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Phillips vs Pozidrive and portable drills

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old mart05/07/2019 17:04:20
4655 forum posts
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As soon as you use posidrive or phillips in an electric drill, it becomes normal to have to throw away the bits after every dozen screws. I always buy my pozidrive #2 bits in boxes of 25 at Screwfix. They are made of "S2" steel, whatever that is.

The square drive screws are excellent, although I personally favour torx.

Robert Atkinson 205/07/2019 17:07:42
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1891 forum posts
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It's not just simple Phillips / Posidrive. Two fairly common variations are the Japanese JIS which is close to phillips but less pointed. Then there is Supadriv which neither Phillips or Posidriv fit properly. JIS headed screws are often identified by a dimple on the head.

More esoterically there is RIBE/Polydrive (used on FCA nd GM vehicles) and Spline which look a bit like Torx. As an aircraft engineer I have also had to deal with Bristol spline TorqSet, Triwing and Hi-Torq.

Robert G8RPI.

Edited By Robert Atkinson 2 on 05/07/2019 19:33:22

JasonB05/07/2019 17:16:22
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25215 forum posts
3105 photos
1 articles
Posted by old mart on 05/07/2019 17:04:20:

As soon as you use posidrive or phillips in an electric drill, it becomes normal to have to throw away the bits after every dozen screws. I always buy my pozidrive #2 bits in boxes of 25 at Screwfix. They are made of "S2" steel, whatever that is.

The square drive screws are excellent, although I personally favour torx.

Well there is your problem, a box of Sh**2 bits will not last as long as a single decent bit costing more than the box full of Titan brand

Michael Gilligan05/07/2019 17:27:24
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23121 forum posts
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Posted by Robert Atkinson 2 on 05/07/2019 17:07:42:

As an aircraft engineer I have also had to deal with Bristol spline

.

Do you happen to know of a reasonably priced supplier [to the UK]

... I have a set of small keys, but need a couple of larger ones.

MichaelG.

Tim Stevens05/07/2019 17:38:51
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1779 forum posts
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Roberton heads were used on Vauxhall motor cars for the bodywork, in the days when they were made in Vauxhall, London UK (up to about 1928). Or, to be more accurate, until they were taken over by General Motors, at least.

Just in case anyone thought they were 'just Canada'.

Cheers, Tim

Edited By Tim Stevens on 05/07/2019 17:40:31

Robert Atkinson 205/07/2019 19:45:13
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1891 forum posts
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Posted by Michael Gilligan on 05/07/2019 17:27:24:
Posted by Robert Atkinson 2 on 05/07/2019 17:07:42:

As an aircraft engineer I have also had to deal with Bristol spline

.

Do you happen to know of a reasonably priced supplier [to the UK]

... I have a set of small keys, but need a couple of larger ones.

MichaelG.

I use Xcelite which are available from RS Comoponents e.g.

https://uk.rs-online.com/web/p/screwdrivers/2550519417/

but even then they are extended range.

Snap-On sell a set of L type ones but they will set you back about £150

Robert G8RPI.

not done it yet05/07/2019 19:52:17
7517 forum posts
20 photos

Cheap screwdriver tips suck. I just have a couple of each size fro HIS or Sterling bolts and nuts. Good quality ones last ages. An electric screwdriver with variable torque limit is a must, or either the screws or the tips will suffer.

Buy Reisser and see the difference in quality. You won’t go wrong with a decent quality product.

Michael Gilligan05/07/2019 20:03:45
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23121 forum posts
1360 photos
Posted by Robert Atkinson 2 on 05/07/2019 19:45:13:

I use Xcelite which are available from RS Comoponents e.g.

https://uk.rs-online.com/web/p/screwdrivers/2550519417/

but even then they are extended range.

.

Thanks Robert ... I hadn't thought to check RS

MichaelG.

Plasma05/07/2019 20:47:12
443 forum posts
1 photos

The impact driver type screwdrivers are great but do go through bits like sh1t through a goose.

Even the bits labelled for impact use seem to suffer wear and tear.

I've just bought a Facom pocket box of bits and a ratchet and the bits are excellent. My old snap on ratchet driver still has the original bit selection and few of them are shot.

Maybe we should all buy a 3foot long yankee driver and bin the Bosch lol

Regards Mick

Robert Atkinson 205/07/2019 22:01:18
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1891 forum posts
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Mick said " Maybe we should all buy a 3 foot long yankee driver and bin the Bosch lol "

About 15 years ago I used to take machines to trade shows in the USA, The machnes were shipped in crates with lots of screws to open them . Having got fed up with short battery life on the cordless drivers back then and restrictions on carrying spare bateries on aircraft, I bought a yankee. Never goes flat (but you can wear out) and has automatic increased contact pressure with increased torque so hardly ever slips. Numerous people would come over and say " that's great, I'd fogotten about those" or similar. Not cheap but a great tool.

Robert G8RPI.

Harry Wilkes05/07/2019 22:13:23
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1613 forum posts
72 photos

I had a 'Brum' fitter work for me he was good he didn't need a brum screwdriver he oxy/acetylene wink

H

HOWARDT05/07/2019 22:16:10
1081 forum posts
39 photos

I also still have a Yankee in my tool bag the bits are still good after 45 years of use. But the thing I found with drill driver bits was to test them for fit in the screw being used, some just don’t fit very well.

Mike Poole05/07/2019 22:53:07
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3676 forum posts
82 photos

A friends father was using a Yankee that slipped out of the screw and powered up his nose, ouch!

Mike

MK_Chris06/07/2019 11:06:57
18 forum posts
3 photos

Here is my “take” / understanding of the difference between Phillips and Pozidrive.

The angle built in to a Phillips head is designed to “cam out” when the torque limit is reached. Hence no shearing of the head due to over tightening. The results can be a bit variable and depend on the pressure exerted on the driver.

Production tools such as air guns, battery tools etc. came with torque adjustment. The tool and not the operator provides the required torque limit. Hence the Pozidrive variation with a different head design was introduced. It retained the quick location of a driver with the pointed target system and the four extra notches added helped with visual identification.

Battery drills almost always have a torque slipping clutch system built in behind the chuck. Usually marked 1 to something and ending with a No slip drill setting. I rarely see anyone use the torque settings on a battery drill : and have met a number of DIY'ers who did not know the purpose of the dial.

Now hoping for more accurate detail from the many knowledgeable on this forum.

Chris.

ega06/07/2019 11:34:51
2805 forum posts
219 photos
Posted by JasonB on 05/07/2019 14:15:30:

The most common use of square drive screws in the UK is for pocket hole joinery where "kreg" are the common brand made popular by Norm on NYWS. That's about the only thing I use them for, driver does tend to stay in the hole well.

I got my Kreg outfit from Axminster before they went over to the ujk brand. The Kreg-supplied screws seem to be Robertson and drive very well as long as axial alignment is maintained. The ujk equivalent is T20 where the connection between driver and screw head is perhaps not quite so positive.

When Pozidriv came in I think the idea was that it could be driven with a Phillips driver but not the other way round which may be the answer to the OP's question.

A character in Victoria Wood's classic sitcom, dinner ladies, was asked if he had any real regrets about his life and replied that he blamed himself for failing to appreciate the importance of the cross point screwdriver!

Michael Gilligan06/07/2019 12:40:48
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23121 forum posts
1360 photos
Posted by ega on 06/07/2019 11:34:51:

When Pozidriv came in ...

.

yes at last, someone spells the name correctly

MichaelG.

.

P.S. this is succinct **LINK**

https://www.pbswisstools.com/en/news/detail/phillips-and-pozidriv-cross-head-screws-explained-in-simple-terms/

.

Edit: Back in 2016, Bugbear posted the patent numbers

https://www.model-engineer.co.uk/forums/postings.asp?th=118584&p=1

Edited By Michael Gilligan on 06/07/2019 13:03:33

Vic06/07/2019 14:25:08
3453 forum posts
23 photos

Almost on topic ... An old friend of mine worked at a school as a physics lab technician. One day one of the physics teachers asked him if he could borrow a screwdriver overnight for a job at home. Yes of course was the reply what type do you want, slotted or cross type? “oh I don’t know I’ll have to go home and have a look”! They walk amongst us ... smiley

ega06/07/2019 16:58:29
2805 forum posts
219 photos

Michael Gilligan:

Thanks for the link and the thumbs up. It's good to know that my recollection was on the right lines.

The linked article mentions colour coding, an excellent idea in the circumstances particularly for bits with tiny markings. I think that Wera used to put a coloured ring on their bits.

Kiwi Bloke07/07/2019 09:25:57
912 forum posts
3 photos

I find it hard to believe that the Phillips drive was designed to 'cam out'. The axial component must be very small, given the very small wedge angle of the drive flanks. Whether the driver 'cams out' or not will depend on the axial force applied by the operator (in my case, often a large proportion of my somewhat excessive weight) and the friction between driver and recess. And if it was an intended feature, the idiot designer didn't think about subsequent removal...

Good old-fashioned screwdrivers for slotted screws (remember them?) are, of course, tapered too. Is this a designed-in torque-limiting feature too? Parallel-tipped drivers are much more secure than tapered tips. Interesting that gun-makers of old often used screws with very narrow and deep slots, designed to be driven by the finely-tapered tips of 'turnscrews'. These fancy-named screwdrivers wedged securely in the slot, making slip-out unlikely. Useful when fixing very expensively-engraved actions into stocks, etc.

I thought that GKN patented Posidriv in the mid-'60s, so it was a late-comer, in competition with long-established Phillips, and the yanks adopted a 'not invented here' attitude. I think the popularity of the different patterns has more to do with commerce than engineering.

The Robertson drive is very common here in NZ. Note that its driver is also tapered, so might be expected to 'cam out', if the Phillips theory is correct. I have driven about 100 in the last few days, without any problem.

Michael Gilligan07/07/2019 15:46:45
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23121 forum posts
1360 photos
Posted by Kiwi Bloke on 07/07/2019 09:25:57:

I find it hard to believe that the Phillips drive was designed to 'cam out'.

[ ... ]

And if it was an intended feature, the idiot designer didn't think about subsequent removal...

.

Why do you find it difficult to believe ?

Rather than 'camming out' ... just think of it being like a self-releasing taper on a machine tool spindle. [so much more convenient than the self-locking Morse]

They were designed for use on production assembly lines, and frankly 'the idiot designer' didn't care about convenience of removal.

MichaelG.

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