Bob wrote:
True Pozidriv screws are not that common on this side of the
pond. But you may not want "genuine Philips" either. The true
Phillips head screws and drivers are designed to "Cam Out" to prevent
over tightening. To prevent that there are Reed and Prince or
Frearson head screws and drivers. They have a variation in the angle
and depth. Another that also "looks" like phillips are the JIS
standard that again changes the angles.
According to various online sources, the original Philips cross-head was
introduced to speed assembly in the automotive industry, and to avoid
damage to bodywork due to the flat screwdriver blade skidding out of the
screw slot. Because the early power screwdrivers didn't have any kind of
clutch, the Philips drivers were deliberately designed to "cam out" and
disengage from the cross head once the screw was reasonably tight.
That feature is no longer needed, and "cam out" is now the major
weakness of the Philips system. Many other systems have been devised to
overcome this. In Europe, Philips has been mostly replaced by the
Pozidriv system, which has more parallel-sided slots and blades and will
deliver a much larger torque without camming out. However, Pozidriv
seems largely unknown in the USA - the irony being that the patents are
owned by the Philips company!
Using a new screwdriver may only be a partial solution, you need to
look real close as to which you want and buy and how they fit. .
The term phillips has become somewhat generic for any cross
headed screw, just as any copy is a Xerox.
We have to trust that when Elecraft say "Philips", that is what they
really mean! However, a Pozi driver is definitely the wrong tool for
the job.
There may even be more variations out there. I don't know
what your old BA stuff was but I'm sure Elecraft isn't using them.
BA is a thread form, and doesn't dictate the shape of the head.
Aren't standards wonderful? There are so many to choose from...
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
_______________________________________________
Elecraft mailing list
Post to: [email protected]
You must be a subscriber to post to the list.
Subscriber Info (Addr. Change, sub, unsub etc.):
http://mailman.qth.net/mailman/listinfo/elecraft
Help: http://mailman.qth.net/subscribers.htm
Elecraft web page: http://www.elecraft.com
