Bonding with Singer 15K80

One day early last autumn I got out the Singer 15K80 to do a quick job sewing some furnishing weight chintz.  The cotton thread I used was pretty old, it came from a wooden spool that arrived with the machine, and thicker than the usual polyester I buy.  I really struggled to get the '15' to produce anything like the kind of stitched vintage Singers usually make.  The stitches were loose at the beginning of the seams then would improve - a bit.  The best I could do was to back the top tension right off to get the top and bottom threads balanced but then the overall impression that the stitches gave was somehow sloppy.  It was hard to distinguish neat individual stitches making up the line.  Hard to explain and I didn't take any pictures at the time.

The poor quality of these stitches in spite of many rethreadings and much adjustment of the top tension were rapidly making me fall out of love with this machine.  I have often thought of the 15 as a bit of an odd ball in the Singer stable with its odd man out bobbin and bobbin case.  Three of my machines take class 66 bobbins so why did I even need the hassle of yet another type of bobbin?  For a few minutes I even considered throwing in my lot with the 15k80 and selling it.

Instead I did some thinking and research and came to the conclusion that my problems were, more than likely, related to bottom tension.

It took me quite some time before I could find some really useful practical advice on how to set up from scratch a class 15 bobbin case.  One method I watched on You Tube relied on buying a new bobbin case set up at the factory and then pulling yards and yards of thread through the tension until you develop a 'feel' for what should be the right tension - er there must be a more scientific way than that…!

And of course there is.  A big thank you to Charles Day who submitted these instructions to singersewinginfo.co.uk helping people like me (and you?) to improve the performance of their vintage Singers.

Step 1: weigh out just under one and a half ounces of sugar

Step 2:  put the sugar inside a tiny ziplock back.  The one I used came with spare buttons for one of The Much Beloved's shirts and was just the right size.

Step 3:  Tie the bobbin thread to the bag of sugar.  My bag happened to have a small hole punched in it for just that job.

Step 4:  Load the bobbin into the bobbin case.  The first time I did this I discovered that the tension on this bobbin case was so light that the bag of sugar quickly dropped to the floor sending the bobbin spinning in its case.  Ah-Ha!  So there's the cause of my sloppy stitches and inconsistent tension.

Step 5:  Using the small screwdriver; little by little I tweaked up the tension until it was sufficient to just hold the bag swinging in mid air.  A sharp upward motion should allow one to two inches of thread to be pulled off the bobbin before it comes to rest in mid air again.

Step 6:  Load the bobbin and case into the machine; check the thread path of the top thread;  adjust top tension to balance the top and bottom threads; admire the beautiful even straight stitches produced by class 15 Singers.  I think I may have just found a new favourite.