Smiths Imperial cal 0104 mainspring size ?

[mikepilk]

Does anyone know the correct mainspring size for the Cal 0104 ?

After cleaning, and fitting a new balance I can't get reasonable amplitude.

The balance jewels are good and the gear train seems really free. I just wonder if I fitted the correct mainspring? 

This watch is causing me so much hassle !

 

[StuartBaker104]

According to Cousins it is 1.20 x .11 x 300 x 9... GR2949

[mikepilk]

32 minutes ago, StuartBaker104 said:

According to Cousins it is 1.20 x .11 x 300 x 9... GR2949

That's the one I fitted. I just wondered if anyone can confirm it's the correct size as I can't find a reference anywhere else

[rodabod]

If you get really stuck, I can pull one out of one of my Imperials here. Or you could ask John Senior at Obsolete Watch And Clock Parts which I am sure would know if he hasn’t already listed on his site. Remember (as I’ve posted here recently) that blue springs have a different strength to modern white alloy. 

[StuartBaker104]

It doesn’t necessarily answer your original question, but have you seen this http://watchguy.co.uk/wp-content/uploads/2012/12/Smiths-0104.pdf ?

Are you using a timing machine to check the amplitude or doing it visually? If the latter there is a note at the end of the document about that being difficult.

There is also a really interesting part about winding the mainspring with a lathe. I’ve never heard of this before and would be interested if anyone has ever tried this.

The GR catalogue on Cousins website doesn’t show cal 0104, but does list the GR2949 for cal 100... https://www.cousinsuk.com/PDF/categories/7813_GR Pages 171 - 180.pdf. Jules Borel doesn’t show cal 0104 or a mainspring for cal 100. Ranfft doesn’t show a cal 0104 either.

I did however come across this example of a cal 0104 with a new mainspring bought from Cousins https://gearhead.engineering/garrard-9ct-dennison-aquatite-wrist-watch-smiths-0104-calibre/ so it seems likely to be the correct part.

I did also spot that John Senior has various spares for this calibre... http://www.obsoletewatchandclockparts.com/Smiths-Imperial-0104-parts.htm

[mikepilk]

Thanks Stuart. All the reference sites you mentioned was where I first looked, and I have the PDF articles.

I thought fitting a new balance would finally solve the problem, but I'm only getting 200 deg amplitude (I use a Timegrapher 1000).

I'll strip it down again today and have another look. The gear train looked really free after cleaning, so maybe it's the barrel/arber.

I wanted the check the mainspring size because it's surprisingly light to wind. I wouldn't expect Cousins to get it wrong. 

 

[rodabod]

I can’t quite get my head around why they suggest not using a conventional mainspring wonder. Can you not just use an arbor with a hook cut for anti-clockwise winding?

[mikepilk]

1 hour ago, rodabod said:

I can’t quite get my head around why they suggest not using a conventional mainspring wonder. Can you not just use an arbor with a hook cut for anti-clockwise winding?

I think it's suggesting that the mainspring winders only worked one way back then.

What I do is use the next smaller spring winder, then push it out in to the the correct sized winder, effectively inverting the spring so it's the right way round 

[rodabod]

Top tip!

[khunter]

I would also thoroughly re-check the train and escapement. There are many issues that can cause problems with poor amplitude. Generally, with no wind on the mainspring, it should only take light presure on the center wheel to impart movement at the balance. If it takes excessive pressure, there's an issue elsewhere besides the mainspring. 

[StuartBaker104]

Sadly, I haven’t yet acquired a set of mainspring winders so I either wind by hand or fit a new spring.

I thought the lathe option was an intriguing idea so I grabbed an old barrel to give it a go.

Well, after a few attempts, I can confidently say that I still have all my fingers, but I won’t be trying that again. Running the spring through your fingers (I used finger cots) is fine until you get to the hook which wants to dig in to your finger in order to hold the tension. Maybe I didn’t quite understand the instructions, but I also know it’s a lot quicker to do it by hand!

[khunter]

1 hour ago, StuartBaker104 said:

Sadly, I haven’t yet acquired a set of mainspring winders so I either wind by hand or fit a new spring.

I thought the lathe option was an intriguing idea so I grabbed an old barrel to give it a go.

Well, after a few attempts, I can confidently say that I still have all my fingers, but I won’t be trying that again. Running the spring through your fingers (I used finger cots) is fine until you get to the hook which wants to dig in to your finger in order to hold the tension. Maybe I didn’t quite understand the instructions, but I also know it’s a lot quicker to do it by hand!

Winding by hand is precarious at best. Keep an eye on ebay for a reasonably priced set. I use a K&D set and it's invaluable, and I think I grabbed it for around  $75. It might sound a little pricey but ruining several  $10-$15 springs will end up costing more in the long run. This set will wind in either direction because the stud in the winding arbor is straight. 

[MrRoundel]

I use a K&D winder that it almost identical to khunter's. I believe mine is a Robbin's patent model 125A, where his is a model 128. From what I can tell, the 128 is an improved design, in that it has a more stable setup for the winding arbor depth. The difference in appearance is that the 128 has that dark, screw-set collar between the handle and the frame. The 125A does not. FWIW. I find this winder works very well on most mainsprings. However, I have had difficulty with smaller mainsprings occasionally, as they distort easily, and therefore have less  room for error. Good luck.

 

[StuartBaker104]

56 minutes ago, khunter said:

Winding by hand is precarious at best. Keep an eye on ebay for a reasonably priced set. I use a K&D set and it's invaluable, and I think I grabbed it for around  $75. It might sound a little pricey but ruining several  $10-$15 springs will end up costing more in the long run. This set will wind in either direction because the stud in the winding arbor is straight. 

Thanks khunter, I will advise my wife that you have approved my purchase...

I have been looking for a decent set at a reasonable for a while, but keep buying other things instead :-)

[khunter]

Just now, StuartBaker104 said:

Thanks khunter, I will advise my wife that you have approved my purchase...

I have been looking for a decent set at a reasonable for a while, but keep buying other things instead :-)

Now now, don't get me in the middle of that! 

I know what you mean though, and I totally agree with what Mark L said in one of his videos, once you start buying watch tools, you never stop buying watch tools!

[mikepilk]

Well I have the answer to my problem, and it's not what I was expecting.  

I just took the mainspring out - a new one from Cousins. As I pushed it straight in to the barrel from the washer, it's odd that it's coned?

I have the old spring so decided to measure them.  The measurements are similar, but when I straightened the new one (not too much) to get an idea of the length, it didn't return to anything like it's original shape. It doesn't feel like spring steel at all, just un-hardened steel. There's barely any spring there at all. 

Has anyone else come across this ?

[StuartBaker104]

That looks pretty bad for a new spring, and will not help matters.

I have seen old springs which have taken a set work perfectly fine though...

[khunter]

The cone shape is from winding by hand (experience), and no, it should not be that way, it should be flat. As to the recoil, I would think it should return to its original shape if it has been manufactured correctly, it may just be a bad spring. Alloy springs should have an "S" shape when unwound, generally. Old brown or blue steel springs were coiled. 

[mikepilk]

Well this one is for the bin. After gently straightening it to get an idea of the length, this is what it looks like. 

It's definitely not spring steel !

It explains why there was very little resistance while winding, and why I couldn't get reasonable amplitude. Pity I've spent so long stripping and examining all the other parts. I never expected a new spring to be the problem.

[rodabod]

I’d be asking Cousins for a refund. That said, they disagreed with me when I claimed their silicone grease was not actually silicone. 

[rodabod]

Also, You might be ok using the original spring. It may be the original and better suited anyway. 

[mikepilk]

10 minutes ago, rodabod said:

I’d be asking Cousins for a refund. That said, they disagreed with me when I claimed their silicone grease was not actually silicone. 

From what I've heard about Cousins, I'm not even going to bother. 

[jdm]

11 minutes ago, mikepilk said:

From what I've heard about Cousins, I'm not even going to bother. 

From personal experience, if the product is defective you'll be refunded. And, what's the branding on the MS?

What is that you have heard? Welcome to post in the running thread.

 

[khunter]

Yep that is not a good spring, it probably distorted into the cone shape when you removed it from the barrel.

[mikepilk]

50 minutes ago, jdm said:

From personal experience, if the product is defective you'll be refunded. And, what's the branding on the MS?

What is that you have heard? Welcome to post in the running thread.

 

Just various complaints about there (lack of) customer service, e.g.