From DIYinfo.org
The router is one of the most versatile tools in a woodworker's workshop and with the wide range of bits available, the router can be used for almost every project you may wish to tackle. But before you buy a router there are a few things you will need to know.
[edit] Fixed Base vs. Plunge Routers
Fixed Base
With a fixed base router, the depth of cut is set before you turn the router on. The lack of a plunge mechanism tends to make these routers lighter and less expensive.
Plunge
A plunge router allows you to adjust the depth of cut while the router is turned on. This feature can come in handy when you need to make multiple passes on a board, taking off a little more wood with each pass. Plunge routers often have depth stops that can be used to accurately plunge the router to the appropriate depth while in use. Plunge routers can also be used to cut mortises, stopped grooves, dados, and incised letters (with special jigs). However, the plunge mechanism adds weight to the router.
[edit] Power
Routers are typically rated by horsepower (hp). A higher horsepower means not only more power but also more weight. To understand why, we need to look inside the router to the motor. If you've ever seen the inside of an electric motor the first thing you probably noticed was the copper wire. A general rule of thumb is that more copper = more power. But more copper also = more weight. So to pack more power into a router the engineers must also pack more copper into it. Next time you're in the hardware store pick up a 1.5hp router in one hand and a 3hp router in the other. You'll feel the difference in weight instantly.
But here's a "little secret". You probably noticed that most of the tools in your shop use amps as their primary power rating, not horsepower. The router is one of the few tools that is rated primarily by its horsepower. When tools are rated by amps the testing is performed by an independent testing and certification organization. However, horsepower ratings are assigned by the manufacturer.
The problem here is that the testing methods may vary from manufacturer to manufacturer and router to router. Also the horsepower rating is a "peak power" rating. This is a rating of the most power the router could put out in the most demanding situation and only for a short period of time. Because of all of these things, we still speak of routers by their horsepower but when buying a router you might want to compare the amp ratings.
[edit] Bit Size
Router bits are generally referred to by their shank size. This naming convention carries over to routers as well and it's common practice to refer to a router by its power rating, bit size, and base configuration. For example, in the hardware store you might find a router referred to as a "Ryobi 2hp 1/2" plunge router". The shank is the part of the router bit that fits into the router. Router bits are available in three sizes; 1/4", 3/8", 1/2" but the most common sizes are 1/4" and 1/2".
When selecting a router it is always important to keep the end projects in mind. There is a wider selection of 1/2" bits available. Also, a 1/2" router can also accept 1/4" bits with a special adapter or a different collet allowing for expanded bit selection options. However a 1/4" router can not use bits of any other size. For more information on router bits read All About Router Bits.
[edit] Electronic Variable Speed (EVS)
Electronic Variable Speed (EVS) routers are relatively new on the woodworking scene. The EVS feature allows the operator to adjust the speed of the router bit. The main reason you'd want to do this is to slow down a larger bit for safety reasons. Smaller bits operating at high speeds are not a major concern. If your project plans don't include raised panel doors and other projects requiring larger (2"+) bits, EVS should not be a major concern. Even if you scale up to larger projects in the future you can still purchase an external speed adjusting unit from most woodworking supply companies. Make sure the unit is designed for routers. These units contain special feedback circuits that adjusts the power levels as the load changes. A unit not designed for routers might burn out your motor.
[edit] Bit Changing
Changing router bits is one of the least favourite tasks of many woodworkers. Older routers often require the use of two wrenches to loosen the bit. One wrench was used to hold the spindle while the other was used to loosen the collet. This tends to be an awkward operation and often one of the wrenches will "disappear" when it's time to make a router bit switch.
Most new routers are made with spindle locks. The spindle lock is a little button that, when pressed in, locks the shaft so that only one wrench is needed to loosen the bit.
[edit] Switches
The type and placement of a router's power switch varies depending on the manufacturer. Generally there are two different switch styles; "Toggle Switches" and "Trigger Switches". A toggle switch is similar to a light switch in function. A trigger switch is similar to the switch on a circular saw. With this type of switch the router is only ON when the switch is pressed. Some manufacturers use trigger switches that can be locked in the ON position. Generally switch design is not a major issue but if you plan to use a router table you will need to purchase a router that can be set to run in the ON position by itself
[edit] Accessories
There are numerous accessories available for a router today. You can purchase jigs to make table legs, dovetail joints, mortises, and many other components. Among the most common router accessories are:
Edge Guide - used to route a straight profile into a board, the edge guide keeps the router a fixed distance from the workpiece.
Bushings - Routers can be fitted with bushings for sign making, inlay work, and pattern making.
Router Tables - The router table is the ultimate router accessory. It allows the router to be inverted and used as a shaper for making moldings, and working on small pieces.
[edit] Price vs. Quality
It's the inescapable rule, you get what you pay for. Routers and other woodworking tools are subject to this rule as well. Is there a difference in quality between a high and low priced router? Yes, generally the higher priced routers are manufactured with tighter tolerances and better components. They also usually include a number of newer features that make them easy to use. Lower priced routers might be designed with bushings instead of bearings or the motors might not be made to highest standards.
[edit] Recommendations
When you are planning on purchasing power tools it's important to ask yourself what you plan to do with the tool, now and in the future. You also need to consider the amount of time you will use it. If you only pull out your tools a few times each month it might not be worth buying the best tool on the market. However, the few exceptions to this rule are if you are looking for a router or a table saw. A lower quality router can be frustrating to use because of all of the work needed to clean up the finish. It can also be equally frustrating to have to pass on a project because the router can't handle the bits required to complete the project. We recommend that you buy the best router you can afford, but try to stay around the 2hp 1/2" plunge style.
As a Guide check out the features of these bad boys
