Grinding Machines

Bench grinders are an all-round, handy power tool. They offer great versitility - whether it's sharpening, cutting, buffing, rust removing or polishing - the bench grinder is a must-have for any workshop or shed. Bench grinders are available in a range of configurations, including portable bench grinders, variable speed bench grinders, woodworking bench grinders and more.

At Cromwell, we stock numerous tried and tested bench grinders, from trusted brands such as SIP® and Ajax Machine Tools®. Ask our experts for further guidance in choosing the perfect model for you.

What are bench grinders?

Bench grinders usually consist of one or two powerful grinding wheels that are used for general workshop tasks. These wheels are available in a range of sizes, grits and materials, and can be suitable for general use or specialised for any one function. Due to their considerable size and power, bench grinders are often bolted to worktables or benches - allowing them to remain sturdy and stable as the workpiece is held against it.

Why a bench grinder?

Industry professionals and hobbyists alike often cite the bench grinder as one of the most valuable tools in any workshop. Whilst they are incredibly versatile and useful in their own right, bench grinders also improve and enhance your other tools. They are essentially high-powered spinning grindstones, meaning you can effortlessly shape and sharpen most hand tools, garden tools and blades. This allows for a greater degree of efficiency across your entire workshop.

When are bench grinders used?

Bench grinders are invaluable for use in a wide range of industrial applications. These include:

• Rust Removal - Quickly and easily remove rust and prepare any metal surface for shaping or sharpening.

• Sharpening - Set your bench grinder to a lower speed to rapidly sharpen chisels, blades, and many other tools, making them work like new.

• Polishing - Easily achieve a quality clean finish on most metals and woods.

• Grinding - Excellent at quickly removing high amounts of hard metals, such as steel.

• Cutting - Bench grinders excel at swiftly cutting through most metals. They can also cut wood when set to a lower RPM.

• Buffing - Allows metal items to retain finish and texture, preventing them from blunting.

Types of bench grinder

Bench grinders come in four main variations:

• Variable Speed Bench Grinder   -   These are the most versatile type of bench grinder as they allow for easy RPM adjustment. This allows them to handle almost any task you throw at them.

• Automotive Bench Grinder   -   Designed for outstanding stability and balance, the automotive bench grinder excels at the repetitive cutting or grinding of hard metals. These are often used for cutting and shaping bolts, engine parts and hinges.

• Portable Bench Grinder   -   Designed to be highly portable, these can easily be moved from one site to another. They are easy to adjust and can do most of the tasks bigger bench grinders can do, although their decreased power output can make grinding harder metals a much longer process.

• Woodworking Bench Grinder   -   Able to grind and sand wood with remarkable efficiency, this type of bench grinder operates at a lower RPM to allow for greater precision and control when working with softer materials.

When buying any bench grinder, it's important to consider the type of grinding wheel you're getting. Naturally, the wheel is the part that controls the outcome of your work - so it's important to pick the right one for your needs.

• Straight Wheel   -   The most popular and versatile wheel for bench grinders, straight wheels make a concave shape and are mainly used for tool sharpening or any other type of surface grinding.

• Tapered Wheel   -   Ideal for precise work, tapered wheels narrow towards the edges for ultimate control and accuracy. These are often used for delicate tasks, such as sharpening gear wheel teeth.

• Diamond Wheel   -   With a diamond-lined edge, these wheels are extremely durable and can cut through just about anything. Perfect for grinding hard metals that require considerable strength and power.

• Cylinder Wheel   -   Typically a very large and hollow wheel, cylinder wheels can be used both horizontally and vertically. Their large surface area makes them ideal for grinding bigger metal objects with ease.

Considerations when choosing a bench grinder

Wheel Material - Alongside the wheel type, the material of your wheel is one of the most important considerations when buying a bench grinder. The general rule is that Aluminium Oxide is best for grinding ferrous metals, whereas Silicon Carbide is the material of choice for softer metals such as copper and aluminium.

Space - Most bench grinders require fitting to a work surface to avoid injury or accidents. Ensure you have the space to do so before buying a fixed bench grinder.

Power - This one is fairly straightforward, but important nonetheless. Should you be looking to grind harder metals, a more powerful motor will be needed to reach a higher RPM. Softer materials or more precise, controlled work doesn't require as much power.

Wheel Size - Again, this largely depends on your usage. General use wheels are between 6 to 8 inches, however wheel sizes can be much bigger or smaller for specialised tasks. Always ensure the wheels you buy fit in your bench grinder.

Base - An important consideration, as a good bench grinder is sturdy and won't move during use. If you plan on regularly performing precise tasks, look for a machine with a cast iron base as this will prevent any wobbling or shaking whilst working. Bear in mind that sturdiness can be compromised when buying a portable bench grinder.

Bench grinder jargon buster

What is 'Wheel Dressing'?

Wheel dressing is a must if you plan on using your bench grinder frequently. A good wheel dresser exposes new grit on the wheel for safer, more efficient cutting or grinding. If a wheel isn't dressed, it may become clogged and dull - causing overheating and slow, inefficient material removal. To do this effectively, press a wheel dresser perpendicular to the wheel face to expose fresh abrasive.

What is 'Wheel Cooling'?
To successfully grind or sharpen metal, it's important it doesn't get too hot, as this can compromise the rigidity of the metal. By regularly dipping your material in water, you can ensure a cool grind. Many professionals use a 'rolling pan' to cool the wheel of the bench grinder, cooling the wheel (and thus the metal) as it spins.


Can a bench grinder be used as a buffer?

With the correct equipment, many bench grinders can be used with a buffer wheel. Ensure your bench grinder is powerful enough to support this and always confirm the buffer wheel is the correct size for your bench grinder.

Do I need safety glasses when using a bench grinder?

Simply put, yes. When grinding, small particles of metal can easily fly off - especially when the bench grinder isn't used correctly. This makes safety glasses a must-have when using a bench grinder, and a dust mask is highly advised.

How do I know when to replace the wheel?

A sturdy wheel is paramount to user safety and working effectiveness. To check if a wheel is cracked or broken, use a screwdriver handle to tap four times on different parts of the wheel's side. If all four taps don't sound the same, it's highly likely your wheel is cracked.