8mm iron expansion bolts with few drilling drill mm?
8mm iron 12mm impact drill drilling expansion bolt, this is because the expansion bolt is normal, the bulk of the direction of 11MM, so we must use 12MM bit, if the use of a small number of bits, the expansion bolt is difficult in the walls, attention should be paid attention when the fastening nut screw slip.
It's a gross mistake to say 8 mm punching. As with a hammer smashed bolt can not. Strictly speaking, 12 mm bit should be used, but if the expansion bolt is not standard, you need to drill 10 millimeters, then twist the hole, it is best to use caliper to measure the diameter of the bolt and then decide
