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I've been out of watch tinkering for a while but recently picked up a Seiko 6300- watch which I cleaned up and had running.
It's a hand winding version of the 6309 movement as I understand it. Late 70's.
Annoyingly the mainspring has snapped. I'm looking for a replacement however it's not a common movement in hand winding guise.
Does anyone know if the 6309 auto mainspring is the same or if not what one I need?
Thanks
Duncan (thewatchbloke) is the best guy to ask, he's got lots of Seiko experience.
I've never been able to find a suplier for Seiko parts, I don't work on them often. Regarding the mainspring, it may be possible to measure it and source a generic from Cousins. They list a lot of springs, if you know the height you can see what' s available. One rule to remember: the strength of a spring is proportional to the cube of the thickness, so a 0.105mm spring is 15% stronger than a 0.100mm.........worth knowing if you can't get exactly the right dimensions. The height has to be the same to fit the barrel but a couple of centimetres in the length won't have much effect.
At the risk of stating the obvious a good quality digital caliper is a must, if you don't have one I suggest you get one.
Ideally, you should source the correct spring from the manufacturer but sometimes it isn't possible.
Paul
Thanks. I've been round Cousins webpage without much joy.
I can get a 6309 spring which visually looks to have the same barrel.
At worse, I could change the spring out of it into the barrel I have.
Financially it's not worth it but I don't like leaving it not working!
Hi
I would think that the 6300 is the no date verion of the 6302 in which case the mainspring from a 63A should fit, The 63A is pretty common so it might be worth looking for a whole scrap movement. a quick google for photos should confirm whether they are the same family of movements
Best of luck with it
wook
Thanks. Yes think you are correct. The movement has 63A stamped on it.
Just to close this off in case anyone ever needs to know this.
A very kind forum member donated a 6309 movement to me and I used the mainspring from it.
Here are the two together. Identically sized.
https://uploads.tapatalk-cdn.com/201...40368be2ef.jpg
I decided not to take the donor spring apart for cleaning on the basis that it was winding and releasing smoothly and you have to use a bit of brute force to separate the barrel.
Installed and about to finish off reassembly.
https://uploads.tapatalk-cdn.com/201...0b52afb572.jpg
These old Seikos are really nice to work on. Well made and well assembled with tight tolerances.
Here it is, not that common in dateless hand winding form but I really like it. I think it's 1978 but it might be 68. Anyone know?
https://uploads.tapatalk-cdn.com/201...278250f228.jpg
Ian
I think it's more likely to be 78,
Think you are right. From what I can find the 63** range of movements was released in '75 and this one has a typically late 70's style about it.
Well done Iain