fixing element 4 mm hole with centrally tapped bore

Mark the center: Use a center punch and hammer to create a small dimple where the hole will be drilled. This prevents the drill bit from wandering.

Chamfer the hole: Create a small chamfer on the edge of the pilot hole. This helps the tap enter the hole more easily and prevents burrs from interfering with the threads.

2. Drilling
Select the correct drill bit: For a 4mm tapped bore (which usually indicates an M4 thread), a pilot hole drill size of 3.3 mm is needed.

Drill the pilot hole: Securely hold the material and the drill at a right angle to the surface. Use a low drill speed to maintain control and prevent the bit from breaking.

3. Tapping
Secure the tap: Attach the tap to a tap handle or a drill press.
Start the tap: Align the tap with the center of the pilot hole and begin turning it by hand or using the drill press.