Incorrect cutting and drilling is one of the main causes of cracks around fixings. Follow these tips.
Cutting
- Thin sheets (up to about 2 mm) can be cut with a strong utility knife: score the line several times and snap gently.
- Thicker and multiwall sheets: a fine-toothed circular saw or jigsaw at a suitable speed.
- Clamp the sheet firmly to avoid vibration, and keep the protective film on while cutting.
- After cutting, blow swarf out of the multiwall flutes.
Drilling
- Use a sharp metal drill bit at medium speed without excessive pressure.
- Make the hole slightly larger than the screw to allow for expansion.
- Keep holes a sufficient distance from the sheet edge.
- On multiwall, drill between the ribs, not on an internal wall.
Never over-tighten screws: excessive pressure is the biggest cause of cracking.
