The critical alignments for a sawmill is to ensure that the log carriage is traveling straight, is perpendicular to the blade, where the mill is cutting specific board lengths, and parallel to the blade, where the mill is cutting/shaping board lumber.

Checking Log Carriage Straightness

The L-742 or L-732 is positioned at the end of the mill and is leveled, using the built-in level vials. Next, a target is mounted on the carriage horizontally and adjusted so that it detects the laser beam. Two reference points are chosen (2 reference points are needed for measuring straightness, one near the laser and one as far as possible at the other end of travel). The target is then zeroed at the closest reference point and the carriage is moved to the other end of its travel to the farthest reference point. Then, using the yaw adjustment on the laser base, the laser is adjusted so the far position and the near position both read zero. This means the laser is now parallel to the reference points.

To measure the straightness, the carriage is moved at user-specified intervals and any deviations from the reference points are noted. If the target is mounted such that its top is to the left of the laser plane, then a "+" reading means the measured point is to the "left" of the reference points and a "-" reading means the point is to the right of the reference points. Since the readings are live, the target can be used as a digital indicator and the point can be brought into alignment by adjusting it until the reading is zero.

Checking Saw-Blade Squareness or Parallelism

When checking the squareness of the blade to the travel of the log carriage, the laser must be placed within 12 to 18 inches (305 mm to 483 mm) of the blade. After following the procedure above to get the first laser plane parallel to the reference points of the log carriage, the second laser plane is, by definition, square to the travel of the machine. This means that to check squareness, it is as simple as taking a target and mounting it horizontally on the part of the blade closest to the laser and positioning it such that it detects the laser beam. Then zero the target and move it to the blade's farthest point from the laser. Any deviation from zero is then a measure of squareness errors of the blade to the travel of the carriage. And since the readings are live the blade can be adjusted so that the reading is zero, which means it is perpendicular to the travel of the carriage.

To check the parallelism of saw blades that cut parallel to the carriage travel, again the setup procedure is followed for "straightness" from above. Once the laser has been "bucked in" to the travel, it is an easy check to measure the parallelism of the blade. First, the target is placed on the blade at the closest point to the laser and zeroed. Next, it is moved to the farthest point on the blade from the laser. Any deviation from zero is a measure of the parallelism errors of the blade to the carriage travel.

Finally, if the laser has been leveled, then by design the laser planes are plumb to earth, which means the plumbness of the blade to the carriage surface can easily be checked by following a similar procedure as outlined above.

A word of caution: If the machine is going to be aligned, rather than just measured, then it is important to put the laser on an instrument stand. If the laser is on the machine bed or table, adjusting it will most likely move the laser and thus affect the setup.