One Solid Carbide 0.635” drill bit.
These bits are made specifically for Needham Ag to drill out the John Deere Extended Wear seed boots which are hard and difficult to drill. These drill bits feature 4 cutting flutes and 3 flats on the other end, to stop the bit spinning in the chuck.
A heavy drill press (preferably a mill), with a heavy vice is required to eliminate all vibration. Lubrication is a must and a chuck which turns at 80-100 RPM is needed. A 5/8″ chuck is required with this drill bit.
Within these set-ups detailed above, its possible to drill hundreds, if not thousands of seed boots with these solid carbide drill bits, especially if the cutting flutes are touched up every now and again with a fine grinding stone.