How Sewing Machines Work

Página 1

The Sewing Machine By Completion Know:

Know the Difference between the Straight Stitch and Zig Zag Stitch sewing machine

Know Machine parts and attachment functions

Define upper and lower threading procedures

Make a machine stitch

the affect of thread tensions on a stitch

Maintenance for the machine

Early Machines The first sewing machines made weak stitches unroll Elias Howe invented the lock stitch machine that use 2 threads, further improved by Singer and Wilson.

Mostly Zig Zag machines are sold but some straight are as well.

STRAIGHT STITCH MACHINES-need attachments for different needle work.

ZIG ZAG MACHINES-can do different stitching types because the needle can move in a zig zag. The ZIG ZAG AUTOMATIC can do more stitches than the SEMIAUTOMATIC. Some machines have two speeds.

OVERLOCK or SERGER MACHINES both trim and finish a hem in one go.

Ergonomics

The workplace affects the worker and the work.

The Table ideal is 27" high and the surface 3' x 6' and 3" high.

PRESSING needs an iron and a board near the workspace.

STORAGE needs shelves, drawers, boxes with covers for garments safety. label clearly for clean organization.

CHAIR is comfortable with feet on floor.

How Machines work

UPPER THREADING- thread goes from SPOOL to THREAD GUIDE or ESCAPEMENT which buts some drag on thread

TENSION ASSEMBLY- puts a limited amount or tension of thread in GRAM WIEGHTS to make solid stitches.

THREAD TENSION is made by king through the guts of the machine

UPTAKE or TAKE IN LEVER measure upper thread and puts up bobbin thread. *The final escapement is important to keep the thread from flopping about.

LOWER THREADING- Located in the SHUTTLE. There are two systems, CENTRAL BOBIN or OSCILATITING HOOK whose racer goes is half circles and ROTARY HOOK whose racer goes in full circles.

BOBBIN CASING goes over the bobbin inside the BOBBIN CASE.

Sewing Machine Attachments

CREATING A STITCH

FEED DOGS draw the fabric

After the dogs drop below the surface the needle pierces.

Needle removes itself, leaving a loop.

The RACES hook picks up the loop and pull it over the bobbin case.

The loop slide around the bobbin thread as the dogs pull more fabric.

When the needle is high more fabric is drawn and the stitch is locked tight.

*For the machine to be in time the sequence must be perfect.

Timing

The timing for each machine is individual, its soul's song. Never try to time the machine, allow a technician to do that. Problems rarely are with the timing of the machine but the within the choice of tension or similar wrongdoings.

Tensions Fabric and tension adjusters change the tension on a thread. it can be changed with upper adjuster or the tension spring screw in the removable bobbin casing.

Wh the needle enters the fabric it can take its thread from the spool to make a good stitch or it can take it from the previous thread making a puckering. Seam puckering happens when tension is incorrect for lighter fabrics, heavier fabrics don't have this issue usually. The Objective is to have equal tension not equal pull, Tension can be equalized by decreasing the upper tension assembly and increasing the lower tension.

Sewing machine care CLEANING

If machine is used daily clean weekly

Lint buildup combined with oil packs like cement for clean regally with tools such as a computer vacuum.

Clean foot digs by removing entire bobbin case, brushing inside with brush and rub down innards with rubbing alcohol.

use shishkabab stitch to clean dog feet and nothing stronger.

Rub Racer regularly as it moves the most. Use sewing machine oil and nothing else as it is thinner and not globby. If I hear a clatter in the shuttle, oil the racer.

LUBRICATION

Some machine self lubricate and have bearings for this.

Put machine at widest zigzag and longest stitch to see which parts move and therefore need oil. Oil when uptake is at its highest.

After oiling run a scrap piece of fabric through the machine to clean up the oil then rub down entire machine with rubbing alcohol to remove dirt and oil.

REMOVING BURRS

Burrs are scratches of metal against metal usually caused by a broken needle in the shuttle. Burrs can cause thread breaking.

Fix with CROCUS CLOTH which is impregnated with jewelers rouge.

causes and prevention of breakdown NEEDLES BREAKING

check settings before threading and using

secure all attchments

use correct needle for thread and fabric

lets feed carry the work

MACHINE WORKING HEAVILY

dust or lint clogs

insufficient oil

thread caught in shuttle or bobbin

UPPER THREAD BREAKAGE

improper threading

tight tension

thread too course

presser foot not adjusted

poo quality thread.

LOWER THREAD BREAKAGE

bad bobbin threading

tight tension

Bobbin would too tight or full

SKIPPING STITCHES

Needle not set right

Needle blunt, bent, or broke

Needle too fine for thread

dust in working parts