# How to protect screw threads in wood?



## Jerry McColgan (Feb 8, 2008)

I use a sheet of painted plywood to cover the end of a storage area. The plywood is secured with deck screws.

Since I remove and reattach this plywood often I am concerned about the deck screws becoming loose in the 2" x 4"s they are screwed into. They also are gradually increasing the depth of the tapered hole in the plywood as the screw head repeatedly hits it.

I like the idea of the deck screws because they cannot be unscrewed with a simple flat or philips screwdriver and I would prefer to avoid having to use washers (one more thing to bother with).

Is there a simple way to strengthen the wood to hold up to repeated insertion and removal of the deck screws?

I've thought of using super glue but there may be a better way.




















I have also considered a piano hinge but they are expensive and any hinge would be a bit tricky to install right because I want the end to fit with the sides and bottom flush with no gap.

Any ideas?

Jerry


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## hcampbell (Jan 2, 2008)

Could use use a threaded insert? They're a nut with wood screw threads on the outside and machine threads in the center. 
They are made for just such problems. 

Harvey C.


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## wchasr (Jan 2, 2008)

Jerry on first reading the title of the thread I too thought Threaded inserts would work but once I read the body and saw the accompanying photos I think it would be best to find some brass decorative washers (http://www.mcmaster.com/#washers/=6de5xp) or these (http://www.mcmaster.com/#washers/=6de5d4) neat washers I found while trying to find those at Mcmaster Carr. Basically a washer to prevent the screws from going in any deeper but allowing you to still tighten them down for some semblance of security. I can think of some other realyl neat ways of doing it better but with the layout already built it might be tough to retro fit. Still involves the use of T nuts and then going to a security bolt of some sort (http://www.mcmaster.com/#security-bolts/=6de7uf) or (http://www.mcmaster.com/#security-bolts/=6de7ng) that requires special tools that not everyone would have normally. 

Chas


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## Totalwrecker (Feb 26, 2009)

I've got it! 
Mount car wheel studs in the 4x4s and use locking lugnuts, drill the wood so the studs come through and then screw on the lugnuts. Not all lugnuts need to lock, just enough to defeat a theif. 
No hinges, no washers and big nuts! 

The lugs ar press fit from the backside of the wheel, so route out an opening deep enough for the lug, then place a piece of sheet metal w/hole in center over the lug and screw in the corners. I'd probably hammer set the lug in the sheet (a spot welder would be good here) on my vise first so the lug doesn't spin upon tightening down the lugnuts...

Use the same size as your trailer and I'm betting you'll have the wrench!

John


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## xo18thfa (Jan 2, 2008)

A trick I use is to drill out the existing hole in the 2 x 4 to 1/2" and a little deeper then the screw length. Glue in a length of 1/2" oak dowel pin. Drill a pilot hole into the oak and run the screw into it. Oak is better for repeated use than the framing lumber. Maple dowel would be better then oak, if it is available. 

Or find some tamper resistant machine screws and go into threaded inserts.


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## Jerry McColgan (Feb 8, 2008)

Hi Guys,

The current "system" is quick and easy. There are eight of the star headed deck screws that come out or go in in less than a minute total (with a power drill).

I'm pretty much looking for a solution that would involve very little effort on my part to make it work and still use the deck screws I like. It may be that the simplest solution would be to start new holes and immediately squirt some super glue into the holes to toughen the wood.

I appreciate the suggestions. 

Jerry


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## Totalwrecker (Feb 26, 2009)

OK OK Make it better and don't make it harder..... 
Simplest suggestion does involve washers... once, use a Spade bit to drill out space for a washer. You want the washer just slightly larger than the drill bit. Hammer set the washer into the plywood. Now the screw will stop pulling itself into the wood. Use your super glue to hold the washers in place. 

Don't go mentioning Piano Hinges if that's too complicated, I used that parameter for my solution.... re; amount of work.... Having the studs mounted would simplify mounting the plywood, you wouldn't have to hold it while tightening the nuts. There are adapters to hold sockets in your drill. 

I've never used the glue that way, becarefull over tightening, the glue may make the threads brittle and break off.... 

John


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## John J (Dec 29, 2007)

Ok I got the ultimate answer. 1/4 20 carrarge bolts long enought to go though the 4x4 and the plywood. Then washers and Wing nuts. the if you want to lock it put Padlock hasps on each side and get two locks keyed the same.


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## DKRickman (Mar 25, 2008)

Probably more useful, and easier to work with - they sell studs which have a wood thread on one end and a bolt thread on the toher - screw them into the wood, and use a bolt and washer on the outside. Use stainless if it spends most of its time outside.


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## hawkeye2 (Jan 6, 2008)

Jerry it looks like your system works well and is simple so I wouldn't change much. I would recomend putting a washer under the head of the screws before you reinstall them. Drywall and decking screws have a head that is designed to pull under the surface when they are driven and they work very well that way. Set your screwdriver to a very low setting and don't let anyone else reinstall the screws. The chances of all the threads failing at the same time is remote so you should be able to get home and fix it later or just relocate the screw. The old screw holes can be filled and painted over. I would staple or screw a Tupperware container inside the storage area someplace and throw in a handful of screws, washers, an extra bit, a manual driver (Torx?) for when the batteries go dead (only at 11:00 PM in the rain), and a magnet to pick up lost screws. A decking screw on the ground will inch its way to the nearest tire and burrow into its warm comfortable new home only to make its presence known much later, they are much like termites. Stripped holes can be repaired as Bob mentioned by drilling them out and installing a dowel. I would use the ones with groves cut in them to hold glue and use a good waterproof wood glue. It might be a good idea to drill a small pilot hole in the dowel if they are hard and use soap, there isn't much you can do when a deck screw twists off. A quick fix that works so well it can be permenant is to whittle a sliver of wood (bamboo skewres), push it in the hole and install the screw.


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## Jerry McColgan (Feb 8, 2008)

Posted By hawkeye2 on 26 Mar 2010 08:25 AM 
Jerry it looks like your system works well and is simple so I wouldn't change much. I would recommend putting a washer under the head of the screws before you reinstall them. Drywall and decking screws have a head that is designed to pull under the surface when they are driven and they work very well that way. Set your screwdriver to a very low setting and don't let anyone else reinstall the screws.


Hi Hawkeye,

That is probably what I will do. As I think about it the problem tends to be more of the screw head sinking in rather than the deck screws pulling out.

It would be great if someone makes concave washers so the screw head would not stick out but I don't think I'll be able to find them locally.

If the screw threads in the 2" x 4"s eventually strip the dowel idea should work well for that.

Thanks,

Jerry


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## DKRickman (Mar 25, 2008)

Regarding concave washers:

The local Lowe's and Home depot stock washers made just for the purpose. They're relatively thin sheet metal, stamped into a half-torus shape so that the head of the screw seats neatly on the inside. The only issue might be that the actual bearing surface against the plywood would not be that great, so they may need a second washer to back them up. Of course, you could get fancy and epoxy a washer to the plywood, and the domed (I can't remember what they're really called) washers to the screw heads, so that you don't have as many parts to loose.


In any case, wood to metal joints do not handle being disassembled and reassembled very well over time. You'll need to strengthen the wood where the screw holes are, or they WILL weaken eventually. Either use studs or some sort of thread insert or drilled & tapped hole, if you want this to last for years.


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