Watchmaking: Machining a 0.6 mm Screw [video]
That's how to make a single screw as a one-off, using basic machine tools. That's not a production process.<p>Screw making was automated by 1871. Here's an early automatic screw machine.[1] The video says 60,000 screws a day, but that must have been the whole shop, not one machine. You can see that the cycle time is about 10 seconds per screw. Who needs computers? We program with <i>cams!</i> Complex cam-programmed industrial machines were what made manufactured parts cheap.<p>Here's synchronized thread rolling using a CNC lathe.[2] That's a more modern one-off approach. Thread rolling squeezes the threads into the screw, rather than cutting out metal. Rolled small screws are stronger than cut screws. Needs a specialized tool.<p>That's not the full speed modern production process. This is.[3] A relatively simple machine turns out small screws at about one every 250ms. Over 100,000 screws per shift. This screw rolling machine can go down to 0.6mm, so it can do the job in the original video.<p>Here's a larger, slower, bolt rolling machine, so you can see the process.[4] It's very simple. A round piece of metal is rolled between two file-grooved die plates, and the threads are pushed into the metal.<p>This is why screws are cheap.<p>[1] <a href="https://www.youtube.com/watch?v=YCmnUP5gx78">https://www.youtube.com/watch?v=YCmnUP5gx78</a><p>[2] <a href="https://www.youtube.com/watch?v=-eWghSLN3ng">https://www.youtube.com/watch?v=-eWghSLN3ng</a><p>[3] <a href="https://www.youtube.com/shorts/HWmu4gxmois">https://www.youtube.com/shorts/HWmu4gxmois</a><p>[4] <a href="https://www.youtube.com/watch?v=Mlfq_Pbh6PQ">https://www.youtube.com/watch?v=Mlfq_Pbh6PQ</a>