Reusing mainsprings in an automatic and slipping

[JohnL]

Hi all,

Might a posit a theory and people can chime in and tell me if I'm barking up the wrong sycamore:

If a mainspring is a bit coned and returned to its barrel for reuse, is it less likely to slip when the spring gets to fully wound? 

For a bit of background: Slava 2427, barrel walls greased with 8217, six dots evenly spaced around each of the barrel walls, then smeared/ spread along the wall before popping the springs in. 

[AndyGSi]

By coned do you mean it sits proud of the barrel before you fit the lid?

[rehajm]

1 hour ago, JohnL said:

six dots evenly spaced around each of the barrel walls

…to clarify, you placed it here, yes?

[JohnL]

Hi Andy, 

Yes, the arbor and a few coils would be a bit higher than the rest of the spring. 

I'm wondering if an alternative possibility is that there is a slight kink close to the end of the spring where the spring overlaps the end of the bridle just before the joint at the end - where the bridle and the end of the spring are joined. This was a bear to wind in/ feed in when winding the spring to put in the barrel. That was on both springs. If it was tough turn against the wall of the washer when winding to go into the barrel, it's probably going to be the same in the barrel, no?

I should probably say, the kink was in both springs, one more than the other, before I got my grubby little paws on them.

@rehajm, I placed it at six spots rather than five, but yes, around the wall evenly spaced as in your diagram. 

Edited 5 hours ago by JohnL
clarity

[AndyGSi]

You may get some extra friction on the barrel lid so may not slip as easy but I wouldn't think it's a problem.

My suggestion would be to finish the assembly and see how it runs.

[JohnL]

2 minutes ago, AndyGSi said:

My suggestion would be to finish the assembly and see how it runs.

Assembled and running well, I'm asking after the fact. I'm waiting on a new oscillating weight as this one was worn (they have a reputation for it apparently, no bearings). So I've been winding it by hand, but meeting quite a bit of resistance at the end, more than I think an automatic weight will overcome. It's not quite as sudden as a manual mechanism, but there's very little in it, certainly enough that I would be concerned about breaking something if I continued.

[AndyGSi]

If the weight was worn how does the post look as normally you'd have to replace both.

There should be no real resistance at the end and just be able to keep on winding.

Did you insert both springs the same and is the idler gear OK.

[JohnL]

Ah, well there is the rub. I ordered a post and oscillating weight, but clicked on the wrong thing when adding the weight to the basket adding an automatic bridge. Ordered a weight, and it's somewhere in the ether after our customs and excise folks rejected it because of the documentation. 

14 minutes ago, AndyGSi said:

Did you insert both springs the same and is the idler gear OK

Yes, both springs inserted the same. "Is the idler gear ok", and here's why I posted to the newbie area: So, reading between the lines, and again correct me if I'm wrong here, the automatic winding mechanism will have an ideler gear, along with the reverse wheels, that prevents over-winding? There is nothing (that I'm aware of) between the crown pinion, crown wheel, and the ratchet wheels to prevent over-winding other than the mainsprings slipping in the barrels. 

This is only the second automatic I've worked on. The other, a Vostok, had a very obvious mechanism. 

I shall look at the automatic winding mechanism in a bit more detail when I've a bit more time. At the moment I'm taking a glance here now and then when work is dragging 

As ever, thank you for your help. Always appreciated.

 

Edited 3 hours ago by JohnL
punctuation

[AndyGSi]

The idler gear I'm referring too is the one between the 2 barrel wheels.

These movements just rely on the spring slipping to prevent over winding.

[JohnL]

Ah, well that's a relief, though the parts document does list a 1520 which is a coupling clutch. This threw me for a while (it's a quiet day in the office) until I realised I couldn't see a listing for the reverser wheels.

So, we're back to the mainspring should slip in the barrel. It can really only be one of three things (that I'm aware of)

• mainspring 'coned' and pressing slightly on the lid
• the kink, close to the  end of the spring, which puts a sort of a self lock grip on the spring and may not allow the spring to release enough there to allow slipping
• quantity of lubrication, either not enough, or too little

Two of those require new mainsprings, which aren't readily available, though I may post a query about alternative mainspring sizes. The third, will more grease or less be required? The word breaking in breaking grease suggests more means more breaking?

[AndyGSi]

Does your parts list actually have the description as mine just shows the parts.

Is 1520 the gear that sits in the auto bridge to couple to the barrel.

You could try letting the power down and then remove the idler gear between the 2 barrels and see how it winds then.

I presume you're doing all this at the moment without the auto bridge in place.

[JohnL]

I've had a look at what I have and compared it to what I can see on a video of the automatic works being dismantled and I'm happy at this stage I'm not missing some part that supposed to slip that I'd overlooked. Everything links as I thought it did. 

I suspect we have similar parts lists. Just pictures of the parts with a number beside them. 1520 is, according to Best Fit, a coupling clutch. I suspect the reverser wheels are what it's labelled as 1520. The reason I'm ready to question the complete vallidity of the document is because it has a part numbered 2574 and I'll be damned if I can find that in either Ebauche or Best Fitt (the pdf copies I have anyway).  I think the wheel that connects the automatic works to the barrel should be 1482, the driving gear, it's either that or 1481 which would be the reduction wheel. Have to say: it would be really handy if they did those parts documents as an exploded diagram. 

Yup, auto bridge isn't in place yet. But weight turns reverse wheels, reverse wheel turns reduction, turns drive gear which turns ratchet. So the mainspring has to slip, and logically both have to as the inter doesn't, and if they don't the weight can't turn. 

The movement is currently in it's holder with face and hands attached so I've examined it while winding. Both ratchet wheels turn happily, the intermediate wheel/ ratchet winding wheel/ idler gear is doing its job. I'll see what happens if I take out that inter wheel and wind it a little later.