Sheet rock screws: fine vs coarse thread?

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.

Reply to
Existential Angst
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The Gougeon Brothers of sailboat fame did tests of coarse- versus fine-thread screws in wood back in the '60s. Coarse-thread won. Sheet metal screws beat wood screws in wood every time. That was before sheet rock screws.

Reply to
Ed Huntress

Typically, it's coarse thread thread for wood studs, fine thread for metal studs. The fine thread screws also have a sharper point so they are easier to start, *especially* when trying to pierce metal studs.

While you might think that you want coarse threads for more "grab" in the metal studs, in reality you want less space *between* the threads so that the thin metal can't move.

Here are some thoughts on using drywall screws for woodworking...

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And we haven't even addressed the different types of heads on drywall screws, from "standard" to bugle to flat.

Reply to
DerbyDad03

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About any screw you might want, and square drive is the ONLY option as far as I'm concerned!

Stuart

Reply to
Stuart Wheaton

re: "square drive is the ONLY option as far as I'm concerned!"

Unless you think you might find yourself with the need to disassemble what you've put together and there's a danger of no (or not enough) square drive bits being available.

I'm often involved in set-up and tear downs for events where lots of dry wall screws are used. You can *always* find a screw gun, usually with a # 2 phillips bit already installed, within arm's reach. Try locating a square drive bit - and of the right size - when something needs to fixed/adjusted with moment's notice.

When it comes to volunteer events like these, you want to go with the most common fasteners so that anyone (and everyone) can pitch in. # 2 phillips screws are still the most common and I don't see that changing any time soon - even if square drives are better.

Reply to
DerbyDad03

And never use drywall screws for staging.

Dave

Reply to
Dave__67

On 4/13/2010 2:23 PM DerbyDad03 spake thus:

Thanks for that; excellent article. Pretty much jibes with my own experience with drywall vs. wood screws. I much prefer coarse threads for wood. (Never used fine-thread drywall screws for their original intended purpose of securing to metal framing.)

Reply to
David Nebenzahl

Yep, nails ("blue nails") and a lath hatchet.

Reply to
Oren

I dunno, I used quite a few pounds of square-drives putting up a shed. The drivers didn't wear like a cross-point/Phillips bit would, but quite a few heads stripped out or screws snapped off without driving home. This was with decking screws, U.S.-made at that. I've used a whole lot of regular-type sheetrock screws and didn't have that problem. Wore out a bunch of driver bits, but never had a head strip. Haven't seen stainless drywall screws or I would have used those.

Have a bunch of trim screws off of Fords I picked up in the scrap yard that had interesting threads, went into plastic parts. Were multi- start threads, one start was coarse and heavy, like a sheetrock screw, the other was shallow and thin. Hadn't seen anything like that before. Seem to be pretty resistant to vibration, have to tighten up the other trim screws after awhile, not those.

Stan

Reply to
stans4

I agree. Less hassle getting enough torque. No phillips chatter.

Reply to
LSMFT

Yeah they do kind of a controlled bind-up but they are bad to strip out if you put them in and take them out more than a few times. May work better in wood than they do plastic.

Jimmie

Reply to
JIMMIE

I have never seen a square drive drywall screw. You actually want drywall screws to cam out before they go in too deep. That is also why a #2 drywall bit is a lot "pointier" that a regular #2. It is a torque limiting design.

I do agree on just about any other type of screw. Phillips is not as good as square for torque but torx is better than both of them,.

Reply to
gfretwell

re: "I have never seen a square drive drywall screw."

After visiting here you will have:

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These don't show the head, but are listed as Drywall Screws, Square Drive Coarse

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Reply to
DerbyDad03

The problem you mention is easily solved by having a few packages of #2 square drive bits. I work in Theatre, we put up and tear down all the time, and there is NO comparison, esp if the head has some paint in it. Also, if a square drive bit becomes slightly worn, it can usually be re-conditioned enough to finish the show, just by lightly tapping it on a running belt sander, you can't do that with a phillips. I have known places that used one type of fastener for all permanent inventory, and the other fastener for stuff that is meant to last just for the show. then if only one driver type is on the deck at strike, the good stuff gets saved.

BTW, screws are a single use item. The biggest source of frustration is trying to save and re-use screws.

Reply to
Stuart Wheaton

I suspect these are "drywall screws" are for drywall like "duct tape" is for ducts., Good for everything but drywall. You do want a drywall screw to cam out as soon as it bottoms, not when it is pulled as tight as you can screw it.

Reply to
gfretwell
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When my old workplace (a government R&D lab) let out a contract to re-cover all the 30-year-old linoleum-topped metal desks with new fake wood (particle board with wood-grain print plastic on it), they simply dropped the new top over the existing one (made to be a pretty good fit with sides which overlapped the metal top sides), and used some intersting screws. At first glance, they looked like drywall screws, but examining one showed that instead of having a sharp spiral point, they had a drill bit point, so they would drill through the metal and then thread in -- going into pre-drilled and countersunk holes in the sides of the new top.

That is now about twenty years ago, so I wonder what the desk tops look like now. :-)

Enjoy, DoN.

Reply to
DoN. Nichols

re:

1 - "The problem you mention is easily solved by having a few packages of #2 square drive bits..."

2 - "BTW, screws are a single use item"

1 - Not really and 2 - not in all cases.

At the events that I'm talking about, the equipment that is used by the competitors require - by rule - upwards of 40 # 2 Philips head dry wall screws. Therefore, that is the bit that everyone has in their screw guns. Square drive screws are not an an option in the competitor's equipment. The screws for the competitor's equipment don't get stressed or torqued very tight, so they are used over and over and over again with no damage. The only time they get replaced is when they get lost or rusty.

Now, as for the set up and tear down portions of the events, the organizers opt for # 2 Philips head screws of various types and sizes so that we're not constantly looking for and changing bits depending on whether we're working on the competitor's equipment or the event infrastructure. I know that these screws are single use items, but there are many "helpers" who don't.

At one point I snuck in a bunch of those Deckmate screws that took the square tip Phillips bits. I used them for the heavier construction parts of the set up. Talk about Phillips bit chatter when other people tried to take apart the stuff I had built! I was promptly told to stick with standard # 2 Phillips in the future.

Reply to
DerbyDad03

I have two screwdrivers I carry in my pockets whenever I'm working. The drivers have flat, Torx, Phillips and square bits because I never know what I'll run into. The bits can also fit a power driver. A good pocket screwdriver is hard to find and I found the best I've ever owned a W W Grainger. It won't poke a hole in your pocket when it's closed up with no bit in it.

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I also carry a lot of other stuff in my pockets that keeps me from having to run back to the van for a tool.

TDD

Reply to
The Daring Dufas

It seems like all of the new electrical panels I'm coming across these days are using square drive screws or combo screws that will work with flat, square or Phillips drivers. I like the torque handling capability of the square drive screws and the absence of cam-out slippage.

TDD

Reply to
The Daring Dufas

On 4/13/2010 7:40 PM snipped-for-privacy@aol.com spake thus:

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But isn't that supposed to be a function of how you adjust your screw gun to just dimple the drywall? Of course you're gonna drive the screw right through the gyprock panel if you crank on it.

Not that I've ever used such a screw gun, nosiree.

But those square-drive screws would have been really nice going into those old, hard Doug fir studs that caused the Phillips heads to get ground into metal flakes ...

Reply to
David Nebenzahl

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