Quick answer

Choose a #8 self-drilling TEK screw for light-to-medium gauge metal up to 1/8" thick. The integrated drill point eliminates pre-drilling, but you must match screw length to material stack thickness and adjust drill speed to prevent bit damage.

Why self-drilling TEK screws save time

A self-drilling TEK screw combines a drill bit tip with a threaded fastener, letting you drill and fasten metal in a single operation. This eliminates the separate step of drilling a pilot hole, which can cut installation time by half on repetitive jobs like attaching metal roofing, ductwork, or steel framing.

Limitations of #8 TEK screws

The #8 size is ideal for light-gauge steel (22–16 gauge) but may struggle with thicker material over 1/8". For 1/4" plate or structural steel, you need a #10 or #12 screw with a larger drill point. Also, zinc-plated finish provides basic corrosion resistance for indoor or dry applications; for exterior use, choose stainless steel or coated screws.

Installation steps

  1. 1. Select the correct length: Measure total material thickness you are fastening (e.g., 0.060" base + 0.040" cap = 0.100"). Add at least 1/4" for the drill point to exit. For two layers of 18-gauge steel, a 1-1/2" screw provides enough thread engagement. Too short a screw strips out; too long a screw leaves exposed threads that snag.
  2. 2. Set drill to medium speed (1500–2500 RPM): Use a variable-speed drill. Too slow stalls the bit; too high speed overheats the drill point and dulls it. A clutch setting of 10–15 prevents over-torquing when the head seats. High speed and no clutch can snap the screw head off before it seats.
  3. 3. Align screw perpendicular to the work surface: Hold the screw at 90° to the metal. Start drilling with gentle pressure. The self-drilling point will penetrate on its own. Once through, increase pressure to drive the threads. Starting at an angle causes the bit to walk and can break the drill point.
  4. 4. Drive until the pan head contacts the surface: Stop as soon as the underside of the pan head touches the top layer. Do not over-drive—this deforms the metal or strips the threads. The Phillips drive should seat fully without slipping. Over-driving creates a countersunk depression that weakens the joint.
  5. 5. Inspect for proper seating and burrs: Check that the screw head is flush and the metal layers are drawn together without a gap. Remove any metal shavings around the head to prevent corrosion. A visible gap means the screw is too short or the drill point didn't fully penetrate.

Product facts