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Flashcards in Sewing and Fabrication Deck (30)
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Seam classes

1. SS-superimposed seam
2. LS- Lap seam
3. BS- binding seam
4. FS- flat seam


6 steps common to all sewing project designs

determine use of project
select fabric/webbing
determine seam requirements
determine closure/connector
create templates


The first resource for fabric design is the.....

aviation life support systems manual


selvage edge

edge of cloth tape, webbing, or fabric and is
woven in such a way as to prevent unraveling.

CGTO PG-85-00-310-A 8-1


warp thread

filler thread

A. threads that run parallel to the selvage edge. The
warp threads form the framework for the material and support most
of the strain during the weaving process.
B.threads that run perpendicular to the warp threads
and selvage edge.

CGTO PG-85-00-310-A 8-1


Bias seam

Seams made on the 45° angle to the filler threads, warp threads and
the selvage edge are said to be made on the bias. Bias construction
will provide more elasticity and strength, and will reduce the effect
tears have on the integrity of the material.

CGTO PG-85-00-310-A 8-1


What are the 4 seam classes

1. Superimposed Seam (SS)
2. Lap Seam (LS)
3. Binding Seam (BS)
4. Flat Seam (FS)

CGTO PG-85-00-310-A 8-6


Superimposed seam types

Two types of Superimposed seams are Ssa-1 and SSc-2

a. The SSa-1 seam is a simplified method of joining two or more
pieces of material. The following example shows a Ssa-1 (one
row of stitching).

b. The SSc-2 seam, as seen below, is formed by superimposing two
plies of material, turning the edges of both plies a specific
distance to the inside, and seaming through both turned edges a
specified distance from the edges.

CGTO PG-85-00-310-A 8-6


Lap seam LSa-2, LSb-2, LSc-2, LSd-2

The lap seam is formed by lapping the plies of material, and seaming
with one or more rows of stitches. The standard seam for connecting fabric panels. There are four types of lap seams.

CGTO PG-85-00-310-A 8-7

a. Overlapping two or more plies of material, and seaming with two
or more rows of stitches as seen below forms the LSa-2.

b. Turning the edge of one ply of the material under itself and
lapping it on top of another ply and seaming with two or more
rows of stitches as seen below forms the LSb-2.

c. Turning the edges of both plies under and lapping them, then
seaming with two rows of stitches as seen below forms the LSc-2.

d. The LSd-2 seam, as seen below (step 2), is formed by placing one
ply on top of another. The top is placed a specified distance from
the edge to be sewed, then seamed with one row of stitches


Binding seam-BSa-2

The BSa-2 binding seam, show below, is formed by folding a binding
strip over the edge of one or more plies of material and seaming the
binding strip to the material with one or more rows of stitches.

CGTO PG-85-00-310-A 8-9


Flat seam- FS

The flat seam is formed by seaming the abutting edges of material
together, as seen below, in such a manner that the stitches extend
across and cover, or tend to cover, the edges of the plies of material

CGTO PG-85-00-310-A 8-9


2 seam classes for stitching

1. Ornamental (OS)
2. Edge Finishing (EF)

CGTO PG-85-00-310-A 8-9


Ornamental stitching

The ornamental stitching, like the OSa-3 below, is formed when a
series of stitches are embodied in material, either in a straight line, a
curve, or following a design for ornamental purposes.

CGTO PG-85-00-310-A 8-11


Edge finishing-EF

The edge finishing stitching is used to prevent the raw edges of the
material from unraveling and can be sewn by one of three ways:
The EFa-1, EFb-2 has the edge of the material folded back one or
more times and then sewn together with one or more stitches.

CGTO PG-85-00-310-A 8-10


Seam specification


Stitch Class- 301
Class of Seam- SS
Type of Class- a
Row of stitches- 1

CGTO PG-85-00-310-A 8-10


Thread type

Normally AST shops will use MIL-T-7870, nylon “Z” twist type
thread for the following reasons:

• The action of a sewing machine will twist the “Z” twist thread
• High strength and controllable elongation
• High abrasion resistance
• Excellent elastic recovery
• Excellent resistance to alkaline and many other chemicals.
• Resistance to attacks by mildew, fungus and other

CGTO PG-85-00-310-A 8-11


Tensile strength

Thread Tensile Strength (Pounds minimum)
A 2.75
AA 3.9
B 5.5
E 8.5
F 11.0
FF 16.0

CGTO PG-85-00-310-A 8-11


Cord strength

size 3- 24
size 6- 50
Type I 100
Type III 550 (300 if gutted)

CGTO PG-85-00-310-A 8-11


Snap fasteners

1. durable dot-used in flight clothing and survival equipment,
2 sizes-regular and small, lift any
direction, most commonly used, regular size wire spring clamp type
2. pull the dot- one direction 3 way locking, used on sph-5cg helmet,
sar warrior, 1 size-regular
3. lift the dot- curtain type, 2 sizes large and small, aircraft
soundproofing, first-aid kits, and protective covers, heavy duty,
only releases from one side

CGTO PG-85-00-310-A 8-18/19


What are the 2 Types of grommets

Brass or aluminum

plain 8 sizes- 00, 0,1,2,3,4,5,6 used for light weight fabric

spur 6 sizes- 0,1,2,3,4,5 used for heavy fabrics where considerable
stress will be applied

CGTO PG-85-00-310-A 8-20


sewing machine oil

type b or d, castor oil base


What is the simplest method of combining 2 threads or lines

Binder knot

CGTO PG-85-00-310-A 8-21


Webbing Strength

Type 1- 500 lb
Type 2- 600 lb
Type 3- 800 lb
Type 4- 1,800 lb
Type 6- 2,500 lb
Type 7- 7,000 lb Harness
Type 10-
Type 13- 7,000 lb Harness webbing

CGTO PG-85-00-310-A 8-12


What is type 1 cord commonly used for

Tie survival items to vests and rafts

CGTO PG-85-00-310-A 8-11


What is type 3 cord commonly used for

Suspend parachute canopy when deployed

CGTO PG-85-00-310-A 8-11


How do you prevent the edge of hook and pile from rolling

A zigzag stitch

CGTO PG 85-00-310-A p. 8-16


Trail line fabrication specs

107 ft polypro
3 in eye splice minimum of 4 tucks
18 in gutted type III for weak link

CGTO PG 85-00-310-A P.8-27


What are the steps in timing a sewing machine

1. Secure power to sewing machine and set to 0 SPI
2. Raise presser foot
3. Ensure needle is in full up position
4. Remove needle and bobbin thread
5. Loosen thumbscrew and remove faceplate
19. Check sewing machine for proper operation

CGTO PG 85-00-310-A p. 8-32


When timing the sewing machine how far do you rotate the balance wheel

Until the needle is in the upstroke

CGTO PG 85-00-310 A p. 8-33


How far to turn the set screws on sewing machine safety clutch when timing, if necessary?

½ turn

CGTO PG 85-00-310-A p.8-34