Angle Grinder Attachments For Automotive Repair
Article by Mark Trotta
Grinding wheels, cutting wheels, flap discs, sanding discs, wire wheels - all of these attachments are useful, but they all serve different purposes. When using an angle grinder for automotive repair, it's important to know which one is best suited for the task at hand.
Grinding Wheels
For metal removal, grinding discs, or grinding wheels, work the quickest. Common usages include shaping and contouring metal, grinding down welds, and cleaning metal before welding. Other uses include sharpening garden tools and mower blades.
Discs (or wheels) will be marked Type 27, Type 28, or Type 29. These refer to the profile of the disc.
Type 27 vs Type 29 Disc
A type 27 disc is suited for grinding planes and outside corners, and best used at a 0-15 degree angle. It is referred to as a flat disc.
A type 29 disc has an upward curvature, which allows it to grind at steeper angles and is best used at a 15-25 degree angle. It is referred to as curved disc.
Less often encountered is a type 28 wheel, which has a saucer-shaped rim and designed for corner and side grinding.
CAUTION: Because of their hardness, grinding discs produce large sparks which are dangerous. Always wear safety glasses and/or a safety shield when grinding metal.
Flap Discs For Metalwork
Shaping and contouring metal can also be done with flap discs, which offer a compromise between fast cutting and final finishing. They remove metal slower than grinding discs, but produce smaller sparks.
Their unique feature is that they wear from the outside edge, so they'll wear more evenly across the entire disc. And unlike sanding discs, the length of each flap can be worn down completely before it needs replacement.
Flap discs are lighter and easier to maneuver than grinding discs, and well-suited for taking off sharp edges, removing burrs, and chamfering edges. And when you're grinding a lot of metal, you'll appreciate that they give less vibration.
Cut-Off Wheels
The thin profile of a cut-off wheel allows you to cut through metal quickly and easily. Although primarily used to cut sheet metal, they're also useful for cutting off muffler clamps and shortening bolts. Common sizes are 1/8" and 1/4" width.
NOTE: The cutting speed of an angle grinder is dependant on it's amperage rating. For example, a 13-amp motor will cut faster than a 7-amp motor.
Read: Best Angle Grinder For Automotive
Wire Cup Brushes
Wire wheels are excellent for removing surface rust and stripping paint from automotive sheet metal. Straight and thin bristles are less abrasive and not as aggressive as twisted bristle wheels.
Twisted vs Straight Wire Wheels
For fastest paint and rust removal, use twisted bristle wire wheels.
TIP: Don't buy the cheapest wire wheels you can find. The strands will come apart quickly and literally fly all over the place! Always wear eye protection when using wire wheel attachments.
Bristle Discs and Strip Discs
With an angle grinder, you strip paint off a car with a bristle disc or strip disc.
Bristle discs come in different grades and are color coded green, yellow, and white. Metal finishing, polishing, and cleaning can also be done with bristle discs.
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Best Angle Grinder Attachments
Dewalt DW4523 Grinding Discs are highly rated by both professionals and DIYers. Measurements are 4-1/2" x 1/4" x 5/8".
Shop: Dewalt Grinding Wheels
Grinding discs come in different grits. Lower numbers (like 40 grit) are coarse and remove material faster. Like all other angle grinder attachments, they are consumables. They'll last for a certain amount of time, and then they need to be replaced.
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The Neiko #11142A Zirconia flap discs won't last as long as the more expensive name brands, but their lower cost makes up for that. They measure 4.5" x 7/8" and are sold in a 10-pack.
Shop: 40 Grit Flap Discs
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Shop: 4-1/2-Inch Cutting Wheels
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Shop: Knotted Wire Wheel
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Shop: Dewalt 3-Inch Wire Cup Brush
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Shop: Strip Discs 4" x 5/8"
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Safety Concerns
When operating an electric grinder, eye protection is essential. Some angle grinders spin at 11,000+ RPM, so flying pieces of brittle aluminum oxide are a real concern. These can not only blind you, they can also give you severe skin cuts. Long sleeve shirts and pants are recommended.
Also recommended are a dust mask or respirator. And since they can be quite loud, ear protection is also worth considering.
Although most angle grinders will accept a knotted wire cup wheel, there are safety warnings regarding this. This is because most wire cup brushes are only rated for 9,000 RPM. The thin wire bristles can come loose and get thrown from the brush even during ordinary operation.
The standard guard on most grinders are too open to protect you if a disc shatters.
Type 1 cut-off discs have a printed warning to remind you to use a proper guard.
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