How To Change the Blade On an Angle Grinder

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The blade of your angle grinder is held in place by a locking nut. Changing the blade requires this nut to be loosened and removed. This is usually done using a special two-pronged wrench. A wrench that fits the size and shape of your angle grinder’s locking nut should have been in the box when you purchased it. 

This article covers how to change an angle grinder blade using a two-pronged wrench. If you’ve misplaced the blade-changing wrench, or if you purchased a used angle grinder without a wrench, refer instead to our article about how to remove an angle grinder blade without tools.

How to Change an Angle Grinder Blade

The disc is attached to the rotating spindle by a clamping flange or locking nut. You should see two small holes or indentations in the surface of the nut. The blade-changing key that came with your angle grinder has two small knobs, one on each prong, that nestle perfectly into those indentations. Force applied in a counterclockwise direction will loosen the nut. 

Some angle grinders feature keyless removal. If you have a keyless angle grinder, you should be able to remove the clamping flange by hand. Simply press the grinder’s wheel lock button to keep the disc from rotating, and unscrew the locking nut. 

Person using an angle grinder to cut a metal bar
  1. Assemble your materials. You will need the angle grinder, the two pronged wrench that came with it, and a new disc that matches the size and RPM of your angle grinder. You should also wear gloves to avoid accidental scrapes and cuts from the abrasive material of the grinder wheel

If you have multiple angle grinders, you may have multiple wrenches.  There is a way to use the wrong size two-pronged wrench. This method is explained at the end of the article. 

  1. Confirm that the angle grinder is unplugged. Visually inspect the blade and the locking mechanism. You can usually remove a dry crust with penetrating oils like WD-40. Allow 15 minutes for the product to work. If the blade is in good condition, you will be able to use it again. A chipped or bent blade will need to be replaced. 
  2. Locate the angle grinder’s wheel lock button. This is usually located on top of the gearbox. If the wheel is allowed to spin, you will not be able to generate sufficient torque to remove the nut. Press the lock button to hold the blade in place. 
  3. Insert the knobs on the prong of the wrench into the corresponding depressions on the angle grinder’s locking nut or clamping flange. While keeping the wheel immobile, rotate the nut counterclockwise. 
  4. Some older models of angle grinder do not have a lock button, or the lock button may be broken. Without a lock button, you cannot control the spin of the wheel. This makes the blade changing process not only more difficult, but also more dangerous. Replacing a broken lock button usually requires you to change the whole gearbox. To change the blade without a lock button, hold it in place using vice grips or a gloved hand. 
  5. When the locking nut has been removed, place it somewhere safe. Without the locking nut, you will not be able to attach the new disc. Coat the threads of the drive bolt with grease. This will make it easier to change the angle grinder blade next time. 
  6. The new angle grinder blade should match the size and speed of your angle grinder. Slide the new angle grinder disc onto the drive bolt. Reattach the locking nut, spinning it clockwise by hand. By holding the nut with one hand, and spinning the disc with the other, you can ensure the blade is securely attached. Make sure you are wearing gloves throughout the process. 
  7. Plug the angle grinder in to check the blade. It should spin freely, with no catching or wobbling. Put the angle grinder blade-changing key in a safe place for the next time you need to change a blade.  

If you’re in need of a new tool, we have a review of the best angle grinders on the market.

Signs that Your Angle Grinder Blade Needs to be Changed. 

The angle grinder blade is the part of the machine that comes into contact with material during use.  Different kinds of angle grinders blades are best for different types of jobs. When switching from one task to another, you will need to switch to an appropriate disc. 

For example, using your angle grinder to cut through metal or concrete pavers is different than bricks or cast iron pipe.

Person using an angle grinder

Even if you only use your angle grinder for one purpose, over time the blade will wear down and need to be changed. Learning how to change the blade on your angle grinder is an important step in mastering this powerful and adaptable tool. 

Watch out for the following signs that indicate it is time to change your angle grinder blade:

  • Disc is bent
  • Visible defect or deformation in the abrasive surface of the disc
  • Disc looks or feels smooth at the edge
  • Little abrasive material remains
  • Strange or unfamiliar sounds during operation
  • Unusual vibration of the angle grinder
  • Reduced cutting speed

Change the Blade With the Wrong Size Wrench

If your workshop boasts multiple angle grinders, chances are you have at least one of the blade removal keys. While the width of the prongs and their placement vary from model to model, the depressions on the clamping flange are a standard size.

You should be able to fit one of the knobs on the angle grinder wrench into the depression.  Brace the wrench against the nut, and use the wrench as a lever to loosen the nut.  

Conclusion

To use an angle grinder safely, the correct disc must be attached.  Discs wear down over time, and will eventually need to be replaced. You may also want to change the disc so that you can perform another task.

The wrench that came with your angle grinder is the easiest tool to use. If you don’t have that wrench, you can improvise with a wrench from another angle grinder. Pay attention to your grinder’s performance during use and be on the lookout for signs that the disc needs to be replaced. 

Ellenkate grew up on job sites run by her family’s construction company. She earned her theater degree from The Hartt School, a prestigious performing arts conservatory in Connecticut. Her design and DIY work from her Chicago loft was featured in the Chicago Reader and on Apartment Therapy.