Citizen 6501

[HectorLooi]

Recently I serviced a watch for a friend. This watch was given to him by his father on his fourteenth birthday. He doesn't remember it ever having a second hand. The case back thread is stripped and cannot be tightened. Life was hard back then. It's of great sentimental value to him.

I managed to get it working again with decent amplitude and accuracy. But it keeps coming back because the ratchet wheel screw keeps coming loose. It puzzled me because both the crown wheel and ratchet wheel had left hand screws. I assumed the previous watchmaker must have lost a screw and just put in any screw he had at hand. But on futher research,  I discovered something interesting.If you look at the photo below from Ranfft's website, the 6501 actually has 2 left hand screws! 

In the end, I resorted to putting Loctite on the screw.

[Nucejoe]

Neccessity is the mother of invention.

So for next service someone will end up heating that screw and would say this must have been last serviced in covid era. 

Just kidding john. 

[jdm]

2 hours ago, HectorLooi said:

But it keeps coming back because the ratchet wheel screw keeps coming loose. It puzzled me because both the crown wheel and ratchet wheel had left hand screws.

In watchmalking there is a reason for everything. I never worked on this mov.t but it could be that the barrell arbor and the screw body are rather small so it was cleverly done to prevent people from winding at the barrel which could snap the screw. On the same line on the 2824 if you the head of the ratchet wheel is so small for the torque involved that a actually deters one from doing that. 

Since the screw doesn't move relative to the ratchet wheel it should not come loose by itself. 

[anilv]

Yeah this and the  old 0200 movement had two left landed screws... god knows why.

Anilv

[rossjackson01]

Hello.

I am working on a HMT Jamal - with a miyota 6501 movement. Anyone any knowledge of the circlip size on the 1st reduction wheel? I have 6501 which, believe it or not used a piece of wire in the place of the clip. It went 'ping' when I touched it, and I have not been able to make an equivalent clip. Is it 0.55? smallest I have is 0.65 and it is too large.

The information is at 10:42 on, in the video

https://www.youtube.com/watch?v=BoQN0rYn61w

Thank you

[rossjackson01]

Not sure if this topic has gone into the system. Apologies if it is repeated.

Hello.

I am working on a HMT Jamal - with a miyota 6501 movement. Anyone any knowledge of the circlip size on the 1st reduction wheel? I have 6501 which, believe it or not used a piece of wire in the place of the clip. It went 'ping' when I touched it, and I have not been able to make an equivalent clip. Is it 0.55? smallest I have is 0.65 and it is too large.

The information is at 10:42 on, in the video

https://www.youtube.com/watch?v=BoQN0rYn61w

Thank you