Many amateurs only use their router to add decorative profiles to table tops and other project parts. But a router can do so much more, including making dadoes and rabbets, cutting circles, copying templates, trimming boards to a pencil line and jointing edges. You can even use a slot cutter to turn your router into a basic biscuit jointer.
On the flip side, the router deserves a lot of respect and care. Like the table saw and radial arm saw, routers and shapers (the router’s cousin) cause a lot of injuries. The router can be overly aggressive at times, causing unexpected safety risks. Fortunately, most of these risks are predictable and can be greatly reduced through careful safety practices.
If there was only one safety tip I could give you, it would concern where you put your hands when using a router table. Beginning woodworkers can be too complacent when using a router table. They assume that it must be far safer than using the router hand-held. But when using it by hand, its weight limits the violent nature of kickback. When in a table, though, the router can throw a relatively light piece of wood with ease.
The most important advice I can give you is: do not place your hands at, or near, the front of the board being routed on the table. Keep your hands at least 6 inches from the front end of the board whenever possible. If a board is kicked back, it will be thrown backwards and to the right (it won’t go to the right if you’re using a fence). This can result in serious injuries if your hands are near the front and are pulled into the spinning bit.
Limit the risk by taking multiple light passes instead of one heavy pass, especially in hardwoods. Also, use a fence whenever possible, as it limits what can happen in a kickback situation. Even though you don’t “technically” need to use a fence when using a bearing-guided router bit, you should still use a fence whenever possible.
My precision tip also relates to a problem caused by the router table. I am not against router tables, as I use one regularly and it’s an important piece of equipment. But putting imperfect lumber on a perfectly flat router table leads to precision problems. For example, if your lumber has even a slightly concave surface resting on the router table, the board cannot touch the table at its centre. A featherboard might work to press the board tightly to the table, but it depends on the amount of bow in the board and how thick (and stiff) it is. Too much downward pressure will also make the board very difficult to push forward, which presents new safety risks. But if the board doesn’t touch the table in the middle and you’re routing a profile on the edge of the board, the profile will not transfer properly.
For this problem, I suggest using your router by hand. The router has a small base, compared to the large size of the router table top. So the router will follow along any slight curvature of the workpiece and rout the profile properly.
Using the router by hand on narrow stock can be difficult, as it is easy for the router to tip sideways. To avoid this, you can clamp another board of the same thickness beside the one you are routing for more stability. In such cases your hand-held router can sometimes do more accurate work than it can in the router table, for the simple reason that your lumber is not likely to be perfectly flat.
In my safety tips, I already mentioned taking several light passes instead of one heavy one. This gives higher quality results as well, as heavy cuts lead to greater vibration and sometimes slower bit speed if your underpowered router starts to bog down under load.
My single most important tip to increase the quality of your routing is to use the correct cutting speed. And this applies both to bit speed and the speed with which you move the router (or move the workpiece across the router table). I’ll start with bit speed. As I mentioned in my article on the drill press (Dec/Jan03), the speed at the outer rim of the bit (hence the name “rim speed”) increases with larger diameter bits. Therefore, use slower bit speeds with larger bits. It’s as simple as that. The number one feature I recommend for a router is variable speed.
Not only should you lower the speed with larger bits, you should also decrease your speed as you plunge more deeply for subsequent passes (especially if the bit becomes larger as you plunge). I will often start the profile on speed 3 (out of 6), decrease my speed to 2 1/2 on the second pass and then use speed 2 on the third pass.
Bit speed is also directly related to the speed with which you move the router.
Moving the router quickly can compensate for an overly fast bit speed. Conversely, you can compensate for an overly slow bit speed by moving the router more slowly. It is always safer and more accurate to move the router fairly slowly. That’s why it’s important to use a variable speed router: so that you can control the bit speed to suit the situation.
How do you know what the correct bit speed is? It depends on a lot of factors, such as depth of cut, sharpness of the bit and hardness of the wood. I recommend that you run the bit as fast as possible without burning the wood. The higher the bit speed, the better the quality of cut, but be careful, burning means the speed is too fast. If you have a one-speed router and you’re burning the wood no matter how quickly you move the router, you can only overcome this by taking very light passes.
However, sometimes the only practical solution is to purchase a good quality variable speed router so that you can control the bit speed. There are also electronic units available that can slow down the bit speed of a fixed speed router, but buying a better router is probably the best solution in the long run.