Kevin is reading a catalog from Random Products, learning more about the grinding wheels, cut-off wheels and flap disks they’ve sent him to try.

They sent some grinding wheels, or grinding stones, from PFXin Germany. One, which has an orange band, is a high performance Zirconia grinding wheel. It has an increased amount of Zirconia in the disk, so it runs a little cooler, runs a little better and lasts longer. Another, which has a blue band, is more generally for steel, stainless and other metals.

Kevin decides to grab some nasty old metal, put it in the vise and “get at it!” He wants to see which grinding wheel does better for what.

First, he’s trying the blue one. It’s a Type 27 with a depressed center so the nut will sit down inside when you put it on your angle grinder.

In the vise, he has a piece of 1″ square steel with rust, paint and an ugly weld that wasn’t quite ground off. It’s perfect for trying out these grinding wheels. Let’s see how fast they can grind it to bare metal.

Kevin puts on his safety equipment – glasses, gloves, ear protection, dust mask – and is ready to make some sparks!

The blue wheel does a good job taking the steel back to clean metal. Then he flips the piece of steel around and uses the higher performance grinding wheel on its other side.

The results are eye-opening. The high performance grinding wheel with the orange band was much more aggressive – Kevin didn’t have to push hard at all and it just gobbled up the metal. He shows the difference between the two – the grrr marks from the orange banded grinding wheel are much deeper.

Why would you use a grinding stone instead of a flap disk? For example, Kevin is working on a sculptural privacy screen for which he is cutting out large sections, raising them with 1/4″ solid square steel stock and welding them back on to make them look just like the more slender metal sections he has been able to simply heat and bend.

He doesn’t want them to look welded, though, so he comes in with his 4-1/2″ grinder with a grinding stone on it, gets into the weld with the best angle, and works it back and forth lightly to blend the weld in. He still has some grrr marks, though, so that’s where the flap disk comes in: he uses it to give the metal a nice surface.

So grinding wheels and flap disks go hand in hand. Grinding wheels remove stock fast; flap disks give a nice, smooth finish. Grinding wheels are noisy and give off lots of sparks; flap disks are quieter and emit fewer sparks. Grinding wheels last a long time; flap disks wear out a little more quickly and seem to create more dust. So using them both makes the work go more quickly.

Before you head out to join Kevin on Facebook (just look for Kevin Caron, Artist), you might want to take one more moment for a little Groundhog Day fun ….