SELF-DRILLING or SELF-TAPPING? What's the difference? If you are confused, don't worry! You are not alone. Confusing self-drilling and self-tapping screws is probably the single most common terminology error we hear at Hillco Fastener Warehouse. A self-drilling screw has a drill-bit point to help drill into metal without pre-drilling holes. They are also called Tek® screws, a brand name, not to be used to refer to generic screws. However, many people who use fasteners in their daily lives, like many of our customers here at Hillco, have come to call self-drillers Teks screws, the way many people refer to all photo copiers as Xerox machines. A self-tapping screw has a sharp point normally and is a type "A" or "AB" tapping screw -- (though there are variations, such as "B" point which are blunt). A self-tapping screw (sheet metal screw, wood screw, lag bolt) cuts its own thread (like a tap), but there must already be a pre-drilled hole. Self-Drilling screws are for metal only and do not work well in wood (except for specially designed parts with reaming wings). Self-tapping screws work well in all materials, but are likely to need a pilot hole in many applications. Hillco sells both self-drillers and self-tappers in steel and stainless steel. We also sell chrome plated trim screws for interiors that come in both variations. Feel free to call us at 714-657-7442 if you'd like to know more!