Most Recent Program Information
November 2024 Program
Program by Charlie Rhoads on making cabochons.Charlie has been making cabs for many years, and continues to buy and accept materials.
He stated that if he used up all the material he already has, he would have to live another 2 or 3 lifetimes!
He showed us the different stages with samples. He had a piece of rough Blue Sheen Moonstone, with a slab he had cut from it.
A stencil with ovals, circles and other shapes is laid on the slab. A felt pen or an aluminum pen is used to mark the slab. (Felt sometimes washes out.)
To begin grinding the slab, an 80 grit wheel is used while it is spinning toward the person. Water is a must while grinding, and the stone edge is held at an angle on the wheel. The flat edge is worn down to a relatively smooth surface. It is important to not put the sharp edge on the wheel, as it would remove the diamond grit and the wheel would wear out quickly.
Some things to consider: Wear a waterproof apron! Use a loupe to study the stone during various stages to see scratches. The bigger the number of grit, the finer the grit. 280, 300, 600 are good for grinding. 14,000 to 50,000 are used for polishing.
The process is very addictive so be sure you really want to start this activity!
Practice, practice, practice makes the process easier. Charlie had 2 books he used when he was beginning this hobby.
- Gemstones of the World by Walter Schumann
- How to Use Diamond Abrasives to Cut Gemstones. He is an experienced cabber so he no longer uses the books. Talking to other people who cab can improve the method.
The polishing process uses different techniques. A leather, felt, or canvas can be used. Tin oxide and silicon carbide are two polishing agents to use. Each cabber uses his own methods.
Charlie has a drip valve set up above his machine at home, and he adds dish detergent to allow for a smoother polish.
Some people hold the stone with their fingers (carefully! Charlie has a few scars from his work). To polish small stones, a dop stick may be used. Charlie makes one from aluminum nails with a tiny drop of super glue on the end. The stone is attached there.
To remove the stone, it can be soaked overnight in nail polish remover, or (being careful again) wearing a protective glove while using a torch can heat the glue until the stone drops. Any remaining glue can be polished out.
The shop in Waynesboro has 6", 8", 9", 14" and 24" saws. Charlie and Jack are onsite to demonstrate the use of these, as well as the cabbing & polishing equipment. All are safe to use. Loose clothing should not be worn, and long hair needs to be tied back. Safety glasses & aprons are needed.
THANK YOU Charlie for this interesting and informative program.
For further study, this link leads to a video tutorial by one of the instructors at The William Holland School on all the techniques and steps for making cabochons: https://www.youtube.com/watch?v=raK4F0G9Tg0
The summary of the video is: “This video demonstrates how to cut and polish a cabochon from a new type of wonderstone. The instructor, Larry Kirby, walks viewers through the process, starting with marking the stone and cutting it on a saw. They then move to the cabbing machine, where they shape and polish the stone using various grits of wheels.”