Router Health CareComments (0)
For many woodworkers, the router gets the hands-down vote as
the most capable and convenient portable power tool in the shop. Whether
handheld or mounted in a table, it excels at tasks ranging from profiling edges
and cutting joints to pattern-routing and creating decorative inlays. The
tool’s design and engineering are just as impressive as its multifaceted
usefulness. Considering all the tricks this workhorse can perform, it’s not
surprising that it requires regular care and occasional first aid.
I’ll first touch on preventive maintenance and then run through six potential problem areas to help you diagnose router ills and perform the necessary cures. Use the Anatomy of a Router illustration on the opposite page to locate the key problem areas on your router. To assist with the inspection and repairs, I’ve prepared a router “first aid kit” consisting of the items listed in the sidebar below. Finally, should the repair be too major, I’ll steer you to the nearest tool service center for professional help.
As part of your router’s health care program, preventive maintenance can help ward off problems due to normal wear and tear. Surprisingly, fine dust and debris are your router’s worst enemies. They can lead to switch failure, accelerated brush wear, and overheating. It’s a good practice to regularly blow out accumulated debris with low-pressure air. (High-pressure air from a compressor can force dirt into previously uncontaminated parts.) A quick visual inspection before each use will help you identify developing problems.
When a router ailment causes poor performance or no performance at all, it’s time to reach for the first aid kit. Always unplug your router before making any repair.
Diagnoses and cures for sick routers
Power cords and strain reliefs
A missing prong or cracked plug can be easily fixed. Replacement plugs, like the one shown below, are available at most hardware stores.
Damaged cords can be more difficult to diagnose. Misuse, wrapping the cord too tightly around the router, an accident, or old age can expose or sever the conductors within the cord’s outer sheath or loosen the connections at the plug or switch. If you can see conductors, it’s time to replace the cord. If the cord appears to be intact, you can sometimes pinpoint a trouble spot by plugging in the tool, turning it on, and then wiggling the cord. Broken conductors can cause a router to run intermittently as the cord is flexed.
When replacing a damaged cord, solder the wire ends or install “crimp-on” connectors before tightening the terminal screws. Note and follow the cord’s color code for the wiring. In the U.S., green is the case ground, white is the neutral, and black is the “hot,” or power, wire.
A power switch or speed control that has been compromised by accumulated dust and dirt may cause a router to run intermittently or not at all. Closely examine these parts and their cord connections and try cleaning them with low-pressure air. Then test the tool. If the problem persists, you can order a new switch or speed control and replace the parts as shown above. Alternatively, you can ship your router to a service center for diagnosis and/or possible part replacement and repair.
Manufacturers recommend checking brushes every 50 to 100 hours of running time. This isn’t easy to track, so make a point of checking brushes once a year or before starting a major job. Brushes typically need replacing when worn to one-fourth of their original length. If your brushes don’t have a wear line, check with a service center for minimum length specifications. Signs of impending brush death include increased noise levels and excessive sparking. Ignore the problem for too long and you risk damage to the commutator’s soft copper surface.
Brush replacement in most routers is fairly simple. On some routers, the two brushes can be accessed by removing threaded plugs in the motor end cap. On others, the cap itself must be removed to expose the brush holders. A hemostat clamp is handy for manipulating parts. With the brushes exposed, disconnect the brush’s electrical connection and carefully reposition the end of the coiled spring that provides the force to keep the brush in contact with the commutator.
After removing the brush, blow away any carbon dust on the commutator, and then inspect it with a strong light. A healthy commutator should reveal a clean copper surface. If it appears burned or excessively worn, get a repair estimate from your service center.
Orient and fit a new brush in each holder (shown left), and reconnect the pigtails. Make sure the brushes contact the commutator and move freely in their holder. Reassemble the parts and test the router.
Broken Castings, And Missing Knobs
Router castings are made of strong, lightweight materials like aluminum, but they’re not indestructible and may crack or break when dropped. To reduce the possibility of breakage, surround your workbench with rubber mats to soften the blow when a router or other tool falls to the floor. You can repair minor cracks with J-B Weld epoxy or similar metal repair products. However, if a casting is completely broken, gluing the part together is risky; order a replacement.
Stripped screw threads in aluminum castings are another common problem. Used for attaching sub-bases or accessory fences, these threads can strip out if you over-tighten or cross-thread a screw. To “fix” stripped threads, you can either redrill the holes and tap them for a larger size screw, or drill and tap a new hole at a different location to serve the same function. Alternatively, you can replace the casting. In any case, never operate a router with broken or missing parts.
Locks, stops, and plunge mechanisms
Routers employ a variety of locks and stops to position and guide the cutter. These function best when they are clean, lubricated, and properly adjusted.
On fixed-base routers, a locking mechanism secures the motor in the base while allowing depth-of-cut adjustment. Whatever the particular mechanism, clean and lubricate it occasionally to ensure smooth operation. On some routers, a pin projecting from the motor casing rides in a spiral groove in the base to raise and lower the motor. These grooves need occasional cleaning as shown at bottom left.
Plunge routers employ telescoping tubes with internal springs that allow the cutter to be plunged into the workpiece. The mechanism should operate smoothly with constant pressure and without catching or wobbling. The plunge lock should engage easily and hold the depth of cut securely. Any problem with the plunge mechanism usually stems from an accumulation of dirt and debris. The fix is to disassemble the moving parts, clean them, and then apply dry lubricant prior to reassembly.
Mechanical depth stops allow presetting the maximum depth of cut. For trouble-free operation, clean them as shown at bottom right and apply dry lubrication such as Bostik DriCote (Woodcraft #124626).
Collet, cutter, and
The business end of a router consists of a removable sleeve called a collet that fits into a chuck, or tapered recess, in the motor’s shaft. Tightening the collet nut forces it to grip the bit, holding it securely for a routing operation.
If you encounter rough cuts when using a sharp, high-quality bit with a clean, unmarred shaft, the problem may be caused by a dirty or worn collet and/or chuck, which can allow bit slippage. Use pitch remover to clean the collet, chuck, and nut (above). Scrutinize the nut and chuck for damaged threads, and replace the nut if needed. Inspect the collet for rough edges, which can be lightly smoothed with 400- or 600-grit wet/dry sandpaper. If your router has additional collets, clean and check them as well.
Excessive tightening of the nut can deform a collet, reducing its grip and allowing bit slippage. Worst case scenario is that a spinning bit could drop from the router. Telltale indications of collet and bit slippage include galling and score marks on the bit’s shank. In some cases, simply cleaning the collet and chuck with solvent and steel wool will remedy the problem. But if the collet surfaces are rough or rusted, replace the part. On some routers, the chuck is actually a separate part that threads onto the end of the spindle. Special tools may be required to remove it, requiring a trip to the repair center.
Spindle wobble, or runout, can also cause rough cuts. Check for runout using a dial indicator pressed against a centering bit or a short piece of appropriate-sized drill rod (from industrial supply houses such a McMasterCarr or Fastenal) chucked in the collet. A dial indicator with a magnetic base as shown top right requires a ferrous attachment surface. To create one, use double-faced tape to attach a tablesaw blade to the router’s sub-base covering the blade’s teeth with tape for safety.
With the dial indicator shaft pressed against the bit about 1" above the collet nut, rotate the shaft by hand and note any movement of the indicator’s dial. There should be little or no runout (.001-.002). Excessive runout could point to bad bearings and a professional repair, or replacement of the tool.
To check for bad bearings, remove the nut and collet and turn the motor shaft by hand. It should rotate freely without catching and with no discernable side play or noise. If you detect a problem, weigh the costs of repair versus replacement.
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