Screw

Uncommon card · No. 119321

A screw is an externally helical threaded fastener capable of being tightened or released by a twisting force (torque) to the head. The most common use of screws is to hold objects together and there are many forms for a variety of materials. Screws might be inserted into holes in assembled parts or a screw may form its own thread. The screw head on one end has a slot or other feature that commonly requires a tool to transfer the twisting force. Common tools for driving screws include screwdrivers, spanners, wrenches, coins and hex keys. The head is usually larger than the body, which provides a bearing surface and keeps the screw from being driven deeper than its length; an exception being the set screw (aka grub screw). The cylindrical portion of the screw from the underside of the head to the tip is called the shank; it may be fully or partially threaded with the distance between each thread called the pitch. Most screws are tightened by clockwise rotation, which is called a right...

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