How a Boring Mill Turned a Crooked Casting into a Cylinder Accurate to a Worn Shilling
How machines learned precision
In the 1770s, making a straight, round cylinder for a steam engine seemed impossible: boring bars sagged, castings were crooked, and the smallest mark on a rule was a sixteenth of an inch. John Wilkinson's boring mill, which supported the bar at both ends, produced a 50-inch cylinder so accurate that Matthew Boulton boasted it did not err the thickness of an old shilling. This article traces how workshops learned flatness, accurate screws, and millionth-of-an-inch measurement through interactive figures.
In 1776, Watt's partner Matthew Boulton wrote that a fifty-inch cylinder Wilkinson had bored for them “does not err the thickness of an old shilling in any part.”
- pillars
Great Work! I want to share some great resources related to Precision Engineering:
[1] Origins of Precision
https://www.youtube.com/watch?v=gNRnrn5DE58
[2] The books that taught me precision
https://www.youtube.com/watch?v=FM9X_gjnleY
[3] 2.75 FUNdaMENTALs of Design - Alexander H.Slocum
https://www.youtube.com/watch?v=wgMq7yha9wU&list=PLksE8LDXGX...
[4] Building the most accurate DIY CNC lathe in the world
https://www.youtube.com/watch?v=vEr2CJruwEM
[5] Design Principles for Precision Mechatronics
https://www.dspe.nl/knowledge/dppm-cases/
[6] Tutorials in Optomechanics
https://wp.optics.arizona.edu/optomech/tutorials-in-optomech...
- ghm2180
Thank you for making this. My dad(now retired) owned a machine tool manufacturing space in the 70s and 80s in a small town in north india. After foreign CNC machines left no demand for manual/semi automatic ones in the country, he switched over to a foundry to manufacture cast iron parts in a blast cupola furnace and later a rotary furnace(better for smaller on demand work). But he kept the lathe around along with an employee to finish the parts. And your animation brings back a lot of memories for me. I learned to operate the lathe and had all manners of fun. It is kind of like yak shaving. Your clothes turn black but you just love the mechanical back and forth of it. He made pulleys, Truck engine parts, housing for water motors(fun fact municipal water is scarce and not of adequate pressurized in homes, farms, factories etc so these are ubiquitous) etc.
I sent this to my dad. I am sure he will enjoy reading this.
- glinscott
Author here. This is a sequel to my beam engine article: https://glinscott.github.io/beam-engine/.
I started digging into Watt's challenges getting an accurate cylinder bore for his pistons, and it spiraled out from there :).
The article covers some of the key techniques developed during the industrial revolution to measure and make incredibly precise parts. There are a lot of animations and interactive figures to explore how it works.
- qchris
Anyone interested in this might also enjoy the book The Perfectionists: How Precision Engineers Created The Modern World, by Simon Winchester. I read it a few years ago, and thought it was a really interesting journey through bootstrapping precision and how that fundamentally changed our relationship to certain types of things, particularly related to mass production of "good enough".
- Joker_vD
> After repeated copying and correction, Maudslay made a master screw five feet long and two inches across, with fifty threads to the inch and a foot-long nut that engaged six hundred of them at once.
That's the stuff I like to read about the historical endeavors. A fifty-threads nut doesn't average the distance between the grooves quite accurately enough? Then let's make a nut with six-hundred threads on it, and so what if it's foot long.