Make setting lever spring

[canthus]

I am having trouble sourcing setting lever springs for older watch movements.  Either they are not available anywhere or economically not viable, so I thought I might try and make my own.  I have most of the drills, files stones etc but don't really know what steel material I need.  I know about tempering and hardening etc, so just need advice on readily obtainable material.  Maybe thicker stock than final form as easier to work with but any help from the many sages on this forum is appreciated.

[Tudor]

A lot of these springs were/are wire, and piano wire or even guitar strings can come in handy. 
 

Some smooth round jaw pliers to wrap the wire around and form loops and you should be halfway there...

[anilv]

Hacksaw blades are good source of steel but I've never tried a set lever bridge.

Thought about it and if I had no other option I would

1. Mark out the piece on the hacksaw blade stock.

2. Drill the holes and triple check that they are correct (this includes the bit which 'clicks' when you pull the crown).

3. Drill the inside corners.

4. Drill holes along the perimeter so that you can cut between them.

5. Rough shape using a dremel and Hand-file to finished shape.

6. Thin down to correct size.

 

Good luck and share if you've managed to maked one!

Anil

 

 

 

[canthus]

Thanks for your ideas.  Wire is unlikely to work as I am talking about a flat plate bridge type spring.  I have plenty of small hacksaw blades and also some unused feeler gauges which may do the job. Not sure if my HSS drills would work on these materials, so would I need to anneal it first to soften it, or would carbide drills work without softening?

[Tudor]

Carbide is best, especially in these smaller diameters fit the increased stiffness. 
 

They do break easily as you probably know. 
 

HSS is great in brass with an increased included angle at the point. 

[nickelsilver]

O1 or 1095 would be good choices. It's available in numerous thicknesses, generally with 1095 having more options in the thin sizes, you'd have to check suppliers in your area to see what they offer. It's quite hard to find it in the very thin thicknesses useful for watch parts, except in the already heat treated state. You can anneal it though, which would make working it far easier.

 

Just a quick look and I found these guys, https://springsteelstock.co.uk/ they say that they are "the small order specialists" which sounds very encouraging, and they offer 1095 from 0.1mm to over 1.5mm in thickness- I'd try them out. They say it's generally offered in heat treated state but that implies that they can sell it annealed as well. For watch work 0.3mm and 0.4mm would cover 90% of what you might want to make.

 

I would stay away from hacksaw blades, they are often a mix of HSS and carbon steel, I don't think it would anneal very well and would be a bear to heat treat.

Edited September 30, 2020 by nickelsilver

[canthus]

Most helpful nickelsilver.  I know this company from my working days, they are a large distributor of sheet steel.  Their single sheet may be far too big for me.  I'll get my beans in a row re thickness etc and may drop them an email to see if they can let me have a small sample or off-cut FOC,  you never know!! I see they do an annealed stainless spring steel which may be suitable.

Edited September 30, 2020 by canthus

[nickelsilver]

A friend of mine in the U.S. contacted a supplier some years back for 1095 and when they figured out what he wanted the guy said look, why don't we send you some "samples"; I think they wanted to help my friend but to actually sell him the quantity he needed would have been too much hassle haha. He's still using what they sent!

[rodabod]

Does anyone have any experience of what colour you would take a plate/cover type set lever spring to, to make it durable as a spring. Smiths are notorious for broken set lever springs and I think that relates to the tempering.

I did have a beautiful Patek Philippe movement a while back which had a graduated colour change on the set lever spring which at the very least looked impressive.

[anilv]

Problem with working with thin steel is that its quite difficult to get to shape.. especially for a set lever bridge which has the 'spring' portion built into it. That's why I think its easier to start with a thicker piece and get the shape correct and then thin it down to the correct thickness.

If anyone has done this please share!

Anilv

[nickelsilver]

When I make parts like this (frequently) I start with stock as close to the desired finished thickness as possible. 2 or 3 hundredths of a millimeter is plenty for finishing. Taking more than that off is a long process, and there's the possibility that it gets thinned unevenly.

 

The old school technique for a set bridge would be to shellac/glue/soft solder the old part with the broken bit in place to the metal stock. Now you can drill through the original holes, and with a jeweler saw and files it's pretty quick work to shape it up using the original as your template. When you're happy with it remove the original and heat treat.

[praezis]

On 10/1/2020 at 3:30 AM, rodabod said:

Smiths are notorious for broken set lever springs and I think that relates to the tempering.

The main issue is shape, not tempering. Spring arms notorious of breaking are usually too thick and/or too short and their form ignores the internal torque. 

Frank

[canthus]

Thanks for all your ideas and thoughts, several options for me to explore.  Have to put on the back burner for a while as other priorities at the moment.  Will post my failures/successes in due course, but still open for suggestions/techniques etc.

I think the shape reverts back to the old engineering gremlin of stress raisers which could be shape, radii in corners, scratchy finishes etc etc so will pay due attention to these and probably try and polish these areas a bit.  Would a wiggly shaped arm (spring part) be better than a straight arm ????