Put an end to splintery corners, blown-out edges and ragged profiles with a few
simple routing tips. Here are six worth trying.
No tool is better at decorating an edge than a router, and it's ideal for cutting
dadoes, rabbets and other joinery. But, tearout is a router bugaboo you'll want
to avoid at all costs. Generally, tearout happens when routing across the grain,
turning corners or removing too much material in one pass. Don't let tearout spoil
a perfectly good piece of wood... or your peace of mind. A few good router tips
are all you need.
Tip #1: Dial it back and slow down
Most routers nowadays have variable
speed control, and it's there for a reason. The larger your bit diameter, the faster
it spins at the cutting edges. When you are routing splinter-prone woods like cedar
or oak with a large bit, turn your router's speed dial down a few notches (see Photo
1). You'll cut cleaner edges with fewer burn marks. Remember to slow your feed rate
when approaching the corners of a workpiece or if you hear the router start to tear
the wood instead of cut it. Don't make routing a race to the finish. A steady and
smooth feed rate is the goal.
Tip #2: Rout like clockwork
For most applications, the correct
way to feed a router is against the bit's rotation. This tip has more to do with
safety than avoiding tearout, but it will improve your router's cutting performance,
too. When routing around the inside of a workpiece, such as a picture frame, feed
the router clockwise (see Photo 2). Switch directions when you're following an outside
edge, and move the router counterclockwise (see Photo 3). You'll know you are feeding
correctly if the router gently resists your efforts. If it jerks forward and pulls
through the cut, it's a telltale sign that you're heading the wrong way and making
a climb cut. Climb cuts are unsafe for ordinary passes where you are removing a
lot of wood.
Tip #3: Sometimes a climb cut works wonders
If you are routing
across just the end grain of a board, be careful of the exit corner. When the bit
breaks through those weak fibers, it's a prime opportunity for tearout. One way
to avoid the problem is to start your routing pass at the exit corner and make a
short climb cut to remove the corner material first (see Photo 4). Ease the router
gently into the corner and pull it slowly back toward you a half inch or so. Then,
stop the tool and start the cut where you normally would, routing across the end
grain to meet your climb cut (see Photo 5). Presto... no tearout!
Tip #4: Crossgrain calls for backup
Routing dadoes can result in
a nasty blowout where the bit exits the wood, especially if you are hogging out
a lot of material. Before you plow the dado, clamp a piece of scrap to the outboard
edge first. Then, rout across your workpiece and slightly into the scrap - it will
support the fragile edge grain resulting in a crisp, clean exit cut (see Photo 6).
Tip #5: Consider investing in shear-cutting bits
bits (left in Photo 7) have cutters aligned with the axis of the bit, and they chop
wood like a chisel. That chopping action is fine for softer long-grain fibers, but
it can tear out or crush bits of hard end grain and leave a ragged cut. A better
option is to use spiral bits or straight bits with cutters set at an angle to the
bit's axis (center and right in Photo 7). Either of these styles will produce a
shearing cut, similar to a hand plane, to help you tame that difficult end grain.
Tip #6: Take smaller bites on big profiles
Trying to remove too
much stock in one pass is a recipe for torn grain and sloppy profile cuts. The best
remedy is to rout big cuts in several passes of increasing depth. Set the bit low
for the first pass (see Photo 8), then expose more of the cutters in the next pass
or two until you reach the amount of profile you want (see Photo 9). Make the final
pass whisper thin to shave away any minor burn marks or torn grain. Shallow passes
allow your bits to cut properly, and they'll help your router breathe a little easier,