My first serious job was demolishing buildings using a Cat digger. The introduction of the Ardox or spiral nail - basically a mixture of a nail and screw - in the early 60's marked a sea change in the demolition biz. Pre Ardox you could literally pull a building apart 2 by 4 by 2 by 4. After Ardox you mainly ended up with firewood. Love the channel
That was good and an awesome demonstration. I quit using nails years ago when it became so easy to use cordless drivers and screws. Now I have to rethink that. It's also a lot easier to disassemble with screws and more often than not they can be reused. Thanks for sharing.
Hold on there, nails and screws have different uses, structural almost exclusively uses nails until GRK structural screws became code compliant. Dont go sticking off the shelf "construction screws" to build structural supports, roof assemblies etc.
Many people don't realize that common nails (and sinkers) are structurally rated for framing applications. So are GRK's; I use their equivalent size to 16d sinkers all the time. Spax is a good brand, too. Stay away from generic hardware store screws. And only use drywall screws for drywall.
Used 16d (.165”) nails in the beams and joist hangers of my deck. Could not find a framing nailer that will fire nails that big, (most do .131”) so did all with a hammer. Hard to beat the shear strength/cost of a 16d nail.
If your connection is subject to that degree of flexion, you have not made a proper connection. I suppose a good take-away is that if you happen to bend a screw, do NOT straighten it and reuse it as it is near failure.
I only learned this within the last 5 years. I always thought a quality screw was stronger due to the threads. Nope. Screws are strong but typically have low shear strength. In building structures, use a nail. Think mild earthquakes or high wind loads. Thanks.
I'm in the grounds crew of our local loggers sports event here in Squamish BC and we use GRK's to attach our blocks to the block stands for our competition. They're the best. Still haven't found anything better. Pricey but well worth it. I swear by them
I’d like to start by saying I love the channel and have the utmost respect for you and your wealth of experience. That said, you’re over simplifying the relation of shear strength of the fastener and the integrity of a fastened joint. Threaded fasteners squeeze, and derive most of their connection strength from the friction of the two pieces being squeezed together. Your test with the hammer is essentially showing which fasteners are the best application for using as a coat peg.
Perhaps a video on the different joints in home construction with not here but here or both types ok here. Given the popularity of screw guns these days and internet missinformation I think most DIYs would be using screws in the wrong application. I know I would rather pull the trigger and drive what I thought was a big strong screw rather than bang in a nail. WOW a real eye opener
I always use nails in shear, screws in compression. There are screws now made for some shear loads, and have used them without failure, but I still defer to nails in shear. Retired professional engineer and amateur woodworker, for whatever that gets me.
Good video. I've recently had to rebuild some cattle sheds. A wind storm came through and tore the roofs off. I learned that the buildings that had more screws or blocking survived while those that were just toe nailed and not blocked or any hurricane clips failed. Since then I have started to use more screws for this application and I ALWAYS use approved screws or tico nails on the hurricane ties. I don't really know if I might have over compensated by using almost all screws, but time will tell. I do believe that there is a time and place for both screws and nails.
Fasteners are Fascinating! There is a lot to consider when specifying fastener type for each unique application. Shear Strength, pullout value, head type, Alloy, material Finnish, thread type. So many options.
I like your videos but this one came up short. Ductility is but 1 factor out of a range of conditions that affect fasteners. Screws can hold up to lateral loads but the main shear force must be on the “shank” or unthreaded portion and not on the threats as this creates a stress riser. Residential lumber construction seams to be anti screw for some reason, but screws and bolts are used all other the place in steel framed construction, automobile industries, aviation etc.
If I remember the old adage correctly, use the right thing for the job at hand, tool or fastener. Most manufacturers will spell things out in the provided material, or their website, or (the good ones) tech support. Thanks Scott! Pray maintain speed and course!
Surprised to see the GRKs break so easily! #8 are supposed to bee around 400lbs of shear as far as I remember vs around 90lbs for a regular deck screw.
@@moutrap the strength comes from the friction of the material and not the screw itself. The clamping power is the advantage. This tested fatigue, not shear strength. GRK all day.
Simpson Strong Tie make structural screws. Other manufacturers do also. It is very true you should not use regular screws in a structural application. Way to many people don't realize that. But please clarify the difference between structural and non structural applications.
This test is somewhat inaccurate because it isn't showing real-world application of force on the screw. I'd trust my life on the big GRK screw over 10 nails.
@@hempcacaogoji831 I felt the same but didn't comment before because I am not familiar with the brand and the camera can foul you on size. The head of that screw tells me it is designed to hold a soft material against wood. I would not call that a structural screw at all.
On you're 10 favorite tools, you said the Chambersburg hammer you have & use, I'm from Chambersburg Pa. & I was wandering if it was manufactured by the Chambersburg Engineering Company, Thank you for all your outstanding pieces of Wisdom.
Simpson makes those new "Framing Screws." I've used them for headers before and other things like that and I suppose they were nice... but I didn't see much difference between them and a large grk or timberlock. I wonder how they would fare in this testing compared to the framing nails in the same class. Nice vid as always.
@@RubyRhod, Yes, especially with coated nails. Maybe do a video on the holding power of coated nails, nails from a air nailer, uncoated nails and any others you can think of.
Over time nails become loose in their holes and you will see gaps in old houses rim joists before hangers were used in connections between floor joists and rim joists.
Nails are more likely to loosen up over time. If your framing is bending like that it's probably being demolished anyway. On the other hand nails are easier to sawsall if needed. I don't build stuff with the intention of making future demolition easy, i want anyone tearing it down to be cussing me the whole way
"If your framing is bending like that it's probably being demolished anyway." ~love it ! I'd add: If your framing is bending like that it probably should be demolished anyway.
Stair stringer hangers are installed with nails because they are under constant lateral shock loads. Screws can break over time. As with framing walls, pull out isn’t a concern but lateral forces are. Walking on stairs and outside forces on a home make small movements you don’t notice. Over time, years, decades or a century, those add up and screws have been shown to sheer. Nails will keep on bending unless the wood gives out or they rust.
It's about hardness, screws are harder so the result is more brittle because they cannot deform easily. Nails are soft and flexible and deform easier, higher ductility.
@@Davesobscurevideos nails don't have high sheer nails deform under sheer, screws do not they just brake when it gets high enough. screws have the high sheer strength but fail when it's exceeded. It's better to have nails that allow for movement than screws that fail suddenly without warning in a lot of applications. Screws should not be subjected to extreme sheer. The structure should be engineered in a way that does not rely on the fasteners for carrying the load. The load needs to be born by the structural members and not the fasteners.
@@rmora1 the fasteners do carry a lot of shear in places like built up studs/ supports or beams. The wood buckles and deforms under load and creates shear between joined lumber. its really about the cross section of the fastener to be able to carry that stress. A 16d nail has a much larger cross sections then a 10x3.5 construction screw, but a 10x3-1/8GRK is code compliant as is a 16D nail in built up columns and beams
@@robertficek7586 You said exactly what I said, but with more clarity. ie the sheer strength must be within engineering spec regardless of the type used. But I see a lot of diy and contractors don't adhere to building as designed and just don't know any better than to use the wrong fasteners or not consider load bearing structures as important as they should.
great video. This is why you should always frame with a nailer if you can instead of screws because the structure does move and expand and contract and the framing nails will tolerate the flex and allow movement far better than screws.
I was in the heat treating business for 30 years and all these fasteners are products of the material composition and heat treating. They all have unique purposes in fastening and a detailed video on them all would be outstanding, Scott! I was always fascinated by the blacksmith trade, as well.... Keep up the good work!
Gonna have to do this test with the Simpson SD and Timber screws I've been using on my deck. They're supposedly viable shear-resistant alternatives to nails.
Perhaps an extended video about which applications are best suited for using nails or screws might be in order. Just a suggestion, certainly not a demand. Thanks for this one!
I built a woodworking bench of Ian Kirby's earlier design. The frame is held together with some odd looking screwed joints, but 25 yr later it is still tight as new. I used stainless steel Spax screws but didn't get enough of one size. I drilled pilot holes in the maple and never broke a Spax screw. I went to a local bolt and screw supply to get some more screws to finish the project. They charged an arm and a leg. The first one broke trying to drive it in. I had to enlarge the pilot holes for the rest. Spax has changed their design since then. They are still good, but I liked the old design better. Screw somewhat exposed to weather, such as exterior door screws, the eyes to hold wooden screen frames shut, etc will eventually rust out, and the moisture that condenses on the metal screw due to temperature changes will dampen the wood around the screw and cause it to rot. It can happen with nails too.
I screwed all my Perlins on a pole barn build last year. They were suppose to be rated for framing. If we didn’t naill the ends and some of the middles I’d have a broken leg. They almost all broke. Not surprising it was dead of winter in Michigan and I didn’t want to use them in the first place.
Tempered construction screws address this problem. Spax screws have been great for me! Granted they will never replace a nail. But ive had good luck with them...as far as screws go! Been happy so far and havnt had a complaint or fail yet. but i dont build in tornado alley, hurricane zones, or earthquake areas... so my opinion is limited,
@@randallmouser5609 Ive used Spax for a few years.. Still not as repeatably pliable as nails... but they are about the best screw ive used. Held up well in any build ive done. About as expensive as grk. Honestly nothing will replace a good quality nail for repeated flexing. my customers have been very happy and i havnt had any complaints. Granted i dont live in a hurricane or fequent tornado zone. However screws are definitely getting much better! Cost to strength though..Ill take a 16p coated ring shank nail all day for framing. Just saying they are getting much better.
@@randallmouser5609 Also.. I am a deck builder, small sheds, fencing, Yurts, cabins etc! I still use nails mostly! However...in applications were a screw is used...i use Spax primarily! For most screw applications They work very well. Sorry i was at lunch when i made the original comment. Im by no means advocating to replace nails... However, for most applications where screws can be used... I have faith in them! unlike most common big box brands! But like i said... im not building large pole barns in tornado alley either!
@@rmora1 i should have added more context. due to my arena pf construction.. They Spax are very good screws for screw applications. Im by no means replacing a good ring shank nail. Iv just seen the to be about the beat screw out there for most small applications. i should have added context!
... has nothing to do with what we saw. The modulus of elasticity is the same for all steels. This is about hardness, yield strength and what crystal structure is in the metal. This topic is quite complicated.
@@duggydo I'm a mechanical engineer. The german kind - with a real degree and stuff. This topic is my daily job. I'm just not good at explaining it in english.
Like your fastener testing, but when bringing up your sword quenching ... test out sword blades or K-bar knives with file-style tangs and they break off right at the hilt. Instead build your swords and knives with full tangs like the "German Messer" Swords. They were built at a time where the knife guilds wanted a piece of the restricted sword market and consumers were restricted from carrying swords, but they could carry big knives.
I always learned that nails are for construction, screws are for non-structural unless you spend the money (eg. Simpson, TimberLok, etc.) and that adhesives are better - especially when combined with nails.
Another tip... Regular "sheet metal" screws... if you don't NEED stainless, use regular steel! Plated or not. Stainless is really brittle by comparison. I was installing some stuff where I was going to go through about 400 screws. Bought stainless not remembering the brittle part. My tiny M12 impact on setting 6 was snapping them in half, but when I pulled them all out and went to plated steel, I had it cranked to 14 and not one snapped.
Nails are terrible for tension or loads fine for compression. Always found it interesting they use a buttload of staples on trusses. I personally have never liked nails.
agreed, I see framers using screws a lot lately and I am puzzled about that because what you demonstrated so clearly. we use to use sheet rock wall screws a lot for all sorts of things but then it I was all we had. now I almost never use sheet rock screws for anything but sheet rock. I now use a lot of torx head screw for a lot of the things I used the sheet rock screw, like attaching one board to another. Speaking of nails, It didn't surprise me that the hanger nail was the most resistant to breaking. years ago we were building a commercial building with a flat roof but there was a mansard Perimeter. each one of the trusses were held in place by a Hurricane clip. I didn't like the application, the shear force on those clips was huge. A hurricane clip was never designed for load bearing application. what was worse was the nails I was asked to use to attach the clips, it looked like a hanger clip nail but was so light that if I hit the head too hard the head of the nail popped off. a real hanger clip nail has a bigger diameter than even a 16d, I don't know how many nails I replaced before I got the hanger as secure as it needed to be.
All fasteners have a rated load, refer to that when doing something like this. The test you did is not an accurate example of failing in sheer, but rather fatigue. At the end you talk about this. Also that first nail, wasn’t bending but rotating in the hole.
Not sure if it is still allowed, but there was a time when drywall was installed with nails. They had to put twice as many nails in the ceiling than the walls.
I visitedin a house that had been hit by lightning years prior. It popped a lot of drywall nails , and years later they were still having trouble with nails popping.
One thing about tapcons, they are tempermental as hell. You have to drill deeper than you plan to set them to I nclude any cuttings they drag in as you drill them in and cannot bottom them out, also you have to set your impact on a low setting or feather the trigger just right or you most definately WILL snap the head off. Ask me how I know. There is a store in SC that has 5 tapcon bodies in the brick with 1 full tapcon holding a small bracket on the column advertising.
Been building shuttering in my wifes country, it's all cheap chinese fasteners, when paired with Ironwood its a nightmare with fasteners breaking. The wood supplied for building work in some cases is heavier than steel, really dense hardwood grain. It's provided the locals with some good laughs though
My rule of thumb is that if there is a lateral load, don't use a screw. With the new impact drivers, it seems like everyone wants to use screws for everything.
Screws are actual better in almost every situation if they are in tight enough that the lateral load can't overcome the clamping friction. If there is a chance for slipping, you probably need an adhesive (flooring for example to stop squeaks).
Because modern tempered screws can handle significantly more lateral load than non tempered screws. The minimal difference between screws and nails is rarely a difference in most applications if using tempered screws
@@terencemerrittthe GRK screws are preferred in many instances. The test didn't take into consideration friction from the clamp force that negates the sheer strength deficiency.
Screw threads are also "stress risers" that is why you never put threads in shear load. A stress riser is the same principle as a crack in a windshield.
Big fan of nails here. Screws certainly have their place but I love building with a hammer and nails. Side note - use the right nail for the job and know how to use it! My friend’s son grabbed dad’s tool belt one evening after school to go work on homemade treestands in anticipation of the upcoming deer season. Long story short, the young man nailed in the steps to the tree stand with 16d duplexes and drove them all the way home. Later that season when he was climbing that ladder, one of the boards gave way and the young fella fell about 6 feet to the ground. The boy was fine. Shook, but fine. Let this be a reminder to provide proper instruction to young men about all tools and materials and their designated uses.
If the internal diameter of a screw is equal to the one of a nail, and of comparable lengths, I'd say they both are of about the same strength; difference is, the screw has horizontal surface in contact, which works in tandem with the outward pressure of the material, this combination is what reduces the actual mobility of the fastener, zero mobility, as in potential of self rotation, causes a rigidity that isolates friction of motion to very few molecules if you will, hence a faster snapping of the screw in comparison to a nail, all compounded by material density and the finally applied internal tension through torque.
Malleability and toughness is what its called. What you want is a pendulum like a sledgehammer swinging. The test piece or the Fastener would go at bottom dead center. The pendulum is swung from a given High each time striking the test piece and bending or braking it over while carrying a indicator needle up to a the height that the pendulum travels after hitting each test piece. But this above is a toughness test not a fatigue test.
Figured deck screws would work just fine on a fence and wouldn't pull like nails do. Darn things shear off every now and again and I have to hang the picket again. Live and learn.
It's always been interesting to me. I mostly deal with failures of one sort of another, especially failures involving all manner of fasteners Pro tips: don't use those damn half wood half machine screws that come with door hardware. Don't use a drill everytime you're driving screws, especially little ones. Use a little titebond III on screws you don't trust going into wood. I could go on....
@@jboyd85 There are levels to coatings for fasteners that are supposed to be OK for outdoors. I work on a building with hundreds of exterior stairs, and all of electro-galvanized lag bolts rusted to the point of failing. The best choice would have been hot dipped, not electro. I've seen many exterior rated screws used on fencing that left rust stains running down at every fastener. Most have a sole or underlying conversion coating. There are levels to conversion coatings as far as ability to resist corrosion. By that I mean some yellow colored steel fasteners don't seem to resist corrosion very well. There's wiki on conversion coatings, it might send you down a rabbit hole, it's interesting. Putting slivers of wood, toothpicks, or golf tees in stripped holes in wood is often a bad idea, especially in door jambs. I drill out and glue in fluted dowels. After the glue dries, I predrill into my repaired area for whatever fastener I'm using.
Yeah, you could do a similar video on how long it takes for the ESSENTIAL oils to rub off blacksmiths hands. Or you could do a video on how long it takes for aprons to get holes in the material from forge welding. You could do another video on why builders build roofs without a protective roof over the top. You could make a house under ground level in cyclone 🌀 territory and show people the cyclone 🌀 passing right by without damaging the house 🏠 You could do a video that teaches birds 🐦 not to eat off the road and they can sit down and watch it and learn from the wise humans. Cause at the moment, birds 🐦 think power poles are you helping birds to have a free multiple level perch. Birds think that they've convinced humans to give them perches everywhere for nothing. Birds 🐦 could sit and watch the internet all day cause they'd be really good at it.
Why didn't you user any of the screws specifically made for framing? GRK makes some that have shear rating designed specifically for work where you would usually use a nail.
So here's a thoughtful disagreement. Nails vs screws, softer vs harder. If you shear a nail, it will tend to bend. If you shear a screw, it will tend to break. UNLESS: The shear force on the screw is significantly less than it's breaking or major stress point. That screw will hold steady, while the nail will tend to drift over time. That's why you see so many more nails per board than screws in the same situation. I'd love to hear more about this concept, as I really do think in that scenario (which is more common, less shear strength than what you'd find at the max of the fastener's capacity), screws win out. Nails have their place in ease of installation for sure, but in terms of holding strength in either pull out or (most!) shear scenarios, screws win. Thoughts?
Installed fasteners aren't usually subject to this type of load (repeated bending back and forth). They are subject to shear loads and screws (even lowly drywall screws) are just fine in shear.
Hm. This makes me think that screws with a thread that stops about an inch before the head are actually softer in that upper part for exactly the reason mentioned in the video, to be more resistant to shear forces. So they are like a nail at just the right part were it matters to be softer, at the gap between two sheets of wood. It's obvious that the threads of screws need to be hardenend like this, because they are essentially cutting edges just like on a knive. And you don't want your screw to become instantly dull when it's being driven into the material. Though I wonder how relevant that actually is. Most of the time you only use screws once. Who cares if the edge of the thread dulls after one time use? Except for really long screws, I guess. I think hardening them this much and keeping them sharp might be a marketing thing. Carpenters will notice that sharp screws will go in smoother and quicker, so that's what they are more likely to buy. Or it's the economy of scale: You absolutely must harden longer screws, but it's not important on short screws, but it's cheaper to use the same hardening process on all types of screws. Since you need to implement it anyway for the longer screws, you can save money by not having a second production line just to save on the hardening process for short screws. Am I overthinking this?
@@lesliespeaker668 You mean proper screws, countersink head, tapered, shanked screws made by somebody like GKN ! You won't break them if you have the right size for the job. We used to buy them in bronze for boat repair. most modern screws are junk, they are parallel and too hard. They are sharp threaded to make them drive easily. The thing is, that you can drive a traditional screw the same way, You could buy an aftermarket step down clutch thingy to put on your nice metal bodied B&D fifty years ago. I remember using one to put in a timber drop ceiling in my dad's house when I was a kid. Didn't break one 4" no10 ! PS. in softwood, piloted in hardwood with the proper drill for the shank.
Ironwood or oak , ash, hickory, elm pins and pegs A nail often acts as a sudden wedge. A screw splits and compresses the fibers but can still split. Look at old, old magazines and notice the countersinks they used to sell. These fit braces and later- rotary drills. They bore a hole in the proportions of a traditional wood screw head, shank, and threads, leaving the ‘perfect’ amount of wood to crush around the threads of the screw. Traditional wood screws are “Grade 2” at best, yet these weak screws will hold better and more firmly than the alloyed and treated whiz-bang expensive screws readily available today. Today’s screws drive easily and somewhat cut their own holes- sortofa a lazy man’s fastener. But a traditional wood screw sunk into a pre-bored hole made with the properly sized “countersink” will clamp two pieces of wood together tighter and more resolutely than nearly any retailed whiz-bang fancy ceramic coated screw from their fancy packaging. Boat builders still drill and countersink wood screw holes for that very reason: they don’t want that fastener to pull out or split anything which might split and weaken the wood or provide opportunities for water to migrate in and rot the wood. Ever notice the odd-looking (by today’s standards) wood screws that gunsmiths use or that you might find in an antique firearm? Those last for a century and longer because the holes were pre-drilled with a sized - appropriately sized- wood screw pilot bit. So get some old-time countersinks as a set and use them on your antiquity timber. Or peg it with dry, fire-scorched strong hardwood.
On a scrap piece you can try the “dull nail” experiment: Dull the point of a nail with several light taps of your hammer directly down on the point. (As if driving the mail in in reverse) Then see if that mail splits the piece of scrap wood. I learned this from an old carpenter and it has saved me a lot of headaches and cuss words. Hope it’s helpful for you.
This is a very misleading nail vs screw test, like most of them. If you are comparing a screw vs a nail the screw's root diameter(non threaded) section must be the equivalent size of the nail. This test is one of ductility not shear strength. The screws are being work hardened, which increases an already hard fastener, which then makes it brittle. The majority of high quality screws have a much higher tensile strength than their nail counterpart. Shear strength is approx 65% of tensile. Therefore screws have a higher shear strength than nails. If you test joist hangers to the point of failure then it is not the shear strength of the fasteners, it is the withdrawal resistance. The screws are obviously going to resist withdrawal exponentially more than nails. If you contact Simpson in the US or Pryda in Australia the tech departments encourage the use of their code screws. It's not to make them more money, it's because the failure rate is lower. The screws are so much better that you can use less than half as many codes screws vs nails. In house construction nails are cheap and fast. Plus you can combine them with adhesives, so they are temporary fixings until the glue dries.
You are correct that this is a misleading test. The fact is: nails come loose. Screws don't. All that business about shear and tensile is irrelevant: neither screws nor nails fail in those fashions. Caveat: Unless you bought Everbilt screws from HomeDepot and then they torsionally shear on install. Perhaps you are meaning to discuss tensile hold which is exactly why they are not subject to the cold working EC is imparting on them in this test.
Please do more of these " to the point " type videos. They are quick , easy to understand and right to the heart of the matter.
❤ This dude is such a wonderful teacher!
The GRK torx screw with 1.5 inch shank spiral thing is my absolutely favorite fastener as a carpenter, its like a tool, love it.
My first serious job was demolishing buildings using a Cat digger. The introduction of the Ardox or spiral nail - basically a mixture of a nail and screw - in the early 60's marked a sea change in the demolition biz. Pre Ardox you could literally pull a building apart 2 by 4 by 2 by 4. After Ardox you mainly ended up with firewood. Love the channel
I've taught this to the young guys many times and at first they don't understand but when you show them they get it pretty fast, great explanation.
That was good and an awesome demonstration. I quit using nails years ago when it became so easy to use cordless drivers and screws. Now I have to rethink that. It's also a lot easier to disassemble with screws and more often than not they can be reused. Thanks for sharing.
Hold on there, nails and screws have different uses, structural almost exclusively uses nails until GRK structural screws became code compliant. Dont go sticking off the shelf "construction screws" to build structural supports, roof assemblies etc.
@@robertficek7586 yeah 😂 don’t use drywall screws on joist hangers
Many people don't realize that common nails (and sinkers) are structurally rated for framing applications. So are GRK's; I use their equivalent size to 16d sinkers all the time. Spax is a good brand, too. Stay away from generic hardware store screws. And only use drywall screws for drywall.
Same here, all about the shear in structural framing.
Used 16d (.165”) nails in the beams and joist hangers of my deck. Could not find a framing nailer that will fire nails that big, (most do .131”) so did all with a hammer. Hard to beat the shear strength/cost of a 16d nail.
Palm nailer is your answer
Paslode acq rated nails at .131 just as good.
That’s one of the first demonstrations I show the kids in my shop class every year
Way more likely that nail heads will pop off - before a screw breaks.
If your connection is subject to that degree of flexion, you have not made a proper connection. I suppose a good take-away is that if you happen to bend a screw, do NOT straighten it and reuse it as it is near failure.
Structures neeed to be able to flex and move most screws do not have that quality they will well break/shear before they bend.
I only learned this within the last 5 years. I always thought a quality screw was stronger due to the threads. Nope. Screws are strong but typically have low shear strength. In building structures, use a nail. Think mild earthquakes or high wind loads. Thanks.
I'm in the grounds crew of our local loggers sports event here in Squamish BC and we use GRK's to attach our blocks to the block stands for our competition. They're the best. Still haven't found anything better. Pricey but well worth it. I swear by them
I’d like to start by saying I love the channel and have the utmost respect for you and your wealth of experience. That said, you’re over simplifying the relation of shear strength of the fastener and the integrity of a fastened joint. Threaded fasteners squeeze, and derive most of their connection strength from the friction of the two pieces being squeezed together. Your test with the hammer is essentially showing which fasteners are the best application for using as a coat peg.
the screwed joint is as strong as the friction: exactly correct.
this vid was a tad insulting to his viewers
Perhaps a video on the different joints in home construction with not here but here or both types ok here.
Given the popularity of screw guns these days and internet missinformation I think most DIYs would be using screws in the wrong application. I know I would rather pull the trigger and drive what I thought was a big strong screw rather than bang in a nail.
WOW a real eye opener
I always use nails in shear, screws in compression. There are screws now made for some shear loads, and have used them without failure, but I still defer to nails in shear. Retired professional engineer and amateur woodworker, for whatever that gets me.
Good video. I've recently had to rebuild some cattle sheds. A wind storm came through and tore the roofs off. I learned that the buildings that had more screws or blocking survived while those that were just toe nailed and not blocked or any hurricane clips failed. Since then I have started to use more screws for this application and I ALWAYS use approved screws or tico nails on the hurricane ties. I don't really know if I might have over compensated by using almost all screws, but time will tell. I do believe that there is a time and place for both screws and nails.
apples to oranges
Fasteners are Fascinating!
There is a lot to consider when specifying fastener type for each unique application. Shear Strength, pullout value, head type, Alloy, material Finnish, thread type. So many options.
I like your videos but this one came up short. Ductility is but 1 factor out of a range of conditions that affect fasteners. Screws can hold up to lateral loads but the main shear force must be on the “shank” or unthreaded portion and not on the threats as this creates a stress riser. Residential lumber construction seams to be anti screw for some reason, but screws and bolts are used all other the place in steel framed construction, automobile industries, aviation etc.
Thanks!
If I remember the old adage correctly, use the right thing for the job at hand, tool or fastener. Most manufacturers will spell things out in the provided material, or their website, or (the good ones) tech support. Thanks Scott! Pray maintain speed and course!
Surprised to see the GRKs break so easily! #8 are supposed to bee around 400lbs of shear as far as I remember vs around 90lbs for a regular deck screw.
@@moutrap the strength comes from the friction of the material and not the screw itself. The clamping power is the advantage. This tested fatigue, not shear strength. GRK all day.
Simpson Strong Tie make structural screws. Other manufacturers do also. It is very true you should not use regular screws in a structural application. Way to many people don't realize that. But please clarify the difference between structural and non structural applications.
That "big GRK" in this video was definitely one of the structural screws.
This test is somewhat inaccurate because it isn't showing real-world application of force on the screw. I'd trust my life on the big GRK screw over 10 nails.
You might bend a timberlok but you won’t break it
That "big GRK" doesn't look very big to me.
@@hempcacaogoji831 I felt the same but didn't comment before because I am not familiar with the brand and the camera can foul you on size.
The head of that screw tells me it is designed to hold a soft material against wood. I would not call that a structural screw at all.
Can’t believe how ignorant I’ve been on this subject. Thanks!
You're saying we've been missing out on Essential Swordsman content this whole time?
Also modern adhesive are often over looked but work well. 👍
"Screws hold it until the glue dries"
On you're 10 favorite tools, you said the Chambersburg hammer you have & use, I'm from Chambersburg Pa. & I was wandering if it was manufactured by the Chambersburg Engineering Company, Thank you for all your outstanding pieces of Wisdom.
You should try this with the nails on strips for nail guns as I find some of them can be really brittle and easy to break...love the videos
Simpson makes those new "Framing Screws." I've used them for headers before and other things like that and I suppose they were nice... but I didn't see much difference between them and a large grk or timberlock. I wonder how they would fare in this testing compared to the framing nails in the same class. Nice vid as always.
Thanks for the awesome content and great videos!!
Most of the lateral strength of a screwed connection comes from friction
Same with nails.
@@RubyRhod, Yes, especially with coated nails. Maybe do a video on the holding power of coated nails, nails from a air nailer, uncoated nails and any others you can think of.
what about non-lateral strength, what about compressive strength or tensile strength?
You nailed it
😂 Like how you hammered that point home!
Over time nails become loose in their holes and you will see gaps in old houses rim joists before hangers were used in connections between floor joists and rim joists.
Nails are more likely to loosen up over time. If your framing is bending like that it's probably being demolished anyway. On the other hand nails are easier to sawsall if needed. I don't build stuff with the intention of making future demolition easy, i want anyone tearing it down to be cussing me the whole way
"If your framing is bending like that it's probably being demolished anyway." ~love it !
I'd add: If your framing is bending like that it probably should be demolished anyway.
Stair stringer hangers are installed with nails because they are under constant lateral shock loads. Screws can break over time. As with framing walls, pull out isn’t a concern but lateral forces are. Walking on stairs and outside forces on a home make small movements you don’t notice. Over time, years, decades or a century, those add up and screws have been shown to sheer. Nails will keep on bending unless the wood gives out or they rust.
What about lag screw and bolts??
Every video you ever made is interesting..I love them all.
its all about sheer factor.....nails have the higher sheer force, screws hold down, ie. decks etc
It's about hardness, screws are harder so the result is more brittle because they cannot deform easily. Nails are soft and flexible and deform easier, higher ductility.
@@rmora1I mean that’s what OP said just in reverse.
@@Davesobscurevideos nails don't have high sheer nails deform under sheer, screws do not they just brake when it gets high enough. screws have the high sheer strength but fail when it's exceeded. It's better to have nails that allow for movement than screws that fail suddenly without warning in a lot of applications. Screws should not be subjected to extreme sheer. The structure should be engineered in a way that does not rely on the fasteners for carrying the load. The load needs to be born by the structural members and not the fasteners.
@@rmora1 the fasteners do carry a lot of shear in places like built up studs/ supports or beams. The wood buckles and deforms under load and creates shear between joined lumber. its really about the cross section of the fastener to be able to carry that stress. A 16d nail has a much larger cross sections then a 10x3.5 construction screw, but a 10x3-1/8GRK is code compliant as is a 16D nail in built up columns and beams
@@robertficek7586 You said exactly what I said, but with more clarity. ie the sheer strength must be within engineering spec regardless of the type used. But I see a lot of diy and contractors don't adhere to building as designed and just don't know any better than to use the wrong fasteners or not consider load bearing structures as important as they should.
I have always used 16p galvys for door installations.
Never really considered this before. Thanks, Scott!
great video. This is why you should always frame with a nailer if you can instead of screws because the structure does move and expand and contract and the framing nails will tolerate the flex and allow movement far better than screws.
He's got my vote.
I was in the heat treating business for 30 years and all these fasteners are products of the material composition and heat treating. They all have unique purposes in fastening and a detailed video on them all would be outstanding, Scott! I was always fascinated by the blacksmith trade, as well.... Keep up the good work!
Gonna have to do this test with the Simpson SD and Timber screws I've been using on my deck. They're supposedly viable shear-resistant alternatives to nails.
Perhaps an extended video about which applications are best suited for using nails or screws might be in order. Just a suggestion, certainly not a demand. Thanks for this one!
I built a woodworking bench of Ian Kirby's earlier design. The frame is held together with some odd looking screwed joints, but 25 yr later it is still tight as new. I used stainless steel Spax screws but didn't get enough of one size. I drilled pilot holes in the maple and never broke a Spax screw. I went to a local bolt and screw supply to get some more screws to finish the project. They charged an arm and a leg. The first one broke trying to drive it in. I had to enlarge the pilot holes for the rest. Spax has changed their design since then. They are still good, but I liked the old design better.
Screw somewhat exposed to weather, such as exterior door screws, the eyes to hold wooden screen frames shut, etc will eventually rust out, and the moisture that condenses on the metal screw due to temperature changes will dampen the wood around the screw and cause it to rot. It can happen with nails too.
That last bit is one of the reasons I'd like to explore the old wooden peg option, at least for holding a wooden door or piece of furniture together.
I screwed all my Perlins on a pole barn build last year. They were suppose to be rated for framing. If we didn’t naill the ends and some of the middles I’d have a broken leg. They almost all broke. Not surprising it was dead of winter in Michigan and I didn’t want to use them in the first place.
Sometimes, it's the best way to learn in life. I bet you had an adrenaline rush. Hahaha
Tempered construction screws address this problem. Spax screws have been great for me! Granted they will never replace a nail. But ive had good luck with them...as far as screws go! Been happy so far and havnt had a complaint or fail yet. but i dont build in tornado alley, hurricane zones, or earthquake areas... so my opinion is limited,
And what brand exactly is that
No, they don't.
@@randallmouser5609 Ive used Spax for a few years.. Still not as repeatably pliable as nails... but they are about the best screw ive used. Held up well in any build ive done. About as expensive as grk. Honestly nothing will replace a good quality nail for repeated flexing. my customers have been very happy and i havnt had any complaints. Granted i dont live in a hurricane or fequent tornado zone. However screws are definitely getting much better! Cost to strength though..Ill take a 16p coated ring shank nail all day for framing. Just saying they are getting much better.
@@randallmouser5609 Also.. I am a deck builder, small sheds, fencing, Yurts, cabins etc! I still use nails mostly! However...in applications were a screw is used...i use Spax primarily! For most screw applications They work very well. Sorry i was at lunch when i made the original comment. Im by no means advocating to replace nails... However, for most applications where screws can be used... I have faith in them! unlike most common big box brands! But like i said... im not building large pole barns in tornado alley either!
@@rmora1 i should have added more context. due to my arena pf construction.. They Spax are very good screws for screw applications. Im by no means replacing a good ring shank nail. Iv just seen the to be about the beat screw out there for most small applications. i should have added context!
Great job. Thank you 😊
What about the "old model" nails ?
The Square and Triangle ones ?
Modulus of elasticity; very good thing to understand.
... has nothing to do with what we saw.
The modulus of elasticity is the same for all steels.
This is about hardness, yield strength and what crystal structure is in the metal.
This topic is quite complicated.
@@RubyRhod you could not be more wrong. Just look it up on the internet man.
@@duggydo I'm a mechanical engineer. The german kind - with a real degree and stuff.
This topic is my daily job.
I'm just not good at explaining it in english.
@@RubyRhod I doubt it
@@duggydo nope he's right, E is the same for all steel.
Like your fastener testing, but when bringing up your sword quenching ... test out sword blades or K-bar knives with file-style tangs and they break off right at the hilt. Instead build your swords and knives with full tangs like the "German Messer" Swords. They were built at a time where the knife guilds wanted a piece of the restricted sword market and consumers were restricted from carrying swords, but they could carry big knives.
Nice.
I always learned that nails are for construction, screws are for non-structural unless you spend the money (eg. Simpson, TimberLok, etc.) and that adhesives are better - especially when combined with nails.
That explains my instinct to replace metal screws with wood dowels.
Yes sir! Great info
Wish you had also included Simpson SDS screws in your test.
Another tip... Regular "sheet metal" screws... if you don't NEED stainless, use regular steel! Plated or not. Stainless is really brittle by comparison.
I was installing some stuff where I was going to go through about 400 screws. Bought stainless not remembering the brittle part. My tiny M12 impact on setting 6 was snapping them in half, but when I pulled them all out and went to plated steel, I had it cranked to 14 and not one snapped.
Nails are terrible for tension or loads fine for compression. Always found it interesting they use a buttload of staples on trusses. I personally have never liked nails.
agreed, I see framers using screws a lot lately and I am puzzled about that because what you demonstrated so clearly. we use to use sheet rock wall screws a lot for all sorts of things but then it I was all we had. now I almost never use sheet rock screws for anything but sheet rock. I now use a lot of torx head screw for a lot of the things I used the sheet rock screw, like attaching one board to another.
Speaking of nails, It didn't surprise me that the hanger nail was the most resistant to breaking. years ago we were building a commercial building with a flat roof but there was a mansard Perimeter. each one of the trusses were held in place by a Hurricane clip. I didn't like the application, the shear force on those clips was huge. A hurricane clip was never designed for load bearing application. what was worse was the nails I was asked to use to attach the clips, it looked like a hanger clip nail but was so light that if I hit the head too hard the head of the nail popped off. a real hanger clip nail has a bigger diameter than even a 16d, I don't know how many nails I replaced before I got the hanger as secure as it needed to be.
Sounds like you worked for a shoddy contractor. Either that or the contractor simply didn't know any better at the time.
All fasteners have a rated load, refer to that when doing something like this.
The test you did is not an accurate example of failing in sheer, but rather fatigue. At the end you talk about this.
Also that first nail, wasn’t bending but rotating in the hole.
The younger bunch seems to suffer from hammer phobia. Screwing everything in sight. Its nuts.
This is the ACTUAL genesis of the vid
Please don’t use nails to install ceiling drywall like the previous owner of my house. 🤦♂️
Not sure if it is still allowed, but there was a time when drywall was installed with nails. They had to put twice as many nails in the ceiling than the walls.
@@markgallagher1376 Yeah they definitely did not do that here.
I visitedin a house that had been hit by lightning years prior. It popped a lot of drywall nails , and years later they were still having trouble with nails popping.
And don't cover real plaster with drywall like a previous owner of my house did. UGGGHHHH!!!!!
@@debluetailfly ok you win.
Nails have good shear strength, while screws have good tensile strength.
One thing about tapcons, they are tempermental as hell. You have to drill deeper than you plan to set them to I nclude any cuttings they drag in as you drill them in and cannot bottom them out, also you have to set your impact on a low setting or feather the trigger just right or you most definately WILL snap the head off. Ask me how I know. There is a store in SC that has 5 tapcon bodies in the brick with 1 full tapcon holding a small bracket on the column advertising.
If you're my dad, you'd use all of them in a single project, and make sure to throw in different screw heads for good measure!
I love your Dad.
Broken like a true apprentice. I always struggle hammering in screws. Edit: Just having fun. Good vid as usual.
Threaded fasteners are usually not made to be put under a lot of shear
Hummmm
Maybe a Road Trip to a nail or screw manufacturing plant would be interesting to see.
Should have put a Simpson strong tie structural screw in the test. They are designed for construction.
One is designed for shear the other for tension
Been building shuttering in my wifes country, it's all cheap chinese fasteners, when paired with Ironwood its a nightmare with fasteners breaking. The wood supplied for building work in some cases is heavier than steel, really dense hardwood grain. It's provided the locals with some good laughs though
My rule of thumb is that if there is a lateral load, don't use a screw. With the new impact drivers, it seems like everyone wants to use screws for everything.
Screws are actual better in almost every situation if they are in tight enough that the lateral load can't overcome the clamping friction. If there is a chance for slipping, you probably need an adhesive (flooring for example to stop squeaks).
Because modern tempered screws can handle significantly more lateral load than non tempered screws. The minimal difference between screws and nails is rarely a difference in most applications if using tempered screws
Will code allow screws in shear applications?
@@coopertracy6581 Takes lots longer to use screws in framing when nailing is cheaper and faster.
@@terencemerrittthe GRK screws are preferred in many instances. The test didn't take into consideration friction from the clamp force that negates the sheer strength deficiency.
Screw threads are also "stress risers" that is why you never put threads in shear load. A stress riser is the same principle as a crack in a windshield.
Big fan of nails here. Screws certainly have their place but I love building with a hammer and nails.
Side note - use the right nail for the job and know how to use it! My friend’s son grabbed dad’s tool belt one evening after school to go work on homemade treestands in anticipation of the upcoming deer season. Long story short, the young man nailed in the steps to the tree stand with 16d duplexes and drove them all the way home. Later that season when he was climbing that ladder, one of the boards gave way and the young fella fell about 6 feet to the ground. The boy was fine. Shook, but fine. Let this be a reminder to provide proper instruction to young men about all tools and materials and their designated uses.
You are the best Scott!
If the internal diameter of a screw is equal to the one of a nail, and of comparable lengths, I'd say they both are of about the same strength; difference is, the screw has horizontal surface in contact, which works in tandem with the outward pressure of the material, this combination is what reduces the actual mobility of the fastener, zero mobility, as in potential of self rotation, causes a rigidity that isolates friction of motion to very few molecules if you will, hence a faster snapping of the screw in comparison to a nail, all compounded by material density and the finally applied internal tension through torque.
Malleability and toughness is what its called. What you want is a pendulum like a sledgehammer swinging. The test piece or the Fastener would go at bottom dead center. The pendulum is swung from a given High each time striking the test piece and bending or braking it over while carrying a indicator needle up to a the height that the pendulum travels after hitting each test piece. But this above is a toughness test not a fatigue test.
I live in a cookie cutter house built on 1996 and the original basement air duct fell because it was held up by roofing nails.
I love those threaded nails with the plus in the head, but I can never hammer 'em in proper.
Figured deck screws would work just fine on a fence and wouldn't pull like nails do. Darn things shear off every now and again and I have to hang the picket again. Live and learn.
Hasn't happened with my fence. Going on five years now. I used Deckmate screws at the time.
This is the best anylization of fasteners I`ve ever seen.Many readers are going dismiss it not knowing how important it is.
It's always been interesting to me. I mostly deal with failures of one sort of another, especially failures involving all manner of fasteners
Pro tips: don't use those damn half wood half machine screws that come with door hardware. Don't use a drill everytime you're driving screws, especially little ones. Use a little titebond III on screws you don't trust going into wood.
I could go on....
Please do.
Yes, Please do!
@@jboyd85 There are levels to coatings for fasteners that are supposed to be OK for outdoors. I work on a building with hundreds of exterior stairs, and all of electro-galvanized lag bolts rusted to the point of failing. The best choice would have been hot dipped, not electro.
I've seen many exterior rated screws used on fencing that left rust stains running down at every fastener. Most have a sole or underlying conversion coating. There are levels to conversion coatings as far as ability to resist corrosion. By that I mean some yellow colored steel fasteners don't seem to resist corrosion very well. There's wiki on conversion coatings, it might send you down a rabbit hole, it's interesting.
Putting slivers of wood, toothpicks, or golf tees in stripped holes in wood is often a bad idea, especially in door jambs. I drill out and glue in fluted dowels. After the glue dries, I predrill into my repaired area for whatever fastener I'm using.
It seems like all that I ever have are drywall screws 😂
Yeah, you could do a similar video on how long it takes for the ESSENTIAL oils to rub off blacksmiths hands.
Or you could do a video on how long it takes for aprons to get holes in the material from forge welding.
You could do another video on why builders build roofs without a protective roof over the top.
You could make a house under ground level in cyclone 🌀 territory and show people the cyclone 🌀 passing right by without damaging the house 🏠
You could do a video that teaches birds 🐦 not to eat off the road and they can sit down and watch it and learn from the wise humans.
Cause at the moment, birds 🐦 think power poles are you helping birds to have a free multiple level perch.
Birds think that they've convinced humans to give them perches everywhere for nothing.
Birds 🐦 could sit and watch the internet all day cause they'd be really good at it.
Also, use rawlplugs as much as you can.
Drywall screws and paint make me the carpenter I ain't 👀
Otherwise good but you really cant harden railroad spikes. Theres just not enough carbon in them to make a good knife.
Nice god bless
I thought tapcon were used in concrete and not in wood?
Yes, that's a main point. Use the right fastner for the job.
@@amandaklapp1171 true
Why didn't you user any of the screws specifically made for framing? GRK makes some that have shear rating designed specifically for work where you would usually use a nail.
Yep, we use construction screws all the time. They aren't GRK's, but they're almost impossible to break.
He used a big GRK
why spend much more money and nailing is faster by far
@@MAGAMAN the strength comes from the friction of the material and not the screw itself. The clamping power is the advantage. GRK all day.
My brothers father in law always brags about how he framed his entire house with screws and not a single nail 😅
When will a screw be subjected to all that back and forth bending? - Never!
So here's a thoughtful disagreement. Nails vs screws, softer vs harder. If you shear a nail, it will tend to bend. If you shear a screw, it will tend to break. UNLESS: The shear force on the screw is significantly less than it's breaking or major stress point. That screw will hold steady, while the nail will tend to drift over time. That's why you see so many more nails per board than screws in the same situation. I'd love to hear more about this concept, as I really do think in that scenario (which is more common, less shear strength than what you'd find at the max of the fastener's capacity), screws win out. Nails have their place in ease of installation for sure, but in terms of holding strength in either pull out or (most!) shear scenarios, screws win. Thoughts?
Installed fasteners aren't usually subject to this type of load (repeated bending back and forth).
They are subject to shear loads and screws (even lowly drywall screws) are just fine in shear.
pole barn nails will snap like glass when the old cow scratches an itch on the fence
It is all about Physics. Load bearing requires nails. Something like fence pickets screws would work fine.
Hm. This makes me think that screws with a thread that stops about an inch before the head are actually softer in that upper part for exactly the reason mentioned in the video, to be more resistant to shear forces. So they are like a nail at just the right part were it matters to be softer, at the gap between two sheets of wood.
It's obvious that the threads of screws need to be hardenend like this, because they are essentially cutting edges just like on a knive. And you don't want your screw to become instantly dull when it's being driven into the material. Though I wonder how relevant that actually is. Most of the time you only use screws once. Who cares if the edge of the thread dulls after one time use? Except for really long screws, I guess. I think hardening them this much and keeping them sharp might be a marketing thing. Carpenters will notice that sharp screws will go in smoother and quicker, so that's what they are more likely to buy. Or it's the economy of scale: You absolutely must harden longer screws, but it's not important on short screws, but it's cheaper to use the same hardening process on all types of screws. Since you need to implement it anyway for the longer screws, you can save money by not having a second production line just to save on the hardening process for short screws. Am I overthinking this?
I agree with the first sentence
@@lesliespeaker668 You mean proper screws, countersink head, tapered, shanked screws made by somebody like GKN ! You won't break them if you have the right size for the job. We used to buy them in bronze for boat repair.
most modern screws are junk, they are parallel and too hard. They are sharp threaded to make them drive easily. The thing is, that you can drive a traditional screw the same way, You could buy an aftermarket step down clutch thingy to put on your nice metal bodied B&D fifty years ago. I remember using one to put in a timber drop ceiling in my dad's house when I was a kid. Didn't break one 4" no10 !
PS. in softwood, piloted in hardwood with the proper drill for the shank.
So i guess they make screws that have more carbon content to withstand flexing?
DO NOT use drywall screws on hinges! They WILL break.
Masonry nails
Hold my beer😅
How about 150yo old growth lumber that’s dry as a bone and splits if you nail it?
Ironwood or oak , ash, hickory, elm pins and pegs
A nail often acts as a sudden wedge. A screw splits and compresses the fibers but can still split.
Look at old, old magazines and notice the countersinks they used to sell. These fit braces and later- rotary drills. They bore a hole in the proportions of a traditional wood screw head, shank, and threads, leaving the ‘perfect’ amount of wood to crush around the threads of the screw.
Traditional wood screws are “Grade 2” at best, yet these weak screws will hold better and more firmly than the alloyed and treated whiz-bang expensive screws readily available today.
Today’s screws drive easily and somewhat cut their own holes- sortofa a lazy man’s fastener. But a traditional wood screw sunk into a pre-bored hole made with the properly sized “countersink” will clamp two pieces of wood together tighter and more resolutely than nearly any retailed whiz-bang fancy ceramic coated screw from their fancy packaging.
Boat builders still drill and countersink wood screw holes for that very reason: they don’t want that fastener to pull out or split anything which might split and weaken the wood or provide opportunities for water to migrate in and rot the wood.
Ever notice the odd-looking (by today’s standards) wood screws that gunsmiths use or that you might find in an antique firearm? Those last for a century and longer because the holes were pre-drilled with a sized - appropriately sized- wood screw pilot bit.
So get some old-time countersinks as a set and use them on your antiquity timber. Or peg it with dry, fire-scorched strong hardwood.
@@fishhuntadventure I have some of those. they may still be available.
On a scrap piece you can try the “dull nail” experiment: Dull the point of a nail with several light taps of your hammer directly down on the point. (As if driving the mail in in reverse)
Then see if that mail splits the piece of scrap wood.
I learned this from an old carpenter and it has saved me a lot of headaches and cuss words. Hope it’s helpful for you.
This is a very misleading nail vs screw test, like most of them. If you are comparing a screw vs a nail the screw's root diameter(non threaded) section must be the equivalent size of the nail. This test is one of ductility not shear strength. The screws are being work hardened, which increases an already hard fastener, which then makes it brittle. The majority of high quality screws have a much higher tensile strength than their nail counterpart. Shear strength is approx 65% of tensile. Therefore screws have a higher shear strength than nails. If you test joist hangers to the point of failure then it is not the shear strength of the fasteners, it is the withdrawal resistance. The screws are obviously going to resist withdrawal exponentially more than nails. If you contact Simpson in the US or Pryda in Australia the tech departments encourage the use of their code screws. It's not to make them more money, it's because the failure rate is lower. The screws are so much better that you can use less than half as many codes screws vs nails. In house construction nails are cheap and fast. Plus you can combine them with adhesives, so they are temporary fixings until the glue dries.
You are correct that this is a misleading test.
The fact is: nails come loose. Screws don't.
All that business about shear and tensile is irrelevant: neither screws nor nails fail in those fashions. Caveat: Unless you bought Everbilt screws from HomeDepot and then they torsionally shear on install.
Perhaps you are meaning to discuss tensile hold which is exactly why they are not subject to the cold working EC is imparting on them in this test.
100% 🔥