How big are the 8 bits that have worked up?
8mm's expansion tube uses a drill with a diameter of 8mm. If it is 8mm's expansion screw, use a drill with a diameter of 12mm.
A drill bit (Drills) is a tool used to drill through holes or blind holes in solid material and to expand existing holes. The commonly used drills are mainly twist drills, flat drills, center drills, deep hole drills and casing drills. Reaming drill and countersink drill is not in solid material drilling, but it is also customary to put them in a bit.
If 8mm's expansion pipe uses a drill with a diameter of 8mm, if it is a 8mm expansion screw, use a drill with a diameter of 12mm.
