The Posi-drive screw

[George]

what a naff invention...why couldn't they just put a square hole instead of the cross hole?

Then again it was a yank idea

[Dave Plowman (News)]

Not so - Pozidriv is a GKN invention. Designed to overcome the deficiencies of the original cross point system - Philips, which is American.

[jal]

I bought Pozidrives when they first came out -- you could even buy a special Pozidrive screwdriver, which I also invested in.

Are all screws Pozidrives now? I don't see the brandname in the sheds when I go.

BTW: I thought (and still think) that in the hardware line they were the best thing since - er - sliced bread. Coo -- they don't half screw in quick! And Tough!

J.

[boltmail]

The trouble with square-hole-headed screws (Robertson type) or even torx headed screws, is that preventing camming out (which I assume is your complaint as there isn't much else that can go wrong with posi- drive) is the same thing as making it harder to insert the driver-bit in the first place. Which is a right pain in the butt and slows things down much more than a bit of cam-out now and then (better still, use an impact driver to eliminate nearly all cam-out anyway).

[Lobster]

I think Pro-drive is more common these days - AFAIK the same thing?

There are certainly other different formats around; eg drywall screws always seem to be Philips, which means continually swapping between identically sized Philips/Prodrive bits or screwdrivers.

David

[Huge]

Some good articles on Wikipedia;

's a table of other types on the RHS.

(Interestingly, I've just discovered from this page that the Pozidriv design is co-owned by Phillips... And that the screws have nothing to do with the Dutch consumer electronics company, which has only one 'l'.)

[dom]

Where larger fasteners (e.g. 6mm spax, 6mm Multimonti, heco-topix) are available in torx head, I much prefer them.

I suspect making smaller high torque fasteners in torx head would make them excessively delicate, as the splines on smaller torx heads look delicate.

OTOH it's nearly always the PZ2 bits I break with the impact driver and rarely the PZ3 (and never T20 or T25). Usually happens as the battery is getting flat and the drive jumpy and in an awkward location so alignment isn't perfect.

I have a Screwfix turbogold 6*80mm with a torx head that fell out of a box PZ3 screws - I'm still hoping that Screwfix launch turbogold in torx head sometime.

[John]

The problem with a square hole (or any hole with straight sides) is that it will break through a countersunk head if it's deep enough to give a good depth of engagement. Posidrive holes taper so can go deeper into the screw.

John

[boltmail]

Can't be bothered with them, it's really too much fuss to get the bit engaged if you are having to drive more than the odd screw here and there. PZ3 is fine for the 6 x 180 Spaxes I've been using (=A31.88 a box of 50 in B&Q's sell-off) some of lately, and I can't imagine using a larger screw. For multi-montis, coach screws and the like I use hex- heads.

Depends on the bits as well, the wera extra-tough ones are pretty good. I was a bit sceptical, as all of the expensive wiha diamond etc ones I've tried have been not much better than cheapos in terms of life-span, but I bought a set a couple of months ago and must have driven well over a thousand screws since, with no breakages of either pz2 or pz3.

[John Rumm]

I feel the need to jump to the defence of pozi... with a well matched screw and bit (and it can take some experimentation to find really good combinations), they are very easy to drive, are self centring, and will tolerate a certain amount of misalignment.

[The Medway Handyman]

Piggin annoying that innit? Most flat pack is also a mixture of pozi & phillips fixings.

[<me9]

True.

The canadians did that. He wouldn't give the idea to Ford (he would sell them screws) so they invented their own.

Marketing over utility.

[<me9]

Supadrive.

[dennis]

You should use torx socket screws. They are positive unlike pozidrive. Very popular in Germany from what I have seen.. not so popular here.

[dennis]

The driver wouldn't slip out of the head when it was supposed to if it were pozi. Those auto-feed guns would be a lot more difficult to make.

[Dave Liquorice]

Naw they are mixture of Phillips, Pozi ad Pro drive. You just need to select the correct bit for the screw you are about to drive. Pozi and Pro are close enough but miss-matching phillips with pozi/pro is asking for trouble. Bits and screws are easy enough to tell apart though.

[Skipweasel]

Always seems to be 4mm Allen to me.

[geoff]

In message , George writes

No it wasn't, unless GKN in Telford has suffered a temporal displacement (now there's a good idea)

It was developed by the father of someone I used to play in a band with

[Bolted]

If you'd used them, you'd know how true that was.

[Bolted]

I thought it was GKN too, but according to the Phillips Screw Company link in an earlier post, that's bollocks, and it was invented by Phillips and licensed to GKN, who had the worldwide clout to make it a standard. So I suppose it depends what your mate's dad meant when he said he 'developed' it - maybe he meant he popularised it by selling loads or something. Or Phillips are lying

(see 1966)