Tuesday, January 12, 2016

The many faces of PHILLIPS

Or, when close is just not close enough. Will the real Mr Phillips please stand up...

Seems I raised a few questions worthy of  a tad closer scrutiny, with regards to some of my statements referencing the Phillips look-A-like confusion...

So here is what I meant by "close but not close enough".
You must use the right driver for the fastener type, or....
Curse(s) to follow for sure :-)

The Original Phillips

Well actually, it should have been known as the "Thompson" screw, for its inventor, but instead it became better known as the "Phillips" as in the business man Henry F. Phillips who bought the rights from John Thompson, inventor, who could not interest anyone with his invention.

PAT 363264
STANLEY (in notch corners box)

Phillips went on to start the Phillips Screw Company in 1934, tweaked the original design slightly and promoted its adoption in the industry.

Code PH

As in PH2 (Phillips No 2)

By then Henry Ford had been seduced by the Robertson. The Ford operation in Milton Ontario Canada was using them and saving $2,60 per car, but Henry could not buy it from P.L. Robertson, rights and all, so he went looking for something else that could save him time on the assembly lines. He found the Phillips, it became "the" fastener to use on the assembly lines (including in Milton On), and the Robertson never became known in the US, only in Canada and abroad (mostly British Commonwealth countries).

Back to Phillips, the reason all these various fasteners have multiplied and evolved to replace the common or slot screw, is because of industrialization and the rise of the assembly lines...
With the introduction of the assembly line Ford reduced the time to manufactured a Model T from 12.6 hours to 93 minutes with a completed car rolling off every 3 minutes.
Now consider this:

- With a slot screw it is difficult to center the driver in the slot, takes trial and errors to keep it centered; Take time.
- With a slot screw it is difficult to have he fastener standing at the driver tip, while handling the driver. You have to hold it, put it on perhaps a few times, losing some, take one more hand to use; Wastage of fasteners and, Take time.
- With a slot screw it is all to easy to cam out and damage the slot.
Need to slow down and be careful, possibly replacement: Take time.

These are some of the reasons for increase efficiency on the assembly lines, which saved Ford $2,60 per car using Robertson. Multiply that by, say 4000+ cars and that is a sizable amount... (almost $10.5K)
In 1926, Ford produced 1,911,705 Model T and sold them for US $260
(approx US $3,510 in 2016)

The Model T made by the Ford Motor Co, was one of Robertson's first major customers, it used over 700 Robertson screws.

Get the point about efficiency and savings ? :-)
But that was not good enough for Ford, so the Robertson were phased out (in Ford Canada also) and the Phillips took over.

The importance of the Robertson and the Crosshead screw (Phillips) design
lies in their self-centering property which is very useful on automated production lines that uses powered screwdrivers.

Ford Assembly line circa 1913. 
Note the uses of braces, and Yankee types screwdrivers. 
The later Robertson and Phillips design enabled the introduction 
of powered drivers, and much saving in time.

These early automated drivers, mechanically belt-driven or by the newly introduced small portable electric motors, revolutionize speed on the assembly line, but it only became possible with the introduction of self centering screw head designs (Robertson and Cruciform(s)).

Whereas Robertson failed to take hold as it should, Henry Phillips major contributions was in driving the crosshead design forward to the point where it was adopted by screwmakers and the automobile industry in the largest market... the U.S. of A.

One of the first Phillips's customer was General Motors, who used the innovative design (Excuse me while I puke) in 1936 for its Cadillac assembly lines.

By 1940, 85% of U.S. Screw manufacturers had a license for the design.

Here's the irony, the Phillips Screw Company, established in 1934, never produced screws or drivers, they just licensed others manufacturers to produced them to their standard. By then the Phillips screw was clearly established to take over the world by storm... Well, then there was that thing called WWII...

AS good as they are to center and engage the pointed tip. Get anywhere close, and it should slide in. Here is probably the ONE, albeit, small advantage over the Robertson.

BUT The cross-shape indentation is so shallow that, when you are fully in (Max torque), the driver pops out (Cam-out). That is great on assembly line during fastening, but is a pain to unscrew by hand. The screwdriver often slip and damages the slot. Remember it cam-out at a given torque.

So... There must be a way, to invent a better way, by modifying the original Phillips... And they sure tried...


Also known under the name of Frearson:

Code PH and RP or F

NOT so easy to tell, is it?

Notice the change in the angle at the tip, that is to reduce Cam-out at higher torque. Problem is they look so alike, if you use a Reed & Prince driver on a Phillips screw, you will not engage very deep and you will cam out faster.
Ironic, it's the problem they were seeking to solve! Notice the slight difference in the middle of the screw. A Phillips may not fit on all Reed & Prince but a Reed & Prince will always fit (poorly) on a Phillips.

It was developed by an English inventor, Frearson, in the 19th century and produced from the late 1930s to the mid-1970s. Why so much time between Frearson invention and R&P manufacturing? You had to wait for the American Screw Company of Providence Rhodes Island to efficiently produces the Phillips screw. Other screws manufacturers of the 30s dismissed the concepts of the Phillips because it called for a relatively complex recessed socket shape in the head of the screw, as distinct from the simple milled slot of a slotted type screw.

In comparison, Robertson "production complexity problems" were solved by 2 drop forge blow to the screw blank to shape the head and stamped the tapered recessed square drive. It is even faster than milling the slot...

The Reed & Prince Mfg Company of Worcester, Mass. was put into bankruptcy in 1987 and liquidated in 1990.


Having not really solved the problem with the Reed & Prince, but introducing confusion, the next bright improvement was the Pozidriv

Code PZ

The Pozidriv screws are visually distinguishable from Phillips by a set of radial indentations (think of tick marks) set at 45 degrees from the main cross recess on the head of the screw.

YES, that makes the manufacture of driver bits slightly more complicated.
Attempting to use a Phillips screwdriver bit on a Pozidriv is likely to cause damages, because the differences in the design are fairly significant.
even if at first glance they somewhat look alike.
The Pozidriv was designed specifically to allow much greater torque to be applied, because of its more positive engagement.

A Phillips driver has an angle on the flanks, a pointed tip and a round corners.
A Pozidriv driver have straight sided flanks, a blunt tip, and additional ribs at 45 degrees to the main slots. (Take away the extra tick marks and you have essentially a JIS screw)

A chief disadvantage of the Pozidrive is that they are quite similar and often confused with Phillips. People are not aware of the major differences and uses the wrong driver tip with the resulting damages done, to both driver and screws.

If you own or install European hinges, you owe it to yourself and the poor adjustable screws on them, to invest in the proper screwdriver bit...

Japanese Phillips

In the confusing world of look alike Phillips screwdrivers, one must make mention of the Japanese version; the JIS B1012:1985 Cross recess for screws.
Japanese Industrial Standard "B" is for Mechanical Engineering, 1012 is the applicable standard Nos, and the last 4 digits are the year of latest revision.
There is incidentally a 1974 version of this document

If you ever dissembled Japanese equipment in the past 30 or so years, you came across it probably without knowing.
Yes, screw and driver bits look like a Phillips, but surprise, they are different and yet again, damages will results if you uses the wrong driver.

Decades ago, the Japanese camera industry designed a different plus/cross shaped (Cruciform) screw head and driver to prevent cam-out and allow more torque.

It looks like a Phillips screw, and are often referred to improperly as Japanese Phillips,  but it is designed not to cam out so easily and will therefore be damaged by a Phillips screwdriver if it is too tight, because it will not afford enough purchase on the screw head.

The JIS screws are usually, but not always, identified by a recessed dot on the head

See the dot on the two screws on the left and the one on the right.
The two red colored ones (Panasonic) are also JIS but do not have the dot.

Notice the dot position. Hard to see but the walls of the cross slots 
are more vertical than the Phillips.

or the fact that they are completely damaged beyond recognition and will only come out with a pair of Vise-Grip :-)

Totally mangled screw recess, not a Phillips, a JIS. 
Or I should say... was! Start to look more like a Robertson :-)

The difference are in the wall of the slots, they are parallel and will cause the regular Phillips to cam-out of the screw as you try to turn it.
The corners at the center of a Phillips head screws have a slight radius supposedly designed to allow the Phillips head screwdriver to cam-out as a sign that maximum torque as been applied.

The JIS also has shallower depth preventing the taller head design of a Phillips head screwdriver to properly grip the sides of the fastener slots.

Phillips driver holding JIS Screw: Poor fit.

The biggest give away is the lack of enlarged space where the two slot meets. Very similar to... YES... the Reed & Prince, but again the angle of the driver wings are, yet, different.

And yes, you can buy specific driver for this type of screw. Electronic servicing supply stores or Japanese bike shops are a good source for these.
And if anybody is trying to sell you a regular Phillips telling you that...
they are the same... Run don't walk out of there...

The Ultimate Phillips

And here is the final proof of what was perhaps the best fastener all along...

The final solution to the cam-out problem was solved by the "Revolutionary" (Excuse me while I puke again) Anti-Cam out Recess (ACR) which was developed for the aerospace industry to avoid costly head stripping and to assure easy insertion and removal of screws during assembly and maintenance. The ACR system creates a stick fit that makes screw driving easier

WOW, Brilliant!
The ultimate solution to the Phillips deficiencies was to add a Square Drive (Robertson) into the middle of the Phillips head, pure genius :-)

The Phillips/square, or Quadrex, or ACR, 
or Pozisquare or Deck Mate and etc.

The original Robertson (Tm)

Holding on to screws effortlessly since 1909

Bob, who you may have guessed, find his Robertson much superior to the many flavours of Phillips... :-)


  1. Now I know why I have cursed so many 'phillips' screws over the years. I always thought the Japanese ones were a cheese head design and I mangled a lot of the R&P screws not knowing any better.
    I just bought 2000 #8 spax screws that are the ACR design. I was hoping to get Robertson heads but maybe this is the best of both worlds meeting?

  2. Hi Bob,
    This seems to be a lot investigation.
    A lot of facts which I did not know, until now.

  3. Sorry Ralph no such things as best of both world, a Phillips under any disguise is still crappy :-)
    But maybe it will fit a smaller Square drive?

  4. Hi Stefan
    yes that was the results of a "few days" research. Seems that is all I can do right now...
    Hopefully, the results will same a few screws from being mangled :-)