From highs to lows in an instant

[Stevelp]

Hi everyone, I hope you are all well!  Been working on a Venus 175 for the last while that needed a few things.  Last on the list was the minute recorder spring, which I have found replacement options for but they are all quite pricy.  So I decided to have a go at making my own.  I have never attempted anything quite like this so this was a very new experience for me.  I did still have the damaged spring which was snapped in half, so I was able to use it as a pattern for the new spring.  I glued the 2 halves to the stock for the new spring.  After much filing and figuring this is what I came up with.  Test fitting and function was good so all that was needed was to tightening it down for the last time.  This is where the low comes in with the final picture.... how quickly things can change with one slip in this hobby of ours!

[jdm]

3 minutes ago, Stevelp said:

This is where the low comes in with the final picture.... how quickly things can change with one slip in this hobby of ours!

Good work but looking at the 2nd last picture the section was made so th8n that In my opinion is not surprising it has snapped. Also, in some cases it's beneficial to harden the spring for extra strength.

[Stevelp]

Thank you.  yes it is quite thin.  The original spring measured 0.01mm and I went to 0.04mm as I was concerned to go any further so it is thicker than the original.  I used a feeler gauge for the stock which I thought were hardened, but if not, thanks for the info I will try that the second time around.

[jdm]

27 minutes ago, Stevelp said:

The original spring measured 0.01mm and I went to 0.04mm as I was concerned to go any further so it is thicker than the original.

Are you sure about that? It's impossible for a setting spring to be only one cent of a millimeter thick. Try flexing a 0.05mm feeler blade to get an idea of how thin and fragile steel is at that thickness. There are 0.05mm mainsprings, but are made of hardened special alloys. I world try again making the spring as thick as possible while it fits and work mechanically.

[Stevelp]

This is the original broken spring.  All it has to do is keep the minute record wheel from moving so not much tension is needed.  

[Plato]

10 hours ago, Stevelp said:

This is where the low comes in with the final picture.... how quickly things can change with one slip in this hobby of ours!

Nearly! You'll get it done right on the next attempt. 

[Stevelp]

Thanks Plato for the encouragement!  Yup I’ll give it another go.  I guess thats a positive out of these situations, you learn what to do better with the next one

[VWatchie]

5 hours ago, Stevelp said:

Impressive work! Just wanted to mention that I have the exact same type of caliper and it is surprisingly exact. I'd say it is usually only off by 1/100 of a millimetre (or so). Anyway, for any precision measuring I use my Bergeon micrometre  (very proud and happy to own it) as seen in this post measuring my AliExpress jeweling tool anvils and pump pushers.

[Klassiker]

Have another go! I'm sure your second attempt will be even better. try to keep the thin section at a consistent thickness. If you used a file so far, maybe try with a stone?

[Stevelp]

Thanks VWatchie!  Wow that is a great looking micrometer no doubt!  I think I may have to invest in a bench micrometer as well in the future for projects such as this.  Yes I had a little trouble keeping the thickness consistent throughout the thinnest portion of the spring.  I held the piece upside down in a hand vise while filing because upside down was the only way to grasp the piece enough while filing.  Before I knew it the piece was so thing that I couldnt file the middle anymore without the possibility of snapping it.  So I will work the top more next time before moving to the bottom.  Would you have a recommendation as to what kind of stone I should consider?

 

[VWatchie]

9 minutes ago, Stevelp said:

Would you have a recommendation as to what kind of stone I should consider?

I have never made any watch parts, so I'm afraid I have no advice to give. I think/hope @Klassiker will have some tip for you!?

The only stones I use these days for my tweezers, screw drivers, etc. are diamond stones. Amazing piece of equipment as they only need water and are super efficient.

[jdm]

Sorry, before I misunderstood what this part is for. I still think that the thin section is not 0,01mm but some amount more than that.  But what's important is not measuring precisely, but making it. The original may not have been just cut off or machined, it may have been pressed between dies in the thin section. And almost certainly it is not made of the same material the OP has at hand, and is heath treated. Reproducing all that in the right sequence at home could be difficult, so perhaps one should think out of the box. When something can't be made as one piece, it could be made in more. For example one could try glueing a strip of 0.04 feeler gauge to the two "bigger" sections.

[Plato]

Mark Lovick has made a similar part, have a look at what he does in his video:

 

[Klassiker]

My thought was, that filing a thin section would be difficult, as even the finest teeth have a tendency to snag. Also, files don't leave the best surface finish behind, and scratches are stress-raisers. So that's why I suggested a stone. I have a selection of the midget Degussit profiles, and I would try with one of those. 

The video posted by Plato above is a must-watch (12 to 17 minutes in). Mark makes the spring uses diamond files which I don't have but are probably even better for this job than stones (less fragile) so if you are buying new, maybe get a set of those. The method he demonstrates, of glueing down the part onto a larger plate to support it during the final stages, is invaluable.

[Stevelp]

Thanks Plato for the link, I’ll give that a watch!  Klassiker, I hadn’t thought of the surface finish problem, that makes total sense.  I was aware of it for mainsprings but it didn’t cross my mind for this application.  I’ll look into those files for sure, as I’m sure they have many applications.  I had glued my piece to thicker on as well but as things were filed thinner and thinner I found it extremely difficult to remove the residual glue without potentially damaging the piece.  I soaked it in 99% IPA and tried acetone as well but it was still very difficult to remove.  I’m curious to watch and see what Mark uses.