Routing Basics – Part 2
For most woodworkers, using a hand-held router is their first introduction to this incredibly versatile tool. The router is a loud and powerful tool and has gained a reputation of being dangerous; but with an understanding of the proper techniques for using this tool, and a healthy measure of respect, this can be one of the safest, most versatile power tools in the shop.
Standard feed direction
Feed direction on router table
Feed direction on frame
Feed direction on panel
Dust collection is a must
Blow dust off switches
Inspect your brushes; replace when worn out
Think ‘Safety’ To Work Without Worry
Before using your router, make sure that you are wearing the right safety gear. Eye protection is an absolute necessity. A router removes a lot of dust and chips, and it ejects this debris with considerable force.
Adequate hearing protection is also mandatory. Routers are among the loudest of power tools in the shop and exposure to noise at this level will have a detrimental effect on your long term hearing. Whether you choose expansion- type foam plugs or full earmuffs, use them every time you use the router.
Keep your work area clear of all obstructions. Remove any tripping hazards from the floor area, and arrange your power cord in such a way that it doesn’t interfere with the travel of the router. If the router has facilities for dust collection, hook up a dust collector or a shop vacuum to collect the chips – this will keep your work area clean and the majority of the debris out of the air.
Before you begin routing a piece of wood, look it over carefully. Locate any cracks or loose knots in the piece – these could shatter when the router bit contacts them, sending debris flying. Disregard such pieces and only use sound stock.
Inspect your router bits before you use them. Clean off any accumulated pitch and sawdust from the carbide edges, and the bearing if it is fitted with one. A clean bit will give a smoother cut with less burning, and the bit will both run cooler and last longer. Check that the screw holding the bearing in place is tight. If the bearing comes off in operation the bit will dig into the wood and could result in injury.
Practice – The Best Instructor
While a router table is a great accessory, there are still many operations that you will need to do while holding the router by hand. Understanding the relationship between the type of wood you are using, the characteristics of the bit, feed rate, depth of cut and bit speed will help you produce professional results. It’s a good idea to practice using the router before you begin to use it on a project.
Just as every species of wood has a unique appearance, each responds to machining with a router in its own way. Western red cedar routs easily, but produces a very fine dust that some people are allergic to, and because of the high silica content in the wood, bits dull very quickly. Routing walnut with a sharp bit is like passing a hot knife through butter. Cherry and maple respond well to the router, but to avoid burning you must use sharp bits and adjust the speed accordingly. You may even find that some boards from the same tree will burn more than others.
Give yourself room to correct any burning with the router by taking incremental (shallow) passes until you arrive at the final cut. If the piece shows a tendency to burn, adjust the speed and feed rate. Get a feel for how the wood responds by experimenting with an off-cut before using the router on a project.
Most new routers come with a variable speed control that allows you to adjust the RPM of the bit, typically from 10,000 – 25,000 RPM. If your router is equipped with speed control, use the slowest speed you can while still maintaining the quality of cut. Not only is a lower speed easier on the router and the bearings, but the bit will run cooler. At a lower speed the router will run considerably quieter and require less effort to maintain control.
Some bits should not be used in a handheld router. These are usually larger bits as well as some joinery bits that must take a full depth cut in one pass. You should only use bits larger than about 1″ diameter in a router table.
Proper Routing Direction
When freehand routing, the bit will be spinning in a clockwise direction. To maintain control of the router, move the router so that the feed direction is against the rotation of the bit. This moves the router along the work piece with a cutting action rather than allowing it to dig in and skip along the surface. When routing the outside edges of a frame or a panel, move the router in a counter-clockwise direction. If you are using the router on an inside opening, move the router in a clockwise direction.
On a router table you move the stock rather than the router, which is suspended upside down under the table. The bit will now be spinning in a counter-clockwise direction. Move the stock against the rotation of the bit – from the right to the left.
There are times when it may not be possible to move the router in the standard direction. Running the router over the work piece in the opposite direction is known as climb cutting. Moving the router in this direction changes the angle of the router bit to the wood. Instead of a cutting action it becomes more of a scraping action. In this case, the rotation of the router bit will want to pull the router bit out of the cut, much like the way the blade on a radial arm saw will want to climb out of the cut as you pull the carriage toward you.
Typically you will use climb cutting to avoid tear-out. To achieve a clean cut on wood fibres, they must be under tension. If they are under compression the tendency will be for the fibres to pile up in front of the router bit until they break off, causing tear out. If you are routing a profile on an edge and the grain is running off the edge at an angle, you may need to climb-cut in from one edge to avoid tearing out the corner.
Climb cutting is probably the most dangerous operation you will perform with the router, but there are ways to perform the operation safely. Clamp your work piece securely to the workbench, adjust your depth of cut to take light passes, and maintain a firm grip on the router. Approach the cut with the expectation that the router will want to run away into the cut, so be prepared to hold a steady feed rate against this pull.
Set the Depth of Cut
Before turning on your router, set the depth of cut. When cutting a profile on an edge, set the depth so that the first cut removes about 30% of the material. This first run through all of the pieces will give you a feel for how the wood is responding to the bit. Based on the feedback, you can either proceed to a 90% cut followed by a light finishing pass, or change the feed direction and take shallower cuts to compensate for any problems. Taking shallow cuts will also help reduce burning and chipping.
Routers operate at very high speeds and generate a lot of heat. The most important thing to remember is to keep your router clean. Most routing operations generate a fair amount of debris, some of which will find its way into the motor. To keep the router running cool, a fan attached to the armature will direct air over the inner sections of the router, typically drawing air in at the top and exhausting it at the bottom. As debris becomes lodged in the router, the cooling flow of air is restricted and the temperature begins to rise. The only insulation on the copper windings of the electric motor is a thin layer of varnish and if the motor continually runs too hot, this varnish will begin to break down and eventually fail.
Variable speed routers now dominate the market and the speed control is achieved using electronics on a small circuit board that is mounted under the external housing of the router. To set the speed you either adjust a rotary dial or slide a multi-position switch to the correct setting. When cleaning up your router after using it, use compressed air with a blowgun to direct air into these areas. Be sure to wear hearing and eye protection when using compressed air.
Not only will dust interfere with the proper electrical operation of the router, many of the adjustments and controls are mechanical and an excessive accumulation of dust can cause problems there as well. Because the router runs at such high speeds, the bearings are subject to heat build-up as well. As fine dust begins to accumulate around the bearings they will run hotter than they should. When the build-up becomes critical, the bearings will fail and will have to be replaced.
Keep the columns on a plunge router free of any dirt and debris for a smooth plunging action. If your router is equipped with a rotating depth stop, watch for accumulations of dust under the mechanism that could lead to erratic operation.
Keeping your router clean will help prolong its life. If you do notice excessive sparking on the armature or if there is a noticeable drop in power and/or a change in pitch from the motor during use, you may need new brushes. Depending on your router, this may be something you can easily do yourself, or you may need to take it to a service centre. If your router has easily accessible brush covers you should be able to do the job yourself.
In Routing Basics III we will be looking at router bits.
· Always wear eye protection and a dust mask.
· Unplug your router before changing bits.
· For the best cuts use clean, sharp bits.
· Connect your router to a shop vac or dust collector.
· Rout against the rotation of the bit (for freehand routing move the router counterclockwise outside and clockwise inside; on the router table move stock to the left).
· Take multiple, shallow cuts.
· Use a constant feed rate.
· Adjust your feed rate for the type of wood, size of bit and speed of bit (if the wood is burning increase your feed rate; if the motor is straining slow the feed rate or reduce bit speed).
· Always use a fence or a ballbearing piloted bit.
· Rout the ends of a board first, then the sides, to prevent end splits.