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By Bill Brockway
Publication Date: May/June 2000

In essence, a laser is just a source of light. The light emitted by a laser diode is different from ordinary light in two important ways: First, each of the billions of photons that make up a laser beam has the exact same wavelength or color. In laser tools, this is usually red light. Almost every other light source we use on this planet emits light in a wide spectrum of colors.

Second, the photons stick together. The beam that comes out of a laser tool stays tightly compacted. If you look at the laser dot on a target 100 feet away from the source, it will be about the same size as it was when it left the tool. Even if it does spread out a bit, the center of the dot is still the center of the beam.

So now you've got a very straight beam of light. What can you do with that on a construction site? Plenty, if you find a way to make the beam level, or split it into two or more beams at 90 degrees from each other, or spin the dot around in a circle to "paint" a level line on the walls. In fact, there are probably a thousand ways to use lasers on site, and, since we've only seen a couple hundred so far, the laser-based tool industry will evolve for quite a while.

I visited several manufacturers to make sense of the laser tools currently on the market. I discussed the tools' construction, function, and future with tool designers and engineers. Here's what I learned.

Optics

Most laser tools sport a single diode, which emits light. That single beam can be split into several beams, bounced off mirrors, refracted through a prism, focused, aimed, and leveled before it comes out of the tool. This manipulation is the science of optics, and it's what laser-technology engineers love even more than stock options.

Companies that make lasers for the construction industry generally use optics to do one of three things with their laser beams: project one or several dots, project lines, or spin a dot like a very fast lighthouse beam to give the impression of a faint line all around the room.

Line projectors and rotators -- the second and third options above -- sound sort of similar. But a line projector actually spreads a dot out sideways so it looks like a line. One advantage of this is a brighter line, since all the light from the diode is gathered in one section of the circle. Another advantage is that it's a lot cheaper to throw a stationary line than it is to rotate a dot. The downside might be that the guy on the other side of the room can't use the line until someone turns the tool around and points it his way.

Dot Lasers

Construction lasers became affordable when someone stuck a bubble vial onto one of those laser pointers used for slide shows. They soon got more sophisticated, and the stick laser was born -- an 18- to 36-inch box-beam level that shoots a laser from one end. Everyone got pretty excited at the prospect of a 300-foot level until they realized that the dot out there was at the mercy of the bubble on the beam. If you moved the beam enough to raise the dot several inches, the bubble wouldn't budge. So, some companies developed more sensitive vials while others suggested working at shorter distances.

Next, engineers found they could split the beam into two dots at right angles to each other, which is useful for layout and squaring frames. Then they found a way to make the laser find level by itself, and still shoot two or three dots at right angles. Pacific Laser Systems (PLS) and Levelite have led the way in developing these multi-beam tools. One PLS tool shoots five beams: up, down, right, left, and straight ahead. Due to optic demands, some of the beams are offset from the others. There's no single common center point from which all the beams originate, so you might need to factor in a correction for certain layouts.

Toolz has developed a five-beam laser in which all the beams have a common origin point, but it's not on the market yet. Watch for the RoboVector to hit the shelves later this summer. And Stabila has a simple new split-beam laser that shoots vertical and horizontal beams at the same time.

A few companies have come up with innovative stick-laser products. Checkpoint Laser makes high-end torpedo levels with laser diodes inside solid aluminum bodies. Checkpoint president Jim Webb reasons that everyone carries a torpedo anyway, so why not increase the tool's usefulness with a laser? The bubbles are standard 45-arc-minute vials, but an optional 15-arc-second vial provides 60 times more accuracy.

Zircon's stick laser finds level for you, or at least tells you which way to move the tool in order to get there. The Laservision X uses a carefully oriented and calibrated electronic sensor to display lines on an LCD screen mounted on the side of the tool. The lines tell you which way to go to find level, and notify you when you get there. In laser mode, accuracy is resolved to 1.4-arc-minutes, which translates to about 1/8-inch at 50 feet. Users can easily recalibrate the tool in the field. The sensor's design lets you turn the tool 90 degrees and find plumb with just as much accuracy.

Levelite now makes a stick laser as well, one that incorporates the company's trademark pendulum technology. The FastLevel, accurate to within 1 arc-minute in 60 feet (or better than 1/4-inch), starts out with the beam aligned carefully with the edges of the rail. But flip a lever, and the diode inside swings freely to find level on its own. Stabila's stick laser, the 80LMX-P+L, shoots a horizontal dot and vertical line that's accurate to within 1/4-inch at 100 feet.

Line Projectors

Dot-spreading optics have been around for a while, but some recent tools make the function more useful. Zircon has a new family of line tools: the Plumb Pyramid, which throws a self-leveled plumb line; the Horizon, which projects a level line; and the Horizon+, which shoots plumb and level lines at once to make a grid on the wall. You can use the plumb line to "paint" a line on the ceiling or floor for aligning lights or flooring. Put the Horizon tool in the corner of a room and you'll cover most of it with a level reference. The Horizon+ is great for wall-covering layouts.

Levelite, long known for dot lasers, now offers an accessory that spreads two dots into right-angle lines on the floor. This opens up a ton of layout options. Snapped chalk lines disappear quickly under mortar and tile, but the laser line is always on top.

Rotating Lasers

While visiting Laser Reference I spoke with engineers about rotating lasers and their applications. There are lots of ways to use this level line on a site, but you've got to trust that the line is actually level. Rotating lasers divide neatly into four categories based on line-leveling systems.

Manual leveling.

These tools are the simplest rotating lasers. They use just three components to find level -- bubble vials, knobs that change the tool's angle, and the user. Twist the knobs until the bubbles read level in both directions, turn the tool on, and you're in business. Carefully check these tools' accuracy specs; most are suitable only for indoor work up to 35 feet away from the tool.

If you do a lot of work in small spaces, a manual-leveling rotator can be a good option. Just remember to check the bubbles frequently. If someone bumps your tripod, the laser could project a sloped line. If your work requires accuracy at a greater distance, consider moving up to one of the most sophisticated models. Manual-leveling rotating lasers generally cost between $280 and $700.

Semi-automatic leveling.

This category's name is a bit misleading. The only automatic thing these tools do is shut off when they get knocked out of level. You still use bubbles, knobs, and your eyes to level them, but they'll tell you if they somehow get thrown out of level. These tools' accuracy is often rated at something like 3/8-inch at 100 feet. That's a little less accurate than some similar models, but semi-automatic laser tools are purposely designed that way. If designers aimed for 1/16-inch at 100 feet, the tools would shut themselves off too frequently to be useful. Every tiny vibration in the area would mean a trek back to the tool to reset it. These tools range widely in cost, but average between $450 and $1,400.

Compensated leveling (narrow-range self-leveling).

This is probably the largest, most popular category in today's laser market. Compensated tools use familiar bubbles and knobs to get the tool roughly close to level. Then a compensator, a small pendulum often suspended by tiny steel wires, takes over from there to find the exact level point.

Some compensators incorporate relatively heavy pendulums that weigh several ounces. Their top ends are secured in complicated ball-bearing arrangements. The weight overcomes any bearing friction to make the compensator hang plumb.

Dependability is one big advantage of this system. Center the bubbles once in the morning, and the tool projects an accurate line all day. The compensator handles any small movements in the tripod. If the tripod moves enough to keep the compensator from leveling, the tool lets you know by shutting off. These tools drop in price all the time, but currently sell for between $600 and $1,700.

The accuracy of compensated laser tools is generally listed as 1/4-inch at 100 feet. One drawback of these tools is they can't shoot a sloped circle, which can be useful for grading or setting drainage pipes. If you need this function, step down to a manually leveled tool, which will send the line where you point it, or step up to our next category.

Servo leveling (wide-range self-leveling).

Now we're talking about the Cadillacs. Servo tools are sometimes also called fully automatic because tiny servo motors, which act like tiny winches, do all the work. Basically, you turn the tool on and walk away. Its sensors detect how far out of level the tool is and tell the servo motors what needs to be done. The servos reel in or ease out slim steel cables to achieve level.

Of course, you pay plenty for this marvelous convenience. Servo models sell for between $1,400 and $2,000. Since pendulums don't control the action inside these tools, some high-end models have slope features. Users can dial in a fraction of a degree or several degrees of slope.

There's also one type of rotating laser that falls somewhere between compensated and servo leveling. This hybrid type uses servo motors to roughly level the unit, and then a compensator finishes the job. These tools cost a little less than fully servo-leveled types because the level sensors and motors needn't be accurate enough to fine-tune the tool, just get it close enough for the compensator to swing. This hybrid category doesn't really have a name yet, but the tools sell for between $1,000 and $1,600. Like compensated tools, they can't project a sloped circle for grading.

A Word of Caution

Most rotating lasers are mounted on tripods for use. Pay attention to tripod materials, because not all are created equal. Differential heating is the bane of tripods. If two legs heat up in the sun and the other one is shaded, there could be enough movement to trigger auto-shutoff on a semi-automatic tool. With a manually-leveled tool, you won't know unless you check the bubbles periodically. Wood is the most stable material for a laser tripod. Next-preferable materials are fiberglass and aluminum.

Sidebar: How Machines Find Level

The advantage of self-leveling lasers is obvious. But how can a machine find level? Methods used depend on tools' ultimate functions.

Pendulum

The most basic way to find level is to find plumb and take a 90 degree turn. Tool designers accomplish this with a pendulum. Gravity always pulls straight down, so anything hanging from a single point always hangs the same way. Add a laser diode and some optics to the pendulum, and you've got a tool that shoots two level beams separated by 90 degrees. You can lay out square corners without pulling a tape, and you can snap a level line if you aim both dots at the same wall.

To keep pendulums from swinging too long, tool manufacturers make the action settle out quickly. The most common method is magnetic damping. A magnet at the bottom of the pendulum reacts to stationary magnets below it. The pendulum moves more slowly, so it settles out to plumb much faster.

Electronics

Automatic-leveling tools generally use fluid to find level. There are many ways to do this. Here are three that I learned about:

Bubble Vial.

This system uses a regular bubble vial, but the eye sensing the bubble's position is electronic. An infrared light shines up through the vial from below, and the bubble's shadow falls on a pair of sensors. The sensors are wired to servo motors that can change the tool's angle. When the amount of light falling on the two sensors is equal, the bubble reads perfectly level.

If one sensor catches more light than the other, that means the bubble's off center in the vial and is shading the other sensor. The over-bright sensor signals that it's too low, and the servo motors raise that side of the tool until the bubble's shadow is spread equally over both sensors. A rotary laser requires two of these setups oriented at right angles to each other.

Wired Vial.

This one looks like a regular vial at first glance, but a closer inspection reveals tiny wires inside -- one in the middle and one on either end. In a self-leveling tool, electronics connected to the wires sense an electrical current flowing through the vial. When the bubble is exactly centered, the impedance is equal to both sides of the vial. If one number is too high, the electronics know which way to tip the tool to correct the situation.

Segmented Disc.

Imagine a pie cut neatly in four pieces with distinct gaps between the pieces. Slap a Frisbee over the pie to create an airspace inside, flip the whole thing up on edge, and fill the space about one-third full of water. Now shrink the contraption to the size of a dime, turn the pie pieces into electrical contacts, the housings into metal, and the water into a proprietary "magic fluid." The surface of the fluid always finds level, and only when the electrical contacts are equally covered by fluid will the electronics find equal capacitance in both contacts. An imbalance indicates that the too isn't level, and also tells it which way it needs to go to get there. This system was invented for Zircon's Laservision X stick level. It can also find plumb -- just swing the tool up and two different contacts come into play.

Bill Brockway is an editor at Creative Homeowner Press, and a former senior editor at Tools of the Trade.

You may be old enough to remember water levels, but you're still young enough to get hooked on lasers.

By Erik Elwell
Publication Date: July 2001

Like cell phones and Palm Pilots, laser levels are rapidly becoming high-tech staples in many contractors' tool bags. If you don't use them yet, you'll probably find yourself left behind on layout speed, daunted by complicated designs. A single laser however, won't perform all the functions you need as efficiently as you'd like. I've found that a fixed-point laser and a separate rotary laser is the best combination for me.

For the last 10 years, I've been a contractor in the New York metro area. I focus on high-end residential and commercial office projects. This work generally requires complex layouts that laser levels can make quick work of. Whether we're laying out a foundation for a new home or establishing perimeter lines in a pre-war office building, our laser levels and chalklines are first out of the box and all of my layout guys use them throughout the job.

Foundations

The more accurate and level a foundation is, the easier it is for all other trades to do their work. If the foundation grades and subsequent floor framing were perfectly level, theoretically you'd only need a tape measure and framing square to build a square and level structure. But we all know that's impossible given the realities of jobsite conditions and lumber variations. Some of us remember laying out foundations with water levels and transits, but these devices have shortcomings that laser levels don't.

Anyone who's used a water level knows how frustrating it is to operate. Transits are a major improvement over water levels, but they're susceptible to human error: The slightest change in position throws a transit fatally out of accuracy. If the set-up man doesn't read the leveling vials properly or bumps the tripod, it knocks everything out of level -- including your foundation.

A good self-leveling rotary laser level can eliminate those problems. Set one up, turn it on, and the laser automatically finds level and shoots a red dot up to 200 hundred-plus feet that's accurate to within an 1/8-inch. With remote-controlled operation and remote receivers, your layout man needn't be near the laser, reducing the chance of bumping into it. If, however, it does get bumped or jostled by a shaky floor, the tool signals you there's a problem. Layout becomes a one-person job and given today's labor rates, those substantial savings justify purchasing the tool.

We use our rotating laser level to lay out excavation stakes. Then our excavator gives us a nice 8- to 10-foot-deep hole so we can start pouring footings and setting up wall forms. Our laser level makes its second appearance for marking footers. It shoots a constant level line, acting like a transit that's infinitely easier to set up and use. Thanks to the tool's automatic leveling feature, a layout man presses the on button and can be completely confident that the laser will shoot a red dot in perfect level.

Since the laser spins, it projects level points 360 degrees. Using a marking stick, footing form boards are easily brought up to level. A remote-controlled device lets us position the laser's red dot exactly and keep it there as long as necessary, which is essential for setting forms -- especially warped or damaged ones. After we've set the wall forms on the footings, we use the laser to set grade for the top of the foundation walls before the pour.

Framing

We also use our lasers to establish level and plumb lines during framing whether it's a new home or an old building. With an old building, we often need to establish a reference line on the floor so we can lay out the rest of the space. For this task, too, I suggest springing for the cost of a self-leveling device. In a few seconds, you can establish a top wall plate location and create a line from which you can then pull measurements to establish your other walls. With the laser mounted horizontally, soffits, doors, and knee walls are quickly laid out. The numerous mounting devices available -- pole stands, adjustable tripods, and mounting brackets -- let you do many layouts on the mark without having to extend points with a tape measure.

On new construction, we return to the site with laser in hand once the foundation has cured. Putting the laser on a tripod, we set the sills and easily bring them to level. Because we shot the foundation with the same tool, it takes only small adjustments to level the sills, which we accomplish with a handful of shims inserted here and there.

The tighter the sill is to the foundation (i.e., fewer shims), the stronger the structure is. It's less likely to settle or squeak. Once the sill is on and leveled properly, the rest of the framing could be done with a tape measure, right? Given today's lumber quality and new guys' inability to read tape measures properly, it's always a good idea to keep a laser level handy. Shooting a level line periodically during the project's course ensures that all framing is built level, which gives you a chance to find problems early on.

Finish

After the rough framing is complete, it's time for all those crazy half walls, dropped soffits, and vaulted ceilings architects love. With the advent of CAD, architects are developing increasingly complex designs and I've found that using a laser level is the only way to keep up. Because we can set one up in virtually any location with the right mounting device, my crew can lay out almost anything an architect can come up with. Even arched vaulted ceilings are fairly easy; once you establish a level line around the room, you can swing your arc using a chalk line or a long, straight 2x4.

Laying out door and window heights with lasers increases the efficiency and quality of our work with very little effort. Using the tools to establish consistent heights on those openings ensures that all interior trim is also consistent. That's especially important for elaborate and expensive moldings. And when your siding crew sees that you've aligned all the doors and windows consistently, they'll probably buy you lunch for making their job easier and their work better-looking.

Uneven window and door heights become a nightmare when siding crews try to maintain reveals and proper spacing. Your siding crew might even have their own laser setup to level and check their courses.

Finish carpenters are also fans of laser levels. Shooting a level line around a room gives our carpenters instant points for chair-rail heights, cabinet locations, and shelving. It's a hassle to wrap a 4- or 6-foot level around a room. It's invariably inaccurate, and measuring off the ceiling or floor for level is a risky proposition.

With a laser tool, there's no need to question floor unevenness or level because self-leveling lasers operate independently of floor imperfections and establish a level line no matter what.

Other Trades, Other Phases

Suspended ceiling installers. These guys were among the first to use laser levels on their jobs, especially in commercial situations where runs are really long. They establish one good reference line, then clip a rotating laser to the ledger. Now they've got a perfect line for the rest of the ledger, track, and all their tie wire. Unlike a pencil line, you shut the laser off and the mark disappears. That's especially nice for painted walls.

Plumbers.

These subs often use point-to-point lasers to mark pipe layouts and establish pitch over long runs. A point-to-point laser shoots two to five points: parallel, plumb, square to each other, or some combination of the three. This makes it easy to mark overhead fixture locations like showerheads and A/C units. Fixture locations are laid out on the floor; then the laser transcribes the marks right up to the ceiling like a plumb bob working in reverse.

We increasingly find our projects being marked out on the floor and then shot up to the ceiling. This makes layouts faster, more accurate, and safer. Nobody has to reach up from the top of a ladder to pull measurements off ceilings and walls or fiddle with a plumb bob.

Electricians.

Many electricians are fond of using lasers for easy fixture placement. Nothing is better suited for outlet and switch height layouts or marking recessed cans or chandeliers. The simple point-to-point devices work well for these tasks. My clients often ask me to center a lighting fixture over a dining room or conference table. After we lay out the table placement on the floor and find its center, the laser does the rest by shooting it straight up to the ceiling.

Tile installers and masons.

Some of the better point-to-point lasers shoot three or more points perpendicular to each other, giving a tile installer an instant grid to lay out a floor. There's no need to rely on a bent framing square, Pythagorus, or those awkward, oversized squares to establish lines. Place the laser in the right location, press the on button, and the tool creates an instant set of points. Snap a few lines and you're ready to roll. Or, if you're climbing a wall with tile, a rotary laser's level line won't disappear under your thinset like chalk does.

Even our painters and landscape contractors use laser levels. The painters use them to set paint breaks on walls so they can tape perfectly straight lines across numerous corners or breaks. And our landscaper tunes his grading and sets retaining wall heights by shooting them with laser tools.

Keep in mind that lasers are only accurate when they're actually in use. Keeping them locked away in a gang box, shop, or office won't help you speed up layouts or improve your accuracy. You must insist that your crew use laser levels as often necessary, not just in the beginning of the project.

The construction industry is slow to change, especially when it comes to tools. But technology is changing fast, and old-school carpenters and tradesmen have to change with it. If you equip an experienced crew with point-to-point and rotary lasers they'll be able to tackle almost anything.

Erik Elwell is a contractor in the New York metro area who specializes in office build-outs and high-end residential construction.