Flap discs are one of the most versatile grinder accessories in metal working. With a light hand you can lightly sand and polish an area then with some elbow grease, you have a metal removing machine. Flap discs do not wear out as fast as typical grinding wheels. As the disc wears it reveals a new piece of gritted sand paper behind it. Since discovering flap discs I tend not to use anything else for my metal grinding and sanding needs. They save time and last!
Diablo offers a variety of grits and styles of flap discs, but I have to say the rounded corner design of the Corner Edge flap disc is one of my favorites. It allows you to get into the corner of a joint to clean up the bead. While we were testing this disc we realized that you can actually cut metal with this disk. It is a beast for almost any application. You can see in the video how it cut and how long it lasted.
If you're in the market for some new flap disks and want great performance with long life, check out Diablo.