power via recoil as the tooth goes forward and reverses on the locking plane (into the pits) as it slides down the jewel.
     
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  3. GeneJockey

    GeneJockey Registered User
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    Interesting. I'd also guess that part of the grit that wore away the pits was tiny chips from the pallet stone sticking in the lubricant.
     
  4. DeweyC

    DeweyC Registered User
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    Could have even been detritis and dust. Coal dust, whatever. Like a brass EW cutting into a steel pallet in a clock.
     
  5. GeneJockey

    GeneJockey Registered User
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    Exactly. Water may wash right over a rock, but given enough time and exposure it will wear it away.
     

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