This is your first fundamental decision to make. There are several advantages and disadvantages to each type of drill:
- Cordless drills are almost always more convenient to use. They can be used in any location quickly without having to deal with extension cords and power outlets; at least, so long as the battery is charged. The advantage of corded drills is that there is no restriction on how long they can be used. When using a corded drill, you will never find yourself waiting for batteries to finishing charging.
- While it may sounds strange, cordless drills tend to be lighter than corded drills. However, if you choose a high-power cordless drill (18V and up), they are sometimes just as heavy as their corded counterparts.
- Cordless drills are safer as there is no cord acting as a trip hazard.
- If power and long usage times are required, a corded drill will fit the bill better than a cordless model. While there are many high-power options obtainable for cordless drills, corded drills will always be able to supply more power, and they will be able to provide it for a longer period of time.
- Even the most expensive batteries have a finite lifetime. You should expect that the batteries on your cordless drill will only last two to three years at most. Batteries are very costly to buy; it's often cheaper to purchase a new cordless drill than to buy two new batteries. So if you are buying a cordless drill, expect to be purchasing a new drill in several years time. By comparison, if you choose a corded drill you are set for at least 10 years, if not more.
- If you are going to opt for a cordless drill, be sure to buy one with Lithium Ion (Li-Ion) batteries; do not buy a drill with Nickel-Metal-Hydride (NiMH) batteries. Li-Ion batteries are more powerful, they have longer lifetimes, they do not have "memory" issues, and they are less harmful to the environment since they have fewer harmful metal elements.
2) Pick a Chuck
The chuck is the assembly on the end of the drill that holds the bits in place. There are two picks to make here: size and type.
The standard chuck sizes are 1/4", 3/8", and 1/2" with the most common size being 3/8". If you plan on using bigger drill bits, go with the 1/2" chuck since many of the bigger bits will not fit in a 3/8" drill. If you do not want or need the capability to use larger drill bits, the 3/8" chuck is a good option since typically they have higher bit speeds in these type of drills.
There are two types of chucks: keyed and keyless. With the keyed chuck, you use a mechanical key to tighten and loosen drill bits in the chuck. With the keyless chuck, you tighten the drill bit into the chuck by holding the chuck with your hand and powering the drill. The mechanical advantage of the keyed chuck makes it able to hold bits tighter so there is less chance of your drill bit slipping. The advantage of the keyless chuck is that it is quicker to change bits, and there is no key to be lost or kept track of.
3) Important Features
To get the most usage out of your new drill, make certain it has these important features:
- A reverse mode. Even if you do not plan on using your drill for driving screws, reverse is still a must-have feature to have for removing bits that get stuck. If you are purchasing a drill that has a keyless chuck, it will always have reverse (you can't remove bits without reverse), so you only need to check for the presence of this feature if you are buying a drill with a keyed chuck.
- A variable speed trigger. If you plan on driving screws, this is essential. If not, this is still a great feature to have as it makes it much easier to drill clean holes since different materials require bit speeds.
- Two speed ranges. This feature is only needed if you plan to drive screws. If you are, this feature is very important to have. Having the lower speed range makes it much easier to drive screws.
- A torque clutch. Again, this is only required if you are driving screws with your drill. The clutch lets you set a maximum torque point after which the drill will stop. This is really handy when you are driving screws so that you do not over-drive the screw into the material. If you are putting in large numbers of screws (like on a deck for example), this feature is a real life-saver.