I’ve had a bench grinder in my workshop for quite some time. It is a must-have tool for professionals with a range of requirements. When I first heard about this machine and saw some pictures, I asked myself. “Why do bench grinders have two wheels?”
Bench grinders come with two wheels that can be used for multiple purposes. The first wheel is usually designed for fine sharpening and precision work, while the other wheel is used for rough shaping. These can be easily swapped out for different wheel configurations according to the user’s needs.
My bench grinder has served me well over the last years, proving to be one of the fastest ways to sharpen, smoothen and polish a number of materials. It was an investment that proved its worth over the long run in my journey as a handyman.
— Also read: Best Bench Grinder for Sharpening Tools (Knives, Chisels, Blades)
This article details important information regarding bench grinders. I have detailed the various parts and functions, while also giving some tips and safety precautions that you must follow while using it. This will give you an idea about how to properly operate the machine and make the best use out of it.
Read on as I have also explained grinding wheels and their different types. I hope that by the end of this article, you have enough knowledge that will help you purchase a bench grinder that best suits your requirements.
Different Parts of a Bench Grinder and their Functions
The motor is the power source that spins the grinding wheels of a bench grinder. The capacity of the motor varies from model to model, spinning the shaft that is then connected to the grinding wheels.
Higher powered grinders are used in industrial applications, while motors with a speed between 3000 – 3700 RPM are sufficient for usage in smaller workshops.
- Grinding Wheels
Grinding wheels are the spinning components of a bench grinder that are powered by the motor. They come in a number of shapes and are made of a wide variety of materials depending on the purpose it is used for.
Grinding wheels come with different abrasive levels, which are measured in grits. The higher the value, the smoother the wheel, which allows for fine work and improved precision. On the other hand, wheels with lower grit values allow for faster grinding and increased speed.
Most bench grinders accommodate two grinding wheels on the machine. While manufacturers provide basic options, users can upgrade the wheel or choose a different material depending on their personal requirements.
- Protective Guard
The protective guard is made of hard materials like plastic as a safety precaution. The guard covers the grinding wheel, with a gap to allow the user to operate the machine. The protective guard deflects debris and sparks and scatters them away from the user.
It also prevents the user’s hands from getting entangled with the wheel if they lose control of the workpiece.
- Eye Shield
The eye shield is another safety feature incorporated on bench grinders. It is a transparent piece of plastic that prevents sparks and debris from flying towards the user during the grinding operation. As a result, users can safely view the workpiece without risking injury.
- Work Rest
The work rest, also known as a tool rest, is a surface provided for users to place the workpiece while using a bench grinder. It helps keep the workpiece stable and secure, improving accuracy and reducing the risk of accidents and injury. A work rest also reduces the overall human effort required while using the bench grinder.
- Tongue Guards
Tongue guards are used to preventing the scattering of debris towards the user at high speeds if the grinding wheel shatters. It is made of a metal plate that rests just over the grinding wheel at the position where the protective guard starts.
- Gap Gauges
Gap gauges are tools used to determine the gap between the resting tool and the grinding wheel when it is at rest. It helps users follow OSHA standards, which dictate that a work rest should have a maximum opening of ⅛”.
This prevents the workpiece from getting jammed between the rest and the spinning wheel, preventing accidents or wheel breakage.
- Allen Wrench
Allen wrenches are tools used to tighten or loosen hexagonal nuts and bolts. This tool is used in bench grinders to remove or tighten the grinding wheels to the shaft driving it, helping increase the stability of the machine.
What are the Safety Rules when Using a Bench Grinder?
Bench grinders are dangerous power tools that can cause severe damage if used incorrectly. Here are some of the basic safety rules you must follow if you are operating a bench grinder to protect yourself and the machine.
- Read the manual
The first thing one should do before operating a new bench grinder is read the manual. It will outline the various parts and specifications of the tool while detailing the safe operating limits of the machine.
Manuals also outline procedures regarding different processes of grinding as well as changing the wheel and so on.
- Wear proper safety equipment
It is essential that operators wear the required safety equipment while operating dangerous tools like bench grinders. Wear safety gloves to protect the hands from debris and sparks while grinding.
Some work sites also mandate that operators must have respiratory protection such as masks to prevent inhalation of fine debris.
Wear safety helmets and eye-goggles to protect your eyes and head from debris that may strike you in any unforeseen circumstances. Face shields offer additional protection to your face while hearing protection helps reduce the damage caused by the loud sound emitted while grinding.
- Avoid loose clothes and untied long hair
Users operating a bench grinder must make sure that they are not wearing loose or baggy clothes. They must ensure that they are wearing buttoned-full sleeve shirts that are tucked in properly along with fitted pants.
Since sparks are emitted while grinding, it is better to wear natural fibers which are less flammable such as cotton and leather. Synthetic fibers like polyester and nylon can catch fire easily, making it a safety risk for operators.
- Setup the grinder wheel correctly
Before actually starting the grinding operation, ensure that the grinding wheel is secured tightly to the shaft of the motor.
Also, ensure that the angle of the grinding wheel forms an angle of 90° with the work rest for maximum efficiency. Also ensure that the work rest is kept ⅛” away from the wheel, following the OSHA standards.
- Use pliers to grind small objects
Avoid going too close to the wheel even if your object is small in size. Ensure the work rest is in the correct position and the gap is correct. Use a plier to grip smaller objects to prevent your hand or fingers from coming in contact with the wheel, which can cause injury.
- Grind with the face of the wheel
Do not grind any object with the side of the wheel. It is designed to be abrasive only at its face while being strong enough to withstand the forces created due to the motion. Using the side face can lead to cracks developing quickly, which can cause the wheel to shatter.
- Ensure the metal is not overheated
The process of grinding creates a large amount of heat due to the friction involved. As a result, ensure that you do not grind a workpiece for too long at a time to prevent deformation or heat damage.
Keep some water next to the bench grinder before grinding any given material. This will allow you to quickly cool the workpiece in case it overheats.
Different Shapes of Grinding Wheels
Grinding wheels are available in a variety of shapes. This allows the bench grinder to be used for a variety of applications such as grinding, polishing, and even cutting
- Straight wheel
The straight wheel is the most commonly used grinding wheel in bench presses. The wheel is used for sharpening a number of commonly used household tools like lawnmower blades and chisels.
- Cutting face wheel
Cutting face wheels are used to cut through materials. This happens as the abrasive surface that comes in contact with the workpiece is very narrow, as a result of which it grinds out a lot more material. This type of precision cutting is used for tiles and shaping saw teeth.
- Tapered wheel
Tapered wheels have a smaller diameter at one end, with a gradual taper in the outward direction. Thanks to its ability to be able to withstand higher lateral loads, these types of grinding wheels are used to grind threads and gear teeth.
- Cup wheel
The cup wheel is used primarily for polishing hard materials like stone and concrete. The cup wheel. This type of wheel also finds applications in re-sharpening and finishing for some materials.
If the grit size is small enough, the cup wheel can also be used in precision applications like adhesive and paint removal.
- Segmented grinders
Segmented grinders consist of abrasive surfaces with grooves in between them. This type of wheel is helpful when the workpiece needs constant cooling during the grinding process.
The grooves allow for coolants or liquids to flow through and cool the surface, with centrifugal forces ensuring the fluid comes in contact with the material.
- Cylinder ring
Cylinder rings are grinding wheels that are used to create flat surfaces. This type of wheel grinds along the entire face of the wheel, increasing the surface area. However, these grinding wheels are used only in horizontal and vertical grinders.
Different Types of Grinding Wheels
Grinding wheels can be further classified based on the type of materials used to manufacture them. They allow for a variety of operations on different materials, ranging from wood to plastic.
- Cubic boron nitride
Cubic boron nitride is one of the most expensive grinding wheel materials available today. This abrasive is bonded to a steel wheel and is used in operations involving carbide tools and hard steel alloys.
- Aluminum oxide
Aluminum oxide is increasingly becoming the stock grinding wheel material offered by bench grinder manufacturers. This abrasive has two grades, both of which are designed for general purpose usage.
The lower-cost material has a gray or brown appearance, while the white wheel is made of higher-grade materials. The white wheel wears away quickly than the low-cost aluminum oxide, exposing a fresh cutting surface more frequently. This material can be used for carbon steel and hard steel alloys.
- Ceramic/aluminum oxide
Having a pale bluish appearance, this abrasive material has reduced tool burn and improved cutting action, making it more efficient in applications involving high-speed steels and other hard alloy steels.
- Silicon carbide
Silicon carbide is the most commonly used material for grinding wheels. This material has a bronze or darkish grey appearance and works well for grinding non-ferrous metals and carbide. Silicon carbide is a low-cost grinding tool but is being phased out as aluminum oxide becomes more affordable.
- Can you run a Bench Grinder with one wheel?
Bench grinders can be used with a single wheel. Bench grinders are designed to spin a single wheel without any problems. Disconnecting the second wheel will not affect the stability or balance of the machine in any manner. However, it is best that you refer to the manual provided by the manufacturer to see if this is an acceptable practice.