For drilling steel, the optimal tip angle to sharpen a drill bit is 118 degrees for mild steel and 135 degrees for hard or stainless steel.
Obviously the angles are different, a 118 degree bit has a sharper point which results in less walking and does not require a split tip like a 135 degree drill bit. 118 degrees makes a great hole and is considered by many to be a universal standard drill bit angle for the mass majority of your drilling needs.
By matching your drill bit angle to your material, you can cut more efficiently and extend the life of your tool. 118° bits are perfect for soft materials like aluminum, wood, and mild steel, while 135° bits are built for tough materials and industrial applications where control and precision matter most.
The general purpose drill points found on most jobber drills are 118° angled drills. They are typically used for cutting into soft metals such as aluminum, whereas the 135° variant is best suited for hardened materials, such as stainless steel.
Either a bench grinder or a belt sander will work for sharpening bits. Just make sure that the guards on either one of these machines is less than 1/8" away from the belt or wheel so that your bit doesn't get caught between the guard!
Pro Tip: Drilling into metal materials can add extra wear and tear on bits, even those designed for metal. Adding a lubricant such as WD-40® Multi-Use Product can reduce friction and allow for easier drilling and cutting into metallic parts.
To sharpen a drill bit correctly, you need to set your angle based on the material you are drilling and ensure a proper relief angle. The most critical factor is that both cutting lips are ground to the exact same angle and length to ensure the bit cuts straight and true.
Always drill metal on a slow speed combined with firm, steady pressure. High speeds generate excessive friction and heat, which will instantly burn and dull your drill bit.
To construct a 135∘135 raised to the composed with power135∘ angle using a compass and straightedge, you combine a 90∘90 raised to the composed with power90∘ angle with a 45∘45 raised to the composed with power45∘ angle (which is half of another 90∘90 raised to the composed with power90∘ angle). Mathematically, 135∘=90∘+45∘.
The standard point angle for general-purpose drill bits is 118∘118 raised to the composed with power𝟏𝟏𝟖∘. This angle is widely used for soft metals, wood, and plastics. For harder materials like stainless steel or cast iron, a 135∘135 raised to the composed with power𝟏𝟑𝟓∘ angle is preferred, as it provides a flatter, more gradual cut.
The sharpest, most durable drill bits for metal are made of carbide for maximum hardness or cobalt for high-heat tolerance. Standard high-speed steel (HSS) and titanium-coated bits will dull quickly on tough metals, while these professional-grade options maintain their edge over repeated use.
For steel, the ideal drill bit point angle depends on the specific type of metal. For general mild steel, an 118∘118 raised to the composed with power𝟏𝟏𝟖∘ angle works best, while hard or stainless steel requires a 135∘135 raised to the composed with power𝟏𝟑𝟓∘ angle.
A 118-degree point angle is the universal standard for drill bits because it provides the best balance of cutting efficiency, tip strength, and self-centering for general-purpose use.
When choosing the "best" drill bits, the right set depends on the material you are drilling and your intended use. For heavy-duty jobs and tough metals, Cobalt is the gold standard. For fast drilling in wood or light metals, Titanium is ideal.
An octagon is a polygon with 8 sides and 8 angles. An octagon where all the sides are the same length and the angles are all 135 degrees, it is a regular octagon.
A 140-degree angle is an obtuse angle.
To make a 120∘120 raised to the composed with power120∘ angle, you can use a compass and ruler to draw a 60∘60 raised to the composed with power60∘ angle and extend its side to create a supplementary 120∘120 raised to the composed with power120∘ angle. Alternatively, using a protractor, mark a base line, place the center on the vertex, mark 120∘120 raised to the composed with power120∘, and draw the line.
Yes, you can use regular WD-40 for light drilling in soft metals like aluminum or brass. However, because it is thin and evaporates quickly, it is not ideal for steel or heavy-duty drilling. For best results, use a dedicated formulation like WD-40 Specialist Drilling and Cutting Oil instead.
Drill at a Slow Speed
In general, it's a good idea to drill through metal using as slow a speed as possible using a drill bit for metal. Hard metals like steel and larger drill bits require even slower speeds. With a small twist bit (1/16 in. to 3/16 in.), you can drill through most metals at 3,000 rpm.
For drilling steel, the ideal RPM depends primarily on your drill bit's diameter and the type of steel. As a rule of thumb, larger bits require slower speeds, and harder steels require slower speeds to prevent the bit from overheating and dulling.
-Durability: 135 degree bits are generally more durable and resistant to wear compared to 118 degree bits. This is particularly important when drilling through harder materials that can quickly dull or damage less robust drill bits.
The best sharpening angle depends on your knife's use: 15∘−18∘ for delicate kitchen tasks, 20∘20 raised to the composed with power20∘ for standard kitchen and everyday carry (EDC) blades, and 25∘−30∘ for rugged outdoor or heavy-duty utility tasks. The angle is measured from the blade to the sharpening surface.
WD-40 and 3-In-One Oil work well for drilling bits because they are low-viscosity and high-quality oils that reduce friction between the drill bit and the surface it is going into. Both have a long history of success, so there really isn't anything negative to say about them in terms of performance.