MIL-DTL-9401C
stitching of at least two consecutive vent lines. The material for the vent reinforcement shall be
one continuous piece.
3.3.5.1 Vent lines. Unless otherwise specified in the TDP, the vent lines shall be of the same
material as the suspension lines.
3.3.6 Stitching. Stitching shall conform to ASTM D 6193. Unless otherwise specified, the
stitch type shall be 301 of ASTM D 6193. The number of stitches per inch shall be as specified
in table I.
Table I. Thread size and stitches per inch
Straight stitching
Zigzag stitching
Thread Size
Type 301
Type 401
Type 304
Type 308
Single throw
Double throw
E
1/
7 to 11
1/
7 to 11
2/ 12 to 16
2/
8 to 12
F
1/
7 to 11
2/ 12 to 14
2/
7 to 10
FF
1/
6 to 9
7 to 11
2/ 12 to 14
2/
7 to 10
3-cord
5 to 8
-
2/
4 to 6
5-cord
4 to 6
-
2/
3 to 5
6-cord
4 to 6
-
2/
3 to 5
1/ Stitches not exceeding 16 stitches per inch will be acceptable for a length not exceeding 2
inches in any one place with a minimum distance between locations of 12 inches. More than 16
stitches per inch will be cause for rejection. Where abrupt changes in material thickness occur, a
variation of ± 2 stitches per inch beyond the specified number for a distance not exceeding ¾
inch shall be acceptable.
2/ When the material thickness is more than doubled, the width of the zigzag stitching may vary
± 50 percent or the number of stitches may vary + 2 stitches per inch beyond the number
specified for a distance not exceeding ¾ inch.
3.3.6.1 Tension. The tension of the bobbin and the needle threads shall be equal so that the
thread locks will lie as close as possible in the center of the layers below the surface. Needles of
multiple- needle machines shall be adjusted to provide the same tension from each needle insofar
as practicable.
3.3.6.2 Straight stitching. Except for stitching made with stitch type 401, straight stitching shall
be backstitched not less than ½ inch, unless turned under in a hem or held down by other
stitching. Unless otherwise specified in the detail specification, the outside row of stitching
made with a multiple-needle machine shall be 1/8 ± 1/16 inch from the edge of the seam or the
material. Multiple rows of straight stitching, when specified in the detail specification, shall be
distributed equally across the seam when a single-needle machine is used. Stitching made with
stitch type 401 shall be properly and carefully locked where the stitching ends.
4
For Parts Inquires call Parts Hangar, Inc (727) 493-0744
© Copyright 2015 Integrated Publishing, Inc.
A Service Disabled Veteran Owned Small Business