Drill Bit Overview

A good drill is important but you also need good drill bits. It can be tough to find the right drill bits, they come in all possible shapes and forms.

The most common types of drill bits are
– Twist bit, used for drilling in wood and light metal
– Brad point bit, used for wood drilling
– Spade bit, used for large holes in wood
– Auger bit, used for wood drilling
– Forstner bit, used for flat bottomed holes in wood
– Masonry bit, used for drilling in masonry, typically using a hammer drill
– Glass bit, used for drilling in glass or tile.

There are a lot of other drill bits but the standard twist bit is used for most DIY tasks. The material the drill bit is made of is very important. The cheapest drill bits are made of steel. Low carbon steel bits are cheap but should only be used for drilling in wood, preferably only softwood. High carbon bits are more expensive but can be used for drilling in metal and hardwood. But they dull quickly and need to be sharpened frequently.

High Speed Steel (HSS) is the most popular material for drill bits. It is a special kind of tool steel that can withstand high temperatures. HSS drill bits can be used at higher speed than bits made of high carbon steel. HSS drills are also available with various coating materials.

HSS bits are often coated with black oxide. It is a cheap coating which provides a higher level of heat resistance and improved lubrication. Titanium nitride coated HSS bits are not much more expensive than normal HSS bits but thanks to the coating the lifetime of the bit is increased up to five times. The titanium nitride coating also allows for higher drilling speeds. The same goes for titanium aluminum nitride coated HSS bits.

Carbide tipped HSS bits are expensive but stay sharp longer than titanium coated bits. They also tolerate heat better other drill bits but they are brittle and must be handled carefully.

Cobalt drill bits are extremely hard and used for drilling in hard materials such as stainless steel. Cobalt bits are very heat tolerant but also very brittle. Many other materials are also used for specialized drill bits but they are typically expensive and need to be handled with care. For basic DIY tasks, HSS drill bits with black oxide coating for wood drilling and titanium nitride coated HSS bits will be good enough.

Regardless of what kind of drill bit you are using, the same rules of thumb apply. When drilling in hard materials, use slow speed. When drilling in soft materials, use fast speed. Also, remember to check the recommendations from the drill manufacturer.

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