On Tue, 24 Sep 2013, Chuck Guzis wrote:
On 09/24/2013 06:02 AM, David Riley wrote:
On the other hand, if you don't need the
cheese or button heads,
McMaster has T15 6-32x1/4" pan head screws for 6.22 per 100, which
doesn't seem like a terrible price to me. Aside from some visual
finish, what's the advantage of a button/cheese head?
If you're working on a piece of older Compaq gear, the cheese head is
part of the slide-in mounting system for the disk drives. That is, the
cheese head forms the protrusion that slides in the groove of a plastic
guide.
Exactly. The older gear has a metal frame though, and only the later
systems starting sometime around the Deskpro EN line or so used those
plastic retaining brackets. The Socket-7 Pentium based Deskpro 2000 and
4000 used these screws, as did the PII based Deskpro 6000, all of which
had the drives slide directly into the metal chassis. The original Deskpro
8086 and 286 have their drives mounted directly to the chassis, and the
later Deskpro 286, 386 and 486 use Compaq-specific metal drive slides.
All of these computers also used cheese head screws for assembling the
chassis and mounting components such as the motherboard. Compaq used these
torx fasteners because they wouldn't cam out like phillips head screws
when used with the torque limiting pneumatic and electric screwdrivers
they used in the assembly plant.
That being said, ordinary slotted cheese-head 6-32
screws will work
fine--the only thing lost is the Torx feature.
Have you had any luck in finding those sort of cheese head screws in
M3x0.5?
HP also used some Torx-washer-head screws on some of
its hard drive
mounting kits.
They also had screws, in both 6-32 and M3x0.5, that were like the cheese
head screws, but had a larger diameter outer lip at the face of the screw
somewhat like a shoulder screw. Those were used in combination with the
cheese head screws in some of the Deskpro chassis for holding drives into
the guide grooves. These were often (but not always) used in pairs for the
two front-most screws closest to the drive bezel with two cheese head
screws used for the rear screws. Some systems only needed one of these
special screws per drive.