Router conversion kits are the latest evolution in router design and utility. By using a detachable, exchangeable motor that can be transferred in and out of either a plunge-base or a fixed-base configuration, tool manufacturers provide two routers in one package.

Since we specialize in high-end finish work with lots of production and custom door hanging thrown in, we use routers all the time, both in a table and handheld. Our first thought when we saw these tools was that we'd be able to have one router motor doing double duty by mounting the fixed base to a router table for all paneling and molding-type work and using the plunge base for cutting radii, hinge mortises, and dadoes. All we'd have to do is swap out the motor to keep cutting. These kits also look great for remodelers who don't use routers as much as we do, because they can provide the utility of having the kind of routers needed without breaking the bank.

Test Criteria

We tested the Bosch 1617EVSPK, DeWalt DW618PK, Makita RF1101KIT, and the Porter-Cable 693LRPK plunge-base/fixed-base router conversion kits. We tested them in both plunge- and fixed-base configurations using an assortment of new, identical bits in material from oak to alder to MDF. We tested for power, depth adjustment, bit change, dust control, and ergonomic features. We evaluated plunge action, and depth adjustments in the plunge mode. We also examined the carrying cases and the accessories that come with each tool. We paid careful attention to ease of conversion, too, which we think is a critical feature. For routers like this to find a home on our sites, it's important they convert quickly, be easy to operate, and work flawlessly.

Power, Noise, and Vibration

We tested the tools for three months, both in the shop and on site, using an assortment of router bits and materials. To really get a flavor for power, we cut 3/4-inch dadoes in hardwood with a straight cutter. Each tool performed admirably, with no big differences in power, noise, or vibration between them and no noticeable power loss during the dado test. In the past, routers vibrated so much your hands would tingle at the end of the day and were so loud your ears would ring. We were happy to see manufacturers' noise- and vibration-reducing advancements in these routers?it really shows.

Switching Bases

The idea of conversion kits adding versatility to the router category depends on the ease with which you can switch between the plunge- and fixed-base systems. We found DeWalt's kit to be the simplest to convert: Release the locking lever, then press both side buttons, and the motor slides straight out of its base.

The Bosch and Makita motors thread into their bases and work nicely. The Bosch has a locking lever on both bases. The Makita has a locking lever on the fixed base but not the plunge base where the motor seats securely and dependably into the base without using a lever.

The Porter-Cable fixed-base unit uses a locking lever similar to the Bosch and Makita setups. The plunge base, however, is different: You slide the motor straight into the base and have to secure it with a small Allen screw, which takes longer than the tool-less designs.

Depth Adjustment, Plunge-Base

There are two methods for controlling cut depth with these tools in the plunge configuration: depth gauges and upper-travel limiting knobs (none of these routers is equipped with a true micro-fine adjustment that you'd find on a high-end plunge router).

Depth Gauge. The depth gauge on a plunge router is really a combination of two elements?the depth rod and turret stops?which combine to determine and limit the cut depth. The depth rod adjusts the intial cut depth; the turret controls a series of subsequent cut depths, required in any multi-step operation like cutting dadoes or mortises.

Bosch and DeWalt equip their depth rods with depth-adjustment knobs that enable you to set rough depths and then dial in the exact cut depths with the adjustable knobs. Good idea, but we found them difficult to operate. Bosch's depth-adjustment knob was hard to turn because there isn't much space around it for your fingers. The DeWalt depth-adjustment knob was even more problematic: It's located on the end of the depth rod, where it contacts the turret stops and might be accidentally rotated by the movement of the turret, potentially changing cut depth.

Upper-Travel Limiting Knobs. The Porter-Cable and Makita tools have upper-travel limiting knobs on their plunge bases. These knobs are useful when the tools are mounted in router tables, because the knobs act somewhat like micro-fine adjustments. Rotating them raises or lowers the bits accurately; however, for handheld plunge-routing functions, an engaged upper-travel limiting knob can stop the motor from rising high enough to extract the bit entirely from the workpiece. In other words, the bit stays partially exposed below the base plate and could strike the work piece or template while removing the tool.

While the Bosch, DeWalt, and Porter-Cable depth rods are smooth, Makita's is threaded. The threads facilitate good fine adjustments above or below the table?one knob revolution equals 1/16 inch?but substantial depth changes, say 1/2 inch, are tedious. Porter-Cable has no fine adjustment on its depth rod.

Depth Adjustment, Fixed-Base

In the fixed-base configuration, the Bosch unit uses a true one-step micro-fine adjustment knob, and it works very well. According to Bosch, it's accurate to 1/256 inch. DeWalt's depth-adjustment is a ring that surrounds the motor.

It's different but works equally well. The company says it's accurate to 1/64 inch. While we didn't measure accuracy with a micrometer, we were able to dependably set a measurement on each tool, say 3/8 inch, change the setting, then go back to 3/8 inch with no problems.

On the Porter-Cable and Makita routers, you make depth measurements and adjustments by first lining up a ring gauge, marked in 1/64-inch increments, with a hash mark on the motor housing. Then you rotate the mark on the motor to your desired depth. This system has been around for years and works well enough, but the two-step process is not as efficient as the Bosch and DeWalt systems.