Self Drilling Screws For Thick Steel. Self drillers, sometimes called drill and tap screws or TEK screws give you the luxury of fastening with out drilling and tapping. Our self drillers for thick steel take it up a notch. With the ability to drill into steel up to 1/2" in under 40 seconds, you will find many uses in install and service work. Check out the video and see for yourself! Samples are available.