The technique of disking ribs is probably the fastest way to remove EDM from ribs; however, the downside can easily outweigh the benefits. Disked ribs can become undercut extremely easily – in a matter of only a second – and this technique should only be used by an experienced polisher with many years of “feeling with his fingers” – or discarding the block and starting all over again is a real possibility.

Young and inexperienced polishers – often intent with impressing the owner with their great speed and who are totally ignorant of the severe consequences possible – are the least qualified people to use this technique, but are often the first to do so. Ironically, the older, more experienced polishers – who are the most capable of handling this technique – are the least eager to use it because of well-founded concerns about damaging the block. They opt to use other slightly slower, but safer methods.

Several methods of disking ribs include:
Putting a two- or three-inch disk in a one-inch disk holder and reaching down into the rib.
Tearing off the attached center mount from a disk and then backing up the disk with a homemade thin steel disk, while using a cut-off wheel arbor to hold it all together. This allows both increased depth and pressure to be applied to the disk at once.

Cutting an extra-large diameter steel disk from a sheet of galvanized steel -as in duct-working material – and mounting this disk onto a quarter-inch screw, then adding sticky-back strips of abrasives all along the cutting surfaces. These strips are easily replaced when they become worn out and allow for the disking of extremely deep ribs.