Tool review: Rail-Guided Saws

Sleek and sexy, smoothly riding a shiny aluminum rail, leaving in its wake not a tattered mess, but crisp, clean edges ... one thing is certain: This isn't your father's circular saw. Dad, meet the rail-guided saw--the next generation of portable circular saw.

• Rail-guided saws beat other circ saws hands down in four areas:
• They crosscut splinterprone veneered plywood as well as or better than a good tablesaw and a top-flight blade.
• Cutting any odd angle is a breeze.
• When you need to start a cut in the middle of a workpiece (a sink cutout comes to mind), a railguided saw makes the job faster, safer, and more accurate than any other method, partly because the zero-clearance edge of the rail shows exactly where the blade will cut.
• Finally, hooked to a vacuum, the guards that surround the blade increase dustcollection efficiency, leaving the floor nearly as clean as the cut.

With quality, though, comes cost. The lowest-priced saw/rail pairing at the time of our test would set you back $465; the most expensive cost $625 with its 75" rail. (Add $125 more for the 55" extension and connectors that let you rip an 8' sheet of plywood.) For about the same price, you could instead buy a good contractor-style tablesaw with a clean-cutting blade.

So, are rail-guided saws worth it? We challenged five machines in a variety of hardwoods, softwoods, and sheet goods to find out. Here's what we learned.

If you've ever crosscut oak-veneered plywood, you know that the porous grain makes it difficult for nearly any saw and blade to cut cleanly. And the brittle surface of melamine-coated particleboard chips if you look at it wrong, much less cut it with a power saw.

All of the saws delivered impressive cuts [photo] on the "keeper" workpiece in both materials, thanks to the zero-clearance edge—a sacrificial plastic strip on the track that you cut the first time you use it. Like a zero-clearance throat insert in your tablesaw, it virtually eliminates tear-out and fuzzing.

These machines excel at cutting sheet goods; but could one replace your tablesaw? In 4/4 poplar, ripcuts required some sanding or a light jointer pass before gluing. But in thick, dense stock (we tried 8/4 hard maple), ripcuts tested the limits of some saws. Although some displayed ample power to slab off strips of 2"-thick hard maple, others required slower feed speeds, which sometimes resulted in burning on the cut edges.

Because of the spring-loaded plunge system, setting cutting depth on these saws isn't as simple as on an ordinary circ saw. Instead of pivoting the base, you must set a depth stop. All operate easily, but we prefer a scale that shows cutting depth by the thickness of material you're cutting--the ¹⁄₂ " setting, for example, actually projects the blade ³⁄₄ " below the saw base to account for the rail thickness. On the metric-marked scales on the some saws, you need to set the stop to at least 16mm for the blade to cut completely through 12mm (¹⁄₂ ") stock.

A slot on the base of each saw fits over a raised guide rib on the 7"-ish-wide rail, and knobs let you dial in the base/rib fit precisely. As a practical matter, you can easily cut pieces as narrow as 4" to 5-¹⁄₂ " (depending on the saw), as long as that rib remains over the workpiece. A little jury-rigging with spacers enables you to work narrower stock.

Pliable strips on the bottom of each rail provide enough bite on the workpiece so that, in most cases, the rail stays put without clamps (optional for all saws). Still, we almost always used the optional (and pricey) clamps on all of the rails: They mount on the underside of the rail so they never interfere, and we found that a little pressure goes a long way. One clamp was often all that was needed for a secure grip.

You can bevel-cut with these saws [Photo], but tilting the saws more than about 25° shifts the center of gravity enough to start lifting the base from the rail. One saw combats this with a sliding lock that hooks into a special channel on the guide rib to prevent tipping.

A rail-guided saw eliminates most of the danger of making a plunge cut: The base remains solidly on the rail throughout the plunge; and an antikickback stop, whether built-in or mounted on the track, prevents the saw from moving backward during the plunge cut. Index marks on all of the saws show where the back and front of the blade will cut at full plunge [Photo].

A rail-guided saw will never replace a tablesaw, but it sure outperforms any panel saw we've tried (at a much lower price, too), and doesn't limit you to perpendicular cuts—you'll get high-quality cuts at any angle. Our Top Tool, the hefty Festool TS75EQ, displayed ample power and precision in everything from sheet goods to thick hardwoods. If you'll work primarily in sheet goods, and make plunge-cuts at that, we call the lighter-weight DeWalt DWS520SK and Festool TS55EQ different but equal. Buy the DeWalt if you value a better depth-of-cut system more than easy blade changes.