What To Look For When Buying A Bench Grinder?

A bench grinder is an essential tool for any workshop. It consists of a motor that turns a set of grinding wheels at high speeds. Bench grinders allow you to perform a variety of grinding, sharpening, polishing, and buffing tasks quickly and efficiently. They are commonly used for sharpening tools like chisels, scissors, shears, and drill bits. Bench grinders can also be used for general metal shaping tasks like deburring, removing rust, and surface prep. Having a quality bench grinder in your shop will save you significant time and allow you to keep your tools in top condition.

When shopping for a new bench grinder, there are several factors to consider in order to select the right model for your needs and budget. This guide will walk through the key specs and features to look for when choosing a bench grinder.

Wheel Size

Bench grinders typically come with either a 6-inch or 8-inch wheel size. The wheel size determines what kind of work the grinder is best suited for.

6-inch wheels are smaller and more portable. They are a good choice for light grinding work like sharpening tools and deburring metal edges. The smaller wheel size allows for more precision work. 6-inch bench grinders are commonly found in home workshops.

8-inch wheels are larger and can handle heavier grinding work. The larger surface area makes them good for grinding larger tools, removing stock from metal bars, and smoothing welds. 8-inch grinders generate higher wheel speeds for faster material removal. They are commonly found in industrial and fabrication shops.

When choosing a bench grinder, consider what type of grinding work you’ll be doing most often. 6-inch wheels offer precision, while 8-inch wheels provide power. Some grinders allow you to swap out wheels, giving you flexibility. But most come with a fixed 6-inch or 8-inch wheel size.

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Wheel Materials

The abrasive material used in the wheel is an important factor to consider when purchasing a bench grinder. The most common abrasive materials used are aluminum oxide and silicon carbide.

Aluminum oxide wheels, sometimes referred to as alumina, are versatile and economical. They work well on most materials including steel, cast iron, non-ferrous metals, wood, and plastics. Aluminum oxide grains fracture easily during grinding, exposing fresh sharp edges for a consistent cut.

Silicon carbide wheels are harder and more brittle than aluminum oxide. They are excellent for grinding hard materials like cemented carbide, ceramic, stone, and glass. The sharp grains of silicon carbide maintain their cutting ability longer than aluminum oxide. However, silicon carbide is more expensive than aluminum oxide.

For general purpose bench grinding of steel and other metals, aluminum oxide wheels are typically recommended. Silicon carbide would be better suited for grinding very hard materials. When selecting a bench grinding wheel, consider the main type of material you plan to grind to determine the ideal abrasive material.

Motor Power

When choosing a bench grinder, selecting the right motor power for your needs is important. Hobbyists generally require less motor power than professional users. For light grinding tasks like tool sharpening or cleaning small metal parts, a 250-400 watt motor is usually sufficient. This provides enough power for most hobbyist tasks without being overpowered. However, for frequent, heavy-duty grinding, professionals require more power.

For professional metal workers, mechanics, or machinists doing extensive grinding, a 500-1000+ watt motor is recommended. The higher power range allows fast material removal rates for heavy grinding without the motor bogging down under load. However, the tradeoff is that powerful motors require more safety precautions as higher speeds increase danger from wheel explosions. For most hobbyists and occasional DIY users, a moderate 250-400 watt motor offers a good balance of grinding capability without excessive power. Evaluate your expected usage and choose a motor with room to grow.

Speed Control

Variable speed control is an important feature for bench grinders that provides versatility and flexibility for different grinding operations. Bench grinders typically operate at a single fixed speed, often 3450 RPM. However, having the ability to reduce the speed allows for more control and prevents overheating the workpiece on delicate operations like sharpening or polishing. This forum discussion explains how bench grinders use induction motors, so speed is determined by the frequency rather than a variable resistor. A variable frequency drive (VFD) can control an induction motor’s speed.

Safety Features

Bench grinders can be dangerous if not used properly, so it’s important to look for key safety features when buying one. At a minimum, bench grinders should have the following:

• Wheel guards – Guards should fully enclose the grinding wheels to prevent pieces from flying out if a wheel breaks. The guards should be adjustable to accommodate different wheel sizes.
• Tool rests – Adjustable tool rests position and support your workpiece. They should be kept adjusted close to the wheel, within 1/8 inch, to prevent the workpiece from being jammed between the rest and wheel.
• Wheel dresser – A dressing tool reshapes and smoothes the wheel if it becomes uneven. Dressing the wheel helps prevent vibration and wheel failure.
• Safety switch – The power switch should have a removable safety key to prevent unauthorized use. Some models have a paddle switch that stops the motor when released.

Other safety features like a spark arrestor, eye shields, and rotating vice attachment also help protect the operator. Always check the owner’s manual and follow the safety instructions provided.

For more on grinder safety, see this article from Make Safe Tools.

Mounting

One key consideration when purchasing a bench grinder is how it will be mounted. Bench grinders are available in either a stand mount design or a bench mount design. Each offers advantages and disadvantages when it comes to stability.

Stand mount bench grinders have a base that allows them to sit directly on the floor or workbench. The weight of the motor and grinding wheels is spread across a wider footprint, providing more stability. Stand mount models also allow for more flexible positioning and can be easily moved around the workspace as needed. However, any vibration from grinding can still transfer through the stand and cause some movement.

In contrast, bench mount grinders are designed to be securely bolted down to a workbench or dedicated grinder stand. Mounting the grinder directly to a sturdy surface prevents the grinder from shifting or rocking during use. This provides maximum stability for precise grinding work. However, bench mount models lose some flexibility in positioning unless multiple mounting holes are pre-drilled. Bench mount grinders also often require purchasing a mounting kit or hardware separately.

When evaluating mounting options, consider the type of grinding tasks and level of precision needed. For occasional, general purpose grinding, a stand mount model may provide enough stability. But for frequent use or highly precise grinding, a bench mount grinder anchored firmly in place is likely the better choice.

Accessories

Some useful accessories to consider for a bench grinder include:

A work light can help illuminate the grinding area for improved visibility and safety. Having proper lighting is important when operating bench grinders.Bench Grinder Accessories – Machinery Accessories | Burnstools.com

A spark guard helps contain sparks and debris for a cleaner workspace. Spark guards attach around the grinding wheel perimeter.Bench Grinder Accessories – Results Page 1

Safety shields protect the operator from flying fragments in case of wheel breakage. Having proper wheel guards in place is a must.Bench Grinder Accessories

Dressing tools help smooth and shape grinding wheels to ensure proper wheel contours and prevent glazing. Dressers prolong wheel life.Bench Grinder Accessories – Machinery Accessories | Burnstools.com

Other useful accessories include sturdy tool rests for support, water attachments for cooling, and mounting stands for stability.

Brands

When shopping for a bench grinder, it’s important to buy from a reputable brand. Some of the top bench grinder brands known for quality and reliability include:

• Delta – Delta is a leading power tool brand that offers bench grinders in different sizes with features like variable speed control. Their grinders are powerful, durable, and backed by a 5-year warranty (https://topbenchgrinders.com/best-bench-grinder/).
• DEWALT – DEWALT is a trusted brand for power tools and their heavy duty bench grinders are designed for demanding shop use. Look for the DW758 model as an excellent choice (https://topbenchgrinders.com/best-bench-grinder/).
• WEN – WEN specializes in reliable and affordable power tools. They offer high quality bench grinders with decent power and good value.
• JET – JET industrial power tools are built for longevity in professional shops. Their bench grinders have rugged cast iron frames and top-notch performance.
• Hitachi – Hitachi grinders feature quiet and smooth operation. Their variable speed grinders give you control over your grinding speed.
• Grizzly – Grizzly is known for heavy-duty woodworking and metalworking machinery. Their industrial bench grinders are powerful and ideal for shops.

Focus on models from these major brands to get a bench grinder you can rely on for years of service.

Conclusion

When looking to purchase a bench grinder, the key factors to consider are the size and material of the wheels, the motor power and speed controls, safety features, mounting options, and any accessories that may be needed for your specific applications.

Determine what tasks you plan to use the grinder for and choose a wheel size and abrasive material accordingly. Larger wheels with finer grits are good for sharpening and removing small amounts of material, while smaller wheels with coarser grits are better for grinding, deburring, and general metal shaping.

Select a grinder with adequate motor power for your needs, and look for one with adjustable speed controls for enhanced performance and safety when working with different materials. Additionally, seek out models with safety guards, spark arrestors, and other protective features to prevent injuries.

Consider how you will mount the grinder, whether to a workbench or on a stand, and what accessories like tool rests, lighting kits, or dust collection systems may be beneficial. Finally, choose a reliable brand known for quality and durability.

Taking the time to evaluate these key factors will help ensure you select the ideal bench grinder for your workshop and projects.