A Case for Diamond Drill Bits

The thing about diamond drill bits is that they look so much like the regular ones that many people do not know that they should have them in the house. I’ve seen people try to drill wholes in concrete kitchen floors and bathroom tiles with the regular bits with some really sad results. Lucky are the ones who had replacement tiles.

Seriously, people. You wouldn’t use a wooden knife to cut a stone, would you? When you are drilling through a hard surface, you really need something that is harder than the surface you are working on. And it doesn’t get harder than diamond. Diamond happens to be the hardest material we know.

But when you get comfortable with the idea of drilling, get yourself a whole bunch of diamond drill bits of various shapes and sizes (twist, core drill bits, etc) and you can do a whole set of fun projects.

In fact, diamond core drill bits are used quite intensively for various craft projects. You can use them to cut out various designs on the glass. Just check out this cool project . That will give you an idea of things you can do with your drill! Seriously, drill bits are not just for the handyman around the house. They are also for the decorist of the place :)

By the way, when I mentioned the sad results of using the wrong drill bits on concrete, I really meant me… Yah… That time when I tried to drill a whole in the ceramic kitchen floor… I learned my lesson though. My diamond drill bit collection is in the place of honor in my basement.

Drill Bit Sharpener - Drill Doctor

As I’ve mentioned in the previous article, sharpening drill bits is a very important ability to have. Whether you have a fancy cordless drill or a high tech drill press, you job won’t get done if the bits are dull. So if you are going to spend on tools, do yourself a favour, and get drill bit sharpener.

Drill Doctor is the most popular brand of sharpeners. It is fairly easy to use. It does take a little manual dexterity to fit the bit in properly, but not nearly as much as if you were using a bench grinder.

Now what many newbies don’t realize is that when sharpening drill bits, you’re only sharpening the tip of the bit. Not the whole thing. The side flutes are not there for cutting, but for passing the waste material out. When you think sharp edges, you’re thinking end mills, which are a totally different tool, used in milling machines. So don’t make it more complicated than it has to be. Recite yourself this mantra “I’m just sharpening the tip of the bit.”

Which is essentially the principle of how a drill bit sharpener such as Drill Doctor works. You stick the bit inside, so that the tip is appropriate distance from a rotating wheel that does the grinding. Inside the Drill Doctor there is a grinding wheel with artificial diamond coating.

The sharpening is done in two steps. First the bits are properly aligned in the holder chuck (clamp). To do that, you must first level it properly by inserting the holder on the side of the Drill Doctor that will help you to get it to the exact position depending on the size of you drill bit. When you get the level properly, the drill bit is then tightened (fixated) for good in the chuck. And then the holder itself is inserted into the sharpening slot.

Then turn the machine on, and as you push the holder inside, slowly rotate it until the characteristic “metal cutting noise” disappears or goes down considerably.

Naturally, when you’re done, inspect the drill bit to make sure it’s as sharp as you want it to be.

Pretty easy. And it sharpens High-Speed Steel bits, carbide bits, cobalt drill bits, Tin-coated and masonry drill bits (confirm for individual models, though... just to be on the safe side.)

Drill Bit Sharpener

Unfortunately nothing lasts forever, and thus regardless of how careful you are with you drill bits, eventually they’ll need sharpening and you’ll be looking for a drill bit sharpener (or new bits… but that’s up to your budget, of course).

Obviously most of us want to save some money and not waste it on a whole new drill bit set, when just some sharpening is required. So what are the options?

Going to a professional sharpener is one. May cost you as much as buying a whole new set, depending on how often you have to pay the visit. Not to mention that there just might not be a professional around when you need him.

Do it yourself is the most cost (and time) effective option. But how?

There are some people who use bench grinders (also called pedestal grinder). Bench grinders are machines that have a spinning wheel with abrasive surface. This method however has some serious safety issues, as one has to keep the hands really close to the wheel. Definitely not recommended for inexperienced users. Though experienced tool-smiths take great pride in being able to do so. Just check out the cnczone.com forums for proof (and tips).

(Note that there are some devices that are aimed at helping with sharpening on the bench grinder. They hold the bit at a proper angle, thus keeping your hands off the danger zone. Referred to as a drill bit sharpening jig, they can be found in most hardware stores for a very reasonable price.)

Luckily for those averse to hovering their hands millimeters from a grinding wheel, there are numerous drill bit sharpeners on the market. These are particularly useful for twist and masonry drill bits.

Drill bit sharpeners come in different types, and you should do your homework to research which is the best for your drill bits, based on their size, type and material. These machines are generally easy to use and require no special extraordinary skill or experience.

Most likely you’ve already heard about the Drill Doctor drill bit sharpeners. Those are a very popular choice, and the company makes many models ranging in price from about $70 to $200 dollars.

There are also cheaper Drill Doctor rip-offs on the market. But with those you never know what you’ll get.

Some sample other manufacturers that make drill bit sharpeners are Plasplugs, Buffalo Tools, Bosch, Westfalia, etc..

Milwaukee Switchblade Selfeed Bit

This is according to a Milwaukee Press Release (available on thomasnet.com):

“Milwaukee Electric Tool Corporation introduces SwitchBlade(TM) selfeed bits, a new solution designed to ensure that contractors maintain a sharp blade.”

Key features include heavy-duty 7/16" quick-change hex shank for ensuring secure chuck grip and blades that are precision-ground for producing clean holes. The selfeed bit is replaceable (comes with second replacable blade) which maintains a sharp blade twice as long as normal (naturally). Material used is investment cast high alloy steel, promising to hold sharp cutting edges longer. Milwaukee also claim that the "newly designed aggressive feed screw provides 12% faster cutting than a standard selfeed bit".

The drill bits come with accessory storage kit, which includes replacement blades and hex wrench for quick replacement.

These bits are targeted for plumbers, electricians and HVAC contractors, and are available in sizes most frequently used by these professionals. The "SwitchBlade selfeed bits are used for drilling multiple holes in all types of wood and for various types of pipe, vent and gas lines and bulk wire routing."

These new drill bits will be available in July of 2008.

Why Do Drill Bits Have Flutes?

The reason for the flutes is that drilling creates waste material, which has to go somewhere. (Its more common trade name is “swarf”). Therefore the flutes are there as the escape path for the swarf. This is why it is recommended that when you drill wholes deeper than about half a centimeter, withdraw the drill now and then to clear the swarf away. This will help to prevent clogging, overheating and various potential resulting damage.

For the same reason, never drill deeper than the drill flutes, because there will be no room for the waste material to escape, and you could damage both the tool and the project.

Types of Drill Bits, Starting With the Twist

Most likely the first drill bit you’ll encounter in your carrier is a twist bit. These are the bits that saturate hardware stores and garage shelves of the Do-It-Yourselfers. They are a good introductory bit to analyze. So let’s dive in…

Here is an example of a typical twist drill bit:

The part that goes into the clamps of the drill is called a shank. There are different shank types as well, but we’ll talk about those later (but as a matter of curiosity satisfaction, the shank on this picture is labeled very creatively -- “straight”).

The rest of it is the body of the drill bit.

The spiral in-cuts are called flutes.

The end tip is called a point.

That was easy.

Now, twist drills generally come as single-flute drill bits or two-fluted drill bits. Both types are used for originating holes. The two-flute type is the most commonly available.

There are also three-fluted (core) and four-fluted (core) drill bits. Those are used interchangeably to enlarge existing holes.

There are also different length ranges. Below is a representative picture of some common lengths.

(click on the picture to enlarge)

Screw Machine Length Drill Bits
These have short flutes and short overall length. They are commonly used on sheet metal. Screw Machine bits are also called “stub length drills” or “stubbies”.

Jobbers Length Drill Bits
This is the standard length used for general purpose drilling. For this bits, the length of the flutes is ten times the diameter of the drill.

Taper Length Drill Bits
These are a little longer than jobbers length bits.

Extra Length Drill Bits
These come in various sizes, and are frequently used in automotive/aerospace industries, and in conditions where the target is hard to reach.

Longboy Drill Bits
These have longer flutes than extension bits and are available in larger diameters.

There are many different variations by different manufacturers, targeted towards unique projects. So always inspect catalogues for options, when settling on size.

One last aspect of twist drills I’d like to cover in this post is right hand drill bits versus left hand drill bits. Left hand bits cut in the opposite direction, and primarily used in large scale manufacturing for efficiency purposes. They are also sometimes used for removing screws. But those would be special screw removal bits…

Tungsten Carbide Drill Bits -- As Good As Diamond Drill Bits for the Do-it-Yourselfer?

Bosch has recently released a new product: tungsten carbide drill bits suitable for cutting glass and tiles. “These tungsten carbide bits are diamond ground to a precision point that eliminates walking and its reinforced head prevents the carbide from cracking.” Quoted from the original press release, February 13, 2008.

According to the company these bits are perfectly suited for working with ceramic, making them “the best solution for cutting glass, bathroom installations, drilling and fastening mirrors or even setting screws in glass furniture.”

As tungsten carbide drill bits are cheaper than diamond drill bits , Bosch is obviously trying to provide the Do-it-yourselfers (and professionals) with a cheaper solution than diamond, while minimizing the chipping issues associated with carbide.

These new bits start at 1/8” and going all the way up to 1” in diameter, the industry’s largest bit size, they are equipped with a 3-flat shank to reduce slippage that leads to more accurate cutting.

For more information, you call toll free 877-BOSCH-99 (877-267-2499).

Diamond Drill Bits

Diamond drill bits are a type of diamond tool, and therefore contain diamond segments bonded to a base material. It is the hardest type of tool and is especially frequently used on highly abrasive materials.

Until recently scientists thought that diamond was first used some time 500 BC in India. However recent new evidence suggests that craftsmen in China used diamond for polishing as far back as 4500 years ago.

The industrial market for this mineral focuses primarily on the hardness and heat conductivity, while clarity and color are considered irrelevant. Thus 80% percent of what the miners find end up in tools (such as diamond drill bits, diamond core drill bits, blades, polishing cups, abrasivesetc…) and not on the necks of Titanic bound debutants.

Due to the fact that it’s the hardest material we use, it is excellent for working on stone, ceramics, marble, glass, fiberglass, porcelain, etc. However, diamond drill bits grind, as opposed to cutting the surface. Nevertheless, they are less noisy and less brittle then other alternatives.

Diamond core drill bits (also known as diamond hole saws) have a hollow center and cut a circle in the material to create or enlarge an existing hole.

It is generally recommended to lubricate these bits with water.

And of course, whatever you do, always pay attention to the manufacturers instructions. Different makers use different material composition, and thus may require different mode of care and application.

Drill Bits Material: From Carbon Steel to Diamond

It is important to choose a drill bit made with the right material for your purpose. Getting a softer drill bit than needed will lead to early dullness and uselessness of the tool, leading to endless replacing at best, and a ruined project as one of the sadder scenarios. When picking the material, consider the surface to be drilled into (Soft wood? Hardwood? Metal? Stone?), and the steadiness of the drill itself – a very brittle bit on a cordless drill in the hands of not a very experienced driller is probably not the best idea.

That said, lets consider the standard options:

Low Carbon Steel Drill Bits

This is the cheapest option. Best used only on softwood. Low Carbon Steel bits require frequent sharpening, have a relatively short useful lifespan, and do not hold the edge too well. Buyer beware.

High Carbon Steel Drill Bits

These are an improvement over the above, and can be used on hardwood and even some metals. However their low resistance to heat causes them to loose their sharpness relatively quickly.

High Speed Steel Drill Bits (HSS Drill Bits)

These have essentially replaced the older Carbon steel bits on the market. HSS is significantly more resistant to heat, and as such these bits are well suited to most wood and metal jobs.

Titanium Coated Drill Bits

Titanium coating makes these bits harder and last longer than the common HSS bits. That is because the coating is a hard ceramic material.

There are a number of different Titanium coatings, most common are Titanium Nitride (TiN), Titanium Aluminum Nitride (TiAN) and Titanium Carbon Nitride (TiCN). TiN can increases the life of a drill bit by three or more times. TiAN is considered even better, and can increase the lifespan five times or more. TiCN is also considered superior to TiN.

The problem with coated bits, however, is that once dulled, they can’t be properly sharpened – the coating will be gone, and so will all the benefits of it.

Carbide Tipped Drill Bits

These are very hard, dissipate heat quickly and hold an edge longer than other types. However, Carbide tipped bits are also brittle and are likely to chip if not used carefully.

Cobalt Drill Bits

Cobalt bits retain hardness at much higher temperatures than the HSS ones. However, they are also more brittle than HSS. Cobalt drill bits are most commonly used for drilling stainless steel and other metals.

Diamond Drill Bits

Polycrystalline diamond (PCD) is one of the hardest tool materials. It actually consists of a layer of diamond particles bonded to a carbide support. And since diamond is the hardest thing found in our environment (or at least it is the hardest we know of), the diamond bits can be used on the toughest materials.

Unlike carbide and other types of drill bits, which use sharp edges to cut through material, diamond drills tend to work by grinding away their nemesis on a micro level.

Diamond drill bits can be used on glass, porcelain, ceramic tiles, granite, marble, stone, fiberglass, etc. They are commonly used in the automotive and aerospace industries, and in other environments where abrasive materials need to be drilled.

Privacy Policy

This is the privacy policy for drill-bits.blogspot.com

Here at drill-bits.blogspot.com you privacy is important. This page exists to make you aware of how information is gathered and disseminated for this site.

Log Files and Stats:

I use a third party service to collect basic data. This is something that most websites do. I use Statcounter that collects information such as browser type, IP address, visited pages, date/time visited etc. None of the information is linked to personally identifiable information.


I publish Google Adsense ads on this site. Google uses the Doubleclick DART cookie to serve ads across it's Adsense network and you can get further information regarding the DART cookie at Doubleclick as well as opt out options at Google's Privacy Center.