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Now as the title suggested we are going to be targeting the older style sewing machines with the vibrating shuttle. I say older style because there were still this type of machines in use with electric motors up into the 1960's. Some of what we will discuss can be directly translated or transferred to the more typical round bobbin style cases and tension assemblies.
|Left Side - Singer 27 Shuttle Upper Right - New Home Shuttle Lower Right - National Shuttle|
Now the shuttle tension spring was so tight that it broke the bottom thread after about 6 stitches. I can clearly see that the bobbin thread was cut off at the leaf spring. I am finally starting to analyze the events and I realize all the problems are revolving around the bobbin and bobbin tension leaf spring. I removed the shuttle and dropped the bobbin out of it. The thread was still caught up under the spring but it wasn't all frazzled and frayed like a cracked spring or worn out spring can do. When I removed the adjustment screw (very tiny) to allow me to remove the leaf spring I began to see what was causing the issue. When I gingerly removed the spring the space between the spring and the shuttle was packed full of 100+ years of old oil,thread, and lint. The old oil had collected the lint and dirt as it hardened into what is best described as varnish. The thread had worn grooves into the surface of the hardened varnish and as a result eliminated the ability to control the bobbin tension. The spring was being held off of the thread by the old varnish. From the outside it was impossible to see but once the hardened oil was cleaned off the shuttle and the spring.The spring had to be gently nudged back into its original shape. Suddenly all my bottom tension issues were gone. Once again my sewing machine was happily clicking out perfect stitches. And we buried one more pesky gremlin. If you find yourself having tension issues maybe my experiences will lend you a hand. If this doesn't help but the symptom is very similar I might also suggest looking inside the shuttle with the bobbin removed. I do on occasion find thread and dirty gunk in the shuttle interfering with the bobbins ability to unwind and feed through the shuttle.
Check out Paul's other posts to learn more about caring for your vintage sewing machines. Also be sure to check out all our vintage sewing machine posts.
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