Laser Distance Meter Features

Tracking, min/max, stake-out. All of these tools can take a continuous reading while moving toward or away from a target, which is called “tracking.” Eight tools can also freeze the minimum and maximum distance measured, which makes the function far more useful. For instance, you can check a room or door jamb for square by sticking the laser’s tailpiece into a corner, sweeping the beam across the opposite corner, reading the maximum length, then repeating for the other diagonal. Tracking the minimum reading between two surfaces is also useful — for fitting built-ins between two out-of-plumb walls, for example. (For some reason, the new Stanley TLM 165 min/max mode only works with indirect measuring, not tracking.) Seven models offer a “stake-out” mode, used for laying out a series of equal intervals by setting the spacing dimension and moving the laser away from a fixed target. A change in tone pitch or frequency indicates when each interval has been reached. It’s reasonably accurate but slower than using a tape.

Inclinometers. The Bosch GLM 80, Leica Disto E7400x, and Stanley TLM 330 have built-in tilt sensors, or inclinometers, that not only measure slopes and angles, but raise indirect vertical and horizontal measuring to the next level. Say you need to measure the horizontal distance to a wall, but there’s a couch in the way. You can angle the meter up until the laser dot clears the couch and hits the wall, click once, and get the precise horizontal measurement (assuming the wall is plumb). Bosch’s optional R60 attachment (shown) instantly converts the GLM 80 into a 24-inch electronic spirit level to make the inclinometer even more versatile.

Indirect measurements. When poor access, obstacles, or the lack of a dependable target prevent direct measurements, units with inclinometers can use internal trig functions to calculate various dimensions indirectly from a distance. Several models can use Pythagorean geometry instead to indirectly calculate certain measurements like wall heights, requiring two or three shots taken from a distance. But you only get precise results with Pythagoras functions if you always pivot the meter off a fixed point and ensure one 90-degree angle. Leica, Milwaukee, Stabila, and Stanley allow you to use the min/max function when taking these measurements, which helps. But in any case, careful freehand shots are fine for estimating.

Target Accessories. Laser-enhancement glasses make it much easier to see the laser dot on distant targets or in bright light. Target plates (above right) maximize the measuring range and brighten the dot. The two items shown above are Hilti accessories. In a pinch, a Post-it note (below) makes a quick and easy target at edges and outside corners.

Area, volume, , -. Eleven of the models can compute square footage, and can also add and subtract dimensions and results. To find the area of a wall, for instance, you measure length and height, then read the result on the display. You can also measure a series of walls this way and add the results as you go. Better yet, the Bosch GLM 80 can store a common ceiling height, then apply it to any number of wall lengths to calculate the total area. The Stanley TLM 330 and the Leica Disto E7300 and E7400x essentially do the same thing, but you have to press the “ ” button between the length measurements. Ten of the models can also measure volumes, which can be especially useful for hvac calculations.

Memory. Lasers with memory store measurements even while the power is off. Nine can store the last five to 50 dimensions or results in order. The Bosch GLM 80, Stanley TLM 330, and Leica Disto E7300 and E7400x let you delete the memory so you can start a new list. Except for the Leica E7300, these also store complete calculations, as does the Spectra Precision QM55.

Power. Twelve of the meters run on two AA or AAA alkaline batteries that allegedly deliver up to 5,000 to 10,000 measurements. But the Bosch GLM 80 uses a convenient rechargeable 3.7-volt lithium-ion battery that’s supposed to deliver up to 25,000 measurements per charge and takes about three hours to recharge. The compact charger plugs the meter into an AC outlet so you don’t have to remove the battery. All of the batteries drain faster if the backlights and beeps are turned on or you leave the power on longer than necessary.

Reference points. The Hilti PD 5 and Spectra Precision QM75 both measure from the back end only, while the other models can also measure from the front. Ten models include a tailpiece that allows you to take measurements easily from inside corners to check diagonals. The Bosch GLM 80, the three Leicas (one of which is shown), the Milwaukee, the Stabila, and the Stanley TLM 330 can also hook outside corners for easier measuring from the back end. Five models can mount to a tripod and be set to measure from the center of the socket.

Helpful display. All of the models have illuminated displays, but the backlight on the Bosch GLM 80 is the brightest. It’s also the only one that can be operated manually or controlled by an ambient-light sensor. What’s more, the unique display can be set to rotate automatically for an easy read regardless of the orientation.

Keypad lock. The Stanley TLM 330 and the Leica Disto 7300 and 7400x allow you to lock the keypad. That prevents them from accidentally turning on and draining the batteries when riding in a pocket or toolbelt.

Durability. Most of the manufacturers claim that they’ve tested the shock-resistance of their lasers by dropping them onto a hard surface from a height of one meter. Spectra Precision drop-tests from 1.5 meters, and Leica drop-tests the Disto E7400x from 2 meters. Nine of the lasers have an IP54 rating, which means that dust intrusion and water splashes have no ill effects. The Hilti PD 5 and Spectra Precision QM75 rate at IP55, while the Leica Disto E7400x rates at IP65; you can drop all three in the mud and wash them off, and the Leica is also completely sealed against dust.

Continuous beam. When shooting a series of lengths, such as when installing baseboard, you normally have to press the top button twice per measurement — once to turn on the beam and a second time to take the measurement and turn the beam off. But the Bosch GLM 80, the Stanley TLM 330, and the Leica Disto E7300 and E7400x also let you keep the beam turned on so you only have to press the button once per measurement. Signal strength. Spectra Precision’s QM55 is the only LDM in the group with a signal-strength indicator. More bars indicate a stronger signal, which means a faster, more dependable measurement.

Timers. Six of the lasers have a programmable timer that delays the shot after you press the measure button. Because you can press then aim (rather than having to press the button while trying to keep the beam on the target) it’s much easier to aim the beam precisely in an awkward position or at long distances.

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