Automatic Levels: All About Automatic Laser Levels

Automatic laser levels, or self-leveling instruments, have become a much more common optical instrument on construction sites. These levels are replacing alternatives, such as builder's levels, because they are easier to use and quicker to set up. Automatic laser levels remain level and accurate no matter how much the ground vibrates, how much the temperature changes, and how unsteady the operator handles it.

Instead of having the traditional graduated leveling vials like the transit level or builder's level, automatic laser levels have a circular level. The circular level, or bulls-eye level, is mounted on the automatic level and is centered to facilitate the leveling. Once the bubble in the circular level is centered, a compensator takes over and maintains a true level line of sight. This provides a very convenient set up; once the instrument is level, no further leveling is required at the location.

Automatic laser levels are useful in many different situations.

Verifying elevations of foundations, footings and walls.
Structural framework.
Establishing proper drainage for structures.
Determining the correct elevation for floors.
Establishing the height of doors and windows.
Developing suspended ceilings.

Parts of an Automatic Laser Level

The basic setup of an automatic level consists of the telescope, the circular level, three leveling screws, and a compensator. However, there are plenty more parts that play a key role in the success of the automatic level. (Insert a diagram locating specified parts)

Telescope - holds lenses that magnify objects in the sight.
Focusing Knob - can be turned to make objects appear crisp and clear.
Objective Lens - catches the object being sighted and magnifies the object.
Graduated Horizontal Circle - marked by degrees, used for setting and reading horizontal angles.
Leveling Screws - allows adjustments to be made to ensure the instrument is level.
Base Plate - area that the automatic level attaches to on the tripod.
Horizontal Tangent Screw - can be adjusted to make the instrument move left or right on the horizontal plate.
Circular Level - mounted on the automatic level, this ensures that the instrument is at a true level point.
Eyepiece - located at the viewing end of the telescope, it can be turned to bring the crosshairs into focus.

Telescope

The telescope is located at the top of the automatic level. Like other leveling devices, the automatic level moves horizontally around a complete circle. The horizontal circle is marked at each 1 degree and has measurements up to 360 degrees.

The telescope contains many parts. The objective lens sits at one end of the telescope. It catches the object being sighted and, with the help of the other lenses inside of the telescope, magnifies the object. On an automatic level, there are two sights along the top of the barrel of the telescope. These sights allow the operator to loosely align the telescope with the object being sighted.

At the opposite end of the objective lens sits the part of the telescope that the user looks into, the eyepiece. Inside the eyepiece are crosshairs running horizontally and vertically. Rotating the eyepiece allows the crosshairs to become focused and clear. There is a focusing knob located on the barrel of the telescope that is used to focus crisply on the object being sighted.

Stadia lines are short horizontal lines that are located in the eyepiece above and below the horizontal crosshair. The stadia lines get bisected by the vertical crosshair which allows the user to find out the distance of the object being sighted.

The focusing knob on the telescope allows the target being sighted to become clear and focused.

Circular Level

The circular level is also known as a bulls-eye level. The circular level is called this because in order to ensure it is level, the bubble will go to the middle point of the circle, creating a bulls-eye. The circular level does not ensure an exact leveling; instead it provides a preliminary reading. Once the circular level is done with the rough estimate, the compensator kicks in and makes sure the instrument is truly level.

The circular level differs from other levels in accuracy and appearance. Vials on transit and builder's levels are much more accurate. However, the circular level used on automatic levels is easier to use than these other leveling instruments.

Base Plate

The base plate of an automatic level is the area in which the level is attached to the tripod. Automatic levels have a convenient hole located on the bottom of the instrument. This hole is used with a center bolt that is located on the tripod.

Compensator

There are three leveling screws that control the level. These are used to set a rough-level before the compensator is used. The compensator automatically takes over to create and maintain a line of sight that is truly level. After the compensator does its job, there is no further leveling that is required with the instrument. This makes the automatic level much more convenient than levels that require manual installation and set up. The compensator uses a pendulum-type set up that relies on gravity. Once the compensator is set to level, it will remain level through ground vibrations, operator handling, as well as temperature changes.

Setting Up an Automatic Laser Level

When preparing to set up an automatic level, it is important to make sure you have the right tripod.

When using a 5/8" center bolt mount: the protective cap from the tripod head should be fitted onto any of the tripod's legs using the attachment found on the cap.

Once your tripod is selected, the set up process may begin.

Mounting an Automatic Laser Level

It is important to place the level directly on the tripod head after removing the level from the carrying case. If the level is placed elsewhere, it could cause serious damages to the instrument. After placing it on the tripod, the next step is bolting the instrument onto the tripod base. At this time, it is safe to remove the protective lens covers and place them in the carrying case. After these steps, the mounting process is finished. You should close and store the carrying case out of the way of other workers or tools.

Leveling an Automatic Laser Level

After mounting your instrument, it is important to make sure it is level around all 360 degrees in order to allow for precise and accurate measurements. Before beginning the leveling process, use this checklist to ensure the safest conditions.

Make sure that the tripod is stable and securely planted before starting the leveling process. It is important to do this step to make sure the instrument will not tip over while doing the leveling process.
Make sure that the attachment between the automatic level and the tripod is secure.
Make sure that the leveling screws are not too tight against the leveling base plate.

How To: Level an Automatic Laser Level

Place the telescope in a position that is parallel to two of the three leveling screws. Place the two screws between your thumb and forefinger on each hand.
Turn both screws simultaneously in opposite directions and watch the bubble in the leveling vial. The bubble will follow the left thumb.
o When both thumbs are turning out; the bubble will move left.
o When both thumbs are turning in; the bubble will move right.
Once the bubble is centered, place the last leveling screw between your thumb and forefinger. Once this leveling screw is in place, center the bubble in the bulls-eye circle.
Rotate the telescope 180 degrees. If the bubble does not stay in the center of the bulls-eye circle, repeat these steps again.

If repeating these steps does not fix the problem of the moving circle, there may be a problem with the leveling device. If the bubble does not stay centered, you cannot move on with your project because the measurements will be incorrect.

Focusing an Automatic Laser Level

After making sure your instrument is level, the next step is focusing the automatic level.

The first step in this process is to aim your telescope at an object. It should look blurry, but turning the eyepiece either left or right should make the object appear clearer.
After focusing the eyepiece, point the telescope directly at the specific target. While keeping the crosshairs in focus, use the focusing knob to make the specified object appear sharp.

Once the instrument is level, you can move on to establishing a level grade line.

Marking a Reference Line

A level grade line, or reference line, is a sight line that is established through the telescope. It is created at the horizontal crosshair and requires two workers to establish.

The operator looks through the eyepiece of the telescope while an additional worker holds a graduated staff or tape measure vertical at the point under measurement.
The instrument and staff are used to gather or transfer elevations during site surveys and building construction.
Measurement starts from a benchmark with a known height, or an arbitrary point with an assumed height.

Helpful Hints for Automatic Laser Levels

Automatic levels should always be transported inside the case to avoid any damage to the compensator.
Left thumb rule - when adjusting the leveling screws, the bubble will always travel in the same direction as the left thumb.
When the objective lens is not in use, it should be covered with a lens cap to prevent damage to the equipment.
Detachable sunshades are useful in preventing glare and protecting the objective lens.
Make sure you turn both screws at the same time and rate when leveling an automatic level.
Make sure the automatic level is level around all 360 degrees of direction; if this is not done, the measurements will be incorrect.
Make sure the leveling screws are not too tight - over tight screws need to be loosened for the most accurate results.
o If the leveling screws are too tight, it can warp the base plate, causing permanent damage.
DO NOT look at the sun through the telescope.
Keep both of your eyes open when looking through the telescope. This will avoid tiring your eyes and will eliminate squinting.
The image being sighted will be sharpest when it is quartered by the crosshairs; this is the most accurate place on the lens.
The jumping of an image is called parallax. With each movement, adjust the focusing knob until the image stops jumping.