Taking the Next Step in Your Lapidary Journey

If you've been cutting stones by hand using sandpaper, or trying to shape cabochons using a rotary Dremel tool, you already know the limitations of those methods. The process is slow, the polish is often inconsistent, and achieving perfect symmetry is nearly impossible.

Moving up to a dedicated cabochon machine (often called a "cabbing machine" or "arbor") is a major milestone for any lapidary artist. These machines feature a single spinning shaft loaded with 4 to 8 grinding and polishing wheels of progressively finer grits. They allow you to take a stone from a rough pre-form to a glossy, finished cabochon in a matter of minutes, moving seamlessly from left to right across the machine.

However, with prices ranging from $1,000 to over $3,000, choosing the right machine is a significant investment. This guide will break down the crucial features you need to consider.

1. Choosing the Arbor Size: 6-Inch vs. 8-Inch

The most fundamental decision you will make is the diameter of the wheels the machine uses.

The 6-Inch Machine (The Hobbyist Standard)

Machines that use 6-inch diameter wheels (like the CabKing 6" or the Diamond Pacific Genie) are the industry standard for hobbyists and jewelers.

  • Pros: They have a smaller footprint, use less water, and replacement 6-inch diamond wheels are significantly cheaper than larger sizes. They are perfect for cutting standard pendants, ring stones, and earrings.
  • Cons: The curvature of a 6-inch wheel is tighter, meaning it can be slightly harder to cut perfectly flat surfaces on the backs of your cabochons.

The 8-Inch Machine (The Production Workhorse)

Machines utilizing 8-inch wheels (like the CabKing 8" or the Diamond Pacific Titan) are favored by production cutters and those working with large specimens.

  • Pros: The larger diameter means a flatter cutting curve, making it much easier to shape large belt buckles, bolo ties, and massive display cabs. Additionally, the wheels are spaced further apart, giving your hands more physical clearance from the splash guards.
  • Cons: The machines are massive, extremely heavy, and require a dedicated, sturdy workbench. When it comes time to replace the wheels, 8-inch diamond wheels are very expensive.

2. Wheel Configuration: Hard vs. Soft

A standard 6-wheel setup is carefully designed to take you through the entire lapidary process without having to stop and change belts.

The Grinding Stage (Hard Wheels)

The first two wheels on the left side of the machine should be hard diamond wheels (usually 80-grit and 220-grit). These are steel wheels with industrial diamond electroplated to the surface. They are aggressive and are used exclusively for shaping the outline of the stone and grinding the initial dome.

The Polishing Stage (Soft Wheels)

The remaining four wheels should be soft resin wheels (typically 280, 600, 1200, and 3000-grit). These wheels have a thick foam backing beneath a layer of diamond-impregnated resin. When you press a stone against a soft wheel, the wheel compresses slightly, wrapping around the curved dome of the cabochon. This ensures a smooth, scratch-free polish without grinding flat, geometric facets into the curve of your stone.

⚠️

Important: Never press sharp edges or corners of rough rock into your expensive soft resin wheels. The sharp stone will gouge the resin and destroy a $100 wheel in seconds. Always round off sharp edges on the hard steel wheels first.

3. Water Delivery Systems

Because you are grinding rocks containing silica, you must cut wet to prevent inhaling toxic rock dust and to keep the diamond wheels from overheating and melting. How a machine delivers this water is a major differentiating factor between brands.

The "Geyser" Spitter System (Diamond Pacific)

Machines like the Diamond Pacific Genie use a mechanical spitter beneath the wheels. A tray of water sits under the machine, and spinning paddles splash the water up onto the wheels.

  • Pros: No plumbing required. Extremely reliable.
  • Cons: You are recirculating dirty water. The sludge built up in the tray can carry coarse grit onto your fine polishing wheels, potentially scratching your stones. You must change the tray water frequently.

The Fresh Water Drip System (CabKing / Covington)

These machines feature small, adjustable nozzles positioned above every single wheel. A water pump (usually sitting in a clean 5-gallon bucket next to the desk) pumps fresh, clean water through the nozzles onto the wheels. The dirty water drains out the back of the machine into a separate waste bucket.

  • Pros: You are always using fresh, clean water, eliminating the risk of cross-contamination between grits.
  • Cons: Requires managing two 5-gallon buckets (one clean, one dirty waste) and relies on an electrical water pump that can occasionally clog.

4. Top Brands to Consider

If you are buying new, you will likely choose between a few industry heavyweights:

  1. CabKing: Currently the most popular choice for modern lapidarists. They offer excellent direct-drip water systems, powerful motors, and bright LED task lighting built directly into the hood. They offer excellent value for the money.
  2. Diamond Pacific (The Genie): The legendary American workhorse. They are built like tanks and use the mechanical spitter system. While more expensive and lacking some modern features (like built-in lighting), many 30-year-old Genies are still running perfectly today.
  3. Highland Park / Covington: Excellent, heavy-duty machines often favored by professional shops. They tend to have very sturdy, industrial builds but take up significant space.

Whichever machine you choose, upgrading to a 6-wheel cabbing arbor will radically transform your lapidary experience, turning hours of frustrating hand-sanding into a fluid, meditative, and highly productive art form.