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Hey there, CR4er!
Take a look to your left. Take a look to your right.
Odds are you are within reach of a hardware fastener that
attributes its mechanical capabilities to the helical groove that extends
around the circumference of the device's shank. These threads provide the friction and
traction that serves the fastener's purpose: to assemble or position two
workpieces in relation to each other.
Get where I'm going here? Of course I'm talking about screws!
I'd like to consider myself pretty knowledgeable. Why? Besides selling nuts,
bolts, screws and anything else in between for two years at Gotham City
Hardware, I also just read GlobalSpec's
super helpful Screw selection guide.
 ...via Life Hack
Ok, so call me a poser. A phony. A fake. Do you know the
difference between a bolt and a screw? No? Well I do: Since these terms were in
use before the advent of easily-produced helix fasteners, they are
often synonymous. However, several standards bodies have attempted to
differentiate the terms, with many concluding that it is not the
devices which are different, but how they are used. As provided by
Machinery's Handbook and ASME B18.2.1, bolts are externally threaded fasteners
that are prevented from being turned during assembly, but are positioned or
released by torqueing a nut. Screws are externally threaded fasteners that can
be inserted into pretapped holes or that can perforate a material and
create their own internal threads. Screws are fastened by torque applied to the
head. This definition is still somewhat ambiguous and is not all-encompassing,
but does provide a basis to begin differentiation.
Do you have a favorite screw-head recess shape? I sure as
heck do. I've always been fond of spline heads. I guess this is a lot like
pizza toppings. Some people like cheese and pepperoni, while I prefer Mega
Pizza. Hamburger, hot dog, bacon, maple syrup pizza. MMMM.
Screws come in a large variety of designs and materials. So
much so that it would be impractical to list them all here. But, to provide
you, my friend, with a quick brush-over:
The chamfer angle on the underside of the head, known as the
countersink, mates with a conical recess in the workpiece so the head may rest
flush with the workpiece surface. ISO metric countersinks are usually 90°,
while imperial screws typically have a countersink of 82°. Common countersink
angles include:
Furthermore, manufacturers produce screws in both imperial
and metric units, and due to their explicit correspondence with nuts and
pretapped holes, the units cannot be mixed. Furthermore, screws are
produced with fine or coarse threads, which are a designation of the
screw's thread pitch--not the quality of the product. Coarse-thread screws
are less susceptible to galling, thread crossing, and seizing, while
fine-thread screws are less likely to loosen from jostling, and are more
easily tapped and adjusted. For screws that cut their own threads in a soft
material, there is no need to determine the thread type.
Do you need a cap screw? A drive screw? Perhaps an eye screw?
Check out the screw
selection guide to figure it out for yourself. Sometimes you just have to teach a
man to fish …and
sometimes you need a new screw to hold that fishing pole together.
...via Terrier Man
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Re: Screw This!
"Almost" Good Answers: