2002-05-23 Since the book was published in 1971, I do believe there was a variety of standards, both within metric and outside. But, sometime around 1980 or the early 1980's, the ISO "cleaned house" and eliminated a lot of the variants within metric, so that today, there is only one ISO fastener standard.
The various standards within metric, was the root of clatter from anti-metric luddites that a Japanese metric screw did not fit a German metric nut, even if they were both Mxx. Besides metric (ISO) thread sizes, I can think of Inch-coarse, Inch-fine, NPT, NPS, and Withworth. I don't know if Withworth also comes in coarse and fine. But, my guess is, Withworth is obsolete, except for replacement on old machines. I'm sure Withworth has been replaced by metric. Who knows, maybe each country had there own sizes, until ISO-metric eliminated all of them except, of course, the American ones. 1841 was the year after metric became the sole legal system in France. Maybe in 1841 is seen as the birth year of the metric system by some as the 40 plus years of uncertainty about its future were over. Also, maybe it was that year that fastener standards were first discussed among engineers. It was also in the 1840's that the industrial revolution was beginning. 1841 can mean almost anything. John ----- Original Message ----- From: "Pat Naughtin" <[EMAIL PROTECTED]> To: "U.S. Metric Association" <[EMAIL PROTECTED]> Sent: Thursday, 2002-05-23 21:26 Subject: [USMA:20178] Screw threads > Dear All, > > Recently I found a small book in a second hand shop called 'SI Units' by > Chiswell and Grigg (John Wiley & Sons 1971). > > On skimming through the book I came across this paragraph. > > "Since 1841 attempts have been made at various times to get standardisation > in screw threads. At the present time over two hundred thread forms exist > and about ten of these are used frequently." > > Can anyone help me with the following questions? > > 1 What happened in 1841, and who were the main players at that time? > > 2 What are the two hundred thread forms (that currently) exist? > > 3 What are the names of the ten of these (that) are used frequently? > > Thanks for your help. > > Cheers, > > Pat Naughtin > CAMS - Certified Advanced Metrication Specialist > - United States Metric Association > ASM - Accredited Speaking Member > - National Speakers Association of Australia > Member, International Federation for Professional Speakers > -- >
