Sheet rock screws: fine vs coarse thread?

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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



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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.
--
Ed Huntress



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Ed Huntress wrote:

www.mcFeelys.com
About any screw you might want, and square drive is the ONLY option as far as I'm concerned!
Stuart
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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.
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DerbyDad03 wrote:

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.
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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.
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DerbyDad03 wrote:

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.
http://www.grainger.com/Grainger/items/5PA35?Pid=search
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
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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
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On Apr 13, 7:08pm, snipped-for-privacy@prolynx.com wrote:

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
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snipped-for-privacy@prolynx.com wrote:

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
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On Tue, 13 Apr 2010 16:08:42 -0700, stans4 wrote:

Maybe there are quality issues between brands? I've seen it before with Phillips-head screws, where the amount of material forming the screw can be a lot less from one vendor compared to another. The 'lesser' screws just loved to snap when driven in, whereas the ones with thicker shafts didn't. These days I always buy fastners from real stores (not online) so I can check what I'm getting.

Seen that on doors before - I think it's so they can be screwed into different types of material while retaining strength.
cheers
Jules
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Stuart Wheaton wrote:

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

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On Tue, 13 Apr 2010 17:37:18 -0400, Stuart Wheaton

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,.
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On Apr 13, 9:22pm, snipped-for-privacy@aol.com wrote:

re: "I have never seen a square drive drywall screw."
After visiting here you will have:
http://www.fastenermegastore.com/fine-thread-square-drive-drywall-screws-p-1544.html?ref=23
These don't show the head, but are listed as Drywall Screws, Square Drive Coarse
http://www.drillspot.com/hardware-and-farm-supplies/screw/drywall-screws-square-drive-coarse /
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On Tue, 13 Apr 2010 19:11:01 -0700 (PDT), DerbyDad03

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

http://www.drillspot.com/hardware-and-farm-supplies/screw/drywall-screws-square-drive-coarse / >>
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 ...
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On Tue, 13 Apr 2010 22:27:20 -0700, David Nebenzahl wrote:

Yeah, that occurred to me, too...
Is there a name for the little clutch assembly that disconnects drive when the screw is driven to the right depth? Can they be bought to fit on regular drills? I don't remember seeing them at the store, but they're the sort of widget that it might be useful to have.

I think all the Phillips bits I have are Dewalt, and they're almost too good - usually the bit takes a long time to wear, and the screw head itself is the bit that gets messed up :-(
cheers
Jules
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In typed:

...
I don't recall what they're called but they aren't expensive. I got mine either at Harbor Freight or Sears; forget which now. Handy for all kinds of jobs.
HTH,
Twayne`

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wrote:

_Dimpler Phillips Drywall Screw Setter, #2_
"Use for drywall applications. The Dimpler is reversible, while chucked, push in, then turn to lock for reverse feature. It is also preset to drive screws to the perfect depth and feature an automatic clutch release to eliminate drywall tear-out..."
http://www.hardwarestore.com /
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In wrote:

That sounds like a very unlikely candidate for doing a good job. Most of the jobs Ive done wouldn't "cam out" until the head of the screw reached the wood underneath.

They are "pointier" to provide a more sure and quicker start. It has little to do with a torque limiting design that I've ever heard of. Once past the "pointy" part, the diameter becomes consistant and unchanging. Can you cite that in any verifiable way? I'd be interested in knowing such information if I'm wrong about it. The torque needed to drive drywall screws is almost nothing to most drivers these days.
I have used square drive drywall screws. No big deal; you stop driving at the proper point or you don't. You either become proficient at knowing when to pull the driver back or you use a tool that stops the drive at the proper point (depth); which is extremely handy BTW and not expensive. Adjustable torque isn't the answer as wood varies a lot in hardness over its length. And trusting "cam out", whatever that means, is even less of an answer since it also depends on the wood having the same hardness throughout which isn't the case. IME only the tool can do a 100% successful job of it and then you still have to adjust it correctly. If you don't have a tool then variable speed and eyeballs are the next best answer IMO.
HTH,
Twayne`

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