A lesson learned about dry wall screws

[Dave Gray]

It was a natural progression, so I tell myself. The plywood laps were stitched together with dry wall screws. So, why not screw everything together, temporarily, with drywall screws? They're hardened steel, right? Heck, you can even reuse them time and time again!

And that is what I did. Until one day -

The apprentice boat builder glued the seat
blocks and the inwales to the boat with epoxy,
using drywall screws to anchor it all. The
inwales are white oak, the blocks, mahogany.
After a week of 90 degree weather (boat is
in detached, uninsulated garage), he decides
its time to take the screws out.

Hey! The head came right off of that screw!
And that screw! And..

And so it went. Fourteen or so screw heads twisted right off. Drilling them out will be laborious at best since I daren't use any lubricant next to the wood. A screw extractor has not proven to be satisfactory. Of course, the few nubs that remained proud of the hull won't unscrew. I bought a pair of vise grips only to have the cheap soft steel of the jaws get chewed up by the one screw I tried it on.

The moaning chair has seen its use these last few days.

[T.KAMILA]

You got to remove them as soon as the epoxy kicks enough to hold everything together. Hard also means brittle.

Tom

[ion barnes]

Dont like saying this but you wont drill them out. They are hard steel all the way. You will only be able to drill out a core with the screw I think, unless you can put some heat directly onto the screw shaft and soften the epoxy. LOL

[Don Maurer]

You need to wax the threads, then twist the screws a half turn after the epoxy sets, but before it cures.

[ 09-10-2003, 07:20 AM: Message edited by: Don Maurer ]

[Del Lansing]

Hmmm, there must be a reason they call them "dry wall screws." About strong enough to hold a sheet of dry-wall.

[Tom Lathrop]

Many builders use them, including me, for temporarily clamping epoxy joinery together. Unfortunately, you have learned the cardinal rule the hard way. If the joint is deep or there is lots of epoxy, they have to come out before the stuff is fully cured.

[On Vacation]

Several notes on drywall or sacrifical screws here. Use the fine thread ones. Use a driver drill to install them. this will not heat up the screws, weakening them, upon installation, as a regular drill will do, especially going into a hardwood. Gluing with epoxy that has been thickened with 403 fibers will break off almost any type of screws, you will be using, with hopes of removing them, after glue has cured.

[cs]

Just a thought, depending on the application. Why not counter-sink the screws and once the epoxy is set just fill the counter sink with epoxy?

Chad

[Keith Wilson]

FWIW (won't help now) they make cheap stainless steel "deck screws" , just about like drywall screws. They're about $6/pound around here, made in China, of course. The onlu advantage is that if you have to leave them in when the head breaks off they won't rust much. I think if it were my boat, I'd drill around the screw with a small hole saw, remove the screw and wood, and glue in a trunnel - it's even semi-traditional! Better than trying to drill out a hardened screw. :(

[On Vacation]

Originally posted by cs:
Just a thought, depending on the application. Why not counter-sink the screws and once the epoxy is set just fill the counter sink with epoxy?

ChadThis can be done. But in some applications, in laminations, for instance, you may not wish to have them in, for future drilling and fastening with other hardware. After the primer and paint is done, the areas that you need clamping for glue joints and stuff, is covered up. Plan accordingly in the bulding stage. Rust streaks and broken drill bits, can be worse, when working on a finished product.
.

[George Roberts]

And I hear that to remove epoxied in screws you apply heat to the screw then just remove it.

Perhaps some heat after the first break would have saved some work.

[Bob Smalser]

Originally posted by George Roberts:
And I hear that to remove epoxied in screws you apply heat to the screw then just remove it.

Perhaps some heat after the first break would have saved some work.Yup....touch the heads for a minute or so with a hot soldering iron before backing them out.

[Ken Hutchins]

The common drywall screws are junk - you already know that. Now spend more $ and buy the coated deck screws, I believe the coating is ceramic. The screws are much stronger and the coating is a lubricant. I've used over 200 lbs of these and havn't broken more than 1/2 doz. ( those that broke were most likely used 15 or 20 times) I use and reuse these for all kinds of things, never use nails and when I remove them for any reason they back right out I've removed a bunch that were in oak for 5 years and they all came out - no problem. BUT STILL DON'T LET THE EPOXY HARDEN!!!!!

[NormMessinger]

We haven't been much help with the problem at hand now have we.

I've seen screw extractors, hollow little hole saws that rotate counter clockwise so as they go in around the screw they will eventually back the screw out. That's the theory. I've only seen them advertised.

[Mike Vogdes]

Maybe you can carefully grind the remaining screw shank below the surface a little and fill with thickened epoxy as mentioned above, having a few mechanical fastners in your oak inwale wouldn't be the end of the world. More than likely your gonna cover the area with a rubrail anyway.

I use the fine thread black drywall screws with the drill bit ends, they hold up well and can be used over and over, very rarely will one break. Those cheap course thread galvanized drywall screw should be avoided alltogether, the heads on those will twist right off driving them in sometimes..

[Dave Gray]

Thanks for the perspectives, everyone. I knew I should have given up after the first one broke and posted here! As it is, I may have to philosophically resolve myself to epoxying over the broken screws, much as I hate the thought of any metal other than bronze being part of this boat. Heat would have been a good thing - I guess the pilot holes were too small and the thickened epoxy was just too thixotropic (sp?).

Live and learn, as they say. Now, the next boat...

[whb]

Dave

Isn't there a screw extractor type of thingy that is essentially a really small hole saw.

I think it might do the job and leave a hole that once filled will look like a normal bung.

howard

[Mike Vogdes]

What kind of boat are you building?

[Dave Gray]

It's a Pooduck skiff, plans from WB. The outwales have already been installed, the inwales have small blocks glued to them to stand them off the sheer. Glue is applied to the blocks, the breasthook, and the stern knees and the assembly screwed through the plywood to the outwales. I'd post a picture but my digital camera got swiped (lost?) when in London this summer. This, my first boat, has been a good learning experience and not so challenging as to be discouraging. The most discouraging part has been SWMBO looking at it and saying, "It's only that big?" I ask, "You were expecting a 40' cruiser perhaps?"

[gary porter]

Dave, just a quick note on using the drywall screws especailly in hardwoods such as White Oak.
Be very careful not to tighten them too much to start with. The epoxy doesn't need to be squeezed tight and you might very well have weakened them when putting them in. I have had them break off when driving them in and have gone to using a very low setting on a cordless drill so as just to snug them up. I also use 1" screws whenever I can.
Good luck getting them out, I think a small hole saw which you can make with some tubing will work and then plug the hole with a bung of the same material or mix up some woodflour of contrasting color like walnut or mahogany.
Good Luck....Gary

[On Vacation]

I think I read it as these broke off on the inside blocking of your rails, inside the boat. Have you given any thought to laminating another small piece to the pieces with the broken off screws in it? These thin pieces can be tacked in place by small brass brads, countersunk with predrilled holes, very small till glue sets. The bore them out or use a small finish nail with a small plywood washer, waxed up or a piece of plstic tape, for removal when glue sets.. This may give you an surface to do what you want to, for the finish work.

[ 09-10-2003, 01:55 PM: Message edited by: Oyster ]

[Nicholas Carey]

I believe Rockler has the iddy-biddy hole saw you're looking for.

http://www.rockler.com/rockler/images/92304.jpg (http://www.rockler.com/ecom7/showdetl.cfm?offerings_id=2354&objectgroup_id=439&catid=7&DID=6)

You might try dropping a plug cutter over it to expose the shank, heating with a soldering iron (I believe epoxy plasticizes at ~ 140°F, so you don't have to get it too hot) and [quickly] unscrew it with an Unscrew-Em (http://www.tltools.com/tlt/) from T & L Tools (http://www.tltools.com/)

http://www.tltools.com/tlt/images/logo3.jpg
(US Patent No. 4,688,315 (http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO1&Sect2=HITOFF&d=PALL&p=1&u=/netahtml/srchnum.htm&r=1&f=G&l=50&s1=4,688,315.WKU.&OS=PN/4,688,315&RS=PN/4,688,315))

Or use a pair of needle-nose vice-grips, which will trash the surrounding wood a bit.

Then fill/repair the holes.

Good luck!

[ 09-10-2003, 01:54 PM: Message edited by: Nicholas Carey ]

[Buddy]

Please, please get yourself one of those clunky "plumber's" soldering irons( not a pistol grip electronics soldering gun) before you moan anymore. It WILL heat up the screw almost instantly, the epoxy bond WILL let go, and the screw WILL back right out. You WILL be amazed that sometimes a magic ( any new technology is indistingushable from magic to us) trick WILL do the job. Get out of that moaning chair.

[Ed Harrow]

Buddy, you're just too quick for me. A hefty electric soldering iron should do the trick. DAMHIKT. The screw remover shown in a post or two above should also work. I've not used one in your exact circumstances, but I have made one using a roll pin. Grind a ^ into the split at one end, chuck it in you drill (maybe not a heavy duty Milwaukee 3/8" drill :mad: ) and see what happens. You might have to use the real thing in your case.

Whatever, as was said, get up off that chair, you don't want to leave them in there.

[Dave Gray]

Thanks again. The screw extractor sounds like a good idea. I have a 40W soldering iron around somewhere that I can use for the screws that broke off above the hull. Oyster is correct, a majority of these broke off inside the wood, so extraction is a good way to go. How come I keep thinking of wisdom teeth?

[Peter Malcolm Jardine]

I believe that dry wall screws are case hardened... which if I have the right term means the outer shell is hard because that means the screw head won't strip out. other than that they're junk. and for drywall only.

[tnert]

Dave, I had this happen very recently. Luckily I had purchased the appropriate Fuller "unscrew-ums" from Jamestown. I was able to remove close to 2 dozen cheap drywall screws before I destroyed the unscrew-um. Buy two of every size you might ever need. Now that I've learned a thing or two about epoxy though, remove them "when it kicks" whatever that means; alternately, the hot plumbers gun sounds good too.

[daddles]

At my boat building course, we screw things together. The boat gets left till the next class, a week later, before the screws are removed so the epoxy, West, is well and truly set. Most screws let go easily. Those that don't shift immediately, get hit with a soldering iron and so far, they've all come out.
BUT
the thing that hasn't been mentioned so far on this thread, we also put a chunck of 9mm ply under the head of the screw when installing it. That way, if a head does break off, you can remove the scrap ply and you've got something to grip with the pliers.

Sorry I can't help with the current problem.

Cheers
Richard

[Dave Hadfield]

Too late, of course, but pine tar makes a good screw lubricant, it's good for the wood, and it interferes with epoxy bonding.

It also smells cool.