Drift pin
In metalworking, a drift pin, drift pin punch, slave pin, simply drift, or even pokey bit is the name for a tool used for enlarging holes, or aligning holes prior to bolting or riveting metal parts together. A drift pin is not used as a punch in the traditional sense of the term. A drift is constructed as a tapered rod, with the hammer acting on the large end of the taper. The tapered end of a drift punch is placed into the semi-aligned bolt holes of two separate components, and then driven into the hole. As it is driven in, the taper forces the two components into alignment, allowing for easy insertion of the fastener. Unlike most punches, force should never be applied to the tip of drift pin.
Drift pins are especially useful for aligning fastener holes in structural steel members. Spud wrenches used for assembling trusses and steel beams have tapered handles to use as drift pins.