Identifying Bobbin Case Springs
Identifying bobbin case springs.
Questions routinely arise around bobbin case springs, also called anti-backlash springs or bobbin case brake springs. I have covered earlier how to tell if one needs to be replaced and how to do it: https://www.facebook.com/LongarmTech/posts/2468903670043385 https://www.facebook.com/LongarmTech/videos/482864352420222 https://www.facebook.com/LongarmTech/posts/2486187801648305
There are many types of rotary hook assemblies but the two most prevalent are the Koban assemblies made by the Koban Sabun Industrial Corporation from Japan, and the Cerliani assemblies made by the Cerliani company from Italy.
If you have a bad spring and need to replace it but don't know which one you need, the pictures below should help.
In picture 1 a Koban case spring is on the left and a Cerliani case spring is on the right. We will cover in more depth shortly, but you can clearly see significant differences even though they are both for Class M bobbins.
In picture 2 a spring and bobbin case are oriented the way they would be if mounted on the machine - with the arrow pointing to the top of the assembly which we will designate as 12:00 as if looking at an analog clock. Note the spring is a Koban and the case is a Cerliani.
In picture 3 we have close-up pictures of the Koban spring and use a vernier caliper to measure the locking tabs. In the case of the Koban spring there are two tabs each ~3.3mm wide. One of the tabs will slide into a slot at about the 10:00 position and the other at about the 4:00 orientation.
In picture 4 the Cerliani spring is captured, and you can see rather than having two tabs like the Koban, it has 4 tabs with 2.25mm gap between the tabs that will insert at the 3:00 position and a 3.8mm gap between the tabs that will insert at the 9:00 position.
I strongly encourage you to buy your bobbin case springs from either your dealer or the manufacturer of your longarm. They cost less than $10.00 and you know they not only have the correct tabs for your case but also have been engineered and manufactured to provide the proper amount of anti-backlash pressure to keep your bobbin thread from looping or other nasty gremlins.
If you are interested links to the hook manufacturers are below.
https://www.cerliani.it/home.aspx?lng=ing
Quilt on!
Do you have questions on this topic or a suggestion for another one you are interested in?