Making a tiny spring?

I have an antique Iver Johnson American Bulldog revolver that needs a tiny hairpin leaf spring and I haven't had much success making one. I have some thin spring stock but when I try to bend it it snaps. I can do it hot I think but then will need to harden and temper and while I have been able to make larger springs successfully, the size of this one makes the tempering part a challenge. All I have is a torch, no oven, so does does anybody have any tips on making such small things?

Years ago I made one out of a feeler gauge. Annealed it probably with a propane torch. Sawed the split (t was a dual spring, one side for the cylinder latch the other side for the trigger) drilled the hole and bent it. Used the torch to heat it again and quenced in oil then tempered. Used the revolver for several years afterwards with no hitches. Sold it when I no longer needed it.

Hi Gazz:
If you can do it from annealed stock you can then harden and temper it.
The whole trick, when you're torch hardening super tiny stuff, is to avoid burning it.
That requires you to shield it from direct contact with the flame.
Put it in a close fitting piece of pipe with end caps and a bit of paper to scavenge the oxygen (when the paper burns it uses up the oxygen in the pipe, so the part doesn't oxidize when it's hot).
You can also wrap it in stainless steel foil made specifically for heat treating.

When it's time to temper it, put it in your wife's oven.
Temper it for a long time, like two hours or so, and don't quench after the temper.
Do it twice.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

The oven! Why didn't I think of that as I temper knife blades in there? Thanks all for the help!

implmex said:

Hi Gazz:
If you can do it from annealed stock you can then harden and temper it.
The whole trick, when you're torch hardening super tiny stuff, is to avoid burning it.
That requires you to shield it from direct contact with the flame.
Put it in a close fitting piece of pipe with end caps and a bit of paper to scavenge the oxygen (when the paper burns it uses up the oxygen in the pipe, so the part doesn't oxidize when it's hot).
You can also wrap it in stainless steel foil made specifically for heat treating.

When it's time to temper it, put it in your wife's oven.
Temper it for a long time, like two hours or so, and don't quench after the temper.
Do it twice.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Click to expand...

beat me to it, the kitchen oven is the way to go. I will add that I would load the oven up with a few pots and pans to act as a heat sink and help regulate the temp of the oven. Kitchen ovens are not the most consistent.

Marcus,
Wha

implmex said:

Hi Gazz:
If you can do it from annealed stock you can then harden and temper it.
The whole trick, when you're torch hardening super tiny stuff, is to avoid burning it.
That requires you to shield it from direct contact with the flame.
Put it in a close fitting piece of pipe with end caps and a bit of paper to scavenge the oxygen (when the paper burns it uses up the oxygen in the pipe, so the part doesn't oxidize when it's hot).
You can also wrap it in stainless steel foil made specifically for heat treating.

When it's time to temper it, put it in your wife's oven.
Temper it for a long time, like two hours or so, and don't quench after the temper.
Do it twice.

Cheers

Marcus
www.implant-mechanix.com
www.vancouverwireedm.com

Click to expand...

Marcus,
What is the reason for not quenching after tempering? I have quenched parts out of the tempering oven for years and seen no ill effects. Thought I was doing the steel a favor by introducing oil into the micro structure and making it more resistant to corrosion.
I had a customer making shafts for balancing props for drones. He was heating up the 1/8 inch drill rod in the kitchen oven and quenching the annealed bars and thought he was making the shafts stronger. I told him no it does not work that way. He insisted that it did make them stronger. To prove him wrong I did an experiment with annealed 1/8 water hard drill rod and sure enough it did make the drill rod more resistant to bending. He knew because he straightened them after his "tempering".

Sheet spring steel always has a grain.....never bend a spring across the grain........sometimes you have to etch the steel to see the direction of the grain.

Check this out

Thanks for sharing!
I need to make a couple of springs!