The Angle Grinder Wheels You Need for Fabrication

If you're doing fabrication, you need four types of wheels for your angle grinder. They are the standard grinding wheel, the flap disc, the cutoff wheel, and the wire wheel. If you scroll to the bottom of the article, you can see what each of these wheels does to a piece of rusty metal.

Angle grinder wheels are consumables: they last for a certain amount of time and then they need to be replaced. We've experimented with super cheap versions of angle grinder wheels and find that they don't last as long and don't hold together as well as versions that cost a little bit more. Here are a few that we've tried and liked:

• DeWalt Grinding Wheel
• DeWalt Cutoff Wheel
• DeWalt Wire Wheel
• Bulk Flap Disc
  

We also like products from Norton, Gemini, and Milwaukee.

The standard grinding wheel is all about fast metal removal. Use the grinding wheel if you want to grind out welds, clean up cuts, and prep metal for welding (since you need bare shiny metal to weld). Of the four wheels, this removes material the fastest. It also produces hot, large sparks. Be sure that the sparks are not hitting anything you care about. Sparks will melt and embed into glass, burn holes in some clothing, and can be a little painful on your skin.

Grinding wheels come in different grits. Just like sandpaper, lower numbers (like 40 grit) are coarse and remove material faster. We will caution that the lower the grit, the larger, hotter, and more painful the sparks are. While this is fine if you're working at a workbench, grinding under a 4x4 in an awkward position can become very uncomfortable with low grit wheels. Even with typical safety gear, it's harder to protect your body, your ears, and your eyes from bouncing sparks when you're jammed under your vehicle, so we suggest a higher grit wheel for that type of work. Stray sparks can easily ricochet and bounce behind a face shield/goggle combination. A higher grit wheel will take a little longer, but it's safer and more comfortable.

We buy angle grinder grinding wheels 5-10 at a time and that quantity can do most of the typical fabrication projects on a single truck.

Low grit grinding wheels can leave "scratches" in your metal. Really coarse grinding wheels can also leave slight burrs on the edge of your workpiece. We usually clean up these scratches by using a flap disc (below) on the affected areas until the metal is smooth and shiny.

This is also the angle grinder wheel you should use for sharpening mower blades, shovels, and other "blunt" garden tools. It's easy to remove your mower blade, put it in a bench vise, and sharpen it with your angle grinder. We often finish a blade with a flap disc to make sure it's smooth.

The grinding wheels above tend to gouge the material you're working on, but a flap disc smooths it out. While the grinding wheel is a hard composite material, the flap disc is basically just overlapping rectangles of sand paper. If you were to run your grinding wheel over an edge on a piece of steel, then you ran your fingernail over that spot, it would catch, since the grinding wheel will push out material at it’s leading edge. This is a burr. Burrs look bad, and can be sharp - they'll easily cut unprotected hands. The flap disc works great to clean up burrs and shine up gouged metal.

Like the standard grinding wheel, these come in different grits. Like sandpaper, the higher grits are for fine work and the coarse grits are for rougher work. We use flap discs all the time for finishing heavy grinding. Flap discs make a huge difference in what your finished piece looks like by removing burrs and scratches, allowing you to put slight chamfers on edges, and also making it easy to take the hard edge off corners.

The cutoff wheel is used for cutting metal. You can use it for cutting out welds, cutting small parts out of sheet or plate metal, or shortening bolts. You only use the edge of the wheel, not the back or front face. In fact, using either face will weaken a cuttoff wheel since they are so thin and the fibers that hold the wheel together are so exposed.

Cutting wheels are considerably thinner than standard grinding wheels. Typically, you'll use something that's either 1/8" or 0.045" thick. This is 1/2 to 1/4 as thick as a 1/4" grinding wheel. Because of their thinness and the fact that they only cut at the edge, they can cut metal extremely quickly.

The best angle grinder cutting wheels for metal are also the thinnest. However, the thinner the wheel, the more dangerous they are. Thin cutting wheels flex more easily and thus shatter more easily. If you're working at a work bench in a comfortable position with a well-positioned workpiece, a thin cutoff wheel is fine. If you plan to work under a vehicle in an awkward position, we recommend using a 1/8" cutoff wheel that is a little more rigid and will resist shattering if you lose your balance or position.

While the cutoff wheel is very, very handy, it is an extremely dangerous wheel because it’s thin. If you twitch, lose your balance, or otherwise accidentally twist the grinder while using this wheel, it will shatter. The projectiles that fly off could break your nose, damage your hands, hurt bystanders, etc. Keep your face away from this and out of the plane of the spinning wheel.

We have shattered perhaps one or two standard 1/4" grinding wheels in several years of fab work, but we've shattered many cutoff wheels. Lots of fabricators have injuries from not wearing proper safety gear or using cutoff wheels unsafely. One of us even has a nice scar and some grinding material permanently embedded under a fingernail after a shattered cutoff wheel impacted his hand and shattered his fingernail. It's tough to get everything set up perfectly for using a cutoff wheel on an angle grinder, so do the best you can and wear lots of safety gear.

Safety glasses, face mask, grinder guard, heavy gloves, and no bystanders are essential when you spin up this wheel. We recommend not using a cutoff wheel unless both ends of your material are properly supported. Otherwise, the hanging piece may to pinch the spinning wheel and shatter it. A chop saw should instead be used for some types of work, like shortening lengths of tubing or angle iron.

Wire wheels are excellent for removing surface rust and paint. The most abrasive wire wheels have thick, twisted bristles. Straight and thin bristles are much less abrasive, but aren’t aggressive enough if you need to do fast paint and rust removal. In fact, all of the wire wheels we use for our angle grinders are twisted. We only use straight bristle wire wheels on drill attachments and die grinders, and they are all small diameter.

Like the other wheels, stuff can fly off this wheel at high speeds - the wires occasionally break loose hard enough to stick in your skin. This isn’t so bad, but that should encourage you to wear eye protection. Don't buy cheap wire wheels for your angle grinder. We've tried wire wheels from Harbor Freight, and besides not lasting very long, they will spray you with wire filaments for as long as the wire wheel lasts. Besides being intolerably annoying, this is also dangerous for you and anyone around you since the filaments can so easily pierce skin (and certainly eyeballs).