03-09-2022, 10:44 AM
(This post was last modified: 03-09-2022, 10:49 AM by Tony Griffiths.)
(03-09-2022, 09:11 AM)David.H Wrote: Even closer to M6☺
....indeed, as BA threads are based on a metric system. I looked it up to be sure and..."They are unusual in that they were probably the most "scientific" design of screw, starting with 0BA at 6.0 mm diameter and 1.0 mm pitch and progressing in a geometric sequence where each larger number was 0.9 times the pitch of the last size. They then rounded to 2 significant figures in metric and then converted to inches and rounded to the thousandth of an inch. This anticipated worldwide metrication by about a century. The design was first proposed by the British Association in 1884[1][2] with a thread angle and depth based on the Swiss Thury thread,[3] it was adopted by the Association in 1903." One can never have too many boxes of nuts and bolts - and I still have the remains of many acquired in my teens. As it will be impossible to use them in a lifetime, if passed along they might prove useful for the great, great grandchildren to repair their horse-drawn plough....