Struggling to find mainspring

[albertopveiga]

Hi!

As it was to be expected, I ran into troubles in my first restoration (see introduction post). Mainspring was broken, and I don’t seem to be able to find it. These are the measurements:

Barrel inside: 22.0 mm
Mainspring thickness: 0.2mm
Mainspring heigth: 2.25mm
Mainspring length (putting the pieces together): 790 mm

The movement looks to me like a Roskopf Patent (1a??), and the mainspring seems to have and additional insert where it attaches to. (See attached pictures).

Any advice would be highly appreciated! Thank you!!!

[watchweasol]

Hi  Can you post some pictures of the watch movement its self, front and back.  Its an odd system to me thats why pictures are important in identifying the watch maker and caliber.     thanks.

[albertopveiga]

Just now, watchweasol said:

Hi  Can you post some pictures of the watch movement its self, front and back.  Its an odd system to me thats why pictures are important in identifying the watch maker and caliber.     thanks.

Attached a few pictures. Many thanks!!

 

[watchweasol]

Hi that is an old guy  30s/40s cylinder movement,   the language looks like Spanish/portugese    There seems to be no distinguishing marks on the plates. Other members will need to have a look, its not one I recognise and I dont think you will find it on the pocketwatchdatabase.com site.

[albertopveiga]

 For what I have identified, the watch is a generic Spanish watch from the 20s based on a Roskopf Patent movement. There are several on sale on eBay with the same movement but under the Roskopf brand. 

Thank you for taking the time to look at it!

Kind regards,

Alberto

[clockboy]

This is the best I could find @Cousins. Looks like this could be too short but not sure how much extra length is made up with the bridle insert.

2.20 x .20 x 540 x 17 TR- End

GR6280TR

However GR 6240. - TR is probably the spring you need.It is so if gutsy under strength and is for a barrel of 19 but the length is  never to your estimated length ..

2.20. X 0.17x 680  x19

Edited August 22, 2022 by clockboy

[albertopveiga]

12 minutes ago, clockboy said:

This is the best I could find @Cousins. Looks like this could be too short but not sure how much extra length is made up with the bridle insert.

2.20 x .20 x 540 x 17 TR- End

GR6280TR

However GR 6240. - TR is probably the spring you need.It is so if gutsy under strength and is for a barrel of 19 but the length is  never to your estimated length ..

2.20. X 0.17x 680  x19

Thanks a lot for your answer. Probably this is a stupid question but… if I can’t find the exact measures… could I use any of the two you mentioned? If so, how would it affect the functionality of the watch? (I.e. being different length or for a different barrel)

 

[clockboy]

The first spring GR6280TR is available from Cousins UK. If the spring dimensions  you supplied are correct then it will work but it won’t run for 8 days because it is short in length. However GR 6240. - TR Seems a better fit but I could not find one for sale. There some Roskopf mainsprings on eBay but not sure of the sizes.

Edited August 22, 2022 by clockboy

[JohnR725]

11 hours ago, watchweasol said:

cylinder movement,

Very casually the balance looks like for cylinder but look carefully there is a lever and a weird escape wheel?

 

12 hours ago, albertopveiga said:

The movement looks to me like a Roskopf Patent (1a??), and the mainspring seems to have and additional insert where it attaches to. (See attached pictures).

I've seen the weird insert before I guess is there to keep people from over winding the watch..

 

 

[nickelsilver]

You can never be sure the spring that's in the watch is the correct spring; it's good to double check the height in particular (especially if it's proving troublesome to find a replacement). If you have a micrometer, check the height of the barrel to the lip inside, then measure the thickness of the barrel end and subtract that. That, minus about 0.05mm is the maximum height of the spring.

 

In the Generale Ressorts book they list about a dozen refs for Roskopf; for a 22mm barrel they have a couple but with spring heights of 1.90 or 2.60. There are a few for 2.20 height, but for significantly thinner and shorter springs.

 

If you aren't used to searching Cousins' list, go to mainsprings by size, put in the height you want and search it, then you can scroll through all springs with that height. I see there's a 2.20 x 0.21 x 780 which is pretty close to what you have.

Edited August 23, 2022 by nickelsilver

[Kalanag]

Interesting read (Rosskopf mainspring):

https://www.watchrepairtalk.com/topic/4949-how-to-get-pocket-watch-mainspring/

[clockboy]

Actually reading this post from 2016 gives another way of dealing with the issue. Purchase a normal bridle end spring and change it to a hole end spring. Perhaps!!!

[albertopveiga]

Well...

First things first: thanks all for all the advice! In the end, and given the fact that the spring was broken towards the outer part, I found a way to fix it using the weird insert. I mounted it and voilá... working!

I have ordered a couple of springs with similar characteristics, so I will try when they arrived. For now, the good news is that the restoration is almost complete.

Unfortunately, I broke one of the very deteriorated hands when removing them, so that´s the nex struggle! but, as you can see below, the before (not running) and after (already running) photos, the difference is noticeable, and I´m really proud that I managed to disassemble, clean, fix and assemble again this nice watch.

Thank you!

On 8/23/2022 at 9:55 AM, nickelsilver said:

You can never be sure the spring that's in the watch is the correct spring; it's good to double check the height in particular (especially if it's proving troublesome to find a replacement). If you have a micrometer, check the height of the barrel to the lip inside, then measure the thickness of the barrel end and subtract that. That, minus about 0.05mm is the maximum height of the spring.

 

In the Generale Ressorts book they list about a dozen refs for Roskopf; for a 22mm barrel they have a couple but with spring heights of 1.90 or 2.60. There are a few for 2.20 height, but for significantly thinner and shorter springs.

 

If you aren't used to searching Cousins' list, go to mainsprings by size, put in the height you want and search it, then you can scroll through all springs with that height. I see there's a 2.20 x 0.21 x 780 which is pretty close to what you have.

Thank you so much. I was finally checking in Cousin´s list and ended up exacty in that list! I´m still waiting for the spring I ordered. The only available that looked similar (GR6840TR). Still waiting for it unfortunately. Indeed I suspected what you mentioned about not to trust the current mainspring. Definitely this watch has been already through a few services in 100 years!