Sheet rock screws: fine vs coarse thread?

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

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

But sheet metal screws don't look like drywall screws. More likely they were Drill Point Drywall Screws, as shown at top of and one screen down in . The latter also shows (near the end, after the Trim Head Drywall Screws section) Auger Point Deck Screws that look somewhat like drywall screws. (With Type-17 point, as mentioned in the link Larry Jaques gave, .)

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`

...

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`

Heh, I'm surprised that some here have asserted that it is the fine thread that's used on metal studs, coarse for wood. Not disputing it, just surprised that this would be so, as it would seem that the greater the ratio of major to minor diameter, the more grab possible on thin sheet metal.

In fact, there's a company that exploits this with some fancy sheet metal screws -- forgot their name, but I have a sample pack from them somewhere...

In re-thinking all this, pilot holes could be used to tailor any material to a coarse thread. Except that, well, altho pilot holes are good, they are also a pita.

I used to buy only fine thread, pretty much out of reflex, but now I find myself much more leaning toward coarse thread, overall. Plus, coarse threads are easier to tap, less chip binding it seems.

My understanding is that fine threads on big bolts is a torque/force consideration, for getting mating stuff really tight.

But, other than that, I think fine threads may be pretty much superfluous for general applications, unless, for example, metal studs really do call for a fine thread screw.

Bottom line is, I think I've convinced myself to dispense with fine thread anything, unless an application specifically benefits from a fine thread. Sure will simplify the organization/storage aspect.

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'

Ah, not so. Well, sometimes, maybe. The fine thread screws are double-threaded, so they go in twice as fast as they would otherwise.

Bob

_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..."

Now I gotta go look. But not 'till morning.

Yes -- drill point bugle head blued like other drywall screws I've seen.

The first SELF-DRILLING in that list (just past "TYPE 25 POINT" is exactly what they were using. And given the application, they made sense. One tool (battery powered drill/driver), one screwdriver bit (Phillips) and the screw which did its own drilling. Not what I would have used to make a pretty job, but something which got the contract done quickly. :-)

The screws were guided by the pre-drilled holes in the replacement desk tops, and the steel which they had to drill through was probably about 12 Gauge or thicker. (I never tried to measure it, but those were *heavy* GSA steel desks.)

In case it matters, I'm in here from rec.crafts.metalworking, not from alt.home.repair, so what I regularly work with is likely quite different from what the ahr crowd (who is part of the cross-posting) does.

Enjoy, DoN.

No, they are not double-threaded. YOu're thinking of something else. Coarse is just that; a much coarser thread, more diameter than a fine, and fewer turns to drive in but I've never found that to be an issue of any kind.

HTH,

Twayne`

Drywall tips usually have a cup that stops the bit from advancing and the tip will disengage right away because of the taper. With a square drive the bit is straight and has to run out a lot farther to disengage, even if it does have the cup.

There are 4 types of screws typically used for drywall..

Coarse Thread from 1inch for pocket door walls to 3 inch for going over old sheetrock/plaster , multiple layers in firewalls ...For use with WOOD studs

Sharp Point fine thread..Same as above except for use in METAL framing..

Self Tapping fine thread , sams as above but for higher gauge steel like in exterior or load bearing steel framed walls..

Laminating Screws...Fat coarse thread 1 1/4 screws for laminating sheetrock on steel framed walls as in stairwells or elevator shafts where sheetrock thickness is an inch or more...

Other than sheetrock I use Torx...Square heads are good as well....