[ROVERNET - UK] P6B nuts and bolts specs

Gundry, Kenneth KG at dolby.com
Mon Nov 5 18:25:16 GMT 2007


Thank you for the clarification, but over the years in dismantling many
piece of consumer gear from Japan and other far eastern countries, I am
pretty sure that the screws (metric, of course) had straight-sided holes
in the heads like Pozidriv, not tapered ones like Phillips.  Certainly
Pozidriv screwdrivers work satisfactorily, whereas US Phillips ones
don't, or not as well.  For the first time, I now have a Japanese daily
driver, with all the annoying electrical design errors that the Germans
sorted out years ago, and in correcting one I had to undo several
screws; I am virtually certain they were not tapered "slots".

I might add that in my previous (German!) daily driver, I had need to
remove the radio, and found I needed to improvise a key with a 5-sided

Ken Gundry, 1925 Rover 16/50 (the only one in North America), San

-----Original Message-----
From: rovernet-bounces at lyris.ccdata.com
[mailto:rovernet-bounces at lyris.ccdata.com] On Behalf Of Vern Klukas
Sent: Monday, November 05, 2007 8:34 AM
To: rovernet at lyris.ccdata.com
Subject: RE: [ROVERNET - UK] P6B nuts and bolts specs

The Phillps head was invented in the 30s, and was designed to cam out as
Ken says. The problem, from a manufacturing standpoint, was that the
recess was often burred by the bit when it rode out, requiring
replacement. In the end, industry moved to torque limited screwdrivers
that either stalled or released the drive, rather than depending on the
design of the Phillips.

Both Phillips and Pozidriv are US inventions, and it is curious that
Pozidriv has had so little success in North America.

As for Pozidriv being the defacto standard int he rest of the world,
Europe perhaps but Phillips (actually the Japanese variation) are more
common in Asia and certainly in electronics manufacture.

The Canadian Robertson (square recess) is better than either Phillips or
Pozidriv (and Torx too) but under-appreciated in the world. I think it
is because the square somehow has a unsophisticated look to it.


>I don't understand Patrick's remark about Pozidrive.  I believe it is 
>the standard screw-head everywhere in the world except the US, and 
>until I moved from Britain to the US (working in design of electronic 
>equipment which certainly contained screws), I had in fact never heard 
>of Philips screw heads.  All my screwdrivers from the period were/are 
>Pozidrive.  As far as improvement is concerned, that depends on the 
>application.  I believe that Philips heads were developed for mass 
>production using electric or air screwdrivers; when you are doing up a 
>screw, you don't want to stall the screwdriver (at least, not those of 
>WWII vintage), so when the screw gets tight, the bit rides up out of 
>the head.  That is of course fine the first time during assembly, but 
>makes it much more difficult to undo the screw subsequently, or to do 
>anything with a normal hand-held screwdriver.  In contrast, Pozidrive 
>screw-driver bits, and of course the corresponding screw heads, have 
>straight parallel sides (no taper), so there is no tendency to ride out

>and thus no need to apply downward force to hold the bit into the
>That is also very convenient for getting screws into inaccessible 
>places, since a screw will remain on the bit; Philips screws fall off 
>the bit.
>Ken Gundry
>-----Original Message-----
>From: rovernet-bounces at lyris.ccdata.com 
>[mailto:rovernet-bounces at lyris.ccdata.com] On Behalf Of phing
>Sent: Saturday, November 03, 2007 8:12 PM
>To: rovernet at lyris.ccdata.com
>Subject: Re: [ROVERNET - UK] P6B nuts and bolts specs
>Thanks . I've been hauling a Posidrive screwdriver around in my tool 
>box since 1972 ,. I knew I would need it one day . Posidrive was a 
>British GKN " improved Phillips" type screw head . It became a world 
>beater , just like Beta max and 8 track tapes !

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