Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

This is not really quite Off-Topic, but it is rather ephemeral to the main thrust of this Board. Still, it is so entirely seminal to the concept of accurate machining that mention of it here is fully appropriate in my opinion!

I just had delivered, after a very long, long wait, a package from England that is oddly enough, a rather amazing Swedish family collection of what may well be the most honored, and revered World-Wide, man from Sweden!

John Ericsson may have similar claim to such a title, but in fact, as prolific and amazingly creative in diverse fields as he was, his impacts on our modern life are substantially less, IMHO.

Carl Edvard Johansson, "He Measures in Millionths" was truly seminal to precision machining and the interchangeability of parts, mass produced in different factories around the world! He is actually the person who standardized the Inch as being exactly 25.4mm, as before he did, the countries of the world each held standards that were different by as many as five decimal places. But that is only one result of his life's work, which basically centered around the creation of sets of Gage (or Gauge) Blocks that allowed for the universal calibration of instruments, fixtures and jigs anywhere in the world to the same exact standards!!!

If anyone is interested, I'll gladly wax as eloquently as I am able, to bring forth the key ingredients of this great man's story, or you could simply look him up in your computer and sit back and be amazed ..... or not!



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An amazing collection.

Thank you for sharing.

Amusingly a few weeks ago I dug out from the back of the tool box my set of Jo blocks for a bit of metrology on the model I'm building.

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Sometimes you just need to verify where you are at and a stack of blocks with a test indicator can be a repeatable way of getting a good measurement. During the cut I was measuring with that depth micrometer at the bottom right but it was good to see everything ended-up where it should be.  These are just shop grade Jo blocks from Inspector Wang Hung Lo, but they are still way more accurate than anything I will make in my climate un-controlled shop.