What is the difference between a grinding and cutting wheel? Masonry wheels? Diamond wheels? Flap disks? Fiber Disks? Read more to find out!

Hey all, some of the stuff that I take for granted isn’t necessarily common knowledge for beginners, so I wanted to dive into some of the different kinds of grinding and cutting wheels that are available.

Safety Warnings

First off before I even get into the different kinds of wheels PLEASE make sure you have your safety gear. I have another article that goes into detail on everything you need to be safe while welding, cutting, and grinding here: Home Metal Fabrication Shop Safety Gear

Also, please do NOT remove the guard on a grinder to run a larger wheel. I have seen plenty of instances where people have done this then wondered why when their finger slipped off the trigger or when the wheel exploded they got cut. The guard in addition to protecting you also protects the grinding wheel from damage when setting the grinder down. Just buy the right size grinder, they are way cheaper than an eye or finger…

Off my soapbox, now on to the discussion!

My junky drawer of grinding and cutoff wheels. It is one of those things where it looks like you have a lot until you get way deep in a project and run out 😛

Grinding wheels vs cutoff wheels

Long story short, grinding wheels are thick and allow you to press down while grinding for removing material. Cutoff wheels are thin and are made for straight cuts with no lateral load.

Cutting wheels typically 1/16″ – 1/8″ thick

Grinding wheels typically 1/8″ – 1/4″ thick

Angle Grinder Arbor Types

There are two different kinds of mount for grinding disks/wheels, one that just has a hole and uses the grinding wheel arbor nuts and the other that comes with a threaded insert and threads directly onto the grinder. I don’t think there is a huge difference here, but from my experience the ones with the threaded insert seem to be heavier duty but are also more expensive. Below are examples of both:

Masonry vs Metal wheels

Per an article I found on Diablo Tools website and my prior experience you CAN use masonry wheels on metal, they just don’t last as long. They have a great FAQ here: Diablo Tools Abrasives FAQ.

They really don’t look any different but in the past whenever I accidentally grabbed a masonry wheel for metal I would notice that it wasn’t cutting as fast until I looked at the label and realized that I grabbed the wrong wheel.

Diamond wheels which will be discussed later can be used on either masonry or steel.

Flap/Sanding disks

Flap disks (also called flap wheels) are basically grinding wheels with small pieces of sandpaper glued to it.
Flap disks can be bought in different grits just like sandpaper. A 36 grit flap wheel is used for aggressive sanding and shaping where a 110 grit flap wheel would be used more for finishing.

Here is a quick reference from the Diablo Tools FAQ linked above:

Abrasive Wheel Grit Guide from Diablo Tools

Fiber Disk Sanding Wheels

These are very similar to the flap wheels in that they are for sanding and cleaning up metal but the design is a lot different. These have a holder/arbor that goes on the grinder then a flat but very stiff sandpaper like disk that can get changed out. These are pretty handy to have around and they flex more than the flap disks above which is good for thinner steel.

Diamond Wheels

Diamond wheels are typically made from steel and have diamonds embedded in the teeth. They can be used on either masonry or steel. The only drawback here that I have heard but not experienced yet is that since the disk is steel if it gets bound up instead of shattering like a regular cutting wheel it has the potential to buck. I have also heard they are louder than regular grinding wheels.

I actually just bought some of these Lenox MetalMax 4.5″ grinding wheels but I haven’t gotten a chance to use them yet. Stay tuned for an article on them. Lenox claims their diamond wheels will last 1,000+ cuts which is pretty impressive if it lives up to the claim.

Summary

There are lots of different grinding wheels for lots of different purposes. Read the reviews and details on the wheels before buying them. If you have a delicate project or specific task you need to do then make sure you get the correct wheel for the job. If you are in a pinch then you can substitute if needed (like using a masonry wheel for grinding metal, but make sure you aren’t comprimising on safety).

If I left something out please feel free to comment below! Your feedback is what helps this community grow!

Try to practice on welding better so you don’t have to do as much grinding. I always get a laugh at the pinterest memes that say “Having to grind your welds to make them look good makes you a grinder not a welder”. Now YOU, get out and work on something.