# Square screwdriver vs robertson screwdrivers



## HARRY304E (Sep 15, 2010)

Tesla_Fusion said:


> Apparently there is a difference between SQ# & S#?
> What you guys know about that?


Not much........:whistling2:
http://en.wikipedia.org/wiki/List_of_screw_drives
*External types*

External drives are characterized by a female tool and a male fastener.
* Square*


A *square* screw drive uses square fastener heads. They can be turned with a crescent-type wrench, open-end wrench, or 8- or 12-point[3] sockets. Common in the 19th and early 20th centuries, when it was easier and thriftier 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, with fewer degrees of swing on each stroke.
* Hex*


A *hex* screw drive uses six-sided fastener heads. The fastener is known as a _hex head cap screw_. It can be turned with an adjustable wrench, combination wrench, and 6- or 12-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.
* Pentagon*


A *pentagon* screw drive uses five-sided fastener heads. The fastener is known as a _penta screw_. They require a special five-point socket in order to be turned. Water meter covers, natural gas valves, and electrical cabinets are commonly secured with penta fasteners. It is also common in the U.S. for fire hydrants to have valves with a pentagon drive.
* Thumbscrew*


A *thumbscrew* is a type of screw drive with either a tall head and ridged or knurled sides, or a flat, 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 and/or slotted screwdrivers as well as having the knurl for finger grip.
* Slotted types*

* Slot*


Slot drive tool and fastener sizes[4] Blade width Fastener size 3⁄32 in (2.4 mm) 0–1 1⁄8 in (3.2 mm) 2 5⁄32 in (4.0 mm) 3 3⁄16 in (4.8 mm) 4–5 1⁄4 in (6.4 mm) 6–7 5⁄16 in (7.9 mm) 8–10 3⁄8 in (9.5 mm) 12–14 7⁄16 in (11 mm) 16–18 1⁄2 in (13 mm) 18–24 The *slot* screw drive has a single slot in the fastener head and is driven by a flat-bladed screwdriver. It was the first type of screw drive to be developed, and for centuries it was the simplest and cheapest to make. The slotted screw is common in simple woodworking applications, but is not often seen in applications where a power tool would be used because a power driver tends to slip out of the head and potentially damage the surrounding material. The tool used to drive a slot is called a _standard_, _flat-blade_, _slot-head_, _flat-tip_,[4] or the _controversial_ name, _flat-head_[5] screwdriver. This last usage can sometimes be confusing, because the term _flat-head_ is also used to describe a screw with a flat top, designed to be installed in a countersunk hole. Such a flat-headed screw may have a slotted, cross, square recessed, or combination head, causing further confusion about the terminology.
* Cross*


A *cross-recess* screw drive has two slots, oriented perpendicular to each other, in the fastener head; a slotted screwdriver is still used to drive just one of the slots. This type is usually found in cheaply made roofing bolts and the like, where a thread of 5 mm (0.20 in) or above has a large flattened pan head. The sole advantage is that they provide some measure of redundancy: should one slot be chewed up in service, the second may still be used.
* Cruciform types*

See also: cross-slotted, Torq-set, and Phillips/square
The following are screw drives based on a _cruciform_ shape, _i.e._ a cross shape. Other names for these types of drives are _cross-head_ and _cross-point_. (Cross-type slotted screw drives are not considered cruciform because the shape is not recessed.)
* Phillips*


Phillips drive tool and fastener sizes[4] Tool size Fastener size 0 0–1 1 2–4 2 5–9 3 10–16 4 18–24 Created by Henry F. Phillips, the *Phillips* screw drive was purposely designed to cam out when the screw stalled, to prevent the fastener damaging the work or the head, instead damaging the driver. This was caused by the relative difficulty in building torque limiting into the early drivers.
The American Screw Company of Providence, Rhode Island was responsible for devising a means of manufacturing the screw, and successfully patented and licensed their method; other screw makers of the 1930s dismissed the Phillips concept because 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.
There are five relatively common (and two rather uncommon) Phillips drive sizes that are different from the screw size; they are designated 000, 00, 0, 1, 2, 3, and 4 (increasing in size).[4][6]


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## HARRY304E (Sep 15, 2010)

*Frearson*


 



The *Frearson* screw drive, also known as the *Reed and Prince* screw drive, is similar to a Phillips but the Frearson has a more pointed 75° V shape.[7] One advantage over the Phillips drive is that one driver or bit fits all screw sizes. 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 was designed to cam out at high torque. It was developed by an English inventor named Frearson in the 19th century and produced from the late 1930s to the mid-1970s by the Reed & Prince Manufacturing Company now of Leominster, Massachusetts. [8]
* French recess*

 
French recess driver bit


 This section requires expansion. _(June 2010)_ Also called *BNAE NFL22-070* after its Bureau de Normalisation de l'Aéronautique et de l'Espace standard number.
* JIS B 1012*

The *JIS B 1012* is commonly found in Japanese equipment. It looks like a Phillips screw, 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 dot or an "X" to one side of the cross slot.[9]
Specific "JIS" standardized cruciform-blade screwdrivers are available for this type of screw.


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## HARRY304E (Sep 15, 2010)

*Pozidriv*


 
Screws with the Pozidriv head.


The *Pozidriv*, sometimes misspelled *Pozidrive*, screw drive is an improved version of the Phillips screw drive. It is jointly patented by the Phillips Screw Company and American Screw Company. The name is thought to be an abbreviation of _posi_tive _driv_e. Its advantage over Phillips drives is its decreased likelihood to cam out, which allows greater torque to be applied.[11][12][13] In ANSI standards it is referred to as _type IA_.[14] It is very similar to, and essentially compatible with, the Supadriv screw drive.[15]
Phillips drivers have an intentional angle on the flanks and rounded corners so they will cam out of the slot before a power tool will twist off the screw head. The Pozidriv screws and drivers have straight sided flanks.
The Pozidriv screwdriver and screws are also visually distinguishable from Phillips by the second set of radial indentations set 45 degrees from the cross recess. The manufacturing process for Pozidriv screwdrivers is slightly more complex. The Phillips driver has four simple slots cut out of it, whereas in the Pozidriv each slot is the result of two machining processes at right angles. The result of this is that the arms of the cross are parallel-sided with the Pozidriv, and tapered with the Phillips.
This design is intended to decrease the likelihood that the Pozidriv screwdriver will slip out, provide a greater driving surface, and decrease wear.[11] 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 with removing the screw and damage to the recess, rendering any subsequent use of a correct screwdriver unsatisfactory. Phillips screwdrivers will fit in and turn Pozidriv screws, but will cam out if enough torque is applied, potentially damaging the screw head. The drive wings on a Pozidriv screwdriver will not fit a Phillips screw correctly, and are likely to slip or tear out the screw head.
* Supadriv*


The *Supadriv* (sometimes found incorrectly as "Supadrive") screw drive is very similar in function and appearance to Pozidriv—indeed, the two are often thought to be identical—and is a later development by the same company. The description of the Pozidriv head applies also to Supadriv. While each has its own driver,[16] 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.[15][17]
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.[16]
* Robertson*


 
Close-up of a Robertson screw


A *Robertson*, also known as a *square*,[18] or *Scrulox*[19] screw drive has a square-shaped socket in the screw head and a square protrusion on the tool. Both the tool and the socket have a taper, which makes inserting the tool easier, and also tends to help keep the screw on the tool tip without the user needing to hold it there. (The taper's earliest reason for being was to make the manufacture of the screws practical using cold forming of the heads,[20] but its other advantages helped popularize the drive.) Robertson screws are commonplace in Canada, though they have been used elsewhere[21] and have become much more common in other countries in recent decades. Robertson screwdrivers are easy to use one-handed, because the tapered socket tends to retain the screw, even if it is shaken.[21] They also allow for the use of angled screw drivers and trim head screws. 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.[21] In industry, they speed up production and reduce product damage.[21]
The internal-wrenching square socket drive for screws (as well as the corresponding triangular socket drive) was conceived several decades before the Canadian P. L. Robertson invented the Robertson screw and screwdriver in 1908 and received patents in 1909 (Canada) and 1911 (U.S. Patent 1,003,657). An earlier patent for square-socket- and triangle-socket-drive wood screws, U.S. Patent 161,390, was issued to one Allan Cummings of New York City on March 30, 1875. However, as with other clever drive types conceived and patented in the 1860s through 1890s, it was not manufactured widely (if at all) during its patent lifespan due to the difficulty and expense of doing so at the time.[20] Robertson's breakthrough in 1908 was to design the socket's taper and proportions in such a combination that the heads could be easily and successfully cold formed,[20] which is what made such screws a valid commercial proposition. Today cold forming (via 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 company into bankruptcy and purchased the rights from the trustee, thus circumventing Robertson.[_citation needed_] He spent a small fortune buying back the rights. Subsequently, he refused to allow anyone to make the screws under license. When Henry Ford tried out the Robertson screws he found they saved considerable time in Model T production, but when Robertson refused to license the screws to Ford, Ford realized that the supply of screws would not be guaranteed and chose to limit their use in production to Ford's Canadian division.[22][23][24] Robertson's refusal to license his screws prevented their widespread adoption in the United States, where the more widely licensed Phillips head has gained acceptance. 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.
Robertson-head screwdrivers are available in range of tip-sizes. A given driver's suitability for use with a particular size of screw and recess size is indicated upon its handle according to the following color code:


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## Holt (Jun 20, 2011)

TRUE roberton has a bit style head and it tapers to the tip. Square drive is just square.


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## Aegis (Mar 18, 2011)

Tesla_Fusion said:


> Apparently there is a difference between SQ# & S#?
> What you guys know about that?


If it fits the hole then screw it.


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## MIKEFLASH (Apr 14, 2012)

Geeeez harry i know who to ask about tools now.


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## wcord (Jan 23, 2011)

Is this the info you are looking for?

Recess dimensions[25][26] Color Screw types Fraction Range
Orange (#00) No. 1 & 2 1/16 in.+ ??
Yellow (#0) No. 3 & 4 3/32 in.- 0.0696–0.071 in (1.77–1.8 mm) 
Green (#1) No. 5, 6 & 7 7/64 in.+ 0.090–0.091 in (2.3–2.3 mm) 
Red (#2) No. 8, 9 & 10 1/8 in.+ 0.111–0.1126 in (2.8–2.86 mm) 
Black (#3) No. 12 & 14 3/16 in.+ 0.1315–0.133 in (3.34–3.4 mm) 
(none) (#4) 5/16 and 3/8 3/16 in.+ 0.1895–0.191 in (4.81–4.9 mm)​


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## ElectricBrent (Jan 1, 2013)

The profile of the end of the tip is different. Take a look if you ever get the chance to compare them side by side. It only makes a difference if you are using true robertson brand screws though (who does that?), so it doesn't really make a difference.


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