Slotted Drives Detail

The slot screw drive has a single slot in the fastener head and is driven by a “common blade” or flat-bladed screwdriver. It was the first type of screw drive to be developed, and for centuries it was the simplest and cheapest to make. Uniquely among common drives, it is straightforward to manufacture a slot head or drive by hand. The slotted screw is commonly found in existing products and installations, and is still used in some simple carpentry, and applications where little torque is needed. It is used in restoration of old and antique furniture, vehicles and equipment. However, it is not well suited to installation with power tools, because a power driver tends to slip out of the head, potentially damaging the screw and surrounding material. For this reason, cruciform and other drives have replaced it in most applications. The tool used to drive a slot is called a common blade, flat-blade, slot-head, flat-tip[3] or flat-head / flathead[4] screwdriver. A hollow-ground screwdriver is less likely to “cam out” (leave the slot due to torque being translated into an axial force), so more torque can be applied without damaging the screw head. Flat-blade jewelers’ screwdrivers and the tips found in 1⁄4-inch or 6.4-millimeter drive sets are generally hollow-ground. Note that it is this typical chisel shape which allows 9 screwdrivers to drive 24 different slotted screw sizes, at the expense of fitting as a hollow ground screwdriver would, and increasing the possibility of damaging the fastener or surrounding area.