Hamilton 992b Nomenclature, Parts, Screw Question

[maitai11]

Hi Guys,

I’m having trouble finding out where a certain screw goes on my Hamilton 992b. It’s a wide pan head with only three or four threads, and it’s a left-handed screw. Problem is, I have not idea where to put it. The ratchet wheel and transmission wheel boss both have screws already – and the transmission boss wheel, normally a lefty, actually seats a right-handed clockwise screw.

I’m thinking maybe I should just put it together dry and see what’s what. The inner movement case was badly scratched, as well as the movement itself – and I always thought it was a screw that did that damage. Maybe it was dropped in by mistake at its last servicing. Pics attached.

Best,

Tim

[chris mabbott]

Usually the left hand screws are used in places where there is an opposing rotation, so the rotation does not loosen the screw. Either on the ratchet wheels or somewhere on the winding mechanism..

You’ll find out when you try to gently start a righty in a lefty

Those marks are normally from a slipping screw driver, slot heads are bad for that, especially if tight and force is required. The majority of scratches are from this, or kids, or kids in an adults body 😆

[maitai11]

More and more, this is looking like a screw that was left in the case. It’s just too small to go anywhere, and I see absolutely no place for it. The transmission wheel and mainspring wheel both have bigger screws, and they are also right handed threads. I’ll get back to you all with a final determination.

Chris, I believe I know what you’re talking about regarding those screwdriver slips, but I have to deviate away from that theory when it comes to the inner rear case cover. There are just too many figure 8’s there! Look again and see if you don’t agree…it’s OK if you don’t! Plus, that little screw kind of fits the location of the damage on the plate…I can perceive the screw being stuck right at that location, and the cover being loose and doing a dance inside there.

I’ll advise once I solve this mystery. Great big thank you for brother Joe for help over the phone and texts, helping me – by deduction – as to whether it did the damage, belongs anywhere in the watch, or was just plain forgotten. To be honest, this little screw looks more like a transmission wheel screw for a wristwatch – possibly a ladies.

Best,

Tim

[chris mabbott]

I think the figure 8 comes from watch pixies skating inside the back cover and not from a screwdriver slip, as there are no screws on the cover 😆 Although the way some people use tools….. Ya never know 🙄

[maitai11]

Hahaha you got me on that one Buddy. Watch pixies. I’ll be doing some more work on it today.

Tim

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