FED-STD-228A
Method 1171.1
18 April 2014
THICKNESS, BEDDING; MICROMETER CALIPER
1. SCOPE
1.1 This method is intended for use in determining the thickness of bedding of armored cable. It is
recommended for use when the wire or cable has an over-all diameter of less than 1 inch.
2. SPECIMEN
2.1 The specimen should be a piece of the inspection unit at least 6 inches in length from which any
covering over the bedding has been removed.
3. APPARATUS AND REAGENTS
3.1 The apparatus and reagents shall be as follows:
3.1.1 Micrometer caliper graduated to read in mils of 0.0001 inch and having flat surfaces on both anvil
and end of spindle, each approximately 0.25 inch in diameter. The surfaces of anvil and spindle shall be
parallel to within 0.0001 inch.
3.1.2 Wiping cloth.
3.1.3 Alcohol or other suitable solvent.
4. PROCEDURE
4.1 The specimen shall be free from mechanical damage. The micrometer caliper shall be applied
directly over the bedding so that the specimen can just be moved between the anvil and the spindle
without distortion of the bedding. The diameter over the bedding shall be read from the micrometer
caliper scale and the value recorded as D1.
4.2 The bedding shall be removed from the specimen and any fibers, saturants or extraneous materials
removed from the surface of the core "assembly under the bedding" by means of the cloth and solvent.
The diameter over the core shall be measured in the same manner as described for diameter over the
bedding and the value recorded as D2. The diameter over the bedding and over the core shall be
determined as nearly as practicable at the same point.
5. RESULTS
5.1 Calculation. The thickness of the bedding at any point shall be calculated as follows:
Thickness, inch=D1-D2
2
where:
D1=the diameter over the bedding at the point measured, inches.
D2=the diameter over the core at the point measured, inches.
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