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Welcome to the art of making tools! This section will focus on making Chasing and Repousse´ tools but, once you know how to anneal, harden and temper steel, the tool making possibilities are endless: Think hammers, chisels, bezel pushers, etc.
Steel Qualities and Phases
Steel is an alloy ( a combination of elements) containing iron and carbon, among other metals. Steel is a ferromagnetic alloy. The type of steel that we are concerned with, in making C&R tools, is High Carbon Steel. It is also known as Tool Steel. To be considered High Carbon Steel, the steel must contain at least .90% to 1% carbon . The carbon allows the steel to “harden” – a term we will be discussing in a moment.
Other types of steel will not work for making chasing tools. Those steels are (among others): Mild Steel (0.4% carbon) and Medium Carbon Steel (0.8% carbon). Mild steel and medium carbon steel are not capable of hardening and tempering so, are therefore, not acceptable. Wrought iron has very little carbon so, it’s out too.
Steel is an amazing material and for me to fully understand its chemical properties would require several years of chemistry – among a bunch of other science classes – and that’s not happening. I’ve included links, if you are interested in further research. Warning: it can hurt your brain!
There are three basics steps in making a steel tool:
- Annealing: which “softens” the steel so that it is more malleable and is therefore, able to be altered with files, grinding wheels or belt sanders. Often, purchased steel is already annealed so, when you purchase steel, find out if it is annealed or not. If so, yippee, you can skip this step. But, it is still important to know – especially if you decide to alter any of the tools that you have on hand.
- Hardening: Hardening is necessary to bring back the strength of the steel – after shaping. At this point it is too brittle to use as a chasing or repousse´ tool.
- Tempering: This process makes the steel less brittle while retaining its strength and durability. This is the final heat treating stage of the steel.
Annealing allows the steel to be relieved of any internal stress and softens the metal. This occurs because there is a refinement in its crystalline structure. The iron atoms form a “Face-centered cubic” – whatever that is!
How to Anneal:
- Hold the tool steel lengthwise, with Vise Grips.
Heat the “working end” (the opposite end of where you will hit it with the hammer) until “red hot”
Bury the “red hot” tool in Charcoal and let it cool to room temperature. That’s it – you are done annealing. At this point the tool can be shaped.
To preserve the shape of the tool, the steel needs to be hardened. Otherwise, it will be too soft and will eventually, either mushroom or become distorted through the force of the hammer and contact with the metal you are chasing.
Hardening is achieved by heating the tool until it is “red hot”. It must be heated long enough that it loses its magnetic attraction i.e.: it won’t stick to a magnet. During the red hot phase, all the Ferrite (the part that loves magnets) gets converted to Austenite – which is why it loses its magnetic attraction. If allowed to cool slowly, the atoms and molecules will reform into that cube shape and become “soft” again.
Quenching the red hot steel, changes it again into Martensite. In this form, the steel is brittle but is resistant to scratching and denting.
To be able to temper correctly, you need to know what type of steel you have: A1, W1, O1. This is because each of these steels is designed to be quenched in its applicable medium. When in doubt, use oil for the quench.
Tempering removes some of the hardness of the steel so it won’t be brittle. Yet, it keeps the steel hard enough so that the tool shape doesn’t deform with use. Not tempering your steel can result in splintering – not only damaging your tool put your body parts!
Please see Threeplanes.net for a more complete explanation of what is happening chemically to the steel during this phase.
BOOK and CD/DVD LINKS
Chasing and Repousse´ , Nancy Megan Corwin
The Complete Modern Blacksmith. Alexander Weyger
Lost Books CD: Chasing and Repousse´ . Charles Lewton-Brain (CD)
Metal Techniques of Bronze Age Masters: Eastern Repousse´ and Chasing, Victoria Lansford (DVD)
Moving Metal: The Art of Chasing and Repousse´, Adolf Steines
TOOL STEEL LINKS
Links to common sizes and types of tool steel at Online Metals are:
W1 Square Stock
- W1 square stock: Average diameters: 1/8″, 5/32″ (they don’t carry in W1 square stock – only O1), 3/16″ and 1/4″. You’ll want larger stock for larger tools. Metric sizes: 3.175mm’s, 3.969mm’s, 4.762mm’s and 6.35mm’s.
O1 Square Stock
- O1 square stock: same diameters as for W1. Links are: 1/8″ (3.175mm), 5/32″ (3.969mms), 3/16″ (4.762mms) and 1/4″ (6.35mms).
- Drill Rod – W1: Same diameters as for square stock, although, you might want to go a bit larger for some repousse´ tools. Links are: 1/8″ (3.175mms), 5/32″ (3.969mms), 3/16″ (4.762mms) and 1/4″ (6.35mms).
- Drill Rod – O1: Links are: 1/8″ (3.175mms), 5/32″ (3.969mms), 3/16″ (4.762mms) and 1/4″ (6.35mms).
If you are going to mix O1 and W1 steels, please engrave, on the steel rod or square stock, what type of steel it is so that you will harden the steel correctly.
I recommend purchasing the rod in three foot lengths. Online Metals does not custom cut the three foot rod.
For Further Research
ThreePlanes.net – a lot of information on steel with explanations of what happens in heat treatment and some steel compositions.
***A tip from a viewer: tape the tool with masking tape to help keep chips of metal from cracking off and flying at you. Of course, you should be wearing safety glasses! Another idea is to anneal the hammering end of the tool when it gets too work hardened. I have not had the flying chips scenario occur to me yet but, you never know.