All other Snap-on trademarks, service marks, domain names, logos, and company names referred to in this catalog are either trademarks, registered trademarks, service marks, domain names, logos, company names of or are otherwise the property of Snap-on Technologies, Inc. Download as Slot bit socket Printable version. One-way screws are commonly used in commercial restroom fixtures and on vehicle registration platesto prevent vandals from tampering slot bit socket them. The TP or Y-type security screw drive is similar to the Phillips screw head, but with three points rather than four. It typically consists of a countersunk flat-head bolt, with a thin shank and hex head protruding from the flat head.

Please click Accept Cookies to continue to use the site. Model SAA-4S. UPC: Condition: New. Scale: SAE. Finish: Chrome. Type: Slot. Current Stock:. Quantity: Decrease Quantity: Increase Quantity:. Snap-On Industrial Brands Warranty Safety Hand tools are generally designed to perform one function do not use them improperly. Screwdrivers are not chisels, adjustables are not hammers and pliers are not intended to replace wrenches.

Each of our product groups contains specific safety tips for proper tool usage. Additionally, wear appropriate clothing for the job, and always wear safety glasses. A special note on safety and use of hand sockets chrome finish with power drive impact equipment is a misuse of the tool and can result in serious injury. Trademarks The following are trademarks of either Snap-on Technologies, Inc.

All other Snap-on trademarks, service marks, domain names, logos, and company names referred to in this catalog are either trademarks, registered trademarks, service marks, domain names, logos, company names of or are otherwise the property of Snap-on Technologies, Inc. These sizes roughly correspond to the Phillips head numbers.

The manufacturing process for Pozidriv screwdriver bits requires a slightly more complex cutter than that for Phillips, however both can be manufactured in four cuts from a tapered blank. Pozidriv and Phillips appear broadly interchangeable, but may cause damage if incorrectly used. Pozidriv screwdrivers will jam fit into Phillips screws, but when tightened they may slip or tear out the Phillips screw head.

Conversely, while Phillips screwdrivers will loosely fit and turn Pozidriv screws, they will cam out if enough torque is applied, potentially damaging the screw head or screwdriver.

Superficially it looks like a Phillips screw with narrower and more vertical slots, to give less tendency to cam out. The bottom of the recess is flat, and the point of the driver has to be blunt.

A Phillips screwdriver has the same A correctly sized JIS driver will engage at full depth into a Phillips or Pozidriv head screw slightly loosely, but without damage. JIS heads are often identified by a single dot or an "X" to one side of the cross slot.

The Supadriv sometimes spelled incorrectly as "Supadrive" screw drive is very similar in function and appearance to Pozidriv. It is a later development by the same company. The description of the Pozidriv head applies also to Supadriv. While each has its own driver, [26] the same screwdriver heads may be used for both types without damage; for most purposes it is unnecessary to distinguish between the two drives.

Pozidriv and Supadriv screws are slightly different in detail; the later Supadriv allows a small angular offset between the screw and the screwdriver, while Pozidriv has to be directly in line. In detail, the Supadriv screwhead is similar to Pozidriv but has only two identification ticks, and the secondary blades are larger. Drive blades are about equal thickness. The main practical difference is in driving screws into vertical surfaces: that close to a near vertical surface to drive the screws into the drivers, Supadriv has superior bite, making screwdriving more efficient, with less cam out.

Phillips II recesses are compatible with Phillips drivers, but have a vertical rib in between the cruciform recesses that interacts with horizontal ribs on a Phillips II driver to create a stick-fit, and to provide anti cam-out properties the ribs are trademarked as "ACR" for Anti Cam-out Ribs.

It is often found in marine hardware and requires a Frearson screwdriver or bit to work properly. The tool recess is a perfect, sharp cross, allowing for higher applied torque, unlike the rounded, tapered Phillips head, which can cam out at high torque. It was developed by an English inventor named Frearson in the 19th century and produced from the late s to the mids. Company of Worcester, Massachusetts, was put into bankruptcy in and liquidated in A cross-head screw with a two-step driver design, with the blade diameter stepping up at a distance from the point.

The Mortorq drive, developed by the Phillips Screw Company, is a format used in automotive [30] and aerospace applications. It is designed to be a lightweight, low-profile and high-strength drive, with full contact over the entire recess wing, reducing risk of stripping.

Both the tool and the socket have a slight taper. Originally to make the manufacture of the screws practical using cold forming of the heads, [13] : 79—81 this taper provides two other advantages which have served to popularize the drive: it makes inserting the tool easier, and tends to help keep the screw on the tool tip without the user needing to hold it there.

Robertson screws are commonplace in Canada , though they have been used elsewhere [13] : 85—86 and have become much more common in other countries. As patents expired and awareness of their advantages spread, Robertson fasteners have become popular in woodworking and in general construction. Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken. The socket-headed Robertson screws are self-centering, reduce cam out , stop a power tool when set, and can be removed if painted over or old and rusty.

The internal-wrenching square socket drive for screws as well as the corresponding triangular socket drive was conceived several decades before the Canadian P. Robertson invented the Robertson screw and screwdriver in and received the Canadian patent in CA , U. Patent 1,, for a manufacturing machine. An earlier patent covering both square-socket- and triangle-socket -drive wood screws, U.

However, as with other clever drive types conceived and patented in the s through s, it was not manufactured widely if at all during its patent lifespan due to the difficulty and expense of doing so at the time. Today, cold forming by stamping in a die is still the common method used for most screws sold, although rotary broaching is also common now.

Linear broaching to cut corners into a drilled hole similar to the action of a mortising machine for woodworking has also been used less commonly over the decades.

Robertson had licensed the screw design to a maker in England, but the party that he was dealing with intentionally drove the licensee company into bankruptcy and purchased the rights at a reduced price from the trustee, thus circumventing the original agreement. When Henry Ford tried out the Robertson screws, he found that they saved considerable time in Model T production, but when Robertson refused to license the screw design, Ford realized that the supply of screws would not be guaranteed and chose to limit their use in production to Ford's Canadian division.

The restriction of licensing of Robertson's internal-wrenching square may have sped the development of the internal-wrenching hexagon , although documentation of this is limited. The design is similar to a square drive Robertson , but can be engaged at more frequent angles by the driver bit.

The name derives from overlaying three equal squares to form such a pattern with 12 right-angled protrusions a pointed star. The design is similar to that of the double-square —in both cases, the idea being that it resembles a square Robertson but can be engaged at more frequent angles by the driver bit. These screws can be driven with standard Robertson bits. Despite the similar naming scheme to metric fasteners, there is no correlation between the name of the size and the dimensions of the tool.

In practice, drivers for the fasteners may be interchangeable, but should be examined carefully for proper fit before application of force. A hex key should not be used where a key of square cross-section is the correct fit. Triple-square drive fasteners have been used in high-torque applications, such as cylinder head bolts and drive train components. The fasteners involved have heads that are hardened and tempered to withstand the driving torque without destroying the star points.

The hex socket screw drive has a hexagonal recess and may be driven by a hex wrench , also known as an Allen wrench , Allen key , hex key , or inbus as well as by a hex screwdriver also known as a hex driver or bit. Tamper-resistant versions with a pin in the recess are available. In many countries it is commonly but incorrectly called "i m bus". Double hex is a screw drive with a socket shaped as two coaxial offset hex recesses; it can be driven by standard hex key tools.

The shape resembles triple square and spline screw drives, but they are incompatible. The radial "height" of each arris is reduced, compared to a six-point, although their number is doubled. They are potentially capable of allowing more torque than a six-point, but greater demands are placed on the metallurgy of the heads and the tools used, to avoid rounding off and slippage.

The pentalobe screw drive often mistaken for 5-point torx screw drives is a five-pointed tamper-resistant system being implemented by Apple in its products. Inexpensive pentalobe screwdrivers, manufactured by third parties, are relatively easy to obtain.

The TS designation is ambiguous as it is also used for a Torq-set screw drive. This recess is optimized to fit on the threaded end of aerospace fasteners. These fasteners allow for tightening the nut and holding the bolt simultaneously, on the same side of the structure, by only one operator.

The tamper-resistant variant of Torx Plus, [47] sometimes called Torx Plus Security , is a five-lobed variant, with a center post. It is used for security as the drivers are uncommon. It was designed to permit increased torque transfer from the driver to the bit compared to other drive systems. The drive was developed in [48] by Camcar Textron. A tamper-resistant Security Torx head has a small pin inside the recess. Owing to its six-fold symmetry, a Torx driver can also be used as an improvised substitute for a hex driver, although careful sizing is critical to prevent stripping the socket.

Torx Plus is an improved version of Torx that extends tool life even further and permits greater torque transfer compared to Torx. An External Torx version exists, where the screw head has the shape of a Torx screwdriver bit, and a Torx socket is used to drive it. A further improvement over Torx Plus. Torx ttap is a version of Torx that reduces wobbling between the fastener and the tool, and is backward compatible with standard hexalobular tools.

Some screws have heads designed to accommodate more than one kind of driver, sometimes referred to as combo-head or combi-head. The idea is that first screwdriver out of the toolbox is used, and the user does not have to waste valuable time searching for the correct driver.

Some screwdriver manufacturers solve this problem offer matching screwdrivers and call them "Modulo", "Plus-minus", or "contractor screwdrivers", although the original concept of not needing to search for a particular driver is defeated.

Other combinations are a Phillips and Robertson, a Robertson and a slotted, a Torx and a slotted and a triple-drive screw that can take a slotted, Phillips or a Robertson. While a standard Phillips or Robertson tool can be used, there is also a dedicated tool for it that increases the surface area between the tool and the fastener so it can handle more torque.

The Recex drive system claims it offers the combined non-slip convenience of a Robertson drive during production assembly and Phillips for after market serviceability. A combined slotted and Torx drive screw was used in electronics manufacturing. For example, Compaq used this type to combine the benefits of Torx in manufacturing and the commonality of flat drive in field repair situations.

The slot was closed on the ends to prevent the flat-blade tool from slipping out sideways and damaging nearby electronics. There are two types of clutch screw drives: Type A and Type G.

Type A, also known as a "standard clutch", resembles a bow tie , with a small circular "knot" at the center. These were common in GM automobiles, trucks and buses of the s and s. Type G resembles a butterfly, and lacks the center "knot". A thumbscrew is a type of screw drive with either a tall head and ridged or knurled sides, or a key-like flat sided vertical head.

They are intended to be tightened and loosened by hand, and not found in structural applications. They are sometimes also cut for Phillips head or slotted screwdrivers as well as having the knurl for finger grip.

ASME They can be found on many computer cases , and in other locations where easy access without tools is desired. External drives are characterized by a female tool and a male fastener. An advantage of external drive fasteners is that they lack a recess in the head, which can collect water, dirt, or paint, which can interfere with later insertion of a driver tool.

Also, some external drives can be engaged from the side, without requiring large inline clearance for tool access, which allows their use in tight spaces such as engines or complex pipework. Because the heads must stand out from the surface they attach to, they are rarely available in countersunk or flush designs. A square screw drive uses four-sided fastener heads which can be turned with an adjustable wrench , open-end wrench , or 8- or point [55] sockets.

Common in the 19th and early 20th centuries, when it was easier and cheaper to manufacture than most other drives, it is less common today although still easy to find because the external hex is now cost-competitive and allows better access for wrenching despite nearby obstructions.

A hex screw drive uses six-sided fastener heads, and the fastener is known as a hex head cap screw. It can be turned with an adjustable wrench, combination wrench and 6- or point sockets. The hex drive is better than square drive for locations where surrounding obstacles limit wrenching access, because smaller wrench-swing arcs can still successfully rotate the fastener.

A pentagon screw drive uses five-sided fastener heads, and the fastener is known as a penta screw or penta bolt. It is designed to be intrinsically incompatible with many tools. Since five is an odd number , it cannot be turned by open-end or adjustable wrenches , which have parallel faces and thus require a fastener with an even number of sides.

Moreover, it cannot be turned by typical consumer- and professional-grade socket drivers, which possess either six or twelve points neither of which are multiples of five. Penta nut security fasteners also are available, which can only be driven by specialized five-sided socket drivers. However, the security feature of this design can be bypassed by using some type of pliers if enough force is applied.

Due to the difficulty of turning these fasteners without specialized and uncommon five-point wrenches such as hydrant wrenches , they are commonly used for tamper resistance by public utilities on water meter covers, natural gas valves, electrical cabinets, and fire hydrants. An external Torx screw has a projecting head in the shape of a Torx screwdriver bit instead of a standard recessed cavity ; a Torx socket is used to drive it. The external "E" Torx nominal sizing does not correspond to the "T" size for example, an E40 socket is too large to fit a T40, while an E8 Torx socket will fit a T40 Torx bit [56].

These screws are most commonly encountered in the motor industry. Standard point hex socket bits and wrenches fit these screws. The screw heads are typically flanged, and may fit into standard Allen hex socket cap screw counterbores molded or machined into parts to be fastened.

Compared to Allen hex sockets, the advantages of these bolts include higher torque capability and the lack of a recess to trap water. A disadvantage is the extra cost involved in forming the heads. Most of the following screw drives are considered tamper-resistant because of their obscurity. Tamper-resistant drives are commonly used on equipment such as home electronics , to prevent easy access thereby reducing the incidence of damage, improper repairs or repairs by people without the relevant technical knowledge.

Recent widespread availability of assorted drive bits including security types minimizes this advantage, at least for some fastener types. True tamper-resistant screw drives include the breakaway head and one-way screw drives. In addition to screw drives, various nut drives have been designed to make removal difficult without specialized tools. The breakaway head also called breakoff or shear fastener [58] is a high-security fastener whose head breaks off during installation, during or immediately after the driving process, to leave only a smooth surface.

It typically consists of a countersunk flat-head bolt, with a thin shank and hex head protruding from the flat head. The hex head is used to drive the bolt into the countersunk hole, then either a wrench or hammer is used to break the shank and hex head from the flat head, or it is driven until the driving head shears off. Either method leaves only a smooth bolt head exposed. This type of bolt is commonly used with prison door locks, automobile ignition switches , and street signs , to prevent easy removal.

An alternative design leaves a low-profile button head visible after installation. In non-security applications, a breakaway head fastener is sometimes used as a crude torque limiter , intended to break off at an approximate torque limit. For example, certain toilet seat fastener bolts use a breakaway plastic nut, with the driver part intended to shear at a torque high enough to prevent wobbling, while not shattering the porcelain toilet from excessive pressure.

Breakaway fasteners used in a non-security application may have a second driveable surface such as a hex head to allow later removal or adjustment of the fastener after the initial breakaway installation.

This drive type has the disadvantage of not being as precisely controlled as can be obtained by proper use of a torque wrench ; applications may still fail due to either too little torque being applied to correctly fasten the joint, or too much torque being required to shear the head, resulting in damage to the material being fastened. The Bristol or Bristol spline screw drive is a fastener with four or six splines , but is not necessarily tamper resistant. The main advantage to this drive system is that almost all of the turning force is applied at right angles to the fastener spline face, which reduces the possibility of stripping the fastener.

For this reason Bristol screw drives are often used in softer, non-ferrous metals. Compared to an Allen drive, Bristol drives are less likely to strip for the same amount of torque; however, the Bristol drive is not much more strip-resistant than a Torx drive.

Goldwin and put into production by the Bristol Wrench Company. This type of drive is commonly used in avionics , higher-end communications equipment, cameras, air brakes, construction and farm equipment, astronomy equipment, and military equipment. Variants with a pin in the center are often found in game systems, to discourage improvised attempts to use a slotted screwdriver to drive the fastener. The line screw drive is a Japanese system with male, female and female tamper-resistant screw configurations.

The fasteners are commonly called "line head screws". They are also known as "game bit screws", due to their use on some video game consoles. One-way screws are special screws that can be turned only in one direction.

They are sometimes called one-way clutch screws , but should not be confused with true "clutch" screws. They can be installed with a standard flat-blade screwdriver, but cannot be easily removed using standard tools.

One-way screws are commonly used in commercial restroom fixtures and on vehicle registration plates , to prevent vandals from tampering with them.

One-way screws are practical only when the need for removal is unlikely. They are difficult to remove with conventional tools because the slot is designed to cause cam out when even minimal torque is applied in the direction to unscrew it. Instead, a one-way screw can be removed by drilling a hole through the head of the screw and inserting a screw extractor. Alternatively, a rotary tool with cutting disk can be used to extend the slot, the head can be gripped with locking pliers , or the screw can be removed with a pin spanner snake-eyes driver after drilling two holes in the slot.

It can also sometimes be removed by attaching a precision drill chuck tightly to the screw head, in a manner similar to removing screws that have broken heads.

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