3 ms·

Maudslay's Methods of Originating Screws (1856)

6 points by Tomte 3y ago

dang 3y ago
Related: Maudslay's Methods of Originating Screws - https://news.ycombinator.com/item?id=26842375 https://news.ycombinator.com/item?id=26842375 - April 2021 (9 comments)
Animats 3y ago
That article confuses screw origination machines with screw cutting lathes. (It's also clickbait for some irrelevant site.) A lathe can be used to make screws, but the one you will make will be no more accurate than the leadscrew that drives the carriage, and probably worse. Maudsley is also noted for making the first good screw-cutting lathe. But this is about Maudslay's screw-origination machine, used to make a reference screw more uniform than the one you started with. Here's the actual origination machine.[1] This cuts a screw in a soft material, to be used for guidance of the screw-cutting lathe to make a steel or brass copy of the master. The basic idea is that a chisel cuts a slot in a rod, and rides up the rod as the rod is rotated, using its own cut for guidance. The good explanation of this, from 1904, is paywalled.[2] Nobody does this much, or ever did, but it needed to be done a few times in history to bootstrap mechanical precision from imprecision. Once you have a reasonably precise leadscrew, there are tricks to average out small errors and make a slightly better one. Maudslay's original lathe is at the Science Museum in London. I've seen it. It looks a lot like a modern lathe. There were earlier metal lathes, with various types of slide rests and power drives, but Maudslay finally got it right. The basic design hasn't changed much since. It's one of those things, like a Bridgeport mill, which somebody got right and it then didn't change much thereafter. [1] https://collection.sciencemuseumgroup.org.uk/objects/co46546/machine-screw-thread-making-tool-by-henry-maudslay-screw-cutting https://collection.sciencemuseumgroup.org.uk/objects/co46546... [2] http://www.gracesguide.co.uk/images/d/d0/Er19040520.pdf http://www.gracesguide.co.uk/images/d/d0/Er19040520.pdf

6 points by Tomte 3y ago

dang 3y ago

Related: Maudslay's Methods of Originating Screws - https://news.ycombinator.com/item?id=26842375 https://news.ycombinator.com/item?id=26842375 - April 2021 (9 comments)

Animats 3y ago

That article confuses screw origination machines with screw cutting lathes. (It's also clickbait for some irrelevant site.) A lathe can be used to make screws, but the one you will make will be no more accurate than the leadscrew that drives the carriage, and probably worse. Maudsley is also noted for making the first good screw-cutting lathe. But this is about Maudslay's screw-origination machine, used to make a reference screw more uniform than the one you started with. Here's the actual origination machine.[1] This cuts a screw in a soft material, to be used for guidance of the screw-cutting lathe to make a steel or brass copy of the master. The basic idea is that a chisel cuts a slot in a rod, and rides up the rod as the rod is rotated, using its own cut for guidance. The good explanation of this, from 1904, is paywalled.[2] Nobody does this much, or ever did, but it needed to be done a few times in history to bootstrap mechanical precision from imprecision. Once you have a reasonably precise leadscrew, there are tricks to average out small errors and make a slightly better one. Maudslay's original lathe is at the Science Museum in London. I've seen it. It looks a lot like a modern lathe. There were earlier metal lathes, with various types of slide rests and power drives, but Maudslay finally got it right. The basic design hasn't changed much since. It's one of those things, like a Bridgeport mill, which somebody got right and it then didn't change much thereafter. [1] https://collection.sciencemuseumgroup.org.uk/objects/co46546/machine-screw-thread-making-tool-by-henry-maudslay-screw-cutting https://collection.sciencemuseumgroup.org.uk/objects/co46546... [2] http://www.gracesguide.co.uk/images/d/d0/Er19040520.pdf http://www.gracesguide.co.uk/images/d/d0/Er19040520.pdf