Screw Drive Types (was Re: Slotted Wood Screws)

[Don Gilmore]

I have a very hard time believing these statistics.  Are you sure you read
them correctly?  You can tighten a socket (Allen) head screw so tight you'll
either break off the screw head or twist the wrench into a pretzle.  Socket
head and hex head capscrews are used almost exclusively in building machines
where torque is critical.  Torx heads are occasionally seen, but only on
critical items such as bearing lock collars...we usually just replace them
with socket heads since many maintenance crews don't have Torx wrenches.

Ordinary machine screws (like slotted or Phillips head) are generally used
only for mass-produced items where speed of installation and cost preclude
strength or torque.  A Phillips (cross-recess) screw head will cam out
and/or strip long before you get any serious torque out of it.

Don A. Gilmore
Mechanical Engineer
Kansas City
----- Original Message ----- 
From: "Phillip Ford" <fordpiano@earthlink.net>
To: <pianotech@ptg.org>
Sent: Friday, February 06, 2004 1:42 PM
Subject: Screw Drive Types (was Re: Slotted Wood Screws)


> In what way are they superior?  What's wrong with TORX?
>
> I have an article comparing torque that can be developed on fasteners with
> various drive types using power drivers.  Interestingly, the Phillips is
> about the same as the square drive.  The TORX can develop almost twice as
> much as either one.  And the TORX PLUS slightly more.  (Also interesting
to
> me is that the internal hex drive develops less than half the torque of
> the Phillips or square drives).
>
> I can post scans of the article if anyone is interested.
>
> Phil Ford
>
>
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