Tissot 28,5-621 mainspring question

[rogart63]

I am about to change the mainspring in a Tissot 28,5-621 - But as i took out the old one i found an extra spring inside. Should that be there? Can see that the new has that slipping spring. Movement is a automatic. 

Look att the first picture and you see tha spring  attached. Second picture is the old spring. Third is new 

[rogart63]

Looked like it was a special made spring. So i removed it and installed the mainspring directly into the barrel. Now working . That was probably the answer to the problem it had with the winding. 

[oldhippy]

That first picture is a bodge up and its not needed. Is that a post that someone has added to the barrel? If so it needs to be removed. The new correct spring will have the slip spring attached. You might need to replace the barrel, check it for wear on the inside.   

[rogart63]

1 hour ago, oldhippy said:

That first picture is a bodge up and its not needed. Is that a post that someone has added to the barrel? If so it needs to be removed. The new correct spring will have the slip spring attached. You might need to replace the barrel, check it for wear on the inside.   

 

That small spring was special made and was sitting inside the barrel. I removed it and replaced it with a new automatic mainspring. The automatic winding didn't work properly before and i think the reason was this special spring. The barrel looks okay. Now properly oiled. 

[JohnR725]

On some early automatic watches the mainspring was two pieces. The spring itself that would look like conventional spring and a shorter spring that was on the outside provided the slipping and some place for the mainspring to attach.  Your shorter Slipping spring looks something homemade or basically it just doesn't look right? Fortunately today when you get your mainspring it's one spring and you don't have to deal with that outer peace that's hard to find and a pain to get into the barrel.

[rogart63]

1 hour ago, JohnR725 said:

On some early automatic watches the mainspring was two pieces. The spring itself that would look like conventional spring and a shorter spring that was on the outside provided the slipping and some place for the mainspring to attach.  Your shorter Slipping spring looks something homemade or basically it just doesn't look right? Fortunately today when you get your mainspring it's one spring and you don't have to deal with that outer peace that's hard to find and a pain to get into the barrel.

The homemade spring was slipping badly. So in an hour the winding was gone.  

[rodabod]

That looks like an early automatic bridle. I think Eterna or Movado invented it possibly. Omega used them on the bumper watches. They can be adjusted. See page 5:

http://watchguy.co.uk/wp-content/uploads/2012/12/Repairing-Omega-self-winding-watches-bumper.pdf

De Carle quotes Omega in his Complicated Watches book about adjusting the slippage.

 

 

[rodabod]

Probably best replacing entire spring with one with a built-in auto bridle as you have done.

[rogart63]

Got this back yesterday. For some reason the mainspring is slipping and there is no tension in the mainspring. 

[oldhippy]

42 minutes ago, rogart63 said:

Got this back yesterday. For some reason the mainspring is slipping and there is no tension in the mainspring. 

Did you send it away if so what repairs did the watchmaker undertake?

[rogart63]

Wonder if the spring isn't to short. What happens if i go up a little? Anyone has some info on how long the mainspring should be? 

Says 280 mm on cousinsuk . But it doesn't fill up more then half of the barrel. Wonder if i go up to 300? 

8 minutes ago, oldhippy said:

Did you send it away if so what repairs did the watchmaker undertake?

It's me that is the so called watchmaker  I have done a service and changed the old mainspring as the old one was broken. I put the autowinding bridge back as that was sent along outside the watch. Sent it to the owner that in his turn sold it to an other guy. But he says it doesn't run okay.  It has a low amplitud. Around 160 degree.  Something i can agree on. When i wind the barrel with the screw it feels like it never got any tension.  Checked the hook on the barrel arbor and it looks fine. 

Edited April 14, 2018 by rogart63

[rogart63]

Maybe should try a vintage mainspring? With attached bridle. https://www.ebay.ie/itm/Tissot-28-28-5-1-28-5-21-mainspring-Ressort-de-barillet-Zugfeder/201600495302?hash=item2ef0536ec6:g:LncAAOSwh-1W4bij

[oldhippy]

It could be that the auto is not winding. As the barrel was in a bit of a mess, a replacement of the whole unit might have been best. If the person is active in his working day wearing the watch and takes it off at night it should still be going in the morning providing it fits on his wrist properly and doesn't flop around.

[rogart63]

4 minutes ago, oldhippy said:

It could be that the auto is not winding. As the barrel was in a bit of a mess, a replacement of the whole unit might have been best. If the person is active in his working day wearing the watch and takes it off at night it should still be going in the morning providing it fits on his wrist properly and doesn't flop around.

 

It works but has a low amplitude. When i wind the barrel screw i can keep turning million of turns. Feels like the mainspring is slipping inside the barrel. The auto is working fine and the rotor is doing it's thing. Wonder if i should give the NOS mainspring a go. Or maybe remove the new one as it can be broken? How knows even it it was new when i put it in. I will check that before i order a new one. 

[oldhippy]

A simple way and rough calculation with barrel and spring 1 third is for the spring, another is the size of the arbor, the final third is the space between spring and arbor.   

[rogart63]

Can't figure this out?  When i look at the Tissot 28,5R-621 family. Ranfft says all the same mainspring. But cousinsuk have different mainsprings for each movement. cousinsuk says 260 mainspring and jules borel says 360 . Wonder if cousinsuk has the right mainspring? 

http://cgi.julesborel.com/cgi-bin/matcgi2?ref=TIS_28.5R-621

Edited April 14, 2018 by rogart63

[rogart63]

And ranfft doesn't says how long it should be? Last time i switch a mainspring on a 28,5 i think i used a 360 mm . Think i wrote about it? 

Anyone has a bestfit catalog or something to verefy my teori? 

Looks like i have been there before? At least now i know the problem. Will order the correct mainspring. Why does cousinsuk says 260mm ? 

 

Edited April 14, 2018 by rogart63

[JohnR725]

So I found a parts list at least it confirms that it's a newer spring with bridal attached. Then bestfit online doesn't have a mainspring at all? It does have other parts like the barrel listed but not with the mainspring. Then it does confirm and agree with the tech sheet that the TIS 28.5R-21 Is the base model for the TIS 28.5R-621. Then the physical bestfit book gives the mainspring as a WA80 3 1/2 x 11 x 10 1/2. So if I do the calculations for length comes out to 266.70 mm to add to your mystery.   

Tissot 28.5R-21 Part Sheet.pdf