Waltham 16s, 15 jewels, model 1908 - mainspring

[PeterS]

I’m struggling to find the correct mainspring for 16s Waltham, 15 jewels, model 1908.
The specification can be found here:
https://pocketwatchdatabase.com/search/result/waltham/22323804

The old mainspring wasn’t the correct one. This barrel required hole end mainspring and that’s not what was in, it was slipping, the end was broken, it needed a replacement and it was set.
I worked out that I needed 2227 mainspring, I bought it, put it in the barrel and it filled way too much space in the barrel. I’m not sure whether the rule of thirds, one third the mainspring, one the barrel arbour and one the space between the two applies here because this is not the usual barrel arbour. Most likely not because the main wheel (the barrel lid) is staked to the arbour hook.

The length of the new mainspring is 640mm and the old one is 450mm. Thickness, they are both 0.19mm. I must say that I don’t have a micrometre and I measured the thickness with my vernier caliper. Not ideal but if anything, it would be 0.19mm or less, not more.
I assembled it, even thought it filled too much space in the barrel, I wanted to see how it performed. It was hard work winding it, I had to use fair amount of force. It took only two and half turns to fully wind it. It was good on the timegrapher, the first half an hour, I was going to put it back on the timegrapher 12 hours later but it came to a stop after ten hours. The amplitude is probably wrong because I don’t know the lift angle but at this moment I don’t think it matters. It’s the two and half turns and ten hours run time I need to sort out first.

Any thoughts/ideas/suggestions what mainspring I need to get?

I’ll post images below in several posts, I don’t think I can add comments to each image and they don’t always are in the order I upload them.

Below, 2227 on the left, the old one in the barrel on the right and the image below is the new 2227 in the barrel.

 

[PeterS]

The broken end and the 2227 with modified hole

 

[PeterS]

The main wheel with the hook

 

[PeterS]

Reading on the timegrapher with the 2227 mainspring inside

 

[JohnR725]

On 7/18/2021 at 10:18 AM, PeterS said:

I wanted to see how it performed. It was hard work winding it, I had to use fair amount of force. It took only two and half turns to fully wind it.

the length of the mainspring should've not influenced how hard it is to wind that indicates a different problem? one of the places you have to really careful is the center and I don't actually know what the parts called arbor that goes through the barrel that has the square at the end that has to go into the square of the barrel and a lot of times it's really hard to get that in an hard to get that the stay in place. That may be where the problem is.

[PeterS]

That should be in correctly as per the picture below.
It is called an arbour. The lid is called the main wheel which is staked to the arbour hook. The barrel is called the shell or lower portion. For simplicity and to avoid confusion I call it the barrel and barrel lid.

The fact that the length of the mainspring doesn't influence how hard it is to wind the mainspring is interesting. I thought that was the cause but I'll have to look elsewhere now.
Sadly, after couple of days of the spring being in the barrel it looks set. Below are pictures of the old and new mainsprings before I put it in the barrel and a picture of the old and new mainspring when I took it out of the barrel.

 

[PeterS]

1 hour ago, JohnR725 said:

a lot of times it's really hard to get that in an hard to get that the stay in place. That may be where the problem is.

Maybe it didn’t stay in place. I will assemble it this weekend and watch for it carefully.

[KarlvonKoln]

I think, were I in your shoes, I would use the specs from the pocket watch database, and go to Otto Frei ("Ofrei" when you Google, or you'll get their jewelry section).  They sell mainsprings by size (length, height, strength/thickness) as well as by the kind of end/anchor it has.  Dave's Watch Parts has some obscure vintage ones too.

[PeterS]

I couldn’t last until the weekend and put the movement together this morning.
I don’t want to speak too soon but it’s looking really good, six turns of the ratchet wheel to full wind, no force required to wind it either. There was one thing I forgot to mention in my initial post, when I was letting the power down, I could hear skipping when letting the power down, perhaps five, there about, no skipping when winding it but skipping when letting the power down. There is no skipping now when I let the power down.

I followed John’s advice and I was very careful placing the barrel in place. I was also very careful placing the barrel bridge in place. These bridges, all of them, including the pallet bridge and balance cock, even though they have the guide pins that go into the holes in the mainplate, you have to hold them down with pegwood or something because they like to move. The bridge can easily lift slightly and move the barrel arbour along the way. I kept the bridge pinned down with pegwood, while adjusting it to sit properly and kept the pegwood on it until it was fully secured with its screws.

The other thing I did this time, I secured the disk below the crown wheel very, very gently. The screw is only on one side, therefore as soon as you feel resistance, the disk will be lifting on the other side, you don’t want that. If you look carefully at the pictures below, you will see a shiny part on the disk just opposite the centre wheel, almost 180 degrees across from the screw. This is how it looked when I disassembled it the first time, it was screwed down a bit too much and that side was lifted and was rubbing against the crown wheel. It doesn't have to be tight, the screw has nowhere to go, see the pictures below.

The third thing I did, I didn’t hold down the ratchet wheel with pegwood when I was securing it like I normally do. I let go when I started to feel resistance just before I’d take the pegwood and secure it more.

I left it on the timegrapher for couple of hours and you can see the reading below what it looks like after couple of hours running. I didn’t touch the regulator, it was good from before as I adjusted it previously. I didn’t lubricate it this time because I didn’t clean it when I took it apart and it was cleaned and lubricated before. I’m going to have to disassemble it, clean it and lubricate it again, this was just a test how it will run.
I couldn’t find out the lift angle because with the problems I was having, when I marked the balance wheel, I was going slowly, click by click to wind it, it took about I guess four clicks and the balance wheel started going like crazy well past 180 degrees so I couldn’t measure it. When it stops and I know the run time I will then find out the lift angle so I can get accurate amplitude reading. Unless somebody knows it?
It’s early days to say how it will perform but the fact that there was no resistance winding it, it took six turns to wind it and there was no skipping letting the power down, so far so good.
The mainspring may need changing but I’ll let it run for now and see how it goes.

I’m keeping my fingers crossed, for 100+ years old watch, this is running exceptionally well.

 

Edited July 20, 2021 by PeterS

[KarlvonKoln]

Out of curiosity, how's the Waltham running so far?  I was just checking in and looking at the pics.  Don't the American watches from the turn of the prior century have the prettiest movements you ever saw?  

[PeterS]

Very pretty indeed. Breguet overcoil too, very nice.
Below are images how it was going after 12, 21 and 36 hours, it stopped at some point between 37 and 41. I’m not certain when it eventually stopped.