I can’t get my head around how a sewing machine sews a hem on material when it just a needle with some thread poked through it stabbing the material in a line. How does that then make the thread loop back under the material to create a hem on both sides?
In: Engineering
This is a difficult thing to describe over writing, and there are many helpful youtube videos showing the inner workings of a sewing machine in slow motion, with descriptions. I recommend checking those out.
There is a good veritasium video on it, just go watch that https://www.youtube.com/watch?v=RQYuyHNLPTQ
it is impossible to explain in text how it works, you really have to see it, but the needle is pushed through the fabric, a hook catches the thread and loops another piece of thread through it with an amazingly impossible device called a bobbin, the needle is then pulled back up and the extra thread is pulled through, then you repeat.
Again, you really have to see it, just watch the video
Basically, there’s another thread in the base of the machine that gets threaded through the loop in the needle’s thread.
It’s also got a wheel thingy feeding thread to make a loop.
https://cdn.theatlantic.com/assets/media/img/posts/just_in_case_you_ever_wonder_how_a_sewing_machine_works-98670.gif
https://i.pinimg.com/originals/8c/1f/e3/8c1fe3b670d08361962f07fa93c52209.gif
As others mention, it’s much easier to understand by looking at a video that shows it in action, but the key is that the machine sews with two threads: one from above the fabric and over from below, and when the needle goes under the fabric the threads are looped together.
there’s a small spool of thread in the base called a bobbin. when the needle goes down a hook grabs the tread off it and loops it around the bobbin spool. then when the thread is pulled right and the needle goes back up the bobbin thread is through the needle thread. tension on the thread is adjusted to make sure this crossing winds up in the middle of the fabric and you get a neat stitch.
It’s not just a needle poking holes through, that’s about half of what it does. It also has a hook from the underside. The needle punches through and drags a piece of thread through the farbic, then it pulls back up from the same hole, pulling the same thread along but just before the thread is pulled out of the hole, a hook catches it and drags it forward, where when the needle goes through again, it will essentially pass the thread through the loop from the previous stroke. They’re actually very impressive machines because they do this actions very fast and purely mechanically, as they have been doing for well over 200 years.
This blew my mind when I first figured it out, because it’s so not clever. Imagine you want to see something using two threads, top and bottom. But you don’t want to cut the thread yet, you don’t want extra knits and you don’t know how much you need. So you take your two spools, use a needle to get a loop of the top down through, then you pull out a big loop, **big enough to get the entire other spool through**. Then you pull the stitches tight, and do it again.
That’s all a sewing machine does. They make you put some of the thread on a small spool (the bobbin), so the machinery can be smaller, but that’s pretty much it.
The clever bits are the timing and calibration to make the stitches neat.
dude sewing machines are like magic but with gears and stuff. the needle does stab but there’s a bobbin that pulls the thread below. it loops and ties it all together like a cool knot. it’s way smarter than it looks
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