Why do we still use bobbins?

[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.

[nejcek74]

There are chain stitch machines :))), they don't have the lower thread. As I see it, that is the engineering solution for the problem of uninterrupted stitching.

[AlZilla]

Well, you guys have been kind enough not to beat me up for my brain fart ...

No idea why the part about looping around the entire bobbin escaped me. I've worked on enough of these (and explained the process to rookie sewists) that I knew better.

Feeding the bottom thread from a full spool while keeping some kind of lock stitch will be the next great leap forward.

[dikman]

Yep, whoever comes up with it and patents the idea should make a fortune!

[suzelle]

I have often wished my industrial machines had 2 spools, like these old 2 spool Domestic machines:

eBay item number:116392660262

The add is funny to read. Also interesting. Really geared toward the ladies as most sewing machines were those days.

You can't see it in the advertisement, but the lower spool in the machine would be contained in a "cannister" type case, similar to a bobbin case in our domestic machines. I've seen these machines come up at auctions and listings, but unfortunately they are only domestic or home machines. I agree, if someone could patent the idea, they'd be rich! I believe the patent for the machine in the ad is exempt. So maybe time for somebody to create a patent to produce industrial machines? I'd buy a machine!  I've had lots of thoughts about this too over the years and did find the old patent a few years ago. Very thought provoking.

Edited November 25, 2024 by suzelle
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[AlZilla]

1 hour ago, suzelle said:

I have often wished my industrial machines had 2 spools, like these old 2 spool Domestic machines:

eBay item number:116392660262

The add is funny to read. Also interesting. Really geared toward the ladies as most sewing machines were those days.

You can't see it in the advertisement, but the lower spool in the machine would be contained in a "cannister" type case, similar to a bobbin case in our domestic machines. I've seen these machines come up at auctions and listings, but unfortunately they are only domestic or home machines. I agree, if someone could patent the idea, they'd be rich! I believe the patent for the machine in the ad is exempt. So maybe time for somebody to create a patent to produce industrial machines? I'd buy a machine!  I've had lots of thoughts about this too over the years and did find the old patent a few years ago. Very thought provoking.

@suzelle, you pulled me out of the fire!  And now I need to find one of these machines!

Here's a post with a pic: https://www.victoriansweatshop.com/post/show_single_post?pid=1326099274&postcount=9774&forum=501752

A little quick searching and it looks like National made these and may have badged them for other makers, but the search is on.

Thanks for that great lead!

EDIT: Here's a video showing how the bobbin works. She talks about it for about 3 minutes starting at 2:10. 

Close to the end of the video she's sewing with it. The tension arm certainly does have a long swing.

Quite a fun looking machine.

Edited November 25, 2024 by AlZilla

[Wizcrafts]

WOW! That bottom spool resembles the bobbins in the 441 and 205 style machines. That ancient National 2 Spool was way ahead of its time. It's like having a Cowboy cb3200, 3500, or 4500 bobbin in a domestic machine using common cotton thread. Amazing!

[Constabulary]

2 Spools, yes but its is still a machine with a hook and "bobbin". But indeed very impressive!

[Wizcrafts]

8 hours ago, Constabulary said:

2 Spools, yes but its is still a machine with a hook and "bobbin". But indeed very impressive!

Yes, it still has a bobbin. But, when this machine came out, its bobbin was actually on one of the tiny spools they used to sell to home sewers. I have some of those wooden spools. People could stock up on the colors they needed on the bottom and sew for a long time before they had to swap spools. I can sew a long time on my cb4500 (441 clone), but rarely with thin thread like the home machines use. I'm not advocating for a new 2 spool machine, just comparing it to our current technology.