In this article, I will explain the different kinds of drill bits and their uses. As a woodworker, I have used many different types of a drill bit or boring cutter.
Drill bits for wood
Wood drills come in twist or brad point the fundamental difference is:
- The brad point drill bit has a small point for accurate starting and winged fast cutting surfaces
- Twist drills look very similar to metal drilling drills but beware because not all wood cutting drills will cut metal.
A popular choice for general purpose drilling available in HSS (high-speed steel), Titanium and Cobalt.
Twist drills have a grinding angle for:
Ideally, you should choose a drill bit of the correct type for your job but in a fix, general-purpose will do ok although inefficient. The Geometry of the cutting angles and flutes or the drill bit plays an important part in the drills ability to cut clean holes.
Brad Point Drill Bits
The Brad Point of this type of drill is designed to aid accurate positioning in wood. Ordinary twist drills Brad drills cut fast and cleanly but be careful when buying brad point drill as cheap offerings are not ground well. It is important that the geometry of Brad Point and cutting surfaces are crazy sharp. Dewalt does make a great brad-point alternative with a Pilot Point centre drill. Sharpening Brad point drills is very difficult and not always successful.
Dewalt Pilot Point
The Pilot Point drill has a smaller drill at the tip of the drill which like the brad-point aids positioning. The pilot point also makes the drill more controllable helping to prevent the drill from wandering during boring. This is especially useful when drilling timber that has either a coarse or wild grain.
Sharpening Drill Bits
I sharpen my drills on a regular basis as this saves money. Not all drills are easy to sharpen but most are.
What to use to sharpen drill bits
You have a few options but here is my selection
- Bench grinder
- Drill doctor
- Diamond sharpener
Is a simple power tool with two grinding wheels. Each wheel is powered with a centrally mounted motor. Most bench grinders come with one coarse and one fine grinding wheel.
How to sharpen a drill bit
Using the fine wheel you touch the drill against the abrasive wheel mimicking the original angle or use a jig.
Cool the bit as you grind
It is a good idea to have a pot of water nearby so you can cool the bit as it will heat up. The tool steel will lose it’s temper if allowed to get too hot.
The all in one drill sharpener is a machine designed to sharpen drill bits of all sizes. I have one of these Drill Doctors and I must say it does a fine job of twist drills.
A simple flat diamond sharpener is a versatile sharpening tool. I use one for sharpening flat bits (Spade), twist drills, brad point and Forstner.
Drills for drilling large holes through the wood
You can get large twist drills for drilling large holes but there is a better way. The problem with twist drill is that when there is a lot of wood to remove the flutes of the drill can overheat and clog. Today you have two types of drill bits that are commonly used
- The Auger drill
- Flat or Spade bit.
What is an Auger drill?
The auger drill uses the Archimedes principle of clearing the wood during the drilling just like the twist drill. Auger drills are designed for slow drilling of wood. Augers are traditionally used with a Hand Brace but can be used with a high torque cordless drill.
What is the Flat drill?
The FLAT BIT is an economical alternative to the auger drill. I have used these for years and find them especially good for drilling through holes in wood. A popular choice for electricians who regularly do cable runs. But as a woodworker, these flat or sometimes called spade bits are great for quickly and cheaply drilling holes up to 2” or 50mm.
Drills for drilling flat bottomed holes
Sometimes the drilling of flat bottom holes is necessary for some woodworking tasks possibly the most common being the kitchen cabinet door hinge. Milling large flat holes can be done with the router and a circle jig but you can easily drill a flat bottom hole with Forstner bit.
What is a Forstner drill bit?
Forstner drills are designed for the drilling flat bottomed holes.
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