Sewing Machine

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Most people have heard of a sewing machine, and probably seen them.  These are the most common textile power tool to be found in homes. They generally are used with a single needle and two threads, one on the bottom of the seam that comes from the bobbin and one on the top that is threaded through the machine and ultimately into the needle. These two thread seams are called interlock seams. It is possible to use double needles in most modern sewing machines, but they will only use a single bobbin thread.

Interlock seams are great for firm woven fabrics, like jeans and most dress shirts.  They are not so good for fabrics that are stretchy or have a lot of drape.

Sewing machines come in many varieties. Most will sew in a straight line or zigzag, and go forwards or backwards. When starting a seam it’s common practice to sew forwards for 3-4 stitches, then backwards the same, then continue forwards.  This creates a tack at the beginning of a seam, making it harder to unravel. There are a few machines that will create a tack automatically when you start sewing a new seam.

Some sewing machines have fancy stitches for embellishment and darning, can create seams suitable for stretch fabrics, and perhaps even embroider complex patterns automatically.  Most sewing machines have a built-in bobbin winder for filling bobbins with thread from spools, so the bobbin and top threads match.

A good test for having proper tension is to sew a seam on two layers of fabric with different colored threads on top and bottom, and then gently tug the seam open to see the threads. If the fabric is puckering and can’t be spread at all then both the needle and bobbin tension are too tight. If you can see only one color thread when you spread the fabrics apart, that thread doesn’t have as much tension as the other, and so you should either tighten it or loosen the other one.


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