Step 5: Robertson® Drive

Picture of Robertson® Drive
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032 robertson invent pix.jpg
041 robertson bit.jpg
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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.
Quarn6 years ago
There is also a #4 screw driver who is blue and is used with screw 5/16 inch and more.
arcticpenguin (author)  Quarn6 years ago
I did run across this since the instructable and it is in the rewrite of all screw drives. Information I found though said it was also black, which I thought really odd. I believe these to be the same tip. Blue would certainly make more sence than a second black for sure. I'm thinking blue is correct, but can't seem to find anything on Google. I've just sent a query to Robertson Screw Company to confirm it. Thank you for this information. Are you Canadian? Do you work with this larger Robertson? Where did you learn about them or where they sell them?
I'm Canadian but i work for Reliable who is a competitor of Robertson. We often but stuff from Robertson when we are in back order. We have in stock the #4 screw drive and it's blue. (well it might not be an official color, and just be blue lake that for no reason.) The dimension are in the IFI (Industrial Fastener Institute)book (ASME B18.6.3 2002) but it does not specifies color.
arcticpenguin (author)  Quarn6 years ago
I got a reply from Brian J. Cooley, Robertson Inc., Tools Division Product Line Manager - North America

Your chart listed below is correct. There is a second Black drive (#4 drive) for 16 gauge fasteners. It is rare, but we do still manufacture and sell some #4 screwdrivers and hex screwdriver bits.

Robertson Inc, to my knowledge, has never assigned the colour blue to any drive.

#00: orange - used with #1-2 Screws
#0: yellow - used with #3-4 Screws
#1: green - used with #5-7 Screws
#2: red - used with #8-10 Screws
#3: black - used with #12-14 Screws
#4: black - used with #16+ Screws

Robertson Inc. does not manufacture any 1 pc. bits. All of our bits are 2 pc.

There is also an easy way for consumers to tell if any fasteners came from us. We use the ® following Robertson® on all of the product we manufacture.

note - the comment on the 1 pc/2 pc bits is due to my incorrect photo used in this step. Brian supplied new photos and the step is now correct.
Meichx6 years ago
I'm a little unclear why no one has copied the Robertson design... patents in the US only last 20 years. The design should be in the public domain.
Fasteners6 years ago
This is all extremely interesting... I also did not know there were so many variations.
Robertson and square drive are different! Did not know that Thank you for sharing this great information!
roboguy6 years ago
You left out one of the most important features of Robertson drive: the square hole is tapered like a Morse taper. This means that you can place a screw on the screwdriver, and no matter how you hold the screwdriver (even if you point it down), the screw will remain attached. Also, the yellow ones are becoming common on small (e.g. #4 and smaller, like 4-40 machine screws). I didn't know that there was an orange size, though.