05.04.2013

Next time the overlock seams won’t tear…

Eit kortfatta samandrag på NORSK kan du finne på Sykroken.net her.

Have you ever sewn a garment in single jersey fabric and experienced that the seams tore when in use? I have! My youngest daughter has a bodysuit with lots of cute little holes along the seams. Here is a photo of a sleeve:

Overlock serger settings to prevent that the seam tears when sewing in thin single jersey fabrics

What has happened here? Answer is: I have forgotten to lower the needle thread tension compared to what I use daily. Keywords are: Thin fabric. And that it is (very) elastic. I’ll explain:

When the fabric is being stretched, the way the overlock seam copes with it, is that it has extra length of thread to offer. The looper threads goes kind of zigzag and are a lot longer than the seam. Plenty of thread! But what about the needle threads? They’re not that long. They run straight forward on top of the fabric, just to dive through the fabric now and then, giving the looper thread on the bottom a little kiss before they go up again.   I’ll go get my electronic pen and paper:

Imagine the cross section of two layers of THIN fabric (black) along the seam. Only one of the two needle threads is shown (blue):

thin fabric

The only extra length this thread has to offer when stretching the fabric, is what goes through the fabric. And as the fabric is thin, the extra available length is short.

Let’s take a look at the seam in thicker knit fabrics, like velour:

Overlock serger settings to prevent that the seam tears when sewing in thin single jersey fabrics

That’s better! The needle thread is longer! There is another thing; thicker knits are often less elastic than thinner jersey knits, and doesn’t demand that elastic seam.)

WHAT TO DO?

Loosen the needle thread tension a little bit (i.e. turn to a lower number on the wheel), and by that, the overlock machine gives the seam some more thread!

giving the needle thread more length to prevent it from tearing when fabric is streatched, when sewing in thin single jersey fabrics

Voila! Longer thread!

Another thing you can do, is to make sure that the stitch length is not too long, and perhaps lower it a little bit. This follows from the same principle; lowering the stitch length gives more stitches, and more thread going up and down through the fabric, helping to lengthen the seam when fabric is stretched.

Principle of getting more elastic overlock serger seams and coverstitch seams whem sewing in thin elastic fabrics or thick very elastic fabrics

These principles also applies to sewing with COVERSTITCH MACHINE in thin elastic fabrics or thick very elastic fabrics.

 

Another thing I’ve experienced, is holes in armholes and crotch (i skrittet) in a jersey garment, shown here (only armhole holes shown):

How to prevent your overlock serger seams from loosen in the armholes and crotch when you sew in light weight/ thin single jersey fabrics

The needle thread tension has been too high, and when the fabric was stretched when putting on the garment, the needle  threads were pulled out from the  crossover seam.

This is basically the same phenomenon as above, but with a slight different mechanism. The vertically-running seams on the picture are sealed by the horisontally-running seam. But, the seam wasn’t elastic enough, needle thread tension too high. Then, when the fabric was being stretched, instead of tearing the needle threads, they were pulled out of the crossing seam. When the needle threads are gone, there is nothing to hold the looper threads in place, hence, the whole seam loosened.

*Phew* Writing english is quite demanding! This post was my friday evening… But it’s fun too, writing english again, after many years almost only reading english ( and listening to, on the TV) My husband is sitting next to me in the sofa, playing Civ 4, watching TV and helping me out when I was needing english words. Thank you, My Love!

3 kommentarer:

  1. Kom over dette innlegget fra sykdommen, oj, sykroken skulle det stå. Autokorrekt asså! :) Bra innlegg. Det jeg egentlig ser etter er andres erfaringer med isoli stoff og overlock. For når jeg syr bukser i isoli blir de veldig ofte dårlige i sømmene som strekkes. Altså bak i rompa, foran og i skrittet. I sidene, både inni og utenpå har jeg ikke det problemet. Men de rakner veldig fort i de andre sømmene. Har du noen som helst erfaring med dette? Og eventuelt tips? Jeg vet jo ikke om det er stoffet som er dårlig eller maskina eller hva som gjør det. Opplever det bare med isoli. Du kommer jo ofte med tips og gode innlegg, og det liker en litt mindre erfaren "syerske". Ha en fin kveld :)

    SvarSlett
    Svar
    1. Kjedeleg når plagga raknar! Eg har ikkje sydd så mykje i isoli, eigentleg. Men det høyrest eigentleg ut som liknande problem som eg har hatt i jersey. Så eg ville prøvd å skru ned trådspenninga på det fyrste og andre trådspenningshjulet frå venstre. På mi maskin har eg spenninga på 3-4-4-4 til vanleg på elastiske stoff, og når det er ekstra tøyeleg og tynt stoff skrur eg ned til ca. 2 1/3 - 3 - 4- 4. Eventuelt skru bittelitt ned på stinglengda i tillegg. Kanskje kunne du sy nokre prøvelappar med liknande kurve som i skrittet på buksa og teste om maskina reagerer ulikt på ulike diff-innstillingar?

      Om ingenting hjelper, er siste tips å sy skrittsaumen to gonger for å gjere den sterkare...

      Om problemet skulle vere at sjølve stoffet revnar, ikkje saumen ryk, bør du sjekke at du brukar nåler som er berekna for stretch-stoff.

      Håpar det ordnar seg!

      Slett
  2. Tusen takk for kjempe gode tips. Jeg skal prøve meg litt frem her, med trådspenning og stinglengder, og se om jeg ikke kan få det til å bli bedre. Den siste buksa jeg har sydd har allerede begynt å rakne litt.. Så da må mi få fiksa det, så neste bukse holder lengre. Igjen, tusen takk, setter stor pris på gode råd :) God uke til du!

    SvarSlett

-Kjempekoseleg om du har lyst til å seie hei!
-You're welcome to place comments in english!
-Svenska kommentarer gjör mig glad, danske kommentarer er sjov!
-Ich verstähe auch ein bischen deutsch, doch ist englisch mehr sicher, you're welcome anyway!

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