On Apr 13, 4:46*pm, "Existential Angst"
wrote:
Awl --

Purpose? *Applications?

The *minor diameter of the fine thread (under 2") appears to be about .115
(mebbe less, due to inadequate penetration of caliper edge), and .090 on the
coarse. *Ergo, more "grab" with the coarse.

I'm guessing the following:

Coarse thread is for sheet rock on metal studs -- more grab on studs.
* *Altho framing screws, which afaik are only for metal stud to metal stud,
also come in coarse and fine thread, so this may muddy this particular
logic. * Mebbe for different gauges of metal studs? *I've seen some much
heavier than others.

Coarse thread for particle board et al.

Fine thread for hardwood.

Opinions?

fyi, there exists a 3/4" and *1 1/8 SR xcrew, very hard to find.
The 3/4 is VERY handy, when screwing from the back side of a good face, and
the 1 1/8 occasionally comes in handy.
A good hardware store, proly one that sells SR screws by the pound, can
order a 25# box. *If he hesitates, tell him that the 3/4" will FLY out of
the store when people grok their utility.
--
EA

Just my two cents worth:

I've always thought that the fine threads were for metal studs.

I've used the self-drilling ones in metal studs, but also in one room
in my house where the ceiling joists were made of something resembling
kryptonite. The normal sharp-pointed screws would just not screw all
the way in. The self-drilling ones shot right in.

Also, for what it's worth, coarse threads require fewer turns to screw
in, and therefore, go in faster.

Just sayin'