When Singer introduced the 500 Slant-o-Matic Rocketeer, it featured a new threading step that Singer called a "thread control."
So what is it? What does it do?
Singer 500A "Thread Control"
"The automatic thread control, located above the tension, ensures a smooth flow of thread from spool to needle. This device eliminates spool weight and drag by pulling off a measured amount of thread before it passes through the tension discs."
So there you have it straight from the horse's mouth! Thread control is clearly the greatest invention since sliced bread!
So this thread control was a giant leap forward in sewing machine technology, right?
Ummm...not so much, because there's no noticeable difference in stitch quality when comparing the 401A and 500A. Singer apparently came to the same conclusion, because "thread control" disappeared after the early 1960's. It does appear on the German-built 401 and 411 models but then Singer went on to produce the "Touch & Sew" series with a horizontal spool spindle which eliminated spool drag completely.
Alternative threading for Singer 500A
Thread control was so underwhelming that Singer went so far as to distribute an alternate threading guide for the 500 that bypasses the thread control. This threading chart was included in the "Knit Kit" that Singer produced for sewing double-knit fabrics.
I've experimented with both threading methods and I prefer to bypass the thread control because it's faster. And the stitches look just as good without it.
So there you have it...thread control. No, it didn't revolutionize sewing machine technology, but it's still a cool feature that sets the Rocketeer apart.
OldSewinGear is the collaborative effort of retired repairman Gary and daughter Barbara. We love old sewing gear and enjoy sharing what we've learned in our vintage sewing machine adventures. We are located in Roseburg, Oregon.