I watched the video linked at the top, and I think I get it. The thread never goes behind the bobbin, it rides on the outside of the metal disc and then falls back on the same side, never having to pass through the axle.
I have no idea what people mean about it not having an axle and being free floating. It must have an axle. It’s not held there by magnets.
I looked inside 2 sewing machines; one did not have any axle, and one did (though not where it would block the thread loop, obviously). Nothing is floating in the air, though, that’s for sure; it all fits into a frame. There is also some variation in the mechanism: in one, the hook rotates, and in the other it oscillates back and forth.
If it’s not attached to anything, then there’s no way to drive it. What is everyone talking about then?
Well, the hook is driven, and so is the needle. But, yes, all the little bobbin does is play out thread. There is also a little case it fits into to keep the thread taut. I recommend looking at a real sewing machine, then you will see for yourself all these bits.
It’s not driven.
The bobbin is free-floating in a cup.
ETA: The bobbin itself doesn’t spin. It just spools the thread out.
There are two ways to pay any rope/cable/thread off any reel.
One way is to have the reel rotate on an axle and the material pays out perpendicular to axle, along the “equator” of the reel. And yes, this requires the reel to rotate at the rate the material is paying out times the diameter of the supply at the moment.
The other way is for the material to depart the reel parallel to the “pole” of the reel. The reel is stationary and the material just leaving the reel rotates around the rim of the reel as it is pulled away by whatever is pulling on the material’s free end.
Most (all?) of the sewing machines I’ve ever looked at closely use the latter system at the bobbin.
I’m talking about the hook. It must be attached and be driven.
I love that show! Back in the late 80s it used to be shown on The Learning Channel (back when that actually meant something) in like 2 hour blocks and I’d watch them over and over again. It looks like it was made in the 60s but it was actually brand new at the time.
The hook is part of the “sleeve” the bobbin sits in, so it moves around the bobbin without driving the bobbin.
Check it out on YouTube. It’s been AI upscaled to help the quality (it’s a marginal improvement, but an improvement nonetheless), and Tim provides a couple minutes of follow-up commentary about how things have changed since the episode was produced.
The Veratisium video goes through the part with the bobbin really fast. I also had to pause and play it many times. I think it’s kind of strange they didn’t focus on it more, as it really is the key part to how sewing machines work.
I pulled out my sewing machine and made a video. It’s hard to see the details in the mechanism, but it’s clear that it only has to pull the loop from left to right (past the bobbin) and then release.
Cool! Thank you.
And while you are there, check his recent series for makers about basics like glue, screws, linkages etc. I wouldn’t say I learned a huge amount I didn’t know, but at the very least he brings it all together in an entertaining way.