[Amps] What is it called?

[G3rzp at aol.com]

Generally speaking, the model engineering suppliers are very much cheaper than RS or Farnell, and in many cases, just as fast. Some of them can even supply 'off the shelf, next day delivery' such niceties as a 3/8-32tpi UNEF tap or die (UG1094 BNC socket thread) or 5/8-32tpi UNEF, which is type N or  UHF socket thread. I can't remember what an SMA thread is, but there's a good chance one of the suppliers will have it in stock.

Tufnol is used in model engineering for making (from thin sheet material) leaf springs for locomotives and other rolling stock axleboxes. PTFE (Teflon) rod and sheet is used for clack valve seatings by some people, so these materials are available. In this respect the UK is much better off than most other countries, having a lot more suppliers. The model engineering suppliers are becoming the last sources of BA fasteners, too. Unified threads seem very hard to get except from specialist suppliers in  UK. Interestingly, the Unified screws, having a coarser thread, are far better in soft materials like tufnol (and aluminium) than the ISO metric stuff. On this tack, does anyone know why the US seemed to have moved from using 4-36 threads to 4-40 threads over the period of about 1946 to 1952?

73


Peter W6/G3RZP