While cordless drills are very popular and convenient, corded drills are a bit more versatile and have the power to handle a number of drilling tasks. Additionally, corded drills are usually variable speed, which allows the user to drill anywhere from a very slow RPM all the way up to the drill’s top speed. I’d recommend a quality 3/8-inch corded version for the beginner’s first drill.
Like most power tools, there is standard corded model and there is the battery-powered cordless drill.
Corded models offer an unlimited amount of drilling time, and offers the power required when drilling through masonry or metal.
Cordless models are available, and these offer the benefit of portability and manoeverability in tight or confined spaces. The limiting factor in cordless drills is the battery life. When looking for a cordless drill, you will be bombarded by a variety of voltages, such as 12V, 14.4V, 18V, etc. In general, the voltage determines the amount of torque (twisting power) that a drill can produce. If you intend on using your cordless drill to drive screws, or use large spoon-head drilling bits, higher voltages offer more torque. Of more importance, perhaps, is the mAh that is listed on the battery. This will give an indication of how long the battery will last before it requires another charge. 2mAh is a good average starting point.
Variable-speed drills offer the opportunity to run the drill at less than full speed. Some drills offer two speeds, one slow speed for driving screws and one high speed for drilling. Other full-variable speed drills allow you to control the speed by how strongly you pull the trigger. I strongly recommend a variable-speed drill if you have any intentions on using screws in any of your projects, since this feature will save you much time and wrist-ache.
Reversible drills can turn the shaft in the opposite (counter-clockwise) direction. This is especially useful if you intend to use your drill to drive screws, since it gives you the option of removing the screws as well.
Voltages such as 12V, 14.4V, 18V, etc. determines the amount of torque (twisting power) that a drill can produce. If you intend on using your cordless drill to drive screws, or use large spoon-head drilling bits, higher voltages offer more torque.
Keyless Chucks give you the ability to change drill bits with a twist of the wrist. Standard keyed chucks require the use of metal “keys” to release or tighten the bit into the chuck. Keyless chucks keep you from searching for lost keys.
Choosing Power Drill Bits
There are many options available with drill bits. The folks over at Wikipedia have an exhaustive article on all the options, but I will just highlight what you will probably find the most useful.
Low carbon steel bits are used only for wood, as they do not hold an edge well, and require frequent sharpening. Working with hardwoods can cause a noticeable reduction in lifespan. They are, however, inexpensive.
High Carbon steel bits are made from high carbon steel and are an improvement on plain steel due to the hardening and tempering capabilities of the material. These bits can be used on wood or metal, however they have a low tolerance to excessive heat which causes them to lose their temper, resulting in a soft cutting edge.
High speed steel (HSS) is a form of tool steel where the bits are much more resistant to the effect of heat. They can be used to drill in metal, hardwood, and most other materials at greater cutting speeds than carbon steel bits and have largely replaced them in commercial applications. HSS drill bits is what I recommend you most woodworkers purchase for most applications.
Cobalt steel alloys are variations on high speed steel which have more cobalt in them. Their main advantage is that they hold their hardness at much higher temperatures, so they are used to drill stainless steel and other hard materials. The main disadvantage of cobalt steels is that they are more brittle than standard HSS.
How To Use a Power Drill
Always read the manual that came with your power tool! Always follow the safety percautions, especially while you are getting acquainted with your tool!
Keep a Straight Shaft
The first test for your drill is simple. Select your smallest drill bit (1/16” or 5/64” is ideal) and chuck it you’re your drill. Plug in your drill and pull the trigger. Carefully look at the tip of the drill as it spins. What you want to see is a tip that does not move. If it does move, you don’t want to see the tip making a circle in the air. If the tip of the bit wobbles slightly but you cannot see a circle, your drill will still deliver acceptable results. If you see a circle in the air, your drill will not give good results. The holes you drill will be oversized (at best) and most probably off-center from where you intended to drill.
If you have determined that your drill does not drill straight you can either purchase a replacement shaft or chuck (depending on the model), or you may be in the market for a new drill.
How do drills get out of shape? One possibility is it truly is a manufacturer’s defect, in which case you should return it to the store as soon as possible and request another unit. If it is a drill you had for a while, the most likely cause is simply rough treatment. It does not take much of a hit to misalign the chuck from the main body of the drill. You should try to keep your drill in its original storage case, and be careful when picking up or putting down the drill. Also avoid the temptation to pickup or put down your drill by using the cord. The balance point on most drills will lead the chuck to hit the ground first, and though each individual hit may seem insignificant, repeated blows can knock the drill out of alignment.
Check Your Bushings
The electric motors in drills will usually have bushings. These are small conductive pieces that are continually pressed against the spinning portion of the motor by springs. These bushings will wear over time, or may simply become clogged with sawdust or other debris. To perform maintenance on these bushings, you should refer to your manual. Well-engineered drills will have easily accessible bushings, and these are usually concealed under screw-off covers located near the handle, along the drill’s shaft. Twist open the cover, carefully remove the spring, and tap out the bushing. Clean out the hole they were located in, clean off the bushings, and replace everything. Repeat the process on the other side. If one bushing is significantly more worn than the other, or if the bushing is less than 1/8” thick (again, refer to your manual), purchase a replacement.
Bad Bits Can’t Bite
This is one time that you can blame the tool, but ultimately you were the fault… Drill bits are meant to be perfectly straight. If there is the slightest bend in one, return it or purchase a new one. Attempting to re-bend a bent bit bound to be a fruitless endevor that will cause you much frustration, and will probably end in a snapped bit.