Link to a good article posted in another newsgroup:
Personally, I'm pretty "old school" and something of a purist, and don't
like to use these other for their intended purpose (securing drywall to
framing), but I'll admit that I've grabbed them and used them a time or
three for other things.
Discussion in other ng was about coarse vs. fine threads: consensus
seems to be that coarse threads are better in wood.
Didja know that the fine-thread screws were originally made for putting
up drywall on metal framing? I didn't.
The fashion in killing has an insouciant, flirty style this spring,
with the flaunting of well-defined muscle, wrapped in flags.
Use coarse thread deck/drywall screws strictly for temporary
applications such as one time jigs, forms, etc.
For wood working, use S/S coarse thread, self tapping sheet metal
screws along with a 75% of thread OD pilot drill.
Don't twist off any heads and haven't had a fastener come loose yet.
I'm curious about your rationale...
1) Why S/S unless it's in a damp location? They're way more expensive
and harder to find.
2) Why sheet metal screws? Aren't they normally threaded the full length?
3) The scientific literature suggests the pilot hole should be 75% of
the root diameter in low density woods and up to 100% of the root
diameter in high density woods. Technically the outer thread diameter
Why for Lew I don't know but I use them because they have more
aggressive threads and drive much easier than traditional wood screw.
Habit developed before there was nearly as much choice as now.
Still use traditional methods where seems appropriate to do so...
I buy fasteners buy the box so S/S are available at a modest premium.
S/S are readily available locally here in SoCal as well as from people
like Jamestown distributors.
The cost of fasteners gets lost in the wash compared to piece of mind
knowing I'm not going to grab the wrong fastener, especially in a
Self tapping screws are threaded full length, NBD.
Their coarse thread bites into the wood easily and engages fully.
I use them all the time. They hold extremely well, and I haven't had
one snap on me in a long time. Perhaps it's due to the impact driver
hammering the screw instead of just twisting it. The drywall screw
heads fit the DeWalt #2 Phillips head perfectly, so there's no slippage
when driving them in.
When screwing into plywood, the fine thread screws may work better.
However, when screwing boards together the coarse screws are far
superior to the fine threads. The fine threads strip out extremely
easily, especially in pine.
The guy mentioned that wood screws don't have the threads all the way
up, so they pull the boards together. The simple solution to this is
simply to drill a larger pilot hole. The pilot hole is there to prevent
the wood from splitting, so as long as it's sufficiently smaller than
the screw head it'll still do it's job.
Never teach your apprentice everything you know.
While that's one reason for it, a suitably sized pilot hole will
actually increase the strength of the joint. A pilot hole that is too
small results in crushed wood fibers which have less structural strength.
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