Leveling for Analytical Tests

TM 38-260

7-5. Leveling for Analytical Tests

a. The importance of leveling machine tools for analytical tests cannot be over-emphasized. This is particularly

true of items such as lathes, grinders, and planers, having long beds which may develop a twist as a result of improper

leveling. This cannot be remedied by merely raising portions of the bed to conform with the required inspection

standards. Irreparable damage may occur from sudden changes to correct misalignment which has been caused by

gradual settling. Machines must be properly leveled. It must be done gradually and the machines allowed to settle or

normalize during the process. Where deformation is present due to the machine's being used when not level, correction

should be made gradually in increments of 0.010 inch (.025mm) to 0.015 inch (0.038mm) with a reasonable length of

time allowed for normalizing. Where conditions permit, slight adjustments may be made daily until the time when

precision leveling to the desired degree is accomplished.

b. Machines which are in noncontrolled humidity storage or which have been in transit should be allowed to reach

room temperature before any leveling is attempted. This may require as much as several days for a large machine. The

average machine tool in the small and medium size groups will present little difficulty in leveling within the required

tolerances. Machines leveled to the proper degree of accuracy on a firm foundation will permit indicator readings of a

conclusive nature. Certain machines with very long beds may require leveling by means other than the spirit level.

State-of-the-art technology for leveling equipment may include the use of a laser which can be accurate to millionths of

an inch. This may be necessary for equipment which must be capable of producing extremely close tolerances.

Equipment should be leveled with sufficient accuracy to meet the tolerances of the machine. In many instances, a

precision level

At will provide sufficient accuracy.

c. The statements in a and b above are for the purpose of stressing the importance of leveling. While this is a

primary consideration, it is not necessarily the first step in performing the analytical test. Chronological sequence may be

as follows:

(1) Clean.

(2) Level.

(3) Check end play.

(4) Check rotary path.

(5) Check parallelism.

(6) Check perpendicularity.

(7) Check angular relationship.

(8) Check concentricity.

7-8