Hardening Springs without a workspace

[TobJohn]

I want to try making some springs but I live in a rented space with a small backyard/driveway to work from. What are some good solutions for hardening springs without damaging or permanently altering the property? Do I get a couple of bricks stack them into a little furnace whenever I need to make a spring? Will a propane blowtorch be hot enough? Or is it just better to wait until I move to a different place?

 

[sussexmuzllodr]

Try a hardware store mini tank of mapp gas. It,s hotter than propane. Or use two propane torches dependant on your size of work. That should get you up to high enough temps.

 

[rich pierce]

A makeshift brick “oven” and 2 wide tip propane torches will even braze small stuff. I do it often. Just takes time to come up to temp.

 

[TobJohn]

Excuse my ignorance, but why two torches? Is it to increase the heat or increase the surface area that can be heated?

 

[rich pierce]

Twice the BTUs being delivered.

 

[Red Owl]

It is a two step process. First, you need a high carbon steel. It needs/should be annealed to bend and form it to shape. Now heat it a dull red, The forge of bricks isn't required and if you heat to a yellow you might burn out all the carbon. Okay....so dull red(this depends on the light- if a dark room it might be more of a brighter red.) Quench. It is supposed to be oil but you can get a flash fire so just use water. This gets the steel brittle hard and you want to take off some of this hardness so immediately scrub/ sand the spring to get a bright shiny area and slowly reheat to a purple to bright blue and quench. You will see the color spectrum in the shiny area as you heat- wait for the purple to start turning blue. Should come out as a spring.

 

[TobJohn]

It is a two step process. First, you need a high carbon steel. It needs/should be annealed to bend and form it to shape. Now heat it a dull red, The forge of bricks isn't required and if you heat to a yellow you might burn out all the carbon. Okay....so dull red(this depends on the light- if a dark room it might be more of a brighter red.) Quench. It is supposed to be oil but you can get a flash fire so just use water. This gets the steel brittle hard and you want to take off some of this hardness so immediately scrub/ sand the spring to get a bright shiny area and slowly reheat to a purple to bright blue and quench. You will see the color spectrum in the shiny area as you heat- wait for the purple to start turning blue. Should come out as a spring.

When you say the bricks aren’t required, does that mean that I could hold the piece up with some sort of tongs and just blow torch it?

 

[TobJohn]

I have the track of the wolf book on making springs. The workspace is the primary concern. Preferred methods of tempering are also greatly appreciated because those seem to be widely varied.

Are there any issues with using a machinist vice to help form the spring? I know direct heat can damage the hardening of tools, but does that apply to a vice, or would the heated spring not be hot enough to damage the vice?

 

[rich pierce]

Dull red will not work to harden anything decently. Water quenches can over-stress many steels. There’s lots of room for multiple failures here. I’d not rely on a forum for a consensus that will lead to success.

Know your steel and what temp and quench medium is best for hardening. Use whatever means you need to get that temp uniformly. Then TEST FOR HARDNESS BEFORE TEMPERING.

A torch tempering using colors as a guide will work with very thin springs and result in a lot of broken springs on thicker stock. Use a long soak at the right temp to give a good spring for your steel.

 

[longcruise]

I’d not rely on a forum for a consensus that will lead to success.

Thats excellent advise for many many things.

I've gotten good advice on many things in many forums but separating the wheat from the chaff requires great care.

 

[TobJohn]

Thats excellent advise for many many things.

I've gotten good advice on many things in many forums but separating the wheat from the chaff requires great care.

Variety is the spice of life. Sometimes that spice is a lot of broken springs…

 

[LRB]

Twice the BTUs being delivered.

Just using propane with a MAPP torch unit will do almost anything that MAPP gas will do. Mapp gas is only a little hotter than propane. It is more the torch unit than the gas that counts. MAPP torches are a bit expensive compared to the common propane torches, but by not having to buy MAPP gas will take you ahead cost wise, and you can still use the MAPP torch as you would the propane torch. MAPP gas max heat is 3730°f. Propane is 3600°f. But also, yes on the bricks.

 

[ZUG]

Making a spring takes a good deal of time and the last thing I want to end up with is a broken spring that I will have to remake and possibly break again. You MUST know the spring steel you are using and its hardening temps along with its tempering temperature. The technique of applying the heat for hardening and tempering should be consistent and accurate. Just using a torch and your eye to guess temperatures is asking for failure. Yes - I know it has been done this way for a LOT of years in the past BUT how many broken springs have been tossed in the scrap heap BEFORE it was perfected?

 

[TobJohn]

Making a spring takes a good deal of time and the last thing I want to end up with is a broken spring that I will have to remake and possibly break again. You MUST know the spring steel you are using and its hardening temps along with its tempering temperature. The technique of applying the heat for hardening and tempering should be consistent and accurate. Just using a torch and your eye to guess temperatures is asking for failure. Yes - I know it has been done this way for a LOT of years in the past BUT how many broken springs have been tossed in the scrap heap BEFORE it was perfected?

Because I am a newbie, I was planning on buying spring stock from McMaster-Carr, to avoid some of the potential guess work and keep possible errors to the user.

 

[LRB]

Dull red will not work to harden anything decently. Water quenches can over-stress many steels. There’s lots of room for multiple failures here. I’d not rely on a forum for a consensus that will lead to success.

Know your steel and what temp and quench medium is best for hardening. Use whatever means you need to get that temp uniformly. Then TEST FOR HARDNESS BEFORE TEMPERING.

A torch tempering using colors as a guide will work with very thin springs and result in a lot of broken springs on thicker stock. Use a long soak at the right temp to give a good spring for your steel.

JUST FYI, not necessarily nor even recommending for spring making, but a brine quench rather than water will make the steel even harder than water alone. one to two Rc points more. It is much less violent in the quench and also less likely to cause cracks and breakage, however, it still carries some risk. Brine is the only way I harden 1095 fire strikers with confidence that they will not crack or break and yet be as hard as possible. The salt in the brine solution is instantly drawn to the steel and prevents the formation of a vapor jacket around the steel piece, which is what causes cracks and breaks by uneven cooling. Your part also comes out clean. One common of box of salt, 26 oz , and two gallons of clean water warmed to about 100°. I would suggest a trial run on scrap before risking a piece you have put a lot of work in. If I were making a few strikers at a time, I would make the brine in a metal 2 gallon bucket, heat to hot but not finger burning hot, then drop the red-orange strikers in one at a time and then temper them at about 300/320°f. Had some crack in water, but never in the brine. Bear in mind, this is just FYI in case you ever want to experiment and is only concerning water hardening rated steels such as 10xx, W1, W2, and some others.

 

[Erwan]

For what it is worth and nothing more...
I make all my springs (large or small) on six refractory bricks...
I use a small oxygen/propane welding torch with disposable cans for forming (with also tongs, hammers, etc.).
Furthermore, I heat the red steel like cherry very clearly and let it fall, briskly and spin in canola oil till it is cold.
After that, three times, I put the spring in the oil, and I rewarm it at the temperature of the point of the flash of the oil with tempering in oil between each.
The last operation is to make the spring work bit by bit in a vice till it closes normally, then my springs are finished...
That old way of making was taught to me by an ancient springs maker from the armaments' factory in Saint-Etienne about sixty years ago, the only difference is that he used linseed oil, I gave up linseed oil because once cooked by tempering it polymerizes and becomes unserviceable...

 

[Billy Boy]

I have the track of the wolf book on making springs. The workspace is the primary concern. Preferred methods of tempering are also greatly appreciated because those seem to be widely varied.

Are there any issues with using a machinist vice to help form the spring? I know direct heat can damage the hardening of tools, but does that apply to a vice, or would the heated spring not be hot enough to damage the vice?

I have some vise grips, custom made for me in China. They work for this kind of stuff and are disposable.

 

[maillemaker]

Lots of good advice here.

I've not made any springs, though I have attempted heat treating some with seemingly good success, in that they worked afterwards and did not break. Most of my heat treating experience comes from making medieval armour.

I will start by saying that real, modern heat treating is a science and requires known steel and a precision furnace and a known quenchant to get consistent hardening and follow-up tempering.

This is a useful handbook for heat treating:

https://www.secowarwick.com/wp-content/uploads/2017/03/HeatTreatingDataEBook.2011.pdf
However, you can do some basic heat treating pretty easily. You can take a piece of steel, heat it as uniformly as possible with a torch, quench it in plain old water, and then heat it until it turns blue and do a moderately good job of heat treating something.

The earliest recorded recipe for heat treating came from Theophilus the Monk in his 12th century book "On Divers Arts" where he described the making of files. From memory, it basically goes:

"Wrap the files in leather and place in an iron box with pig fat. Heat in the fire until the time fit and then quench in water. Then place the files near the fire until they turn grey."

These guys had figured out, through trial and error, how to do it with very basic materials at hand. So, you can, too.

It's pretty easy to get a reasonable heat treat on a piece of steel. Springs are tricky because they have to be hard enough to function like a spring but tough enough not to break after thousands of bends.

You can easily take a piece of 1075 or 1040 sheet metal, heat it till it glows, quench it in water, and then toss it on a concrete floor and watch it break like glass.

So you can do it without sophisticated setups but in the end you will still have to come up with a consistent way to get consistent results with what you have.

 

[TobJohn]

Lots of good advice here.

I've not made any springs, though I have attempted heat treating some with seemingly good success, in that they worked afterwards and did not break. Most of my heat treating experience comes from making medieval armour.

I will start by saying that real, modern heat treating is a science and requires known steel and a precision furnace and a known quenchant to get consistent hardening and follow-up tempering.

This is a useful handbook for heat treating:

https://www.secowarwick.com/wp-content/uploads/2017/03/HeatTreatingDataEBook.2011.pdf
However, you can do some basic heat treating pretty easily. You can take a piece of steel, heat it as uniformly as possible with a torch, quench it in plain old water, and then heat it until it turns blue and do a moderately good job of heat treating something.

The earliest recorded recipe for heat treating came from Theophilus the Monk in his 12th century book "On Divers Arts" where he described the making of files. From memory, it basically goes:

"Wrap the files in leather and place in an iron box with pig fat. Heat in the fire until the time fit and then quench in water. Then place the files near the fire until they turn grey."

These guys had figured out, through trial and error, how to do it with very basic materials at hand. So, you can, too.

It's pretty easy to get a reasonable heat treat on a piece of steel. Springs are tricky because they have to be hard enough to function like a spring but tough enough not to break after thousands of bends.

You can easily take a piece of 1075 or 1040 sheet metal, heat it till it glows, quench it in water, and then toss it on a concrete floor and watch it break like glass.

So you can do it without sophisticated setups but in the end you will still have to come up with a consistent way to get consistent results with what you have.

Thanks for the book link! I always like to have the background information/science/the "why" for anything I am working on.

Also very cool you make armor! What medieval time period?

 

[Red Owl]

Well, the responses were about what I expected. Listen to Wick (LRB) as he is the only one here that I know- knows his stuff. I was going to suggest brine but from your original question of being in cramped quarters and no space for a big set up- I thought I'd keep it as simple as possible.
I make springs for folding knives and the stress is probably a lot less than than a main spring for a lock on a gun. Actually, I wouldn't suggest a newbie try to make a main spring for a gun lock- buy that.
On the refractory type brick- Wayne Goddard sold a book- the $50 knife shop. It had the one brick forge. I did that, forged blades, etc.- just using a propane torch, in fact that's the set up when I got the blade up to yellow and burnt out all the carbon. But- you don't need to do that. You can hold the metal in thongs and heat with a propane torch although a shelter area of fireproof material in which the metal is placed would probably be better.
In any event I've made springs as I described with propane, no special bricks, just heat as I said. Since brine has been mentioned- use that, This isn't a life and death kind of thing- I hope. Play around with it, on the color, I work in an enclosed area with low light so a heated metal shows more color than in a better lit area. You learn by doing, so try some springs- test until they bend, break, or fail. Quenching to a brittle temper isn't so hard, drawing it until you get to the spring temper, that's what you ought to focus upon. You polish to get the color spectrum.