Precision Technology Supplies are one of the largest distributors of stainless steel screws in Europe and have a comprehensive stock range of self drilling screws in various head styles. All are available to buy now online. Self drillers (also sometimes known as Tek screws) drill their own pilot hole and should not be confused with self tapping screws, which need a pre-drilled pilot hole. The drill bit flute penetrates the sheet metal before the threads start to engage. They are very popular as roofing screws or cladding screws, especially when coupled with a sealing washer and should be used for metal only. They do not work well with wood (except for specially designed parts with reaming wings on the drill tips to provide clearance). The length of the drill bit flute determines the thickness of the metal that can be drilled. The flute provides a channel for chip removal during the drilling action. The unthreaded section from the point to the first thread should be long enough to assure the drilling action is complete before the first thread engages the drilled metal. As the screw threads advance at a rate several times faster than the drill flute can remove metal, all drilling therefore should be completed before threads begin to form. Our standard stock to DIN 7504 generally features a drill flute in the range of 4-5mm. If you can't see the self drilling screws you need online then please call us on +44 (0) 1342 410758 or email us at email@example.com.