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Small lasers packaged in compact "boxes" hold more promise than the point-and-shoot stick variety

by Clayton DeKorne

Pick up nearly any tool catalog or trade magazine and you'll find a slew of "construction lasers" that claim to provide an efficient alternative to traditional layout methods. To be sure, laser technology holds great promise for the building trades, but this industry is still young. Many of the products available today may not prove as practical as you might first expect.

A Spectrum of Lasers

The commercial and industrial trades have been using lasers for years. Although the technology has changed in the last decade, the performance of these tools has been well established. In the residential trades, however, the advantage of a laser is not so obvious. Nevertheless, scores of manufacturers have recently mobilized to deliver low-power visible lasers in small, relatively inexpensive packages. For safety, the power output of any laser must be limited. Federal regulations set minimums for construction lasers at less than 1 milliwatt (Class II), and less than 5 milliwatts (Class IIIa). Even the brighter Class IIIa laser is safe for your eyes, as long as you don't stare straight into the beam for a long time. But this low power rating also means that the beam isn't very bright, and in strong sunlight, all of these lasers are very difficult to spot outdoors.

Dot Lasers

A "dot laser" is essentially a laser diode mounted on a level rail. Regardless of what some advertising photos show, these instruments project a dot, not a continuous beam; to be visible, the output of the laser must reflect off a target. Unless your site is shrouded in fog, you won't see a continuous reference line shining through the air. Accuracy for these instruments is defined by the speed of the vial and by two alignments - one between the bubble and the rail, the other between the rail and the laser beam. Check the manufacturer's specs carefully. Too often only one alignment, that between laser and rail, is given as the measure of accuracy. But the accuracy of an instrument is only as good as its weakest link, and on a dot laser, this link is usually the sensitivity of the vial. A 5-arc-minute vial works fine on a 4- or 8-foot stick. Project that line out 100 feet, however, and you could have an error of up to 3 inches. For accurate marks at longer distances, you need leveling accuracies measured in arc-seconds. If you work with shorter distances, you must still keep in mind that a dot laser by itself can only project one dot in one direction. How often you have to set up to level a longer run will determine whether this type of laser is useful to your work. If you have to turn the corner and expect to keep your elevation, you'll have to put up more cash for accessories - namely, a swivel base or a beam splitter. Most swivel bases rely on bubble vials, which add another layer of inaccuracy to the equation. And for every elevation you run, you have to level the base, then level the instrument. If you change elevations, then change back, you double the chances of getting an inaccurate reading. This leveling procedure reduces the dependability of these instruments to establish accurate repeat elevations. And the time you spend leveling the base and instrument seriously cuts into any labor savings. A beam splitter typically uses some form of prism to divide the beam - at 90 degrees, or at 180 degrees (90 degrees left and right). A few companies also offer a line lens, which spreads the beam into a line. The most versatile of these accessory "systems" comes from CheckPoint Laser. While you still have to deal with all kinds of extra parts, CheckPoint has packaged them in a job-site-friendly kit filled with a well-designed family of tools. The basic level - a 1-foot-long, 1x2-inch rail milled to within .002 inch - has been machined so that all sides of the rail can be used as references. All the relevant dimensions and centerlines have been carefully scribed on the tools. Perhaps the most ingenious feature is a protractor dial, complete with detents at common angles, for accurately projecting angles, either parallel or perpendicular to the instrument. Success with this tool will depend on how committed you are to learning new tricks. To get the full benefit of all its features, you almost have to become a student of the tool, much the way some folks have done with Construction Master feet-inch calculators.

Square Dots

LeveLite Technologies and Pacific Laser Systems incorporate beam splitting inside self-leveling instruments that provide several dots aligned at right angles. LeveLite makes two models - the SLX2 and the Tri-Lite. The SLX2 shoots two dots at 90 degrees to each other. The top-of-the-line Tri-Lite adds a third dot for plumb (see Figure 1). Pacific Laser's PLS5 adds two more dots - one perpendicular to the plumb line in front, and another plumb line below the instrument (Figure 2).


Figure 1. Square dots.

Though not much bigger than a tape measure, and nearly as durable, the Tri-Lite has won fans in the commercial interiors market for quickly plumbing steel partitions. The unit is self-leveling and accurate for distances under 50 feet.



Figure 2. Plumb, level, square.

Accurate to 1/8 inch over 100 feet, the self-leveling PLS5 is one of the most exact instruments among the new breed of lasers. It has two plumb beams (one up and one down) and three level beams (at 90 degrees to each other), so you can accurately mark both ends of every layout line.

Because these instruments are self-leveling, setup is fast and dependable. The diode swings on the pendulum, allowing gravity to establish level. Provided the diode stays square to the pendulum, this bypasses the inaccuracies of a bubble vial. The LeveLite tools (also sold in the Hilti and Quadriga lines) are accurate to within about 1/4 inch in 60 feet; the PLS5 is accurate to a much higher degree - 1/8 inch in 100 feet. In this category, it seems, you get what you pay for. The SLX2 retails for about $500; the Tri-Lite goes for about $700; and Pacific Laser's PLS5 sells for close to $1,000. While this may sound like a lot of money to pay for a layout tool, it can make economic sense. According to Oakland remodeler Jonathan Dougall, the PLS5 has easily paid for itself several times over. "I never hesitate to buy new tools to save labor," Dougall explains. "In the work we do - upper-level house remodeling - we use the PLS5 all the time. The existing floor is never level, but everything above that - windows, trim, cabinets, and ceilings - must be dead on." Dougall used to use a transit for this work (and still does for most exterior layout). "I've owned a couple of [stick] lasers, too, but I don't use them anymore." For Dougall, the reliable self-leveling PLS5 offers a tangible time savings without sacrificing precision. A big part of this savings, claims Dougall, is in its being easy to use. Just set it down and wait a few seconds for the dot to settle out. There's almost no training involved for the crew. The plumb beams on the PLS5 and Tri-Lite are frequently employed for plumbing tall walls, and for setting the location of can lights in cathedral ceilings. Speeding up these applications alone can go a long way towards paying off the instrument. Dougall and other West Coast contractors note that 9-foot plate heights and vaulted interiors have become quasi-standard in upper-end residences, and lasers can speed this layout. With its multiple reference points, the PLS5 offers the fastest alignment. In each reference plane, you get two dots that define one straight line. Dougall and other PLS5 users emphasize that these multiple reference points offer immediate and reliable checks. With other instruments, you are beholden to the level or plumb accuracy of the instrument, and you never have a concrete visual reference point for perfect alignment.

Square Lines

As a flooring contractor in northern Illinois, Dan Lewis long ago recognized that an easy-to-use laser device could substantially speed the installation of tile, carpet, and sheet goods. For this type of work, Lewis needed a tool that would show clear layout lines, not just a couple of abstract dots. His answer is the $650 Laser Square - a simple instrument with two laser diodes aligned at a perfect right angle (Figure 3). Switchable optics make it possible to project three different patterns - two dots, two horizontal lines, or two vertical lines. For floor layouts, the vertical lines prove the most useful. When projected low to the floor, these vertical lines show up on the deck as two solid lines of bright light. Whether you're aligning wall plates, a tile grid, or a countertop, having a solid line to sight along speeds the task considerably.



Figure 3. Square lines.

More of a layout tool than a long-distance leveling tool, the Laser Square gives you visible lines at a right angle. For some layout jobs, such as laying out floor tile or leveling a countertop, it's more useful to have actual lines to sight along than a single reference dot.

Solidly encased in a heavy powder-coated aluminum body, the Laser Square seems built to last. This is one instrument you won't hesitate to throw in a toolbox. Its ability to level is limited by two bubble vials. While this would work well for leveling a short run of kitchen cabinets, the real advantage of this instrument is in establishing square reference lines. According to several tile installers, the Laser Square gives them an exact picture of the reference lines they need. "This is a no-brainer," tile installer Todd Schwartz of Akron, Ohio, explains. "The Laser Square is obvious to any floor mechanic who picks it up." Michael Byrne, director of the Ceramic Tile Education Foundation, echoes this claim. "If an installer doesn't understand the Laser Square, he or she needs training in the basic principles of layout. The Laser Square just makes these lines easier to see and quicker to establish. You can do the same thing with a chalk line and tape measure, though perhaps not as quickly."