Re: Gap insurance


Andy Bonwick wrote:

> What gf might have been implying is that you get a finer pitch on BSF
> than standard metric threads but that's negated by the fact that most
> Jap bike threads are a finer pitch anyway so that doesn't count. The
> advantage of this is that they take longer to vibrate all the way off
> when they're loose...

(I'll ignore the "jap bike threads are a finer pitch anyway" rubbish
for now.)

not quite.

very few people realise just how much history is in everything we do
every day and so invisible, so invisible that if it is pointed out most
people will even deny it... examples are metrication being a "foreign"
thing etc.

everyone knows the names of frank and orville wright and the kitty
hawk, nobody knows the name of the man who actually designed and built
the motor without which frank and orville would have been forgotten 80
years ago

bottom line here is screw threads are as old as engineering,
standardised screw threads were the beginning of the industrial
revolution, some standards were adopted from the thousands of
pre-standards options because the main proponent was hugely
influential, others were adopted because they simle worked better than
the others.

there are numerous examples of what are now traditional engineering
solutions that were known and trusted for working well, which have only
been adequately explained by the advance of science to the point of
x-ray crystallography, electron microscopes, laser spectrography, and
so on...

inversely there are many examples of very old engineering that seem
frankly impossible when you ask a bunch of apprentice / student
engineers to list the range of metalworking technologies available in
the middle ages, then make them study an artifact such as a suit of
mail with a view to duplicating it.

screw scrapyard challenge, take a goup of engineers, give them a task
that they know has been done like gun barrel rifling, then give them a
lathe, an old horizontal mill, a drill press, and hand tools, and tell
them to design and built a tool and via this produce a match grade
rifle barrel, which can be done in scrapyard challenge time scales and
for bugger all value of materials, you want to see panic... but then
both teams miserably and utterly failing the "challenge" wouldn't make
good television would it...

in the old days BSF was just one of many that was known and trusted to
hold well and not undo unless you wanted it to, and selected and used
on the basis that it simply worked.... nowadays a modern materials
scientist armed with x-ray crystallography etcetera can explain why it
is a superior thread to metric (coarse or fine) in each of a wide
variety of specific metals and alloys.

.

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