The Metals of Gem Carving by Michael Dyber

Michael Dyber is an internationally acclaimed, award-winning gem carver who creates works from jewelry-sized stones to large-scale sculpture. He has been carving stones for more than two decades and has also designed and fabricated jewelry.

Many metals serve the gem carver. Among the most often used are mild steel, carbon steel, cast iron, copper, brass, sintered steel, and bronze/powdered metal. We'll start with a look at the potential uses and drawbacks of mild steel as a material for carving tools.

Mild steel: Also called common steel, mild steel by definition has a carbon content of less than 0.2% by volume. Because it is easily shaped, wears quite well, and holds an abrasive well enough, mild steel is well suited for gem-carving tools. It is also readily available and inexpensive, making it still more attractive, especially for those starting out. I made my first tools from mild steel I bought at my local hardware store - in the form of nuts, bolts, and common nails.

Once you've obtained these “tool blanks” from your own local hardware store, you can start to shape them into carving tools in a vast number of shapes and sizes. Start with the nails because you'll be able to make tools out of them quickly.

Carefully saw off the points on the nails. Do not cut the points off with wire cutters, as this would deform the shank, which must be kept round. Remove any bur left from sawing, and then install the “blank” into your carving chuck.

Turn on the motor and use a file to shape the nail head into whatever shape you want. This may take a little practice, but it's not hard or time consuming. The goal is to make the tool as smooth-turning as possible.

Making tools from carriage bolts takes more skill, but the range of sizes is greater. Carriage bolts offer a good section of smooth shank, which is what you'll be putting into your machine chuck. As with a nail, start by sawing off the bolt head. Once the head has been severed, thread one or more nuts on until you have produced the length of tool needed. Silver-solder the nuts to the bolt.

Next, saw off any remaining thread that is exposed beyond the nuts. Chuck this blank at very slow speed and carefully shape the nuts with your file.

Carbon steel: By definition, carbon steel is steel with 0.2% or more carbon by volume and is commonly known as drill rod. Because of its greater strength, particularly in smaller sizes, compared to mild steel, carbon steel will be one of your choices for the smallest tools you'll produce. It doesn't hold a charge of abrasive as well as other metals do, but it is easy to form and obtain. Just be sure that it is annealed before shaping. Otherwise, it will be very hard to produce the shapes needed and the abrasive will not be effective.

Cast iron works well as a tool metal. Its drawbacks are that it is difficult to obtain in the necessary sizes and it wears readily when used with abrasives. The upside is that it has microscopic openings that tend to trap the abrasive particles.

Copper has traditionally been used for very small carving points. Diamond and copper have a natural affinity for each other that makes charging these tools easy. The reason that more tools are not made of copper is that it wears too quickly: the smallest tools may last for only one or two uses before they are history.

Brass makes wonderful tools, but it should only be used with fine abrasives. Its softness makes it hold the abrasive but also limits this metal's durability. It is readily available in appropriate sizes.

Sintered steel offers the best of two worlds. It's durable and also holds the abrasive well because of pore spacing, which tends to lock the abrasive to the metal's surface. It can also be easily fashioned into tools. The downside is that there doesn't seem to be a supplier in the U.S. and it's expensive to obtain.

Bronze/powdered metal: Powdered bronze mixed with diamond abrasive is a material used as the bonding agent of sintered diamond tools, although it is not used as a tool material directly. The diamond and the powdered metal are combined, pressed into a mold of the desired shape, and then fused together in a furnace in a reducing atmosphere. These tools are the most effective for gem carving. However, they are expensive and, if not used carefully, will wear out prematurely. They can be purchased from several outstanding companies both in the U.S. and abroad.

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