Making springs

[tom in nc]

For the novice, (first attempt at spring making), who might not be a good judge of the proper color to stop at when applying the heat, is it true that the proper temp is when a magnet will no longer stick? I saw one builder who believed it to be true and tried holding his spring with a magnet white hearing it but the magnet crumbled from the heat. Thanks.

 

[Justin.P]

You can use a magnet to determine if simple carbon steels have reached the Curie point, but the Curie point may not correlate exactly to the temperature to transform to austenite.
But it's probably close enough to harden steel for a spring.
You don't leave the magnet on the steel while heating. Touch it to the steel briefly when you think you are getting close.
After quenching you will have to temper it too.

 

[Sam squanch]

Brownells had a product call Temp-I’ll-Lac…. I think…. It was a “ paint” you put on your item to be tempered and melted or changed color when your desired temperature was reached? I know I’ve seen it!

 

[painter]

Also available in stick form TEMPILSTIK TEMPERATURE INDICATORS - Railroad Tools and Solutions, Inc.

 

[rchas]

this picture was helpful to me when I started working on springs. To anneal, heat to bright read and cool slowly. To harden, heat to bright red and quench. To. temper, heat to blue and quench.

 

[rich pierce]

I sacrifice a piece of steel to learn what works. Cut off a piece the size of a nail. Heat till it’s very bright red and quench in warm canola oil. Test with a good file. If it slides and doesn’t cut, then repeat that eyeball temp and quench with the spring.

Too soft? Heat to orange and quench in warm canola oil. If not good, repeat tests quenching in water. To be sure it’s as hard as can be, when you’ve got what you think will work with eyeball heat and quenching medium, clamp it in a vise with an inch sticking up. Wang at it with a hammer, directing the blow sideways and having a clear down range path. It should snap right off.

 

[ZUG]

When using a magnet to test when to quench MOST harden able carbon steels is to heat a bit more when the magnet does not stick to the steel then go quickly into warn Canola oil (heated to about 125 degrees). Move the steel briskly around in the oil until warm to the touch then go into the tempering process. To my eye the hardening temp color is orange/red - salmon color. My tempering color is silver-blue to gray. If you overshoot the color then just start over - better to be too soft than not enough temper color and break the spring. My favorite spring steel is 1075. Your milage may vary

 

[LongWalker]

For the novice, (first attempt at spring making), who might not be a good judge of the proper color to stop at when applying the heat, is it true that the proper temp is when a magnet will no longer stick? I saw one builder who believed it to be true and tried holding his spring with a magnet white hearing it but the magnet crumbled from the heat. Thanks.

Among my teachers, the "traditional" set up was a speaker magnet (one of those round magnets from a car radio speaker works well) suspended on a piece of fine wire. When the metal is red transitioning to bright red, we'd hold it near the magnet. The magnet would deflect toward the steel, and we'd continue heating and repeat the process. When the magnet would no longer deflect toward the hot steel, it was time to quench.

 

[LRB]

The Curie point and non-magnetic point with simple steels is 1414°f and far too low for a good austenic solution. Especially, with hyper-eutectic, those above .8% carbon simple steels, such as 10xx types, your target heat should be in the range of 1475°f, but not much over. Hypo-eutectic steels respond well to the same but can take a little more heat with no concerns. Common table salt melts at 1474°/1475°. You might manage a way to put that fact to use such as taking note of color at that that temp under a certain predetermined level of light or some other of using it as a gauge. I agree with ZUG that if by color you should just go orange. Red orange is good. Quench in warmed canola oil and don't skimp on the amount of oil. As for temper, the ideal temp is 725°f/750°f. There is NO color at that temp. The steel is gray, which makes it difficult with no oven or thermostat to monitor. If you have access to a temp controlled lead pot, molten lead is a great way to temper springs