"Wild_Bill" wrote in message
...
Drywall screws probably aren't a good choice for much more than wood or
their intended use (although they do self-drill thru fiberglas nicely).
The bad feature of most DW screws is that they're brittle, and just snap.

And rust like crazy.
The coarse thread has an especially nice "bite", as the root diam to total
diam is much smaller.
Yeah, these things have a good Rockwell, I think. I occasionally use them
(and concrete nails) as scribers.


I prefer to use decking screws (for wood projects), which will typically
bend before breaking, but testing a chosen brand? (likely to be imported)
is probably a good idea.

Decking screws appear to me to be higher quality drywall screws. I have a
bunch of SS DeckFast deck screws: square drive, "auger point" (slit like in
tapping chassis screws), and *two* included angles (one a transition to the
neck) as you mentioned, and raised lines under the head, presumably an
anti-loosening strategy.
Starborn Industries, Avenel, NJ. Not cheap.


The way the heads are transitioned from the shank isn't very consistent
for either type.. there may be a radius as mentioned, or a combination of
a countersink that blends into a tapered section.

You've neglected to mention what materials are to be fastened, but quality
countersunk-head machine, sheetmetal or wood screws will likely have more
accurate/better matching head geometry for a machine-cut countersunk hole.

Attaching metal apparatus to wood.
From a c-sink pov, I should proly go to sheetmetal, but from a
drilling/grabbing pov, I really like coarse drywall screws, whose threads
are deeper, sharper.


If this fastening task is related to an earlier situation of applying a
thin, hard skin over a soft substrate, I'd expect DW screws to be about
the worst choice.

Oh, the wood filler/epoxy thread.... Why are drywall screws bad for that,
besides rusting like crazy?
What is a good choice?



--
WB
.........


"Existential Angst" wrote in message
...
Dayum.... google has not been my friend.... nor Bing....

I found the included angle of bugle head drywall (60-63 deg, fyi), but
not of regular head drywall screws.

The reason I'm looking is to get the right spot drill or c-sink... MSC
carries 82 deg spot drills, as well as a variety of other angles.

Not all FH screws are 82 deg... I was informed that metric FH are in
fact 90 deg, some sheetmetal stuff 100 deg, and some aircraft stuff 120
deg.

Which also raises the Q: where did 82 deg come from? 90 deg shore
makes sense to me!!
--
EA