About four years ago, we met with an engineer and inventor who said he had designed a new type of screw head, one, he said, “that would revolutionize screws as we know them.”
He pulled his new driver bit out along with a handful of screws and it was unlike anything we had ever used. The driver tip looked kind of like a cross between a Phillips and a square head.
What makes this new style of screwdriver different is that it has been designed with eight points of contact, which is double that of either the Phillips or the square head.
The Phillips is certainly quick and easy to use. The tapered tip makes it very forgiving for the novice (or anyone for that matter) when attacking a screw from almost any angle. However, the taper that makes the Phillips easy to insert is the same thing that makes it hard to hold in high-torque situations where a great deal of pressure is needed to install the screw – as in hardwood or metal.
We no longer buy slotted screws. For the important jobs that require positive fastening, we have gotten used to using the square head. There is no slip-out (cam-out) and no operator force required to hold the tip in the screw slot (to get a tight high-torque connection).
Unfortunately, square heads shear very easily and we find ourselves going through tips by the dozens. Basically, the very corners of the square-shaped bit wear down in no time. When this happens, the tip slips and strips (rounds out) the inside of the screw and makes it almost impossible to remove.
With square heads, it is imperative to change the bit regularly as not to have this cause a problem. Otherwise, the square drive is a great tool.
Here’s the technical mumbo jumbo:
Phillips: The Phillips tip has four points of contact with the screw (one at the face of each of four surfaces). These points are perpendicular to the screw axis. Perpendicular force is the strongest and provides maximum allowable force. However, the taper of the tip that makes it slip in easily also allows cam-out or slippage when force is applied.
Square head: The square head tip also has four points of contact (one at each of four corners). These points of contact are diagonal to the screw axis. Diagonal force is not as strong as perpendicular force and shear can occur under high torque. The good thing is that the square tip has almost no taper and therefore doesn’t slip or cam-out.
So, the Phillips is really quick and easy to use. But, it’s no good for high torque jobs. The square head doesn’t require a truck driver’s power to send a screw home like the Phillips does and the square head does high torque driving “fast and tight”. But, because there is not a lot of “bite” or grip surface with a square head it takes about 10 bits to do the job you would expect from one.
The new screw tip looks like a cross between a Phillips and a square head. Actually, four little square heads clustered together and slightly offset from center (and each other). Thus, the screw offers eight points of contact. Four are perpendicular to the screw axis like the Phillips and four are diagonal to the axis like the square head. There is almost zero taper, so the tip doesn’t cam-out and because of the perpendicular grip feature the screw tip doesn’t wear out.
Here’s a real caution. Be sure to use this tip/screw combination with a reduced torque setting. Without setting the torque on a driver drill you can literally break screws all day long.
And, that’s all there is to it.
For more home improvement tips and information from James and Morris Carey, visit their Web site at www.onthehouse.com or call 800-737-2474 Saturdays from 6 a.m. to 10 a.m. The Careys are also on KRKO (1380-AM) from 6 to 8 a.m. every Saturday.
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