Omega Seamaster 2757 Calendar - Charge time

Hi Daren,
…. And welcome to OF.
It might be helpful if you mention how long you had it on your wrist before 10pm

Whenever I put on a vintage watch that has stopped for a while; whether it’s a few weeks, or days or, as in your case, a few hours, I always give the crown 6-10 turns before I strap it on.

Bumpers aren’t quite as efficient in converting your daily motion into mainspring charge as full rotor movements but nevertheless you should expect a longer reserve from a healthy one

What assurance do you have that it actually was serviced before you bought it? Many sellers routinely lie and it’s best to assume a watch without proof of such intervention never had it.

You should expect it to run indefinitely assuming you wear it every day and are reasonably active. If it is stopping overnight that suggests something is not right, which is why I queried the service status above. The bumper power reserve when fully wound is circa 42 hours ie nearly 2 days so maybe try fully hand winding it and seeing how long it runs for without wearing it, that will give you an idea of how healthy the movement is generally. If it is stopping sooner it needs a service, regardless of the spurious assurances of the seller.

As noted above, you need to start by a manual full winding. Then the auto-winding may keep it wound.

Hi Daren and welcome. Has the watch held time since last week?
To speak to what both Padders and Dan said, if you are picking it up and just throwing it on from it being totally dead, it isn’t starting with a fully wound mainspring- the bumper rotor kind of just tops them up. Those of us who have multiple watches and rotate them regularly are just used to winding automatic watches about 15-20 winds before setting and throwing them on the wrist. You won’t overwind an automatic movement as there is a clutch mechanism that prevents this.

Bumpers were one of the earliest forms of automatic winding system. They only wind in one direction and since they don’t make a full rotation, it’s actually only a 1/4 wind when it travels. The springs the rotor bounces off of give them that “ping-pong” sound which is part of their charm.
My grandfather wore manual wind watches most of his life but was given a Gruen bumper by my grandmother around 1950. He was a CPA so spent most of his time sitting with his left arm on a ledger. Needless to say bumpers didn’t suit his sedentary lifestyle and his watch was constantly dying on him- so in a drawer it went.

If it’s not holding at least 40 hours after manually winding it 20+ times, then most likely whoever serviced it didn’t replace the mainspring. It’s usually SOP to replace them but some watchmakers who are working in bulk skip that step to save time/money.