[TR] Assorted Fastener Questions

[Randall]

> Do fine threads offer more holding power because 
> there's more
> threads per inch or are there other reasons?

A related reason : for a given nominal diameter, fine threads have a larger
minimum diameter.  So, for example, a 1/2-13 bolt has a minimum diameter (at
the bottom of the threads) of around .444", while a 1/2-20 is around .462"

However our cars seem to have a lot more fine threads than I think can be
justified on the basis of strength, and I have no idea why that is true.

> I thought maybe the Nyloc 
> worked better in a
> component prone to vibration but....heck our whole cars 
> vibrate! So why one
> over the other?

One reason is that nylocs don't work when there isn't a separate nut (like
bolts into castings, captive nuts, etc.)  They also don't stand up to high
temperatures (like exhaust systems).  But they do work better than lock
washers in places where there isn't a lot of clamping force (like suspension
pivots).  Also somewhat easier to install on an assembly line.  There's
more, but that's a start.

>  Someone
> could probably write a book on just their use!

Someone has.  Legend has it that it was going to be called "Screw to Win"
(being the companion volume to "Tune to Win", "Drive to Win", etc.) but the
publisher wouldn't go for it.
http://www.carrollsmith.com/books/nutsbolts.html

> If I knew then what I know now, I would have ordered from 
> McMaster boxes of
> bolts, nuts and washers rather then buying them locally in twosies and
> threesies! I probably would have saved 50% over the big box stores.

Yup.  Especially those dang Nyloc nuts that need to be replaced from time to
time.

Randall