Tools fascinate me. I often think how many times I have struggled with a task, only to find out later that had I known of the specialty tool I needed, the job would have taken minutes, not hours, to perform. Of course, on the other side of that coin is the reality that having specialty tools on hand when needed is also an expensive investment of time and money.
Still, I like to browse through the tool sections of catalogs and home improvement stores just to see what’s new. An area where I often find myself is the space devoted to drill bits. I think this stems from my own farm shop layout. The first thing everyone notices when they enter my shop is the old drill press. It is a monster. An old monster, but a monster, nonetheless.
Dad acquired our drill press from the old dealership where he worked until it closed in 1967. When they auctioned off the contents, one of the treasures Dad ended up with was the drill press, along with a selection of bits up to 4 inches across. (I told you it was a big rascal.)
We had an old 1-ton flatbed truck, and we hauled the press the 3 miles to our shop, but not before it nearly turned the truck on its side as we scooted it onto the bed. We were prepared a little better when we unloaded it and placed it on the shop floor. The reality is that Dad put it down on the shop floor and built the shop around it ….
Its sheer size and power can test a drill bit’s worth. If a bit is dull, the speed of the press is too fast or too slow, or the material is too tough – and I have another broken bit to add to the collection. That is one collection I do not want to grow.
So what is the right drill bit for the job? The answer lies in the job itself – and just like any other job, there is a bit for most every application. (Amusingly, even people who sell bits can’t agree on just how many different types of bits there are.)
Even the material the bits are made of is a point of the selection process. Materials used to make drill bits include carbon steel, high-speed steel (HSS), cobalt steel, tool steel with carbide tips and solid carbide. These options are listed in order of hardness but not necessarily in the order of best to worst. For example, carbide is the hardest and most brittle of th
e drill bit materials. It is used mostly for production drilling where a high-quality tool holder and equipment are used. It should not be used in hand drills or even drill presses. These drill bits are designed for the most demanding and hardest materials.
Twist drill bits are the most common type of drill bit and are used for everyday drilling in all types of material. They are also the most confusing due to the sheer number of size, tip and material specifications.
Twist bits tips help indicate how and where they are to be used. This is the most common tip style as seen on everyday general-purpose drills. The tip angle is usually 118 degrees but can vary from 90 degrees to high angle "plexi point" for use in acrylics. Conventional drill-point drills are the most economical and are easily re-sharpened – suitable for wood, non-ferrous metals and mild steel.
Split drill point bits have an advanced drill point that prevents walking and provides improved penetration with less effort. Available in 118 or 135 degree angles, split point drill bits are better for drilling in curved surfaces or in alloy steels. They are more expensive and more difficult to re-sharpen than standard drill points.
Another common twist bit point is the Bradpoint bit. Designed for creating blind holes in wood and other soft materials for shelf pins, dowels, etc. Bradpoints are also used for thru-holes in computer numerical control (CNC) applications where a conventional drill point would penetrate the table below the panel. Bradpoints have spurs on the outer edges to prevent splintering and chipping of the surface material, as well as a center spur to prevent walking as the bit penetrates the surface.
Other specialty bit points I have in my limited collection include hole saw, glass and tile, masonry, spade and auger bits. Hole saws do just that, saw holes. The saw blade design has everything to do with the material to be punctured. They can be very expensive, and I usually buy them when the need arises.
Glass and tile bits can be very handy when working with brittle materials that shatter easily. They are used to drill holes (usually for fasteners) in non-tempered glass, tile and similar materials. These bits feature carbide tips and straight shanks that can be used in either hand drills or automated machinery.
Masonry bits are specially suited for their application. They, of course, are used to drill holes in concrete, brick, etc., using a special "hammer drill" which pounds the drill bit as it rotates. A threaded anchor is usually installed if the hole is to be used to attach objects to the surface. Masonry drills have carbide tips and either standard or high-helix flutes depending on the intended use. They are typically coated with black oxide to prevent corrosion and feature shanks that are either the same size as the bit or reduced in diameter to fit the portable drill chuck.
Finally, spade and auger bits are used for wood and soft materials. While their application is similar, auger bits tend to be longer to produce deeper holes in the wood. They feature open designs that move the cut material away from the cutting edge quickly and easily.
We’ve only scratched the surface of the world of drill bits, but it is clear: Bits are not created equal. Before investing large sums of money in expensive drill bit sets, think about your applications and purchase accordingly.