Saturday, July 14, 2012

Tension Snags Part 2

In the previous post, we discovered that equalizing the drag  of the upper and lower thread systems produced balanced tensions. Unless the  pull equalized; tensions are faulty.

Thread systems on a sewing machine are much like a tug of war contest. The system that pulls the hardest gets the excess threads. If the top pulls harder than the bobbin, thread will pucker on top of the fabric. If the bobbin pulls harder, threads will collect under the fabric.

Problems may be from improper threading, improper adjustments, or snags in the thread line.

If you have problems with the tension on your sewing machine, first identify which thread system is pulling harder.  Is it the upper thread or lower thread.  Again this is a matter of looking for the excess threads on your test seam.  If the excess appears on the top, the pull up is greater than the pull down.  If excess appears under the fabric or on the bottowm, the pull down is greater than the pull up. 

Sewing machine repair is often the result of the user making a mistake.  It is important for ever user to learn to sew and master these basic fixes.  Understanding how to sew will reduce frustration and insure a technician will not be needed to repair sewing machines for you at every turn.

Check or rethread upper thread and lower thread. Test the upper tension at the needle and the bobbin tension at the carrier. Sew a test seam. Check and adjust. If thread collect under the fabric, tighten upper tension. If thread puckers on top of the fabric, loosen the upper tension.

If the problem is with improper threading, careful rethreading should solve the problem.  Rethreading upper thread and bobbin thread can make a big difference. 

If the problem is with improper adjustment, adjusting the upper tension will help.  However, sometimes the bobbin tension gets out of whack.  This is especially true if you change the size of thead in your bobbin.  Going from a larger thread to a smaller thread will cause a decrease in bobbin tension.  Going from smaller to larger thread will causse increased tension.  To adjust this, simply turn the tension adjusting screw to tighen or loosen.

The third problem source is a bit more troublesome.  Snags can distort tensions.  Often a slight burr or rough spot will intermittendly grab the thread increasing the tension, only to release it and leave a drop in tension balance.  To fix this problem, you must find the snags and eliminate them. 

Excess lint in the tension mechanisma is common.  Clean out the tension assemblies for upper and lower tensions. 

Burrs on the point of the hook are also common and must be smoothed. 

Before you begin sewing on your project, it is a good idea to test your tensions by performing a quick sewing test on test cloth or scrap fabric. Simply sew a four to five inch seam using a medium straight stitch and a medium zig zag stitch. Adjust the tensions until they properly balance.

You may see   irregularities on one side of a zig zag stitch and not on the other. Test and Set  until it looks the best you can make it. Some machines have design issues that make a precise  zig zag stitch almost impossible. Test  using a medium stitch width and length setting on the zig zag for better  results. If you want a perfect zig zag stitch on one of these older machines, think about  getting a newer  machine.

If adjusting the tension dials fails to balance the tensions, look for lint or dirt collected in the bobbin tension or upper tension assembly. Clean these out regularly. Lint can alter tensions and cause poor stitch quality. Also look for anything that might snag the thread. Burrs on the point of the needle or hook are common. Eliminate anything that might snag.

When you properly adjust tensions, sewing is fun.