Making Springs

[Doug MacQueen]

Ok to kick this off here are some pictures I took when a made my first and so only black powder gun mainspring. It was made from 1075 carbon steel flat plate, probably from Brownell's. This is a high carbon steel suitable for spring making. It is supplied in an annealed state, meaning it is soft enough to file and bend into shape. Not shown is how I hardened it it the metal furnace. I used this because the heating was more uniform than using a torch. I brought the steel spring up to a red hot and then quenched it in oil. How hot is hot enough? It is difficult for a beginner to determine by eye the proper redness to bring to the steel. So we cheat by using a magnet. There are 2 pictures of a pencil magnet mounted in a piece of tubing. Quenching the steel should occur at what is called the "critical" temperature. Identifying this temperature is easily done with a magnet, as the steel loses its magnetic property at this temperature. Going far above this temperature is detrimental to proper hardening. Not reaching critical temp is equally bad. Since the springs are small they lose heat quickly, slightly overheating is required so when the steel hits the quench its at the right temp. The problem with using the magnet is that both the magnet and the spring must be securely held so the magnet can be easily swiped against the spring and not stick together. Also the weaker the magnet the better.