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Choosing and Using a Lapidary Cabbing Machine/Grinder

Choosing and Using a Lapidary Cabbing Machine/Grinder

Choosing a Grinder/Polisher

We have a wide variety of grinding and polishing machines for working with both glass and stones. Our stone grinders come in a wide variety of styles and options to suit many different needs. This article will go over what the differences are and why certain grinders lend themselves to specific uses. 

If you are a glass artist we suggest a glass lathe style unit as they have more reach for working large pieces.

Expandable Drum Units

expandable drum cabbing unit

Covington has 2 different machines that come with expandable drums included. Expandable drums are soft wheels that expand when they spin. They are used with either silicon carbide or diamond sanding belts. The belts easily slide onto the wheel when the wheel is stationary and then lock into place when the wheel is spinning.

Expandable drums are a great choice for contouring your rocks. Their soft surface flexes under your touch which makes smoothing of cabochons and other domed shapes easy.

Covington has an economical 2-station machine as well as a 4-station machine which allows you to go through all of the pre-polish grinding stages without changing wheels or machines. You can also set up your expandable drum machine with polishing belts such as cork and felt for glass or fine diamond belts for stone.

Customizable Grinder/Polishers

customizable lapidary arbor

We also has several more versatile grinding unit options. Two Covington machines do not come with wheels attached, which gives the user the freedom to customize the machine to their exact needs. Use different resin wheels for polishing like Nova or use different grinding wheels like Cutting Edge Supply's carving wheels.

The Heavy Duty Grinder/Polisher and Variable Speed Grinder are both 2-station arbor units that can accommodate 6” and 8” grinding and polishing wheels. Wheel options range from silicon carbide stone wheels to diamond-plated and sintered wheels, to cork and felt wheels. The Variable Speed Grinder allows you to control how fast or slow you need the wheels to turn. Both units are pulley driven, which allows for a truer-running shaft and reduced vibration on the wheels.

Complete Grinder/Polishers

lapidary grinder/polisher

Complete Grinder/Polisher machines allow you to fully grind and polish pieces on one machine without changing out wheels. These machines are perfect for you if you already have your pieces slabbed and are simply going to finish your pieces by grinding, shaping, and polishing.

Covington has an 8" Grinder/Polisher that comes with 2 hard wheels (either silicon carbide or diamond), an expandable drum, and a polishing head on the end. The 2 wheels at the center are used for grinding and shaping your piece. The expandable drum then gives you the ability to pre-polish and ready the piece for the final polish.

The polishing head comes with a leather disc attached, which is a universal polishing disc for working with stones. This disc can be changed out easily for pieces that require the friction of felt or if you prefer to polish using diamond discs.

Cabbing Machines

cabking cabbing machine

Cabbing Machines are machines specially built for making cabochons. Barranca Diamond has several Cab Makers in both 6" and 8" versions and either diamond or silicon carbide versions. The GP6 models come in Silicon Carbide, Diamond and a Wheels & Pads model. The GP6-6 is a six wheel machine that gives you lots of versatility and the GP8 Super Cab Maker uses 8" wheels and comes with a long list of accessories.

The Diamond Pacific Cabbing Machines come with Galaxy and Nova Diamond Wheels. The best resin bonded cabbing wheels on the market. The Diamond Pacific Cabbing Machines will run for many years because of their extremely high quality of materials and manufacturing. These machines require no upkeep and do not require any assembly when it arrives to you.

The Cab King 6" and 8" machines are excellent for making cabochons for hobbyists and professionals. These 8-station grinder/polishers come with a full list of accessories. They are built on a sturdy base board and have aluminum splash hoods with adjustable clear splash shields, plastic pans with drain holes, side splash guards, and metal hand rests. Both sizes also have optional Trim Saw Attachments.


lapidary arbor

For the truly do-it-yourself types, Cutting Edge Supply has Covington arbors and Hi-Tech Arbors that are suitable for a variety of needs and purposes. The Covington simple 2-station arbors are fully customizable. They do not come with a motor or base board. Instead these units are designed to build yourself and place into any available location in a workshop. These arbors come with a mild steel shaft, a fixed flange, a floating flange, and a nut on either side. The Hi-Tech Arbors come with a bottom reservoir for holding your water. However, the rest of the machine is completely customizable to you. Water system will need to be figured out as well since that does not come with either. Cutting Edge Supply suggests using a submersible pump with a bucket of water or a drip system. Both can be found on Cutting Edge Supply.

We sell motors to go along with your arbors if you do not have one already.*

The first main difference between the Covington open and the closed arbor is the height and the size of the wheel that it can hold. The Open Arbor can hold larger wheels with a small shim to raise the unit up. Secondly the open arbor has an exposed pulley and v-belt while the Closed Arbor has a fully enclosed front pulley and arbor. Additionally, the open arbors come with a longer shaft.

Water Supply

All of Covington's grinding units utilize 1/4in valves for input and 3/8in pipe for output. Pump and Drain Kits are a highly recommended accessories for all grinder units. Plumbing kits are a great additional purchase to have your unit up and running the same day you receive it. Different units have different plumbing requirements. The kits are an excellent options for all users who would rather not make a trip to the hardware store for a variety of supplies. We always recommend that the pans drain into separate buckets to keep the stone dust from contaminating the wheels via water supply.


One of the most common questions regarding grinding units is in regard to water supply. Here at Cutting Edge Supply we recommend always having a fresh supply of water coming in and letting the dirty water run out. Never reuse water with a recycling system. Recycling water will reintroduce contaminants to later steps and will render steps useless instead of remaining effective. Water should only provide a light misting r steady drip on the surface of the wheel. If water is splashing everywhere there is too much water being used, and the grinding process is not effective. All units that have water supplies have 1/4in inputs and quickly connect to standard 1/4in pipe. 


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