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Making a leaf spring out of a sword


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Well sort of. I need a new spring for my star power hammer. It broke in the middle of a big job, and I presses an early ford front spring into service with the help of a press. Now I need to make a new spring for my hammer. I understand that I can pay a couple hundred bucks and go into the city twice to get one made up, but I see no reason why I should. Spring steel is readily available. I have the tooling to form eyes. That said who knows how to make them? I watched a guy make some years ago for one of my work trucks, but that was long before blacksmithing and I didn't pay close enough attention then. It seems the difficult part lies in the hardening/tempering process. If anyone has any information I would appreciate it.

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Do you have the right set up to heat the entire spring to hardening temp *evenly*? If not think seriously about letting the pro's do it.

Think about the failure modes. Is it possible that any of them would result in your injury? Cost of ER visit/downtime vs cost of professional made spring?

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Besides heating the whole thing evenly to the proper temp, there's the matter of quenching (you'd need a big tank, and a good amount of quenchant). Tempering something that big would hold a couple challenges, too. (But perhaps your shop is much better equipped than mine.) Professionally made leaf springs aren't very hard to come by. I, too, would leave this one to the pros.

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The car spring is not quite the right size and I lost some of the space between the dies. I did find a couple of snippets on the web and don't think this is quite as difficult as you all are thinking. As far as failure, sure it could fail. In fact it has three times. i have welded the spring and re heat treated them (different leaves) It is just so fatigued now that I can no longer keep the spring glued together. I am not afraid to make one, but I would like to talk to someone with firsthand experience first. One of the web things I saw showed them heating to non magnetic and water quenching, with no further heat treating. I suppose I need to find out what steel they use exactly and just look up the hardening/temepering method for it.

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I can see you're not taking the advice of our more experienced smiths. It isn't hard, if you have the right set up. Any inconsistencies in the temper will lead to stress lines and failure. If it has failed 3 times already, you must have good guards in place. How long before they go? I've seen hammers with holes in the guards from the sping going through. You're life isn't worth it. If you don't take our advice, all I can say is test its flex really well before using it. And use it from behind a solid brick wall. I've seen metal snap under tension on the farm. It isn't pretty when it goes. And wear brown shorts because you won't want the stains to show. I would also suggest doing more reading as it seems you either underestimate the danger or haven't read and seen enough to know that it is a danger. You've survived 3 so far. A cat only has 9 lives, how many do you?

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This video might give you a little insight...

http://www.youtube.c...h?v=pO_tEcdgGtg

There used to be a spring shop near here and I watched them make new springs many times. They would heat the end of the spring and turn the eye in a Hossfeld bender, then put the spring on the floor to cool. No heat treat. The springs were put back together and put back on trucks hauling rock or whatever.

They bought their spring stock 'pre arced'. Then they bent them as needed , cold, in a big press.

I have only made new springs for leg vises. I forge and bend hot. Let cool in air and put them on a vise. No breaking.

Go for it, this isn't magic.

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If the spring has broken 3 times I would say your living on borrowed time now. Pay the experts if it fails and ya get hurt sue um. Had a co worker yrs ago in FL Had a 150K boat. Only trailered it 2-3 times a yr. Broke a spring
thought "I can make a new set" 25 miles up the road hit a pot hole. Springs broke rolled the boat. Ins investigator
spotted the springs and would not pay. How much are your parts/life worth?
Ken.

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There's a local rancher who broke his pickup frame and "welded it back up" at least twice more now. I talked to him about HAZ in heat treated items---like a frame.

I do admit to flinching when I see that truck coming down the narrow winding road with the hill on one side and the irrigation canal on the other side...

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We`ve talked about this in other threads,it`s the difference between doing because you`ve seen someone else do it and get away with it and understanding the whys and wherefores of a process or assembly.

I`ve watched people cobble something together that I knew was set up to fail and told them so.They did it anyway and when they flipped the switch it worked and they felt vindicated and successful.
Right about the time they began to feel comfortable with it it failed and hurt them or someone else,sometimes badly.When I reminded them of my predictions the reply was usually along the lines of"Well,nothing lasts forever!".
As they say on TV,"You can`t fix stupid".Some folks just flat refuse to climb out of the numb zone. :(

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If it was me, I would make sure it was annealed very well and uniform and rely on the inherent strength of the steel alone not the temper. Will wear out faster but less likely to shatter although it still can if not done right. I would still not do it because of the danger. You're only 10' tall and bullet-proof until the bullet hits you.

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For starters, I am not a begining fabricator or blacksmith. I do this stuff everyday for my own company. There seems to be a great deal of fear about making a spring, yet watch the video of valley spring making them (and notice the guy not wearing safety glasses). This is the same company that wants roughly $200 for a leaf spring. I think this must be so because there is not a lot of good info on spring making. Essentially it is 5160 steel that needs to be forged at 1200*, reheated to 1200* and quenched (not sure of the quench yet), and the tempered at roughly 800* for 60 minutes (though there is some debate over this as well)(I also might have the details slightly wrong as I am just going off memory). So long as I can find a way to tell the temperature a little better than just color change I don't think this is undoable. Here is a link to the Alcan spring site showing their process. http://www.alcanspring.com/making.htm .
Leaf springs are fairly safe springs, as if a leaf breaks the rest in the pack hold the pack together. The reason mine kept breaking is that it is a 100 year old hammer running the original spring. You can tell by looking at the break that it is fatigued beyond repair. There is also not as much strain on this spring as you might be thinking. Could a spring I make (or anyone else for that matter) break? Sure, which is why we wear PPE and install guards, so I really don't see a huge area of concern.
So, has anyone here actually made leaf springs?

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Well sort of. I need a new spring for my star power hammer. It broke in the middle of a big job, and I presses an early ford front spring into service with the help of a press. Now I need to make a new spring for my hammer. I understand that I can pay a couple hundred bucks and go into the city twice to get one made up, but I see no reason why I should. Spring steel is readily available. I have the tooling to form eyes. That said who knows how to make them? I watched a guy make some years ago for one of my work trucks, but that was long before blacksmithing and I didn't pay close enough attention then. It seems the difficult part lies in the hardening/tempering process. If anyone has any information I would appreciate it.


Hi Andy
I have covered quenching and tempering springs before in the forum, just search for "greasy stick" and go to about the 7th page in, you'll find a post, "I think I need a new heat treater" it will be in there. I also posted some other stuff re spring heat treatment back further, but you will need to search for it. The post was some one wanting to make a leaf spring for a vintage car. If you have any other questions you can PM me direct. Yes I have made leaf springs before,(started my apprenticeship in a shop that only had 2 forge fires and we were making Ford Louiville main leaves, as well as a lot of other truck springs, on a daily basis)


Phil
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So long as I can find a way to tell the temperature a little better than just color change I don't think this is undoable.


I have a nice little non-contact thermometer that works well when I need pretty accurate temps on something that cannot be directly measured (like drying paint or hot iron). You could buy one of these but Phil's greasy stick method ought to get you by without the investment... I mostly use it myself.
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Awalker, it's just that your questions suggest that you're basically clueless about heat treating, and a leaf spring for this application seems a heck of a place to start learning.

Besides that, when I think about what it would take for me to do this -- building a temporary forge that'd allow me to evenly austenitize something the size of a leaf spring, coming up with a sufficiently large quench tank full of oil, figuring out how to temper it in controlled fashion -- and see the way you're sort of breezily shrugging it off, it suggests to me that either you don't really understand the problem, or else you're comfortable with a kind of "call it good" approach that would make me nervous. Maybe you already have furnaces and ovens and quench baths big enough to handle this sort of stuff, but in that case I'd expect you to know a little more about heat treating off the top of your head.


Essentially it is 5160 steel that needs to be forged at 1200*, reheated to 1200* and quenched (not sure of the quench yet), and the tempered at roughly 800* for 60 minutes (though there is some debate over this as well)


1200 is way too cool. At 1200 you're not making any austenite. The Heat Treater's Guide says to austenitize 5160 at 1525 F and quench in oil or polymer. The Heat Treater's Guide also suggests that 46-52 HRC is a good spring temper for 5160. That's roughly 430-515 Brinell. Going from the hardness vs. tempering temp table in the HTG, if you fully harden it, tempering at 800 F should give you a Brinell hardness of a bit over 450. Tempering at 700 should give you a Brinell of a little over 500. So that 700-800 F range is about where you want to temper.

So long as I can find a way to tell the temperature a little better than just color change I don't think this is undoable.


Tempilaq works well. Tempilstiks are a little harder to use. Or go with the greasy stick method (for tempering -- you'll need something else for austenitizng).
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Interesting reading on the greasy stick method. You are right on the forging temperature, my fingers are faster than my eyes, should have been 2100*. Also, I am not taking lightly the heat treating, or making of this spring. I just don't think that it is undoable with what may be in the shop. I built my forge and built it to be expandable for larger jobs. I also have metal tubs and bins that can be pressed into service for quenching, though you are right about the amount of oil required to fill them. As far as knowledge to heat treat, I have done many things in the past, mostly tooling, but just found it difficult to find solid information on leaf springs making.

Here is an excerpt from a data sheet on 5160 that I have showing quench/forging temps


Carbon 0.56 - 0.64
Chromium 0.7 - 0.9
Manganese 0.75 - 1
Phosphorus 0.035 max
Silicon 0.15 - 0.35
Sulphur 0.04 max
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Principal Design Features 5160 is a carbon-chromium spring steel. It exhibits excellent toughness and high ductility, with a high tensile-yield ratio.

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Applications Commonly employed in heavy spring applications primarily in the automotive field for leaf springs.

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Machinability Machining this grade can be very difficult in the "as rolled" condition, and the alloy should be annealed prior to machining to obtain maximum speeds and feeds.

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Welding Weldability is poor in this alloy due to its high carbon and chromium content. For best results, preheat the section and stress relieve after welding. Either gas or arc welding methods may be used.

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Heat Treatment 5160 is normally hardened in oil. Recommended quenching temperature is 1525 F, with a wide range of mechanical available by tempering between 800 and 1300 F.

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Forging Forge this grade between 2100 and 2200 F.

--------------------------------------------------------------------------------
Annealing Heat to 1450 F and air cool.

--------------------------------------------------------------------------------
Physical Data : [top

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  • 3 weeks later...

Why don't you make ONE trip to the spring shop (call them first and see if they can do it while you wait/fax them, email them a drawing and have it done when you get there). Take your old broken spring w/ you. Tell them what you do and ask if you could watch them make you a new one. Make sure to tell them the machine is 100 years old and probably won't need another one in your lifetime, how important it is to you etc. I get springs made here in chicago at a spring shop. They use prearched, treated stock and do all the work cold, bend eyes, punch holes etc. The other option is just buy the stock from them when you go and do it yourself (what I do now)

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