It Probably Means Nothing But...
 

I wonder why my bobbins have four holes when I only use one.

The four holes keep the bobbin weight even so that it's balanced when in use!

Huh, never knew that. Thanks, PP! I've always wondered about this, too.

My bobbins for my Viking Mega Quilter only have one hole but they are balanced.

Dh said in case I missed one! LOL! But thanks Paperprincess. Makes sense! Still funny.

I have three different bobbins. I guess I am not very curious, never gave the holes a bit of thought. I am always learning something new.

Well, they can make more bobbins if they take a tad out of each and the holes that were become new bobbins....just a thought.....

Yep, I have the same ones. Usually ones with single holes have smaller holes and are positioned near the center spindle so the effect is minimized.

I have bobbins for my 1980's Viking and they don't have a hole. When I fill it there's a place on the machine to secure it.

My 1970's era Viking most have a tiny hole on one side which helps me keep the direction straight. I put the hole side on the outside of the bobbin winder and then on the outside of the bobbin case. My vintage Singer has bobbins with holes all around on both sides. My new Janome has a hole on each side that I thread the thread through to get it started. These differences also help me keep the bobbins straight for the different machines. The fact that some are metal and some are plastic helps too except the newer ones I got for my Viking are plastic and look similar to the Janome ones so I have to be careful.