It was surprising how mush of metric system was designed in America and later was ISO standard.?
Try this size most metric bearing? is just little smaller than inch.
So could machine the metric bearings seat easily in America.?
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But same time America is still on inch standard.??
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Then English has few odds ones to work. We have ?" pipe threads 27 tpi English ? 28 tpi?
Just try finding 19 tpi tpi on a America lathe.?
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Dave?
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On Thu, Jul 25, 2024 at 10:24 AM, chrisser wrote:
Don't know if this helps.? Did a bit of Googling.? Dates on the sharpener are kind of hard to pin down.? Saw "1920s", 1890-1919, 1910-1928...
That said, according to Wikipedia: "The metric system became compulsory on 1 January 1872, in Germany and on 1 January 1876, in Austria.".??
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However, I also found this: .
"Metric thread development started in Switzerland in 1876 with a metric thread with an angle of 47.5 degrees developed for the clock screw market by professor Thury. This was followed in Germany in 1894 by Leopold Loewenherz who designed a thread with a flank angle of 53 degrees 8 minutes.??A metric standard thread evolved from these Swiss and German threads that were agreed but not formalised by the American, British and French in 1919. Metric threads are based upon a 60-degree flank angle with flat crests and rounded roots. It was not until 1947 with the re-founding of the International Standards Organisation (ISO) that further development took place eventually leading to the promotion of the ISO standard metric thread in 1960. "
So it sounds like they could be metric, but maybe not the standard metric we use today.
On Thursday, July 25th, 2024 at 12:24 PM, Johannes <johannes@...> wrote:
I have got a C1900 "Guhl & Harbeck , Hamburg" pencil sharpener for restoration . Jupiter 1
Some screws are missing, and before I force in some modern ISO screws;?
Had Germany their own screws size 100+ years ago??
I cannot find a " pencil sharpener IO group" , so I am asking you.
New screws can easy be made with a 7x12 lathe ?
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Johannes
Mexico
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