Equipment Used for Inspection and Test

TM 38-260

(9) Check indexing.

(10) Summarize results of test.

7-6. Equipment Used for Inspection and Test

a. Most manufacturing plants or installations have available all the equipment necessary for properly testing of

the alignment and accuracy of machine tools. Generally, this equipment consists of items such as precision levels,

straight edges, parallel squares, test arbors, and indicators.

b. Testing equipment shall be of unquestionable quality both from an engineering and accuracy standpoint.

Makeshift testing equipment crudely made from improper designs or materials cannot be depended upon for accurate

results. Test results can be no more accurate than the accuracy of the instruments used. Information pertinent to the

quality and use of these tools and instruments is listed in (1) through (4) below.

(1) Dial indicators. Dial indicators are commonly used to determine parallel and square alignments of machine

units and to check run-out of spindles. The dials should be sufficiently large so that the graduations are clearly visible.

For checking square and parallel alignment of machine tools, dial indicators with 0.001 (0.01 mm) inch graduations are

normally satisfactory. However, indicators used in checking run-out of spindles, spindle tapers, and spindle sleeve nose

should have 0.001 inch (0.01m) or 0.0005 inch (0.002mm) graduations. In all cases, dial indicators shall be securely

clamped to substantial holders or posts to avoid vibration and deflection. When testing with dial indicators, the initial

pressure applied shall not cause a reading of less than 0.005 (0.01mm) inch.

(2) Precision levels. Only precision type levels should be used. These levels should have a sensitivity of 0.0005

of an inch or 0.0127 of a millimeter for each division. Levels should be placed only on clean scraped, ground, or finished,

planed surfaces. To check the traverse levels of surfaces with two or more ways, place the level on top of parallels which

span the way surface.

(3) Angle plates, master squares, straight edges, and parallels. This type of instrument must be free of nicks and

burrs which can cause inaccurate readings. Surfaces should be machined and scraped flat and parallel to within 0.00025

of an inch or 0.00635mm.

(4) Test arbors. Test arbors shall be made of hardened steel with the cylindrical portion and the taper shank

accurately ground. The concentricity diameters shall not vary more than 0.0002 inch (0.005mm) in diameter for the entire

length. Countersink centers shall be provided in both ends so that arbors may be used between centers for true running.

Test arbors shall be clean and free from burrs and defects.

7-9