SPRING MAKING - General Info

Discussion in 'Technical Questions & Information' started by rhmc24, Jan 1, 2017.

  1. rhmc24

    rhmc24 Well-Known Member

    855
    Dec 1, 2010
    Ardmore, OK
    From my files, of possible interest --

    This is about springs you usually have to make because you can't buy a replacement, carbon steel springs, typical in old guns.

    This is not the only way and may not be the best way but it has worked for me for 50 years. Be sure to do some trial runs to gain experience with it before attacking your first serious spring job.

    A few basics:
    1. We anneal or soften steel by heating it to red and allowing it to cool. The usual steel with enough carbon to make a spring will be quite soft. Higher carbon content steel won't get as soft.
    2. We harden steel by heating to red and quenching, by plunging it into water while it is red hot and allowing it to cool there. High carbon steel such as SAE 1095 or clock spring steel is quenched in oil to avoid exposure to breakage in use. I use #30 motor oil, whether high carbon on not.
    3. Tempering makes the spring, reducing the hardness somewhat and makes it flexible. Bringing the hardened spring to 560 degrees Fahrenheit will temper it. Steel changes color with temprature and 560 degrees F is a deep blue. The best way to temper is by using an oven that assures accurate temperature control. Since I don't have one, here are the other ways I do it.

    If you are careful enough with your propane torch you can temper your spring by color. You want the deep heat blue like that seen on heat blued screw heads, etc. After it is quenched and glass hard, you carefully clean it enough to plainly see the bare metal. Then carefully heat it with your torch. preferably in shaded daylight, until it is all the same color of blue. Allow to cool. If it is all the same color of deep blue you will have tempered it. If any of it shows a straw or lighter color it is too hard and will break rather than flex. If the color goes beyond blue to light blue or gray, it will have lost much, most or all of its flex and be too soft and will bend. Mastering this takes some skill, experience and judgment. Experiment and learn.

    I had to temper a mainspring I made for a French wheel lock, about 7" long. After heating and quenching in oil, glass hard, I cleaned and put it into the kitchen oven, set the temp to a bit over its max and hoped for the best. After half an hour I looked at it an found it to be a beautiful blue.

    Most springs up to about 3"+ long, I temper by burning oil. Make a little dish or tray from a food can, cut off to leave the bottom with about half inch of the sides. I beat it to flatten the bottom so oil will not tend to collect around the edges. I set it bridging my vise jaws leaving the bottom exposed. In the little dish I put a half teaspoon or less of #30 oil, put in my hardened spring and heat from below. The heat is with my propane or mapp gas torch to get the oil to vaporize and soon catch fire. Just keep enough heat to make the oil burn off - without allowing your torch flame to touch your spring. When the oil is all burned away, leave it to cool. You then have a spring.

    Tiny very thin springs gave me a problem. I finally got results in tempering by polishing a piece of sheet steel, usually about 1/16" thick, a couple inches bigger than the spring. I place my hardened spring on it and slowly heat it from below till it turns blue. Slowly heating is important so the spring can take on the heat of the sheet it is setting on. My latest use of this was making springs from .030" wire, in a form something like a safety pin, with the center making a full curl, the ends shaped to fit the work.

    Another tempering method for thin springs is to put quarter teaspoon of alcohol in a small dish (maybe a 2" diameter jar lid), set it burning and hold the part in the flame. Alcohol burns with no smoke and its easy to see the color change. Some experiment to gain experience is helpful.

    Some general comments: You can buy carbon steel spring stock from suppliers. I collect carbon steel in the form of old kitchen knives, old files, old carpenter hand saws, most any cutting tools from early 1900s or before. If you use a file as spring stock, be sure to file or grind away all trace of the original file surface. Crosswise scratches, etc, on a finished spring propagate early failure. Cigarette lighters are source of tiny coil springs, at least two different diameters I've found that push the flint up.

    A few simple tests: Grinding on a bench grinder will produce sparks; iron with little carbon throws streaks with a few 'stars', the higher the carbon the more the streaks and the more 'stars'. Try this a few times to demonstrate. Heat and quench a piece of your proposed spring material. If it can be filed, or it will bend and not break, it won't make a spring. Conversely if it gets glass hard and brittle it probably is good for making a spring. Heat, quench and do one of the tempering methods on a piece of your stock as a trial. An example, I had to make a spring almost quarter inch thick. For material I used an old file. To be sure of it I annealed, cut off a suitable test strip, ground off the filing surface, hardened and did my oil-pan procedure (above). It withstood all the tests I could give it. The point of this is that it takes a lot of work to craft a spring and it is a waste if the spring material is not right in the first place.
     
  2. goofy

    goofy Well-Known Member

    Feb 7, 2011
    That's is a good read.
    I just buy spring stock and it comes with all dimensions and strengths.
    Just find the right spring and cut it to length.
    Lazy I am.......
    But when I need a odd shaped spring I will keep your post in mind.
    Thank you.
    Mike
     
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  3. Bill DeShivs

    Bill DeShivs Well-Known Member

    Apr 7, 2006
    rhmc24's methods and mine are similar.
    I make more springs than most people. Most are leaf springs and I make enough to order 1095 steel in 3-6 ft. lengths in all thicknesses up to 5/16". I use canola oil to quench.
    It is important to use a heat-reflecting surface when hardening any larger part, and you must get the entire part hard, before tempering back to spring hardness.
     
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  4. tuckerd1

    tuckerd1 Moderator Supporting Member

    Very interesting!
     
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  5. sharps4590

    sharps4590 Well-Known Member

    Aug 10, 2013
    Missouri Ozarks
    Wow...I'd love to spend a few days at least with you, Bill, Griz & goofy. I really appreciate you taking the time to post that, thanks.

    Give me an old rifle to make a cartridge for and work up the load and I'm pretty much good to go but you guys practice black magic.....:p
     
    goofy, joe45c and rhmc24 like this.
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