Angle grinding 101

The do’s and don’ts of cutting and grinding

Practical Welding Today July/August 2013
July 8, 2013
By: Terry Tuerk

In fabrication shops across America and around the globe, power tools—more specifically, angle grinders—are often used in an improper and unsafe manner. Taking the time to learn the do’s and don’ts of cutting and grinding can help prevent serious injury to yourself or those around you.

Angle grinding

Angle grinders can be used for a variety of applications including cutting, grinding, and polishing. Being familiar with a tool’s safety guidelines keeps you safe.

To do or not do to, that is the question. When it comes to cutting and grinding with professional-grade electric power tools, the answer to that question could mean the difference between a safe work environment and an accident waiting to happen.

In fabrication shops across the U.S. and around the globe, power tools—more specifically, angle grinders—are being used in an improper and unsafe manner, especially by workers who are less experienced in metal fabricating. Taking the time to learn the do’s and don’ts of cutting and grinding can help prevent serious injury to yourself or those around you.

The Background on Angle Grinders

Over the past several years, the small angle grinder has become the most versatile tool in a fabrication shop. The tool used to be considered bulky, heavy, and hard to manipulate, but a lot has changed. Power tool design engineers have worked hard to make angle grinders lighter, safer, more ergonomic, and more powerful. This is particularly true for small angle grinders now offered with 12 amps or more of power, as well as for cordless versions that can deliver up to 100 amps with an 18-volt lithium-ion battery.

The design advances of today’s angle grinders have increased the number of applications you can use them for.

Quality angle grinders usually have industry-standard safety features such as a toolless, easily positioned wheel guard that allows you to quickly reposition the guard rather than remove it entirely. Safety slip clutches also are available on many industrial-grade angle grinders. The safety slip clutch helps to protect you from kickback should the wheel bind or snag.

All angle grinders are equipped with a side handle, which helps you to better control the tool while it is in operation, especially when performing heavy grinding or cutting. Antivibration side handles and side handles that are offset from 90 degrees are safe, ergonomic, and allow you to work for long periods of time without fatigue. By keeping two hands on the tool, not only will you work safer, but you’ll work more efficiently too.

Safety First

All humans become complacent at one time or another, especially when we have done a job over and over and over again. I’m sure you’ve experienced a moment when you’ve thought, “What’s the worst that could happen? It will only take a second.”

This invariably translates into ignoring the written or unwritten rules of whatever you are doing—in this case, ignoring basic safety by using a cutting or grinding disc that is not meant for the application you are performing, or simply deciding not to attach a wheel guard or a side handle to a grinder. It seems benign, harmless even, but if done enough over a period of time, sooner or later an accident will happen. So, how do we avoid complacency?

First, familiarize yourself with the rules of operating your angle grinder, and second, follow those rules. Underlying translation: Read the instruction manual!

The owner’s manual not only offers excellent information about the tool and how to operate it safely, it also gives you all the information you need, from how to care and maintain your tool to how to select the appropriate accessories.

It should be no surprise that because angle grinders are being used in a wider variety of applications than ever before—such as removing metal, deburring, cleaning, brushing, sanding, finishing, polishing, and cutting—the number of operator injuries has increased. By simply taking the time to read the manual and becoming familiar with all of the tool’s safety guidelines, you can avoid a majority of these injuries.

Accessorizing Your Angle Grinder

As a power tool user, you really need to think about your application and properly match the accessory to the grinder itself. It’s important that whatever you choose falls within the manufacturer’s tool and accessory recommendations.

Accessories always should be rated at or above the no-load speed of the angle grinder. Start by choosing the correct grinding wheel size for your angle grinder. By using wheels that are oversized, you run the risk that they may shatter or explode at very high speeds.

Depending on the type of accessory, different safety guards may be required. For example, thin cutting wheels require a guard that encloses the wheel on two sides by 180 degrees. Cup-type wheels require a different guard than regular grinding wheels.

Some grinding wheel manufacturers have released a reinforced wheel that can be used for both cutting and grinding applications. This type of wheel not only saves you time because you don’t have to switch wheels between applications, but also enhances safety because you don’t have to remember to switch wheels when working on a job.

The Do’s and Don’ts: A Checklist

Before you operate your grinder, be sure to go through this checklist before turning it on.


  • Visually inspect the tool and all wheels for possible damage before mounting.
  • Check the mounting flanges for equal and correct diameter. They should be at least one-third the diameter of the wheel and relieved around the hole.
  • Always use a safety guard that covers at least one-half of the grinding wheel.
  • Run a newly mounted wheel at operating speed for at least one minute before grinding.
  • Wear safety goggles or some sort of eye protection during grinding.
  • Handle and store wheels carefully. Avoid dropping or bumping them.
  • Store abrasive wheels in a dry area not subject to extreme temperature changes. Some bonds may be adversely affected by excessive humidity and temperature differentials.


  • Use a cracked wheel or one that has been dropped or damaged.
  • Force the wheel onto the tool or alter the size of the mounting hole. If it doesn’t fit, don’t use it.
  • Exceed the maximum operating speed specified by the manufacturer.
  • Overtighten the mounting nut.
  • Stand in front of the grinding wheel when the grinder is turned on.
  • Grind material that the wheel is not intended to grind.

Expect the Unexpected

Always expect the unexpected. When using a grinder, be aware of your environment and situation. Keep your mind on the task and be prepared for the possibility of tool kickback. If you are alert, the tool will be more easily controlled and less dangerous.

Many power tool and abrasive manufacturers offer on-site safety training and support programs to review proper tool and accessory use. Training can last anywhere from 15 minutes to an hour and a half, covering everything from safety tips to hands-on demonstrations of safe tool operation.

Making yourself familiar with a tool’s safety requirements is a must. Knowing safety guidelines and understanding why, how, and how fast an accident can happen is the first step toward a safe work environment.

Terry Tuerk

Senior Product Manager
Metabo Corp.
1231 Wilson Drive
West Chester, PA 19380
Phone: 800-638-2264

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