[Elecraft] Prospective K3 Owner

[Ian White GM3SEK]

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