The industry standard for general-purpose drilling is 118°. This angle works well on a wide range of materials including mild steel, wood, and most common metals. It's the default angle found on most off-the-shelf drill bits. For more demanding applications, a 135° split-point bit offers better centering and works better on harder steels.

For stainless steel, a 135° point angle is strongly recommended. Stainless steel is tough and work-hardens quickly, so a blunter angle provides a stronger cutting edge that resists chipping and overheating. Pair this with a split point geometry for better self-centering and reduced thrust pressure. Use a lip relief angle of 6-10° for optimal results.

Different materials have varying hardness, ductility, and thermal properties. A sharper point (60-90°) slices through soft, ductile materials like plastics and aluminum more cleanly, reducing deformation and burrs. A blunter point (135-140°) provides a stronger, more heat-resistant cutting edge for hard materials like stainless steel and titanium. Using the wrong angle leads to poor hole quality, excessive wear, overheating, and potential drill bit breakage.

The 118° bit has a sharper, more pointed tip that penetrates faster in softer materials like mild steel and wood. The 135° bit has a flatter tip with a stronger cutting edge, better suited for hard materials. Additionally, 135° bits often feature a split point design that eliminates the chisel edge, providing better self-centering and requiring less feed pressure. For a general workshop, having both 118° and 135° bits on hand covers most drilling needs.

For aluminum and aluminum alloys, a point angle of 90° to 118° works best. The sharper 90° angle produces cleaner entry holes with less burring. A higher lip relief angle of 12-15° prevents the bit from grabbing or "screwing" into the soft material. Using a high helix angle (30-40°) also helps with chip evacuation, which is critical when drilling aluminum's long, stringy chips.

You can measure the point angle using a drill point gauge (an inexpensive tool with notches at common angles like 118° and 135°). Alternatively, use a protractor or an optical comparator for precision. A quick check: place the drill tip against a known 118° or 135° reference and see if the cutting lips align. For consistent sharpening, consider a dedicated drill sharpening machine with preset angle guides.

While a 118° bit can drill stainless steel in a pinch, it's not ideal. The sharper angle is more prone to chipping and rapid dulling on tough, work-hardening materials like stainless. You'll likely experience poor hole quality, excessive heat, and shortened bit life. For best results, use a 135° cobalt or HSS bit specifically designed for hard metals, with adequate cooling/lubrication.

For soft wood and most plastics (acrylic, nylon, PVC, polycarbonate), a 60° to 90° point angle is recommended. The sharper point reduces splitting in wood and minimizes melting or cracking in plastics. For hardwoods, you can use up to 90°. A higher lip relief angle (12-15°) also helps prevent the bit from grabbing in these softer materials.

The point angle directly impacts centering accuracy, burr formation, and exit hole quality. A sharper angle (60-90°) centers more precisely but can cause more burrs on exit in metals. A blunter angle (135°) is more stable in hard materials but may wander more on entry without a center punch. The right angle minimizes these trade-offs for each specific material.

A split point drill bit has a notched or split chisel edge at the very tip, which greatly improves self-centering and reduces the thrust force needed to start drilling. This means less walking/skating on the material surface and a more accurate hole. Split points are especially beneficial on 135° bits used for hard metals, and they're also excellent for drilling curved or uneven surfaces.