So, I thought I’d start a feature here on AA where I answer questions submitted by you, the Readers.

I get some questions via email that you would normally never see, but the same questions seem to come up time and time again. In the hopes of addressing some of them in “public”, I present to you:

Reader Mail.

Matt wrote me about his model 127, with a replacement shuttle:

… the stitches don’t always stay tight and straight as I think it should. Maybe it’s the needle size and tension isn’t adjusted right?

How can I properly adjust the tension and what needle size does it need?

Hey Matt,

I’m not sure what you mean by the stitches not staying tight.  If you mean that if you separate the two pieces of fabric and they gap, that’s a tension problem.

If they’re not straight, it can be a couple of things – tension, feed dogs are crooked (see if they’re mounted straight – sometimes  there’s a little room where they mount to wiggle one way or the other, feed dogs are worn more on one side than the other (sort of like a Styrofoam cup, it will always roll in a circle…) or the presser foot is similarly worn.

This all assumes you can sew a straighter line than I can and you’re not guiding it off course.  🙂

Tension is adjusted in two ways.

For the upper thread, that’s the portion with the dial that’s to the left and lower than the “shovel” shaped plate on the front.  Righty Tighty, Lefty Loosey.

Make sure that the thread is all the way into that tensioner too.  Just laying inside won’t cut it.

Make small adjustments and test again.

If the lower tension needs to be adjusted, it’s that screw on the shuttle that hold the spring.  Again Righty Tighty, Lefty Loosey.

Adjust this only in 1/8 turn increments and test again.  This should be a last resort.

If on “Average” material, you can’t adjust the upper tension to make a nice stitch within about the “middle” of the number of turns available on the upper tensioner, then you need to look at the bobbin tension and adjust it until the upper tension does work in the range you’d expect.

Upper and lower tension is affected by the material you’re sewing too, that’s why there’s adjustment.

Testing

To figure out which tension is too tight, sew a line, about 6 or more inches long, then grasp the fabric at each end of the line you just sewed, and give it a sharp “snap” (yank it apart)  The thread that breaks is the one that’s too tight.  If neither breaks, try adjusting the top tension tighter.

Threading:

The other thing that will affect tension is if the machine is threaded wrong.  Missing one guide will make a big difference.

Check that it’s threaded according to your manual too.

Needles:

As for needles, any 15×1 needle should be OK.

Best to stay with the 80/12 – 110/18 range, and the most common is a 90/14 for size.  Needle size is dictated by the fabric you’re sewing and the thickness of your thread (which should be matched to your fabric).

Skipped stitches:

If it starts skipping stitches, then make sure that the needle is in flat to the right and threads from the left.

If all else fails:

If after you’ve looked at all of this, it’s still stitching funny, it may need to be serviced.