Cutting rough stones is a fundamental skill for a gemstone cutter. As a lapidary, you'll face a myriad of assorted stones: small, large, round, oval, misshapen, raw, and everything in between. As you carve, cut, shape and polish, you'll want to take care to preserve as much of the natural specimen as you can. In other words, cutting gemstones can be very wasteful, but we're going to help you avoid unnecessary waste.
Rough stones are large pieces of natural, uncut materials that lapidary's break and cut into smaller pieces. There are two primary methods for cutting rough stones and a breadth of information involved with each.
Continuing with our Lapidary Fundamentals series, read on as we carve out the fine details of cutting rough stones.
As mentioned, there are two options for how to approach cutting rough stones. The ultimate goal of cutting is to make smaller pieces from large, uncut specimens. In doing so, you can accrue a lot of wasted materials. Here's how you can get the most out of uncut materials.
The most effective method for cutting rough stones is to break the rock with a rock hammer. As you might suspect from the name, the process is quite simple: you take a large, uncut stone, and hit it hard with a rock hammer. We should mention that this method doesn't emphasize precision. Instead, the goal is to make large breaks in rough stones. From there, you can use other tools to shape the smaller pieces.
A kerf enables the lapidary to exercise greater precision and control over the process. Lapidaries cut small, shallow incisions, called kerfs, about an inch deep into a rough stone as a starting point. Then, a chisel or cutting tool stabilizes into the kerf, enabling the lapidary to slam the tool with the rock hammer. After the force of this strategic blow, the rock splits into two separate pieces. Cutting a kerf into a rough stone may result in a clean cut, but that isn't always the case. Furthermore, if you are handling precious materials, you might feel reticent to slam a hammer down into something so valuable. Are there other methods for cutting rough, valuable stones?
Some gemstones are softer and more fragile and require more finesse during the cutting process. Instead of compromising a precious stone like an opal, you can cut delicate gems more gently with saws and nippers.
Once you crack open a rough stone, you'll need tile nippers to remove small bits of material from the edges and crevices of the stone. Fasten the nippers around the area you'd like to remove and squeeze the tool. The pieces will fall from the stone effortlessly and with minimal effort. Nippers are vital aids when cutting fractured gemstones as you can finely cut curved lines along small gems.
A grinding wheel is a tool used for cutting curves into rough stones. However, the utmost care should be placed into grinding fragile stones, which can crumble from the fractures within. Grinders are optimal for durable, resistant gemstones.
One of the essential tools in your studio for cutting rough stones is a saw. There are a variety of different saws you can use to cut rough stones, each designed for specific jobs. Regardless of which saw you use on a given day, one thing is sure: you'll be spending a lot of time sawing gemstones. Time to get familiar with the different types of saws:
Mud saws are a traditional tool used for running blades through a silicon carbide mud trough. They are inexpensive but require hefty upkeep and can break down over time.
Slab Saws have thicker blades that cut away bulky chunks of material
Trim Saws have thin blades optimal for finely cutting away small amounts of materials
We've covered all the tools you'll need and the various types of cutting saws. Now, how to go about using them?
There are three critical steps to cutting rough stones with saws, and we'll walk you through each step below.
Before you get to work cutting stones with a saw, ensure the feeding component runs parallel to the machine's blade. To feed a saw, you'll place your stones right in front of the blade. Take care not to place uncut stones at an angle in front of the blade as it can bend and damage it.
The type of saw you are working with will determine how you feed the stones to the blade. For example, with a trim saw, you'll feed the saw with your hand. However, the material you are working with will also determine how you feed the stones to the saw. That's why it's vital to read the manufacturer's recommendations to ensure you cut the stones safely and efficiently.
Most saws require a lubricating oil to prevent the blades from rusting. Lapidary saw oils are typically water-soluble and should be applied outdoors to eliminate the chance of ingesting any toxins in the solution.
After you finish cutting, you'll need to clean your saw to keep it in prime condition. With frequent use, it's normal for the blades to become dull. A simple solution is to use the blades to saw into a brick, which will remove grit and grime that accumulates over time.
One of the less glamorous tasks involved is cleaning the sump. Grab a large bucket, rubber gloves, and scrapers, open the valve and empty the lubricant. Then, take the scrapers to the sump and scrape away the accumulated sludge. While this job is anything but enjoyable, it's critical maintenance to keep your saw functioning long-term.
That wraps up all the details on cutting rough stones! As with many techniques of gemstone cutting, the materials you'll need depend on the stones you're cutting. With some uncut specimens, you can use brute force, while others require precision and fine detailing. In any case, the more you cut, the deeper your understanding becomes of the exciting process of cutting rough stones.
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