Sewing and Fabrication Flashcards
6 steps common to all sewing project designs
determine use of project select fabric/webbing determine seam requirements determine closure/connector measure create templates
Seam classes
- SS-superimposed seam
- LS- Lap seam
- BS- binding seam
- FS- flat seam
The first resource for fabric design is the…..
aviation life support systems manual
COMDTINST M13520.1
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
- Superimposed Seam (SS)
- Lap Seam (LS)
- Binding Seam (BS)
- Flat Seam (FS)
CGTO PG-85-00-310-A 8-6
Superimposed seam types
SS
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
joined.
CGTO PG-85-00-310-A 8-9
2 seam classes for stitching
- Ornamental (OS)
- Edge Finishing (EF)
CGTO PG-85-00-310-A 8-9
Ornamental stitching
OS
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
301-SSa-1
301-SSa-1 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
tighter.
• 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
microorganisms.
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
- 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 - pull the dot- one direction 3 way locking, used on sph-5cg helmet,
sar warrior, 1 size-regular - 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
- Secure power to sewing machine and set to 0 SPI
- Raise presser foot
- Ensure needle is in full up position
- Remove needle and bobbin thread
- Loosen thumbscrew and remove faceplate
………….. - 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
