Converting an automatic watch to be hand winding - How to modify the mainspring?

[kaan]

Why? Well it's an unnecessary complication, 99%+ of the watches have regular crowns (not screwed), just the occasional 5-10 turns is enough to wind watches, I personally find the weight shift annoying too, and I just want to get the feedback when the watch is fully wound. When I have the option I buy handwinding varieties, but with vintage watches, most good ones are automatic :/

I'm sure there are others who feel this way too, while most don't care

In theory, steps:

1) Remove the winding weight and optionally the winding assembly (easy)

2) Modify the mainspring to negate the bridle mechanism

Any ideas how to most practically and safely approach the mainspring modification? The only thing I can think of is to weld the bridle/spring end to the mainspring barrel

I want to do this with an Omega 550 series movement, I just wish NOS or used mainspring assemblies were available in abundance so I could just buy a new one and modify, or commission this project to an experienced and open minded watchmaker, but it seems they are all out of stock :/

[Nucejoe]

Just take the selfwinder out and you are done.

If barrel discharges power at low wind, that is an issue onto itself, breaking grease and some tricks would improve the power reserve.

Inspired I just might cut my car in half to come up with two motorcycles. 

Just kidding Kaan.  

Keep safe.

[kaan]

The whole point is to get the winding stop feedback though, I opened the thread to get ideas on how to modify the mainspring

[Marc]

You would need to modify the barrel. Manual barrels have a hook or notch in the barrel wall to engage with a tang on the end of the m/s. Auto barrels don't so what ever mod you did to the m/s you still wouldn't get that fully wound feedback. 

Quite a lot of Auto movements have a manual winding equivalent. You might be better off swapping the barrels out.

[kaan]

29 minutes ago, Marc said:

Quite a lot of Auto movements have a manual winding equivalent. You might be better off swapping the barrels out.

That makes so so so much sense, thanks for the idea

For this particular attempt, I want to convert an Omega 751, my knowledge of movements is very limited, only hand winding Omega's I've seen were small 620/485-like movements - as they pop up a lot on the market

Does anyone know if there's a hand winding movement with the same barrel size as the Omega 751?

Edited August 7, 2020 by kaan

[Marc]

57 minutes ago, kaan said:

Does anyone know if there's a hand winding movement with the same barrel size as the Omega 751?

If you check Omega 751 on Ranfft he lists the various family/generations which should give you a starting point. It would be worth checking all of the dimensions involved first to make sure that you can just swap.

[kaan]

I'm so happy, thank you

Teeth counts match with the 600-613 barrel, the arbor connection looked identical to me, I guess I'll test and see