Sheet rock screws: fine vs coarse thread?

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.

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...

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

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

Stuart

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.

And never use drywall screws for staging.

Dave

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.)

Normally I'd go with what you said but, I constructed two envelope walls (no studs having conduction from inside to outside for my machine room. The studs are tamarack, fine pitch was easier to use but I did finally resort to drywall nails, some that bent over. For a soft wood, tamarack sure doesn't know it.

Generally fine pitch is for steel studs iirc.

Wes

Robertson screws are pretty good but the ones with torx heads are really awesome. I re-pitched a roof once with adder trusses held on by torx fasteners that screwed into the original trusses. Long as they were, they never stripped. Unlike some Robertson screws I've used in building decks.

Wes

-- "Additionally as a security officer, I carry a gun to protect government officials but my life isn't worth protecting at home in their eyes." Dick Anthony Heller

I'm sure there are exceptions. What the Gougeons learned first was that conventional wood screws didn't hold as well as sheet-metal screws in any wood they tested, probably due to their deeper and fuller threads.

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

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

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

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

I bought a package of Torx head deck screws for erecting pump staging. It's nice to not have to push on the driver at all when you're up on a ladder and reaching as far as you can to fasten the pole braces. Expensive, but much better than Phillips or Robertsons.

screwed into the

A couple of yrs ago I built for my daughter's old cottage in Wales some new kitchen units. She wanted then out of solid wood, in the medieval style. The framing was from 4 by 2 with the tops in 2in thick all from cedar inc the doors which were 1in thick, boards some 20in wide. These boards were planked up when she was 6 and put by. I used them for her some 19yrs later!!.The wood came from her school at that time as we had had the storm of the century and most of the school trees were blown down. I helped to clear up the resultant damage. To fix the frame to the top from the underside needed 3&3/4 in screws. I pilot drilled the 1st 2in through the framing then the remainder with ,would you believe my 1/2in car wheel nut air hammer. the screw heads were countersunk no3 pozidrive and nothing put them in better or faster. Thought it might just be of interest, as no other power tool would work to pull them up real tight. Didnt cam out any. ted in Dorset UK

On Tue, 13 Apr 2010 18:30:38 -0400, the infamous Wes scrawled the following:

Yeah, my head favorites, in order of favor are: Torx, Robertson, Pozidrive (square and phillips), and Phillips.

For repair work a year or ten later, Robertson/square beats them all. A nail or screw pushed into the recess removes enough dirt and grit to allow the drive to remove the screw without stripping. I keep a camera lens puffer (rubber bulb with small brass tube for blowing) in the truck for things like that. It saves a whole lot of time and frustration when you don't have to drill out any hardened screw heads.

-- Climb the mountains and get their good tidings. Nature's peace will flow into you as sunshine flows into trees. The winds will blow their own freshness into you, and the storms their energy, while cares will drop away from you like the leaves of Autumn. -- John Muir

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.

[ ... ]

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.

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.