When a Phillips Is Not a Phillips!

Cross-head, Cross-Point, Cruciform,
Square Drive Screws and Drivers

These screw types have a "+" shaped recess on the head and are driven by a cross-head screwdriver, designed originally for use with mass-production mechanical screwing machines. There are a few other recessed drive screws presented that you also want to be aware.

So, why all the confusion? Why all the damaged screw heads and drivers? Why is this screw and driver thing so awkward? Read on and be amazed while I unravel the mystery of screw drives and present some you may have never seen.

For each screw drive type, from ancient Slot through to space-age Lox we present a quick view of the screw head, the drive name, a picture of the appropriate drive bit, followed by an explanation of the type. Also presented are the advantages and disadvantages of each drive type. Slot type are also included because that is where the screw began and a double slot becomes a cross drive, and the Robertson or square drive enter the story with recent combined Phillips/Square drives. The Allan, Spline, Torx etc drives are not included and maybe neither should the Uni-Screw, it is just so darn new and interesting.

This article contains a lot of information and pictures from the Internet. Maybe it will be the definitive guide with your help it could get close. If you disagree with any of the information or if I missed a related drive you know of, please let me know where I can validate the information. Misinformation, incorrect illustrations, screwed up usage of terms on the Internet and elsewhere is rampant and part of the problem created by so many drives.

First a little background:

A screw is really a shaft with a helical groove or thread formed on its surface. Its main uses are as a threaded fastener used to hold objects together, and as a simple machine used to translate torque into linear force. It can also be defined as an inclined plane wrapped around a shaft.

Every threaded fastener needs a way of turning it. Whether a wrench fits a hex-head bolt or a nut, or it may have a shaped and recessed hole into which a driver can be inserted.

Around the first century, screw shaped tools became common, however, historians do not know who invented the first. Early screws were made from wood and were used in wine presses, olive oil presses, and for pressing clothes. Turning the screw was accomplished with a drive rod handle positioned through the perpendicular hole.

Metal screws and nuts used to fasten two objects together first appeared in the fifteenth century.

In 1770, English instrument maker, Jesse Ramsden (1735-1800) invented the first satisfactory screw-cutting lathe. Ramsden inspired other inventors. In 1797, Englishmen, Henry Maudslay (1771-1831) invented a large screw-cutting lathe that made it possible to mass-produce accurately sized screws. In 1798, American David Wilkinson also invented machinery for the mass production of threaded metal screws.

The screw on the left (A) was handmade in the late 18th century. Note the flat spot on the shaft, the irregular threads, blunt tip and the off center slot. The screw in the center (B) is machine made around 1830. It has sharp, even threads, a cylindrical shape, blunt end and the slot is still off center. The screw on the right (C) is a modern gimlet screw, post 1848, with tapered shaft, even threads, pointed tip and centered slot.

Cutting a slot in a screw head to turn it is an old idea: drawings from the 16th century show screws with slotted heads.

Advantages and Disadvantages of Slot Screws

The advantages of the slotted head are that: most people have a screwdriver that fits them (sort of); worn drivers are easily reground; a new screwhead slot can easily be cut with a hacksaw. Otherwise the slotted head is the worst screw drive system, and while very common, it is also generally obsolete. Some of its deficiencies include: a screwdriver does not automatically line up with the slot; it is easy to get off center; the user must keep the axis of the screwdriver aligned with the axis of the screw; the driver can engage the head in only two possible positions, at 180 degree to each other. The sides of most slotted screwdriver bits are tapered. When the driver is turned it tends to be pushed up and out of the screw head. This is called camout.

To add to the shortcomings of the slotted head, screwdrivers for slotted screws are usually described by the length of the shaft and the width of the tip; the crucial measurement, the tip's thickness, is not given. Any given tip width is sold in a range of thicknesses; the longer shafts usually have the thicker blades.

Double-slot cut screw heads, with cuts offset by 90 degree is rarely used or seen today.

Advantages and Disadvantages of Crossed- Slot Drive

The advantage of this type of screw head is there are 4 ways to engage the screw. Screw heads need to be thicker and harder to accept the drive. Otherwise all other advantages and disadvantages remain the same as the single Slot Type Drive.

The Shuenn Chang Fa Enterprise Co of Taiwan makes this unique cross slot drive head type. No other information on these or even if there is a special driver for them. Let me know by email if you can verify the applications and whether a special driver is used or required.

Fellow Instructable contributor further explains ironsmiter says:

The Lotus Head Drive is basically a standard cross-slot screw, as it looks, but the slots are produced by a "much cheaper process". Basically, the head is split by a chisel type tool.

The theory is that, by not removing any material, the head retains the full material strength. This is a similar theory as to how a hole that was been punched and drifted, by a blacksmith, is stronger than one that has been drilled out. The head can also be formed by a machine that costs significantly less to buy and to operate than a recessed head.

The use for these screws is mainly for machine assembly. The constant pressure of the machine driver spindle prevents "skipping" of the bit (that would cause a stripped head, if using hand tools to drive the screw). There is a slightly modified Phillips bit that is used to drive them. It has a matching taper and flat bottom.

The example shown is a "quickthread" allowing it to be driven at twice the depth per turn, as compared to a normal screw. It is also a self-drilling model. Primarily designed for use in plastics. You will find similar threads holding almost any cheap plastic radio, light fixture, toy, together.

These are all "improvements" to speed up manufacture, and use of the screw. How successful it is at that, I do not know. Just hope you never have to remove one of these. Trying to get a standard Phillips bit, even if you modify it for the flat bottom profile, to grip on these screws is a Royal Pain (frowning) See end-load in appendix.

While not a true cruciform recessed drive (similar physical force principals apply to a square and a cruciform as shown in Step 7), it will be important to understand these as well. Note: Square Drive is not identical to Robertson.

In 1908, square drive screws were invented by Canadian Peter L. Robertson. Twenty-eight years before Henry Phillips patented his Phillips head screws. The Robertson screw is considered the "first recess-drive type fastener practical for production usage." The design became a North American standard.

Henry Ford used Robertson screws in the Model A car made by the Ford Motor Company (one of Robertson's first customers). The Model T used over seven hundred Robertson screws. Ford dropped these screws when Robertson refused to give him exclusive rights to its use. Robertson also refused to license other fastener manufacturers, so the design spread very slowly. Many recreational vehicles built in the 1950s use these screws. In Canada, most wood and electrical screws have Robertson recess heads.

Advantages and Disadvantages of Robertson Screws

A square recess drive allowed the screw to be placed on the driver prior to the screw being placed in position, so for the first time ever you could start a screw overhead or in a tight spot without an extra hand holding the screw onto the driver. A Robertson head on a screw is much better than a slot head because the screwdriver has great resistance to camout of the screw's head during installation and 4 possible positions to insert the driver. The Robertson drive design utilizes a "Morse-like" taper so the screw will stick to the bit even when held straight down. This taper allows the tool bit to insert deeper into the recess for more contact surface and thus less camout. To avoid problems make sure both screw and driver are of the matching type as there are many square drive drivers and screws around today that are not Robertson. See Square Drive (next topic). Robertson screwdrivers are available in 6 standard tip-sizes, none metric. Orange and orange are seldom used. The largest black is quite rare. Each identified usually by the handle color rather than by number.

Thanks Brian J. Cooley, Robertson Inc., Tools Division Product Line Manager for North America, for adding information on the 6th Robertson size and for pointing out ALL true Robertson Inc. power bits and insert bits are of the 2 piece variety, they have never produced one piece bits. (I've changed the reference picture as the original one was not not a true Robertson). An easy way for consumers to tell if any fasteners came from Robertson Inc. They use the ® following Robertson ® on all of the products manufactured.

Only Robertson makes Robertson screws and drivers, the others are generically called Square Drive and are made by several manufacturers and brands since the patents have expired on the Robertson. The Square Drive head is an American clone of the Canadian Robertson that has a square recess but not tapered and has very sharp corners. Likely this difference was to avoid patent infringements. The patented Robertson driver has a slight taper, and slightly rounded corners.

Two methods of fabrication are the machined one piece and the two-piece is a forged steel tip press fitted into a regular steel tip holder part. Several companies each with their own select brand name produce square Drive.


Advantages and Disadvantages of Square Drive

Due to the lack of taper, the hole must be oversize relative to the screwdriver, and is much more likely to camout than the Robertson. It is infuriating that Home Depot and the tool companies like Bosch and Dewalt bring square drive bits into Canada that nearly fit Robertson screws and are marketed as equal and are unmarked. For any Canadian readers that want bits that work, try to buy the bits that are color-coded red, green, black as well check the engraving is an R on the bit. Dont trust the cheaper bulk packs. Never trust a Robertson that says "Made in America"; it is likely a Square Drive. A "fresh" US square drive driver with a "real" Robertson screw head sticks so tightly that it can take a significant yank to get them disengaged. This is advertised as a selling point of the US Square drivers here in Canada. Unfortunately, if you have a pop out, the driver is usually means youre damaging the tool and is difficult to use from then on. Real Robertson drivers do not suffer from this with Robertson screws. So, while they don't stick quite so tightly, the drivers really do last a long time, and they're just as good at keeping grip under power. Bit sizes come in only four sizes and application and are rarely color-coded.

This cross drive screw story starts when Henry Phillips purchased a crude form of a cruciform-recessed screw head concept from an Oregon inventor named J.P. Thompson.

Henry F. Phillips (1890 to 1958), a U.S. businessman from Portland, Oregon, has the honor of having the Phillips head screw and screwdriver named after him.

The cruciform shape can be considered to be a cruciform design with their 90 degree shapes as most have similar physics properties.

Phillips developed Thompsons invention screw into a workable form. Phillips had come up with a recessed cross screw designed for efficiency on an auto assembly line. The idea was that the screwdriver would turn the screw with increasing force until the tip of the driver popped out, called camout. When tightening a Phillips screw with a Phillips screw driver you will notice that when the torque gets to be too strong, the screw driver winds itself out of the screw so the screw head would not be ruined or brake off.

Phillips also founded the Phillips Screw Company in Oregon in 1933, but never actually made screws. He had called on every established screw manufacturer in the US and was told simply that the screw could not be made. Screw makers of the 1930s dismissed the Phillips concept since it calls 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.

Phillips then called on the American Screw Company, a newcomer to the industry whose new president, Eugene Clark, personally became interested in the new product, despite the opposition of his engineers, who like others in the industry had insisted it could not be made. According to one printed report, the president of American Screw Company said: "I finally told my head men that I would put on pension all who insisted it could not be done. After that an efficient method was evolved to manufacture the fasteners and now we have licensed all other major companies to use it."

Use of the Phillips screws spread through the automobile industry at a rapid rate. By 1939 it was used by all but two automobile manufacturers. By 1940, Phillips screws were used by the entire automotive industry, although one major manufacturer still would not use them on its passenger cars. Gradually the Phillips screw and screwdriver worked their way into other industrial applications; then consumer products, and eventually showed up in hardware stores.

The American Screw Company spent approximately $500,000 in the 1930s to produce the Phillips screw and obtained patents on the manufacturing methods. It was the sole licenser of the process. By 1940 10 American and 10 foreign companies were licensed to manufacture the screw. Although Henry Phillips received patents for the drive design in 1936 (US Patent #2,046,343, US Patents #2,046,837 to 2,046,840), it was so widely copied that by 1949 Phillips lost his patent.

Phillips' major contribution was in driving the crosshead concept forward to the point where it was adopted by screwmakers and automobile companies. Henry Phillips died in 1958 at the age of sixty-eight.

The Phillips system was invented for use in assembling aluminum aircraft, with the object of preventing assemblers from tightening screws so tightly that the aluminum threads strip. The driver will cam out before that happens. The Phillips driver has four simple slots cut out of it, each slot is the result of two machining processes at right angles. The result of this process is that the arms of the cross are tapered and has slightly rounded corners in the tool recess. Phillips is designed so that when excess torque is applied it will camout rather than ream the recess and destroy the bit. The driver has a 57 degree point with a blunt tip, tapered wings. Identified in ANSI standards as type I.

Advantages & Disadvantages of Phillips

In all cross drive systems the driver will self-align with the fastener. The tapered design that allows camout can become a problem as the tooling that forges the recess in the head of the screws begins to show signs of wear. The recess becomes more and more shallow, which means the driver will bottomout too soon and will cause the driver to camout early. Another problem is even though the ease to insert, Phillips screws can be tough to get back out. The main disadvantage is the screwdriver pops out too readily, stripping the screw, gouging the work, and in general transferring all the problems that were formerly with the Slot design. Consumers are likely to think that any screw head with a cross drive recess is a Phillips, which can lead to problems.

A later cross drive system referred to in ANSI standards as Type 2 recess. It was developed by an English inventor named Frearson and was produced from the late 1930s to the mid 1970s by the former Reed & Prince Manufacturing Company of Worcester, Massachusetts (was liquidated in 1990 with the sale of company assets). Today it is mostly referred to as Frearson but occationally still by its former name of Reed & Prince. This drive is very similar to a Phillips but has a more pointed 75 degree V shape. It is found mainly in marine hardware. The tool recess is a perfect cross, unlike the Phillips head, which is designed to cam out.

Advantages and Disadvantages of Frearson

Its advantage over the Phillips drive is that one Frearson driver or bit fits all Frearson screw sizes, although there are 2 sizes available. Improved torque with minimal camout. Unfortunately the screw head recess appears to be a Phillips and so it is too easy to use the wrong tool or screw.

Often improperly referred to as Japanese Phillips. Commonly found in Japanese equipment. JIS looks much like a Phillips screw (and even more similar to Frearson), but is designed not to cam out and will, therefore, be damaged by a Phillips screwdriver if it is too tight. Heads are usually identifiable by a single raised dot to one side of the cross slot. JIS B 1012:1985 screw standard is throughout the Asia market and Japanese imports. The driver has a 57 degree point with a flat tip, parallel wings.


Advantages and Disadvantages of JIS

Most people and companies outside of Japan have absolutely no idea what they are. With the similarity in appearance to the Frearson and the Phillips the screws are often damaged in removing and installing with the wrong tools. JIS tends not to camout like Philips. The JIS driver can be used on Phillips quite easily but not reciprically. Drivers are not easily available in North America, try your local RC Airplane hobby shop. Most RC Helicopters use JIS screws to mount the propeller. JIS-spec cross-head screws are generally marked with a single raised dot or an "X". JIS always fit Phillip fasteners, but because of slight design differences, Phillips drivers may not fit JIS fasteners. (unless the tip is ground down a bit).

Sel-O-Fit is a registered trademark of Cooper Industries. The bits are designed to provide a more efficient means of driving Pozidriv screws. The driver has a 46 degree point with a flat tip, parallel wings.

The Sel-O-Fit bit places torque on the strongest and most mechanically advantageous portion of the driver tip. This allows more torque to be applied while minimizing the possibility of breakage and camout.

Also called BNAE NFL22-070 after its Bureau de Normalisation de l'Aeronautique et de l'Espace standard number. Possibly a security screw drive system. Easily confused with a JIS or Frearson recess screw but with driver blades are modified into two step diameters.

Pozidriv was jointly patented by the Phillips Screw Company and American Screw Company in the USA. Developed by GKN in the 1960s, the recess is licensed from Trifast PLC in the rest of the world. It is the de facto standard in Europe and most of the Far East, where Phillips is almost nonexistent. The proper Pozidriv screws have a flatter bottom to the socket, and steeper sides, so the driver doesn't cam out as easily. The name is thought to be an abbreviation of positive drive.

Pozidriv is similar in appearance to the classic Phillips crosshead, but in fact is substantially different. On close examination you will notice a second set of cross-blades at the root of the large cross-blades. These added blades are for identification and match the additional makings on the head of Pozidriv screws, known as "tick" marks, single lines at 45 degrees to the cross recess. So, the marks are for identification purpose. Pozidriv also does not have the rounded corners that the Phillips screw drive has. The tip or the driver is blunt which also helps it to seat better into the recess in the screw, unlike the Phillips which comes to a sharper point.

Identified in ANSI standards as type IA. Pozidriv drivers will not turn Phillips screws; but Posidriv screws can be turned by Phillips screwdrivers, although they should not be used as they tend to ride out of the recess and round the corners of both the tool and screw recess.

Advantages and Disadvantages of Pozidriv

The largest advantage it offers is that, when used with the correct tooling in good condition, it does not cam out, allowing great torque to be applied. The chief disadvantage of Pozidriv screws is that they are visually quite similar to Phillips, thus many people are unaware of the difference or do not own the correct drivers for them, and use incorrect screwdrivers. This results in difficulty in unscrewing the screw and in damage to the slot, rendering any subsequent use of a correct screwdriver unsatisfactory.

Often refered to as Pozidriv, these two drives are not exactly the same. Each has its own driver but both will also work with the other. The screwhead is similar to Pozidriv but has only two identification ticks and the secondary blades are larger.


Advantages and Disadvantages of Supadriv

The Supadrivs basic shape is similar to Posidriv and the drive blades are about equal thickness. The main difference is close to a near vertical surface to drive the screws into the drivers. With this superior bite screw driving is more efficient, with less come out.

Patented by the Phillips Screw Company to compliment the Phillips drive. ACR 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 advanced ACR Phillips system keeps the driver securely mated to the screw during fastener removal eliminating damaged screw heads and drives while preventing damage to costly panels, avionics and structures. The ribbed mating surfaces of the driver and screw head lock together providing greater maintainability. There are 3 types of the drive bit but the most common is for removal and driving.

Advantages and Disadvantages of ACR Phillips

Maintainers prefer the ACR Phillips system because they dont have to push hard on the driver, reducing fatigue and the risk of injury. The results are securely removed screws every time with lowered cost, more productive workers, fewer drill outs, and fewer problems to fix in overhaul. ACR Phillips screws are also compatible with common Phillips drivers allowing emergency modifications and repairs.

A combination drive designed by marrying the classic Phillips cruciform recess and the popular square drive recess. The result is a highly efficient and functional multi-driver servicable recess.

Advantages and Disadvantages of Phillips Square Drive

This drive system has an increased driver bit cross-section significantly increases the longevity of the driver bit, reducing overall tool costs. Combines positive characteristics of both the Phillips and the Square Drive with few negative characteristics. Not as prone to camout; higher torques than either original drive. Screw damage is minimiied and drive tool life is extended. In addition, there is a consistent stick between the driver and the screw, making hard to reach joints a simple task.

Also from the Phillips Screw Company and very similar a Phillips Square-Driv plus the added ACR Anti-Camout Ribs.

Advantages and Disadvantages of ACR Phillips Square-Driv

All the advantages of the Phillips Square-Driv. ACR is for reduced camout, reliable stick-on and high torque. The screw heads are marked with double ticks as shown.

Also by Phillips Screw Company. Yet another combination drive system. Not much information on the Internet about this drive. It could mean the head and drive is just not common yet or that the artists version of the screw head pattern is incorrect. I question the thin tick lines. Except for the identification on the bit, could this really just be Phillips II?

A recent evolution of the Phillips design resulted in a next generation, patented Phillips II. The ACR improvement is basically a Phillips screwdriver that has ACR ribs, making it ideal for assembly line and home use. Phillips II screws have ribs in the recess of the screw. The ribs mate with the ribs found on the Platinum tipped Phillips II ACR driver bit. This rib-to-rib connection allows for driving in and backing out the screw. The ribs are on either or both the driving and removal faces on the wings. The patented anti camout ribs (ACR) guarantee stick fit, easier drive and less fatigue. Deck Mate screws are a good example of these and the Deck Mate driver bit often comes with the screws. Screw heads are marked with double hash marks 45 degree to cross recess.

Advantages and Disadvantages of Phillips II

The rib-to-rib connection allows for more torque, off-angle driving, heads that will not snap off, and screws that will not strip. You will never have another stripped screw that can not be removed! You can not drive a square drive or a star drive off angle! Proprietary threads means faster drive. Patented anti-camout ribs (ACR), guarantee stick fit, easier drive and less fatigue. Deck Mate screws can be driven with #2 Phillips or #2 square driver bits but for best performance use Deck Mate driver bits with ACR. You will never have a stripped screw that cant be removed.

Founded in 1978, AVA Specialty Fasteners Ltd. of Canada presents Quadrex which combines the best features of Cross Recess and Square Socket drives. The Quadrex recess increases productivity by incorporating the superior torque transmission and cling fit of the Square Socket drive with the desirable field repair and retrofitting features of the Phillips drive.

This controlled radius recess has been designed for optimum driver engagement while providing clearance for wear and plating buildup. Added features include: Universal Application, Increased Productivity, Reduced Inventories, Assembly Line Economics and Universal Acceptance

The Idea of the Robertson/Phillips (Recex) combo drive was invented by Robertson Inc. in Milton Ontario and Recex® is the only combo drive Robertson Inc. endorses. The patented Recex Combo Recess drive insures you always have the correct driver bit to install or adjust your finished wood working project.

Information by Brian J. Cooley, Robertson Inc., Tools Division Product Line Manager for North America

The Mortorq Spiral Drive recess developed by Phillips, is much shallower than other standard recesses on the market, and can be put into a much shallower head without affecting the strength of the screw. This assembly allows for a shallower counterbore, reducing material thickness without compromising the joint strength, because it does not affect the material thickness below the counterbore. A Mortorq recess uses full wing contact with driver bit in both drive and removal directions.

Advantages and Disadvantages of Mortorq

Aerospace designers have had to compromise on fastener performance. Previously, shallow head styles had poor torque transfer and damaged easily while robust drives required thicker material and added weight. The unique shape provides full contact of the driver over the entire recess wing resulting in extremely high torque capability without the risk of damage. Depth of the recess in the fastener head is minimized resulting in true high performance in 100 degree flush head and shear head applications. The open recess concept allows driver to recess misalignment and compensates for paint build-up without degrading torque performance. Workers can easily install and remove panel and structure fasteners at odd angles without high muscle stress or fear of damage to surrounding surfaces. Larger driver cross-sections and curved surfaces provide extended tool life and resistance to tensile fatigue fracture when used with high load pulse tools.

The Torq-Set offset cruciform fastener system is a proven product in the aerospace market. For applications where screws or bolts must be torque-tight, Torq-Set meets the requirements and beats the competition. One look at the innovative recess design of Torq-Set tells the story. Its offset cruciform configuration takes the sure-fitting dependability of the original Phillips design one step further toward an ultimate torque driving system. Torq-Set ensures a torque tightness that satisfies the rigorous demands of todays aerospace applications.

ACR Torq-Set ribbed offset cruciform drive has become the revolutionary fastener system preferred by aeronautical engineers for use on military and commercial aircraft, missiles, satellites, and weapons systems worldwide.

Advantages and Disadvantages of ACR Torq-Set

A single driver inserts and removes the fasteners. The interlocking ribs - applied to the removal side of the driver bit and screw surfaces - eases fastener removal, even after a threaded fastener has become corroded, seized, or frozen. Camout is never a problem when driving in either direction with the ACR system. When meeting demands of high torque applications, the ACR Torq-Set drive system delivers ultimate performance while protecting against camout. The offset cruciform shape with interlocking ribs of the ACR Torq-Set design is unmatched for sure steady driving. Additionally, all ACR Torq-Set driver bits and recesses are interchangeable with standard Torq-Set components, thereby eliminating potential difficulties during emergency field maintenance. Available in sizes #0, 1, 2, 3, 4, 5, 6, 8, 10.

In 2001, John "Brad" Wagner patented LOX recess and driver bit designed specifically for power tools. LOX features twelve contact points, three times as many as the four points of Phillips and Robertson designs. Twelve points that transfer extraordinary torque while holding a positive engagement, drive after drive. In a recent independent test, LOX screws demonstrated more than triple the torque capacity of square.

Advantages and Disadvantages of LOX

The patented LOX recess easily outperforms every competing drive system on the market, delivering three distinct advantages: 12 points of contact and a near zero degree drive angle, the LOX recess is engineered to accept torque loads many times higher than competing technologies. LOX has vertical sidewalls that transfer forces radially, keeping the bit seated and minimizing end load. The near zero drive angle (4 degrees) optimizes torque transmission and eliminates radial stresses, dramatically increasing bit life. The unique four offset square design four projections that effectively eliminate stripping. These projections maximize bit life while minimizing material waste. Directional stability with multiple, concentric driving surfaces are directionally stable to within less than two degrees which makes this a ideal choice where there is poor access or no direct line of sight to the fastener location. The design also works as a tamper resistant feature and is suitable for high RPM drives (up to 2000 rpm). Because of its precise fit and evenly distributed forces, the LOX bit life is at least 5-10 times longer than competing systems. Even if the material costs are negligible, workers don't like stopping to replace worn bits. It throws off their rhythm and slows their progress. They often wait until bits are completely worn before stopping to changing them.

The Uni-screw is being manufactured and distributed by Forward Engineering under a licence from Uni-Screw and the first commercial products are aimed at the building and DIY markets. Strong interest has also been shown by several industrial organisations. Uni-Screw can be a direct replacement for 25 other types of screwdrivers. No need for surplus drivers anymore!

A new design of screw head, the Uni-Screw, has been developed to rival the well-established slotted, Phillips and Pozidriv screws. It is based on a series of hexagonal recesses that avoids camout, which occurs with the other designs when higher torques are applied.

Advantages and Disadvantages of Uni-screw

Website claims Uni-Screw to be the first driver to drive both imperial and metric fasteners, virtually eliminates camout and stripping, positive control with stick fit, and increased productivity. Other benefits include the need for only one driver over a wide range of screw sizes and easy alignment of driver to screw.

Other recess forms can be used including pentagon and heptagon to provide high tamper resistance, and these can be tailored for a single user to give total security.

Talking drive bits? Why not include this tamperproof one because there is also a Phillips version too. Basically the recess has a center pin, the drive must have the mating hole in the center end.

Theft Proof fasteners are virtually impossible to remove without the matching driver.

The Tamperproof Screw Company was founded in the late 1970s when George Friedman developed the Phillips Pin-Head security screw. It consists of a traditional Phillips drive with a tamper-resistant pin added for security. Prevents unauthorized tampering with the screws. The Philips/Cross tamperproof profile has the same properties as the classic Philips/Cross; the difference is that the tool has a hole located in the tip and the screw head has a small central pin.

Advantages and Disadvantages of Phillips Pin-Head

Theft Proof fasteners are virtually impossible to remove without the matching driver. These screws are easy to drive & remove with matching tool. Also cannot be removed with Phillips Screwdriver. Available in sizes #1, 2, 3.

Terms

Camout (or cam-out) is a process by which a screwdriver slips out of the head of a screw being driven once the torque required to turn the screw exceeds a certain amount. Frequently, camout damages the screw, and possibly also the screwdriver, and should normally be avoided. However, the Phillips head screw and screwdriver combination was designed specifically to cam out, as at the time of its invention torque sensing automatic screwdrivers did not exist.

Phillips is a trademark used for a screw with a head having two intersecting perpendicular slots and for a screwdriver with a tip shaped to fit into these slots.

Recess refers to the shaped socket into which a driver can be inserted

End-Load is the force required to keep the bit to not camout. Low end-load is usually most desirable.

References

History of Screws and Screwdrivers, by Mary Bellis, About.com

Phillips Screw Company; www.phillips-screw.com

Phillips or Pozidriv? Healey Magazine, Feb 1996

Semblex Corporation; www.semblex.com

Why did this guy Phillips think we needed a new type of screw? by Adams, Nov 24 1989

Assembly Technology Buyer's Guide, Wheeling, IL, Hitchcock Publishing, annual.

Collections Canada; www.collectionscanada.gc.ca/cool/002027-150-e...

A New Design of Screw Head by Brian Rooks, Assembly Automation Vol 21-4, 2001

Furniture screws: primitive to gimlet by Fred Taylor, Discover Mid-America - Aug 2007

S.C.F. Fasteners, Taiwan; www.scffastener.com/main/products/specialS.html

Robertson Screws by Ricketts, www.mysteriesofcanada.com/Ontario/robertson_screws

www.thestuccocompany.com/maintenance/Phillips-vs-roberts-138476- by Chris Lewis

Hands-On: LOX Screws by Chuck Cage; www.toolmonger.com

http://scholar.lib.vt.edu/theses/available/etd-42698-205111/unrestricted/chapter_2.pdf

http://www.emeraldinsight.com/10.1108/01445150110407322

Uni-Screw Worldwide, Inc; www.uniscrewworld.com

Discussion Groups;

Google Answers Researcher by Tutuzdad ?, Jun 10 2004

Re: star vs square drive; http//forums.jlconline.com/forums dave_k Veteran Contributor

http://boards.fool.co.uk/Message.asp?mid=11161184&sort=whole; Julian F. G. W.

http://www.electronicspoint.com/torx-hex-star-bits-t39076.html; Fred Abse

Instructables feedback of article by contributor ironsmiter

When I wrote this "ible" the original intent was to stick to Phillips look-a-likes. It grew to this.

Due to input and interest shown by readers, I'm already working on a sequal, or re-write to include combo drives, security drives, and incorporate comments and new pictures.

Remember to Vote when it appears in a contest.

Stay Tuned!