Monday, January 11, 2010

WHAT TO KNOW ABOUT ROUTERS

          The wood router is essential among woodworking tools because it adds decorative detail that enhances and defines the final appearance of your woodworking project. Used correctly, the wood router is to the woodworker what a fine paintbrush is to an artist. It's all in the details.


          There are four, basic types of wood routers on the market today: laminate trimmers, lightweight or low-powered routers in the 7/8 to 1 1/2 HP range, medium-powered routers in the 1¾ to 2¼ HP range and high-powered routers in the 3-4 HP range. Each has its use and I have owned all of them at the same time. The laminate trimmers do what their name implies as well as other light-weight tasks such as making hinge mortises. They are only suitable for small router bits but they are easily maneuverable and fit nicely right in your palm.

          If you need more horsepower but still like the ease of a lightweight router, the 7/8 to 1/12 HP routers will do a fine job of spinning router bits up to ½” radius round-over bits. Every shop should have one of these handy for bench-top work. They are a bit small for router table use. 2¼ HP woodworking routers have sufficient power to spin large router bits through hardwood and yet they are still light enough to be manageable as bench-top wood routers. While any wood router over 2 HP can be used in a router table, I prefer the high powered ones for that application because there is no need to worry about how heavy they are and you might as well have as much power handy as you might need. Most, but not all, of these larger routers are plunge routers. The high horsepower is necessary to plunge large bits deep into hardwood to make mortises and the like.
           If I could only afford one wood router, it would be the 2¼ HP variety because it is light enough for most bench-top work and can also be used in a router table. If I could afford two routers, I would probably have a 7/8 to 1½ HP wood router for bench-top work and a 3½ HP wood router under my router table. I don’t like mounting and dismounting routers under my router table, so having a lighter wood router on hand near the bench at all times really speeds things up.

          I’d like to make a few observations about routers. First, I suggest you consider using only high-quality carbide-tipped router bits in these woodworking tools whenever possible. They can be re-sharpened many times and they usually don’t burn up and load up if they are kept sharp. High-speed steel bits don’t last long, they are not worth sharpening and they dull quickly, burning your workpiece as they soon load up and turn black from burning. Sometimes, however, the bit profile you need may only be available in a high speed steel bit but this is the exception rather than the rule.


          Second, as hand-held power woodworking tools, heavy and/or top-heavy routers are hard to manage. Not only will you be struggling with them all day, they tend to tip easily which can often ruin a cut or leave an incomplete cut. If a smaller, low-profile wood router could have spun that bit, then that is the wood router you should have been using. On the other hand, an under-powered wood router will not do a good job and may not even be safe. Also, be sure to check the weight of any wood router you may be considering, if it is to be hand-held. Heavy woodworking tools are tiring and clumsy to use all day long. A pound or two less can make a big difference.
           Third, consider how you will be hanging onto the wood router while it is cutting. Are the handles comfortable enough for continuous use? Do the shape and material of the handles allow you to control the wood router properly. Some of these woodworking tools are also available with “D” handles (at extra cost) which may give you better control and feel. One wood router from Milwaukee even offers a padded grip around the exterior of the router base. One hand goes on the rubber grip while the other goes on a conventional knob.

          Fourth, if your wood router is in the 2 1/4 HP range, you will want it to have a variable speed feature, especially if you are planning on using large bits like raised panel bits. You will need to run these large bits a bit slower. They will stay cooler and cut better at a lower speed. On the other hand, you will get smoother cuts with small bits of you keep the speed high. No matter what RPM you choose, you will want your wood router to be able to maintain that speed at all times, no matter how hard you push it. Electronic speed control allows your wood router to compensate for heavy loads by automatically adding a sufficient amount of extra power to keep your wood router spinning at the same speed it was before the cut began.
           Fifth, (and this is a safety consideration) try to buy a wood router that has “soft” start-up. This would not be a needed feature in stationary woodworking tools but is an important safety device in a hand-held wood router. Historically, routers have had only one speed (high) and when you turn them on, they spin up quickly and the gyroscopic force of that can flip a spinning wood router right out of your hands. A soft start-up wood router gradually increases its speed from zero to full, thus eliminating almost all of the gyroscopic effect.
 

          Sixth, if you are going to be changing bits all the time, consider what steps you will have to go through to accomplish that task. Some routers have a shaft lock button so you only need one hand to hold down the button and one wrench to turn the collet nut. I’m kind of used to the two-wrench variety. I usually take the router motor completely out of its base, lay it on its side on the table, putting one wrench on the flat part of the shaft and the other wrench on the collet nut. If I am loosening the collet nut, I will first lower the shaft wrench to the table top and then push down towards the bench with the wrench that’s on the collet nut. If I am tightening the collet nut, I will put the collet nut wrench down to the table top and then push down against that with the shaft wrench on the flat part of the shaft.

          If you’ve used routers at all, you must have noticed that when you are loosening a collet nut, you will feel resistance at the start of the turn of the wrench and then it will turn freely for a while before resisting the wrench one more time. The first resistance comes from loosening the nut itself. The nut then unscrews a bit down the thread and then it begins to push against the collet, releasing it from the shaft of the router bit. When you are tightening a bit into a wood router, you will feel resistance only once as you squeeze the collet around the shaft of the bit while turning the nut as far as it will go.

          Some people like to change router bits with the wood router upside down on the table with the two wrenches sticking out to the side. In this case, the technique is to arrange the wrenches so that you can squeeze their handles together with one hand to loosen, or tighten, the collet nut. For these people, some manufacturers make routers with flat tops. If find this way to be a bit more clumsy than laying the wood router down on the bench and there is less leverage in case of a stuck bit.


          Seventh, router bits come in three shank sizes, ¼”, 3/8” and ½”. The half-inch shank bits are only slightly more expensive than the quarter-inch ones and yet, they give you a distinct advantage. With a larger diameter shank and a larger diameter collet, there is much less chance of slippage under heavy loads. Consider buying only ½” shank bits, especially if you are spinning large cutters.
           Eighth, some of these routers offer “above router table” height adjustment capability. This is usually accomplished by sticking a hex T-wrench into a hole provided. It’s hard to adjust the height of a wood router accurately from underneath a router table while on your knees, fighting gravity. An even more elegant solution is to purchase a router lift for your router table. If this interests you, check out my article at PerfectWoodworking.com/routertablearticle/ entitled “How to Build Your Own Router Table.”
           Ninth, there are three types of wood router bases: conventional, spiral and plunge. In a conventional fixed base, the router motor just slides straight up and down in the base and is clamped into position. The spiral-type base has an adjustment ring that turns in a spiral groove cut into the outside of the router motor casing, thus raising or lowering the router motor relative to the base. A plunge router base clamps onto the router motor and then pushes the wood router and router bit down unto the work piece from above. Some routers are offered in kits containing two or more types of bases so that you only need to buy one router motor for a variety of uses.
 

          Tenth, some of these woodworking tools gauge and control their fine depth-of-cut with a spiral ring while others utilize a geared shaft attached to a calibration knob. All routers have a means of making gross height adjustments by releasing the lever or cam that locks the router motor into the base. Once adjusted to a position close to the final position, the fine depth-of-cut adjustments can be made in increments as small as 1/64 of an inch and, in the case of one router reviewed here, 1/128 of an inch.

          Eleventh, consider that motor amperage is usually a better indicator of motor power in woodworking tools than stated horsepower. All 2 1/4 HP routers claim to develop 2 ¼ HP but their amperage (electrical power used) varies from 11 to 13 amps.
           Twelfth, and finally, there are some less important (to me) but nice features available on some, but not all, of these woodworking tools including: the availability of a 3/8” collet, an automatic motor power lock-off during bit-changing, a carrying case, a clear plastic sub-base for better viewing, a detachable cord set, a dust proof switch, a switch that can be located left or right for the comfort and convenience of the operator, oval, rubber-molded handles, self-releasing collets and a way to fine adjust the sub-base so that it is exactly centered around the bit shaft.

          The ability to center the sub-base means nothing if you are only using ball bearing router buts but if you are using router guides mounted around the bit shaft, it is vitally important that the bit shaft be centered within the guide. If your bit is not perfectly centered when using template guides, your cut will move from side to side as you turn the router around while cutting. Since the guide is mounted to the sub-base, the hole on the center of the sub-base must be concentric with the router bit shaft.

          If you think, after reading this post that a 2 1/4 H.P. router might be the right size for you and your shop, be sure to check out the review of five different routers of that size from Bosch, DeWalt, Makita, Milwaukee and Porter-Cable at PerfectWoodworking.com/routerreviews/.


Bob Gillespie
Woodworker
© 2010

For similar articles and tool reviews see:
PerfectWoodworking.com


1 comment:

  1. Basic woodworking can be as simple or as complex as we want it to be. Really, woodworking is a craft or hobby that will provide a new experience with every item you make. Thanks!
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