Why do we still use bobbins?

[AlZilla]

I watched a High-tex video today of basically a longarm quilter, making upholstery panels. It looked to me like they were feeding the bottom thread from a cone at the back of the machine. 

It got me wondering if other industrial machines fed the bottom thread that way. I looked around and don't see any evidence of it.

I could see it being an advantage, not having to mess around with winding bobbins, even on a domestic machine.

 

Look towards the back of the machine at the 2 thread cones. The bottom thread on the workpiece is blue.

"EDIT: So, obviously, this machine is using a standard bobbin setup. The question still remains, why couldn't the hook be fed from a full size spool located away from the bobbin/hook area?"

Edited 7 hours ago by Northmount
Edit added at AlZilla's request

[Constabulary]

maybe it is a chain stitch machine then it does not need a bottom thread.

EDIT:

No - has shuttle hook so it has a bobbin.

http://www.hightex-solution.com/a/Products/machine/Programmable_sewing_m/2021/0218/208.html

Quote

Look towards the back of the machine at the 2 thread cones. The bottom thread on the workpiece is blue.

they wound the bobbin from the blue spool. See the bobbin winder with blue threaded bobbin on the top of the machine? Using 2 spools is quite common in the sewing industries. One for top thread (you can leave machine threaded) and wind the bobbin from the 2nd spool.

Edited yesterday at 01:59 PM by Constabulary

[AlZilla]

@Constabulary yep, I do see the bobbin winder on top now.

 

But, still ... It seems like feeding the bottom thread from a full spool would make more sense than winding and changing bobbins. Especially in a production environment. 

[Constabulary]

I doubt that it is technically possible. if it was don´t you think someone alreday had invented something in the last 200 years. Well I´m not a technician but in my nut shell I cannot figure how it could work.

When you look at min 3:18 (approx) you will see the hook and bobbin case.

[AlZilla]

I just don't know why the bobbin tension device would care where the bobbin thread itself came from - a little bobbin spool right next to it, or snaking in from a large cone a foot away, at the back of the machine.

[Northmount]

17 minutes ago, AlZilla said:

I just don't know why the bobbin tension device would care where the bobbin thread itself came from - a little bobbin spool right next to it, or snaking in from a large cone a foot away, at the back of the machine.

Just the same as the top thread has to be pulled around the bobbin, it would have to be pulled around the spool.  Huge loop and space required.  How long/high would the take-up lever have to be to pull that loop back up snug?

 

[AlZilla]

18 minutes ago, Northmount said:

Just the same as the top thread has to be pulled around the bobbin, it would have to be pulled around the spool.  Huge loop and space required.  How long/high would the take-up lever have to be to pull that loop back up snug?

 

Isn't the loop all top thread, though? As far as I can tell, the bobbin thread just pays out as needed, no back and forth (or up and down), like the top thread.

"EDIT: So, obviously, this machine is using a standard bobbin setup. The question still remains, why couldn't the hook be fed from a full size spool located away from the bobbin/hook area?"

Edited 7 hours ago by Wizcrafts
AlZilla requested that I add this edit to his last post.

[Northmount]

4 minutes ago, AlZilla said:

Isn't the loop all top thread, though? As far as I can tell, the bobbin thread just pays out as needed, no back and forth (or up and down), like the top thread.

Yes it is all top thread.  Draw it out on a piece of paper showing how it would have to go around a 2# spool and be pulled back up.

 

[AlZilla]

5 minutes ago, Northmount said:

Yes it is all top thread.  Draw it out on a piece of paper showing how it would have to go around a 2# spool and be pulled back up.

 

OK, I'm seeing the flaw in my thinking. It needs to get around the whole spool.

Well, you guys saved me a trip to the patent office, anyway ...  :

[fredk]

If I remember correctly, the very earliest sewing machines used two large spools of thread. The top thread was pulled through the material by the needle and as the needle came up again a loop was made in the thread on the underside of the material. A shuttle, like the shuttle a weaver uses but in miniature, went though the loop pulling the second thread through. At the time this was efficient but prone to timing failures. As the invention of sewing machines progressed the bobbin as we know it was invented and was more efficient, with fewer timing failures. All the inventors adopted the cylindrical bobbin and its circular shuttle. Some fitted it vertical and some had it horizontal and some even had it at an angle, but its the same workings 

[DG1]

Like lots of things, the bobbin size is an engineering compromise. As the bobbin gets larger to hold more thread, the loop of thread that goes around the bobbin case will need to get larger which of course will mean the hook will need to be larger, the takeup arm, etc, essentially the machine would have to be larger/heavier.

There is another consideration also: As stitches are being made, when the needle goes down thread is fed down through the eye of the needle as it goes around the bobbin and then is pulled  back up through the eye of the needle to make the stitch. With a typical sized bobbin case, you can see it's quite a bit of thread, maybe several inches of thread going down and up the eye of the needle, to make one stitch that is say 1/8 of an inch in length. It's kind of hard to picture but basically you have the same segment of thread going through the eye of the needle multiple times. The bigger the bobbin case, the more times the thread will need to go through the eye of the needle, which would probably weaken or fray the thread.

[dikman]

I too pondered this subject some time ago, but then it occurred to me that if it was easy to solve someone smarter than me would have already done it.