Dan_the_DJ

Leaf spring making from mild steel?

Recommended Posts

Hello everyone,

Ive been fooling around with some mild steel scraps I had lying around. Been trying to make steel out of them, by case hardening I believe its called.
Well, Im not really sure, if its true hardened, could it still be called case hardening?? :D

Anyways, it turned out successful so far, for my need of making a few parts for my percussion lock project, dont know the exact terminology...
I reached the point where I need to make the big spring for my lock. So Ive been thinking, since my angle grinder is toast at the moment, and it would be a pain to saw through an old truck leaf spring by hand, could I make a spring by case hardening mild steel?

I shaped and polished the thing, put it into a nice little box made from scrap rusted iron plates, filled with charcoal, flour and salt mix, and sealed the whole thing with plaster of paris(Its a little tricky, but it worked fine for me so far).
While Im waiting for it to dry, I was wondering, what are your thoughts on this?


Has anyone tried making a spring this way?

Also, when I do indeed make the spring, be it from this project, or from a decent piece of spring steel and quench it, I would need to temper it of course. And since I had, lets say, a few unfortunate situations with the kitchen oven and not the best of luck with color tempering, I wanted to try a different method for my temper on this one.


 I recently started learning soldering, brazing and all that fun stuff, so It occured to me to try and use some of those solders as a tempering medium. Different alloys of lead and tin have different melting points, so In my head, I figured, I can heat up this mixture, and as soon as it melts, I drop my spring in and then just keep it there, maintaining the temperature as best I can.
But, given that stuff is rather expensive to buy in quantities I need, I wanted to know if using pure tin or lead can cut it?


Pure tin would be to my understanding too cold as a medium, with a melting point of 232c/450f, it might be fine for knife making, but no bueno for springs.


While Im at it, would pure tin, or something else with that similar melting temp be good for tempering knives?

It would really mean a lot, given Im banned from the kitchen now, and I really suck with tempering by color, and I dont really trust it to be honest.


Pure lead on the other hand, melts at about 328c/622f, so that might be a bit too much for me?
I really dont know, I have no clue, been searching the net for a while now and I found out that lead is used to heat things up to critical temperature, prior to quenching, but I wanted to ask if someone has experience with using tin/lead alloys for tempering?

I hope you can separate some time to answer these questions, I want to know if its worth it wasting time on this case hardening, and more importantly to me, using tin/lead for my tempering...

 


Thank you all, have a nice day, cheers!

Share this post


Link to post
Share on other sites

not a good idea to use lead to  heat up to quenching temp, you need to read different material, there is a long post about heat treating at the top of the page I already wrote so I wont repeat it here.

Share this post


Link to post
Share on other sites

First of all: yes it can be done.

Have you read up on making blister steel?  A historic method of making real wrought iron into steel through "excessive" case hardening.

How many hours are you going to keep it at heat to soak in the carbon?

Plaster of Paris starts degrading around 800 degF below the temperature you will need to maintain. Traditionally clay was used for luting.

Steve the melting point of lead is quite low; the boiling point of lead is over 3000 degF. The problem is:  how do you know the temp your molten lead is at?  

Also the amount of vaporized lead fumes increases with the temperature and such fumes are EXTREMELY TOXIC and will condense on stuff nearby. I don't know your age but may I point out that it's a reproductive toxin as well as being a neurotoxin for kids?

Have you read up on the traditional methods used to temper gun springs?  (Like burning off the oil?)

Yes you could find an alloy that melts at just below the correct temperature; but why not use the old machinists pan of sand to temper it.  More control of the heating rate and very low in the stupidity index.  (I went to college with a fellow who spilled molten lead on himself---great adjunct to halloween! Though he said it was not much fun at the time...) 

Share this post


Link to post
Share on other sites
58 minutes ago, Dan_the_DJ said:

 

Ive been fooling around with some mild steel scraps I had lying around. Been trying to make steel out of them, by case hardening I believe its called.
Well, Im not really sure, if its true hardened, could it still be called case hardening?? :D

Anyways, it turned out successful so far, for my need of making a few parts for my percussion lock project, dont know the exact terminology...

Also, when I do indeed make the spring, be it from this project, or from a decent piece of spring steel and quench it, I would need to temper it of course. And since I had, lets say, a few unfortunate situations with the kitchen oven and not the best of luck with color tempering, I wanted to try a different method for my temper on this one.

Trying to make steel out of Mild steel ? It is already steel, so what you are doing is starting the process of  case hardening (carburising) the existing material by adding carbon to its external surface, you then have to rehat and quench to harden the external surface, and that surface then is normally a wearing prevention surface, and does not make the mild steel into a spring steel.

To temper items you have to first harden them and that usually requires a carbon steel.

If you are going to use a molten bath to uniformly temper that hardened steel, it will depend on the use for the spring.

For watch springs historically we use 48 parts lead to 4 parts tin,  and for more heavy duty springs you can use boiling Linseed oil. Both of these methods are highly risky and can be downright dangerous, I would suggest using other methods that can be found elsewhere in the forum as Mr Sells has already suggested, or consult your local blacksmith group

Share this post


Link to post
Share on other sites

ok I stand corrected didnt realize lead boiled so high, but I was only thinking about melting temp because of his budget limits, I have no clue how he will know exact temp otherwise.  still I would worry about lead vapors and avoid using lead for heating

Share this post


Link to post
Share on other sites

I've made case hardened springs in the past..  If you can't forge very well but understand the process of carborizing, quenching and then tempering it can work well enough depending on the spring size and amount of pressure in the spring.. 

In the way back I made a hammer spring for a musket by case hardening it.. It needed almost no temper at all.. 

If making springs the hardening and quenching, then re heat to the iron smokes /flashes and then quench again 3 times works well and needs no color.. The idea is solid and have used this many times.. 

The other ways to do it can be a little tricky like using a lead bath for tempering or using a sand bath over a plate heated on the forge.  

I prefer the oil burn off method and it works very well.. 

I've maybe made 10 case hardened springs and the last 1 I made is still in use on a muzzle loader but the guy only shoots for fun now.. 

I also made a few springs for revolvers (cap and ball) an the last one I made was a little to heavy so damaged the hammer and the nipples didn't last as long.. 

There is a process of fining the spring to get the right amount of pressure out of it.. I can't remember what the exact term is now..  This is where you thin the spring down till it has the exact properties you want.. 

I was making springs with no reference or to copy.. 

Share this post


Link to post
Share on other sites
1 hour ago, ThomasPowers said:

First of all: yes it can be done.

Have you read up on making blister steel?  A historic method of making real wrought iron into steel through "excessive" case hardening.

How many hours are you going to keep it at heat to soak in the carbon?

Plaster of Paris starts degrading around 800 degF below the temperature you will need to maintain. Traditionally clay was used for luting.

Steve the melting point of lead is quite low; the boiling point of lead is over 3000 degF. The problem is:  how do you know the temp your molten lead is at?  

Also the amount of vaporized lead fumes increases with the temperature and such fumes are EXTREMELY TOXIC and will condense on stuff nearby. I don't know your age but may I point out that it's a reproductive toxin as well as being a neurotoxin for kids?

Have you read up on the traditional methods used to temper gun springs?  (Like burning off the oil?)

Yes you could find an alloy that melts at just below the correct temperature; but why not use the old machinists pan of sand to temper it.  More control of the heating rate and very low in the stupidity index.  (I went to college with a fellow who spilled molten lead on himself---great adjunct to halloween! Though he said it was not much fun at the time...) 

Yes, Im familiar with that method, we even talked about it briefly at my university. In fact, that might be the reason I even tried messing with this in the first place...

Hours, I dont know how many would the spring need, Ive been using this only to case harden some throwing knives and spikes made of rebar. But as you said, plaster tends to degrade, so I make it a bit thicker, that way it can withstand about an hour with no visible cracks. I havent soaked anything past one and a half hour, because there was no need, was working with very small or thin parts, 15x20x6mm for the lock parts and I only hardened the pointy end of each knife. Now, I dont know how deep the carbon diffused into the metal, but for those parts, it was good enough, I need to check that next time...
About the lead, yes, I was referring to its boiling point, in this video, the gunsmith uses boiling lead, to evenly heat his springs and then quench in oil, after he proceeds to temper them on an iron plate over the coals...
heres the video 

About that boiling point though, I guess he just eyeballed it, I mean, the whole thing is eyeballing it from the start, he says it himself. I guess having tons of experience helps too :D

Lead is extremely toxic, I know that much, Im having trouble being near it when its only molten, let alone boiling. Dont worry about that, Im doing it in a special place, with lots draft and open space.

I have read some articles regarding gun spring rempering, but still, lead or tin just feels like the easiest thing to do, not to mention it cant catch on fire, we dont want that!
I will get banned from forging altogether :(

I could try that pan of sand, Ive seen another video where a guy takes a pan and fills it with brass filings to heat blue a set of clock hands, the color was phenomenal.

Thank you for your help, I will post my results, if there are any. If not tomorrow, then the day after, cheers!

Share this post


Link to post
Share on other sites
2 hours ago, John B said:

Trying to make steel out of Mild steel ? It is already steel, so what you are doing is starting the process of  case hardening (carburising) the existing material by adding carbon to its external surface, you then have to rehat and quench to harden the external surface, and that surface then is normally a wearing prevention surface, and does not make the mild steel into a spring steel.

To temper items you have to first harden them and that usually requires a carbon steel.

If you are going to use a molten bath to uniformly temper that hardened steel, it will depend on the use for the spring.

For watch springs historically we use 48 parts lead to 4 parts tin,  and for more heavy duty springs you can use boiling Linseed oil. Both of these methods are highly risky and can be downright dangerous, I would suggest using other methods that can be found elsewhere in the forum as Mr Sells has already suggested, or consult your local blacksmith group

Im sorry, English is not my native language, and my terminology is all wrong.

I meant making high, or higher carbon steel out of that piece of mild steel.

And Im quenching right out of the crucible, while the steel is still red hot from the carburising process. It saves me a step of reheating.

By spring steel, I meant steel that is spring tempered I believe its the term?

Usage wise, the spring Im making is for a mainspring of a musket, and I would very much like to know the Sn to Pb ratio for this kind of spring, If youre familiar with that.

Sadly, there is no blacksmith community anywhere near me, its a frowned upon craft in my general area even, dont get me started on that, its that sad -_-

Thank you for your help, I will do some more research on the forum tomorrow.
 

Im reminding ya all this is but an experiment, I will eventually use a proper spring steel for this purpose, I just want to go about and try to make it this way, compare the results later.
 

59 minutes ago, Irondragon Forge & Clay said:

Welcome to IFI...have you read this yet?https://www.iforgeiron.com/topic/53873-read-this-first/

 

Im so sorry, Ive read it now.
 Hope everything is alright?

P.S. Ive just learned how to do multiple quotes in one answer, sorry. :rolleyes:

Edited by Dan_the_DJ

Share this post


Link to post
Share on other sites
2 hours ago, jlpservicesinc said:

If making springs the hardening and quenching, then re heat to the iron smokes /flashes and then quench again 3 times works well and needs no color.. The idea is solid and have used this many times.. 

Im not sure I understand what you described here...

Again, Im not a native English speaker, so bear with me.

The other things I understood quite well, thank you for the help.

I am too making this as I go along, the only measurement I have is to fit the thing in the lock when its finished.

Cheers!

Share this post


Link to post
Share on other sites

Every thing is fine and no need to apologize. I have made muzzleloader v main springs out of "mystery steel" in the past. Take a small sample of the steel and heat it to critical non-magnetic, quench in water than see if it will snap off a small section when hit on the anvil edge with a hammer. If it snaps off the steel has enough carbon to make v springs. Make the spring and heat it to non magnetic and quench in oil to harden it. Then temper it in melted lead till the lead no longer sticks to it. That's how I do it.

Share this post


Link to post
Share on other sites

Could be worse; you could have asked about doing fire gilding where you make an amalgam of gold and mercury and apply it to the iron/steel and then drive off the mercury with heat.  We call it a "disposable apprentice technique". OTOH I actually knew a fellow who did it safely!  He had access to a mercury scavenging hood  and all the correct industrial grade ppe!

Folks all this modern muzzleloading musket stuff is way to recent for my book collection; but I know there are good books on building them out there.  Some suggestions please?  (I have a matchlock and a wheellock and abjure the fancy modern flintlocks!)

Share this post


Link to post
Share on other sites
11 hours ago, Irondragon Forge & Clay said:

Take a small sample of the steel and heat it to critical non-magnetic, quench in water than see if it will snap off

Thus the proper answer.

I can't understand any reason to use case hardened mild steel for a spring. the availability of high carbon steels is just too easy to come by from flea markets to dealers.

And the best reason? well imagine using a substandard steel with a less than millimeter thick layer of an unknown amount of carbon impregnated steel standing between you and an angry charging bear,,,  ;) I'd rather use a rr spike.  :)

Spring steel should be a 1095 high carbon steel. I have an armload of potato planter belt that's 3/8" round. this acts like 1095 and I treat it as such. Thus I water quench to harden. It makes excellent springs. 

Tom Bredlow recommend flashing gun springs in corn oil to get the correct temper. I believe he flashes it 3 times. If you don't know who he is, he was an early ABANA person and  did 7 gates for the National Cathedral. He is from Tucson.

A great video, and the one that inspired me long ago. I am pretty certain that Wallace Gussler did not use case hardened wrought iron for springs. I do have this vid in my collection but have not watched it in a while, so this is from memory,, forewarned.  ;) He did case harden other items. He would not have used mild steel that did not exist in the period Williamsburg represents.

And lest we forget, if you don't know the temp of melted lead, or a way of maintaining this temp, you ar in the dark. And, case hardening takes a bit more time than an hour or so in an oxygen free environment.  From memory, seems it is 4 plus hours. 

Share this post


Link to post
Share on other sites
48 minutes ago, anvil said:

I can't understand any reason to use case hardened mild steel for a spring. the availability of high carbon steels is just too easy to come by from flea markets to dealers.

I am pretty certain that Wallace Gussler did not use case hardened wrought iron for springs. I do have this vid in my collection but have not watched it in a while, so this is from memory,, forewarned.  ;) He did case harden other items. He would not have used mild steel that did not exist in the period Williamsburg represents.

I understand, its just, I wanted to try making it this way, just for the sake of it, to see what happens, I will make a proper spring from some high carbon piece of steel when I get the chance.

And you are absolutely correct that Mr Gussler wasnt using case hardened springs, they are made from "imported spring steel" as stated by the narrator. A reference to the old days I guess, when people from the colonies imported that stuff from Europe.

Its hard to get commercially available steel in my country, I have to find a dealer who will ship it to me from abroad, and most of the times they either dont do that, or the shipping plus taxes makes the trade not worth it. Or they just dont have what I need in stock. So Im pretty much stuck using mystery steel all the time. :lol:


Thank you for your help, cheers!

Share this post


Link to post
Share on other sites

Dan-the- …,

Is there any source for 'used', watch, or clock, or chronometer springs.  Or better a watch/clock makers supply seller.

All of the afore-mentioned springs are made from spring steel.

Indeed, Mr. Harrison (circa 1743), developed his crucible process for evening out the carbon in steel from high carbon carburized steel.  (usually, Swedish steel). Much of it known as "blister steel".

Good luck in your search.

SLAG.

Share this post


Link to post
Share on other sites

Huntsman not Harrison; watch/clock springs would be way too small for what is needed.

I would start with a spring from a car hood as I expect there are junked cars most everywhere but antarctica these days.

Share this post


Link to post
Share on other sites

Garage door springs and automotive valve springs are other excellent sources. I'm lucky in the tempering of small springs in molten lead, as I have a lead melting thermostat controlled melting pot for casting balls & bullets and a lead thermometer to control the heat.

Share this post


Link to post
Share on other sites
On 11/3/2018 at 9:27 AM, Dan_the_DJ said:

Its hard to get commercially available steel in my country, 

You have the best reason for your making your springs. Because you want to. ;)

I saw where you were from. My Grandfather was from there, and my Grandmother was Croat. Quite the combination. 

I worked in Prague in '87 with a blacksmith. If I remember correctly, the Gypsies can solve your coal and steel needs. If I could, I'd go to your country and find a Smith to spend some time with, and see your countryries beautiful iron. 

 

 

 

Share this post


Link to post
Share on other sites
1 hour ago, anvil said:

 

I dont use coal though. Im working with charcoal, cause I can make it in bulk, or just buy it if Im feeling lazy.
I could try coal, but its a bit more of a hustle for me, and If I change fuels, Ill change to propane, way cleaner in my opinion.
Charcoal served me great so far, Im experimenting with forge welding next, which might prove difficult with charcoal, but should be doable...

The spring was a success by the way, its a bit sluggish, I might replace it with a proper steel spring sooner than I thought.

But I need to complete and fine tune some of the lock parts to see if its usable or not.

I forgot to bring my lead and sand box for tempering, and by the time I remembered I needed them, it was already dark, so I winged it and used the same method mister Gussler used in the video, with a hot plate. It worked like a charm! :lol:

Thanks everyone for the help again, couldnt do it without ya!
 

P.S. Plaster crucibles release sulfur fumes when left in the fire for that long. I learned the hard way... :rolleyes:

Share this post


Link to post
Share on other sites

Plaster of Paris is Calcium Sulfate and degrades way before proper temperatures for forging.

As forge welding of steel has been done for around 3000 years with charcoal and only 800 years using coal and less than 100 years with propane I think that if your forge is properly set up for using charcoal you will be able to forge weld with charcoal.

Share this post


Link to post
Share on other sites

Thomas when did oil fired forges come on the scene? Any good books on the use and construction of oil fired forges?  I know they were in use back in the 20's for sure but assume it was earlier.. 

Share this post


Link to post
Share on other sites

After spindletop.  My library is not as good for this modern stuff.  As for books I would check Naval Smithing books.

Modern Machine Shop Practice does not mention oil furnaces but does say that Gas furnaces are the best---copyrighted 1914

No mention in skimming Practical Blacksmithing indexes (1889,1890,1891)

Oil as a fuel for furnaces is briefly mentioned in The Manufacture and Properties of Iron and Steel, 1896

I'll have to dig deeper later

Share this post


Link to post
Share on other sites

I have another follow up question...

Ive been experimenting with case hardening lately and Ive noticed that thiner sections can indeed be through hardened if left to carburize long enough...

So, my question is, in a certain scenario, if one can not get steel for whatever reason, can said one make a decent knife this way?

Thank you for your time, cheers!

Share this post


Link to post
Share on other sites

Yes and no.    If you can control the depth of the hardness enough and limit the amount of carbon loss while forge welding you can in fact make a blade with good carbon content throughout.. It for sure is advanced technique.  

 The way they did it in the old days is simply to only sharpen the knife on one side.. 

The early settlers in the new world (USA) had blacksmiths and the Indians wanted to trade for goods.. Knives, hatchets and such..  Because of the Human conditions many a settler smith sold case hardened blades to the American Indians.. The Indians soon learned only to sharpen one side of the knife or ax so to retain the fine cutting edge.. 

The best way to do it is to make a high carbon piece  and then weld it to a mild steel or wrought iron backing.. Or just do what the Indians did and sharpen it on one side only.. 

Share this post


Link to post
Share on other sites
9 minutes ago, jlpservicesinc said:

If you can control the depth of the hardness enough and limit the amount of carbon loss while forge welding you can in fact make a blade with good carbon content throughout.. It for sure is advanced technique.  

That is way beyond me sir :unsure:

I was thinking about making the blade blank out of mild steel alone, using stock removal/forging methods, then bringing it to its finished state before HT and then case harden it for a time to allow the carbon to penetrate as deep as possible.

Ive been experimenting with thin pieces of mild steel, which soaked in carbon almost, or all the way through in the "case" hardening process.

I personally dont see a problem doing it like this, maybe, after a number of sharpenings, some of the mild steel might get exposed on the edge making the knife unusable.

Im interested if there could be some other potential problems making a knife like this, like maybe lower overall hardness of the edge, lower thoughness or something like that...

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now