I don't know what the point of them is compared to the slotted ones. They don't hold the screwdriver well and if you give them a good push and twist the pozi-cross disintegrates and you end up with a misshapen hole that you can't unscrew, something that never happened to me with the slotted ones. I'm also anxious when dealing with them about this point, never wanting to destroy the cross. I hate them.
Sounds like you used a philips screwdriver and not the proper pozidriv one. If you use the right one (there is only one size that fits a given screw, neither amller nor larger works) they are really nice and don't tend to drop off from the screwdriver.
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Just use Robertson...
Chris
Well if you are using these screws for woodworking may I suggest you step up or back to a 19th or 20th century design screw, actually older than the pozi-cross and Phillips screw. Try the Square drive screw. You'll never look back.
Me too. Why don't more people (or manufacturers or retailers, I guess) use square drive? Far less likely to strip, the screw stays on your bit, and the bit doesn't tend to cam itself out of the screw like most of the common designs now. Is Robertson a brand of square drive? I couldn't tell for sure after 30 sec of looking at their website. I find myself using Rockler's square drive screws (I know, McFeeley's or Robertson? are probably better...) even when a cheapo drywall screw will do, just because I like the square drive. Andy
Posidriv screws were developed primarily for high-speed automated assembly systems. Dr. Hanappel is correct that there is a specific driver for a specific screw. The majority of the European style cabinet hinges adjust with Posidriv screwdrivers. Adjusting them with Philips drivers can cam-out and destroy the screws.
Robertson square drive screws are the best for woodworking applications as they come in all the right sizes, thread-counts and thread-depths. McFeely's sells screws that simply can't be beat for holding power and strength. The reason why square drive screws didn't get the attention they deserved was that the automotive industry didn't like them. The can jam an automatic-feed driver. The bit won't insert at 45 degrees to the hole. Posidriv screws solved that problem.
Never use a Philips bit to drive a Posidriv.
That may very well be true but originally Henry Ford was looking for a better screw than the slotted screw. Robertson showed him his screw, Ford liked it and wanted to buy the rights to manufacture the Robertson screw. Robertson was only interested in supplying the screw and not selling the rights to manufacture the screw. Negotiations stopped there. Later, this guy Phillips came along, showed him his screw, and the rest is history.
Although that's also my understanding of the chronology, there's a little more to it according to McFeeley's catalog. As it turns out the thing the Robertson is great for (positive action without slipping) is anathema to mass assembly. It's much easier to have the tip "cam out" of the head (as a Phillips will do) for torque control than can be done with the square drive. So the failure of the negotiations was a happy accident (for industry).
Robertson is the original square drive, named after the inventor.
He got screwed over by a British licensee, then because of that refused to let Ford license and exclusively distribute them in the US. Phillips had no problems with those terms.
The rest is history.
The patent expired in '64, so they're slowly making their way out of Canada now, becoming more popular elsewhere.
Chris
Ultimately yes indeed. I think Ford was probably putting each screw in by human power back then One at a time. Had he had a fast way of using slotted screws the square drive surely would have been faster. LOL Ultimately the Philips is quicker for fast multiple installations. Dry wall screws are another situation where the Phillips design works out better.
If I remember correctly from the Modern Marvels episode on "The Hardware Store", Phillips, himself, didn't invent the screw named for him. He was just a business guy who bought the rights.
Josh
Le> >
How would I know the difference between a Philips and a Pozi-cross?
Amen to hating the pozi-drive. I used to buy the Spax uni-drive( a Robertson -Phillips hybrid) from LV in #8 x1 1/4 ". Now it seems that length is available only in the much hated pozi-drive version. I'm almost out of my supply of the good ones, with no replacement in sight( except ordinary robertson head screws). I guess I should be complaining to Robin Lee
A Phillips is in the shape of a four pointed star. So is the posidriv, but it has small lines running at 45 degrees from the centre of the star... so it looks like two Phillips stars... one of them too shallow to take a driver.
That version sounds plausible too. But try to find an auto-feed square drive screw system. It is not suitable for rapid insertion as the driver and screw can find themselves at exactly 45 degrees, stopping the driver bit from insertion. The other reason is that the bit and hole are almost the same size, .. with Phillips or Posidriv, the tip is much smaller than the opening at the head of the screw making insertion inevitable without risk of a jam.
I'm talking about automation screw drivers which can screw several per second. (Usually stationary equipment on an assembly line.)
I wouldn't be a bit surprised if Mr. Robertson got 'Avro-Arrowed'.
The Model T Ford had 700 square drive screws in them according to this blurb:
Robertson Screw In 1908, square-drive screws were invented by Canadian P. L. Robertson. Twenty-eight years before Henry Phillips patented his Phillips head screws, which are also square-drive screws.The Robertson screw is considered the "first recess-drive type fastener practical for production usage." The design became a North American standard, as published in the sixth edition of Industrial Fasteners Institute Metric and Inch Standards. A square-drive head on a screw can be better than a slot head because the screwdriver will not slip out of the screw's head during installation. The Model T car made by the Ford Motor Company (one of Robertson's first customers) used over seven hundred Robertson screws.
Phillips Head Screw In the early 1930s, the Phillips head screw was invented by Henry Phillips. Automobile manufacturers now used car assembly lines. They needed screws that could take greater torque and could provide tighter fastenings. The Phillips head screw was compatible with the automated screwdrivers used in assembly line.
Source:
They seem hard to find. I went to the store today with the Robertson in mind and I couldn't see any. They had all sorts of slotted and pozi-cross, perhaps 50 or more varities each, but I never saw any square ones.
Oh, that explains it! I always wondered what they're doing in those DIY TV shows when the host is stripping the screw head - they're controlling the torque by cam-out! ;)
Seriously, it seems to me that it must be a piss poor manufacturing operation that utilizes cam-out to control torque. Kind of like using blood loss to indicate the end of the work day.
R
A Pozi driver will not fit in a Philips screw. A Philips driver will fit very loose in a Pozi screw. A Pozi driver will have PZ and a number on it, such as PZ2. I think Pozi screws are getting a bad rap here. For some applications they are fine, such as for Euro hardware and the hi-lo screws for Melamine.
Well CRAP Robatoy...!!!! The History Channel sure has a different spin on that. I'll keep that in mind the next time some one asks. Thanks.
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