[Amps] What is it called?

[Will Matney]

See if formatting is better;

Peter,

See below,


>
> On Sun, 23 Jan 2005 09:34:48 -0500, <G3rzp at aol.com> wrote:
>
> 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?

  My guess is because 4-40 screws have more holding power than a 4-36
  screw does. This is due to more threads in the thickness of whatever
  it's screwed into, either tapped material or a nut. Fine threads are
  always used in places where more holding power is needed in a thin
  section. Coarse threads are for thicker sections.


>
> 73
>
>
> Peter W6/G3RZP
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Will


Some reason the last one didn't hold its formatting, try it again!

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