Need to make some spring steel pieces for a bracelet to snap closed - help w/ process

Hey!

I'm a CAD designer at a jewelry place in NYC. I'm trying to design a piece for my company, but it requires the bracelet to open up and snap closed.

What I need:

I did as much research as I could and it seems like I need stainless 301,302 etc. I was even told by a manufacturer that maybe what I need is 310.

Anyway, I need a decent amount of strength to auto-close this bracelet, and I think it comes down to layering 2 or more small strips of this spring steel (1/2 inch X 1/4 inch rectangle) to build up to the desired spring strength. It will have to be curved almost to about the circumference of a sharpie marker.


My Questions:

1) What steel should I get
2) do I buy it already springy, or is it better to get it in a different state, form it, and then make it springy?
3) how do I form it to the shape I need if that is the case? Or how can I modify it without breaking it?

Complete novice here. I have a basic understanding of the processes of hardening and annealing and quenching, but it's fuzzy on exactly what thing makes the steel springy or just makes it hard and brittle.

Thanks so much for your time everyone, I really appreciate it! Any courses or other resources would also be very much appreciated!

Is this going to be a production item or a one-off? Makes a difference to the info you will get. Probably would help to get a better idea of what this is going to look like mechanically as well.

Generally springs are made by forming while the steel is soft, then heat treating to obtain spring temper.

Most stainless springs are work-hardened 300-series. They never get as hard/strong as heat-treated carbon spring steel. For a small spring as you describe, probably you want to make it out of pre-hardened spring stock, which does have enough ductility to be formed, within limits. A drawing, with numbers relating to the force and travel you need, would help.

eKretz said:

Is this going to be a production item or a one-off? Makes a difference to the info you will get. Probably would help to get a better idea of what this is going to look like mechanically as well.

Generally springs are made by forming while the steel is soft, then heat treating to obtain spring temper.

Click to expand...

Thanks for the reply! It's a one off sample, but we are planning to produce a line of them and manufacture them in house in small quantities.

I can't provide an image right now, but it's essentially a C shaped bracelet, and in the center there's a hinge that we want to spring back closed. The most simple representation I can think of, is a Tiffany Square Bracelet.

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Talk to D.R. Templeman, they are a speceialty spring manufacturer and have made some custom springs for us. You could spend years of your life learning this, or they can make them for pennies a piece.

Custom Springs Manufacturer \| Wire Forms \| Stock Springs

as you said, layers. any spring that bend open far enough, 30-40 degrees... and is not very long, and not permanently deform would have to be layered to have enough force. and the layers will have to be able to slide past each other. as in the leaf springs on a truck. the ends of the springs slotted and a pin to retain them?

Alternatively, look at how glasses frames have a coil spring in tension inside a tiny hinge.
I'm fairly certain that is how the Tiffany example works.

If you wish to experiment you should buy a couple sets sets of feeler gauges. they are all springs in a variety of thickness and they are CHEAP. you can cut them and form them if you don't get to crazy. I have used them for this purpose.