Even the simplest sewing machine is a sophisticated machine tool. The mechanics of getting a machine to sew posed a similar problem to the first aeroplane : there were several very different design features which all needed to be right before the thing would work at all.

Here’s an animation of the clever way the machine makes its lockstitch.

If you prefer something slower, here’s a pdf with detail about the mechanism.

Here’s an entertaining UK documentary about the history of sewing machine mechanisms (26 mins.)

Another documentary about the history of sewing machines, this time from the US and not free, Still Stitching (100 mins.) A paean of praise to the mechanical machine.

Machines have to be manufactured.
Here’s an amazing (silent, black and white) documentary about the huge factory in Scotland which made Singer black and gold machines in their heyday (70 mins.). Also incidentally a clear reminder about changes in manufacturing. That was before computers and laser measuring. 80 years ago the film was made to show off marvellous modern methods !
In complete contrast, here are a few minutes in a Bernina modern factory (though admittedly that is for their long-arm machine, which are made to order not mass-produced).

Basic sewing machines are still entirely mechanical. They just need position and speed control skills to operate them successfully.
Top-of-the-line machines also include quite complex computing and communications technologies, with special software for controlling stitching patterns. The stitching may be controlled by the machine, but those machines need much knowledge to make full use of all the facilities available.

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