Plunge routers go where no other router can.
by Seth Keller
The plunge router deserves a place in every shop. Routing chores, such as mortising, stopped dados and inlay pattern work, are safer and easier to perform using a plunge router. Its unique base allows the motor housing to ride up and down on a pair of posts fixed to the base. The plunge mechanism is spring-loaded so the motor housing always wants to spring up to the top of the posts. A lock/release lever allows free up-and-down movement of the router housing or locks it in place at a given depth. The depth of cut can be preset, allowing you to position the router over the work and plunge the bit to an exact depth. The depth stop works much like the stop does on a drill press.
Plunge routers have been around for years. Some die-hard users of fixed-base models may argue that a fixed-base router can do everything that a plunge router can do, but they don’t realize what a great, unique tool the plunge router is. Here are eight things a plunge router can do with ease that present a challenge for a fixed-base model.
Great Template Router
Template routing with guide bushings is trouble-free when you use a plunge router. Just set the router over the template, turn it on, plunge the bit to the preset depth and rout. The plastic bowtie inlay template, shown above, would probably have a few battle scars if a fixed base router had been used. You may get away with tipping it into the cut for a while, but sooner or later that template would be nicked.
Required by Some Jig
A plunge router is a must when it comes to sophisticated jigs, such as the WoodRat and the FMT by Leigh (see photo, above). These jigs cut mortises, tenons, dovetails and a whole lot more, but they simply can’t perform all their operations without the use of a plunge router.
Ideal for Inlay Grooves
The plunge router is ideally suited for stringing and delicate inlay work, often called captured inlay, because the plunge mechanism allows a smooth entrance and exit from the cut. Try tipping your fixed-base model into a cut like this and your cut will likely be misaligned right where the groove starts. This is one operation you definitely want to get right the first time, and a plunge router is the surest way to get the job done well.
Burn-Free Stopped Flutes
There’s no better way to mill stopped grooves and flutes than by using a plunge router. This type of milling is safer and simpler than using a fixed-base router. All you need to cut perfect flutes is a start block, a stop block and an edge guide. With the router set on the start block, plunge the bit to the preset depth and press the lock lever as you make the cut along the length of the board. At the end of the cut, release the plunge lock lever and the bit retracts off the workpiece, leaving you with the cleanest flutes possible. You won’t leave burn marks, as you might if you tipped the router in or waited for it to spin down before extracting it at the end of the cut.
Onboard Scale for Fine Adjustments
Micro-adjustable depth knobs make fine-tuning a plunge router simple. Small changes in bit height can be frustrating to make on some fixed-based routers. Plunge routers allow you to read and fine-tune the depth right on the router’s face.
Built-In Bit Protection
One advantage a plunge router has over a fixed-base model is bit protection. A plunge router automatically surrounds and protects your expensive bits when it’s not in use. Just push your finger to disengage the lock lever and the spring-loaded mechanism retracts the housing, lifting the bit into the safety of the router base. This protects your bits, your fingers and your benchtop from accidental nicks.
A Star at Cutting Mortises
Cutting mortises is much easier with a plunge router than with a fixed-base model. A deep mortise can be cut without overtaxing the router or the bit. An adjustable stepped turret is the key. It allows a plunge router to make a series of relatively shallow but ever deeper cuts. You don’t have to tip a spinning bit into the work as you would with a fixed-base router. A simple twist of the plunge router’s stepped turret allows to you increase the depth-of-cut setting for the next pass, guaranteeing a cut that’s not too deep.
Best for Some Specialized Bits
Some popular bits are best used with a plunge router. A keyhole/picture-hanging groove, for example, would be virtually impossible with a fixed-base router. To create this keyhole groove requires the bit to plunge down into the stock, slide laterally to cut the groove and then reverse-plunge to create the keyhole on the opposite end. These specialized bits have cutters on the top, bottom and side. Imagine lifting the bit up out of the cut while using a fixed-based router. On second thought, don’t even try to imagine it.
Use the Right Bit for Plunging
This story originally appeared in American Woodworker Feb/Mar 2007, issue #127.
Feb/Mar 2007, issue #127
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