A Complete Course in Dressmaking/Lesson 1/Regulating the tensions
REGULATING THE TENSIONS
On a lock stitch sewing machine, if the tensions are properly regulated, the thread links in the exact center of the fabric. The stitch on the right and wrong side of the goods will look identical. See Fig. 27.
If the tension on the upper thread is too tight, or the bobbin thread too loose, the upper thread will lie on the surface of the goods. See Fig. 28. The thread is apt to catch and pucker.
On the other hand, where the bobbin thread is tight or the upper thread too loose, the reverse happens, and the thread on the under side (next to the feed) will appear straight on the surface. See Fig. 29. This does not make a pretty stitching, and the thread is apt to pucker. However, it makes a stitching that is easy to rip. Try it sometime, when you are just testing the fit of a garment.
Once the bobbin tension has been properly adjusted, it will need but little change. Usually the tension can be suited to different materials by changing the needle tension.
Always test the tension and length of stitch before starting to stitch the garment.
The Pressure on the Material.—Do you ever regulate the pressure of your sewing machine foot? There should be just sufficient pressure to prevent the goods from raising with the needle. On very sheer or flimsy goods, increase the pressure. On extremely thick goods, lessen it.
If your machine is running hard, look at the presser foot. There may be too much pressure.
Turning a Corner.—Run the stitching to the exact corner. Stop the machine with the needle in the goods. Raise the presser foot, turn the material so that it is in the correct position for the next stitching, lower the presser foot, and stitch.