Yanking screws out of wood to test for strength

Modifying my strength testing machine for pull (tensile) tests.
Then using the machine to test how well wood screws hold in wood against pull out.
Also testing head pull through force and effect of pilot hole size on how well the screw holds.

[@lewisbyerly9831]

I usually find these type of tests interesting but kind of useless until, a few months or so later, I run into an application where it matters and then I think "Darn, I'm glad Matthias ran that test so I don't have to." Thanks for doing the work and keep it up. I really do like these videos.

[@custos3249]

Similar. Apart from wood splitting, I've always questioned why my dad would randomly stop to drill a pilot hole when just throwing a screw at something and moving on seemed fine. I'd always assumed pilot holes had a greater negative impact, but seeing hold strength is nearly unaffected is pretty unexpected.

[@jeffpower6473]

@@custos3249my pops taught me to drill an oversized hole (slightly larger than the thread diameter) in the first piece to prevent screw jacking and a pilot hole in the 2nd piece to prevent splitting. An oversized hole comes in super handy when setting doors.

[@user-mr5di3pf3c]

بالعكس هذا الاختبار مفيد جدا وخصوصا لأصحاب التخصص

[@smashyrashy]

I still think theyre useless

[@leifhietala8074]

This is definitely NOT way more than I wanted to hear. This is the kind of experimental hands-on finding-out that we've come to expect from you. More? Yes, please, absolutely.

[@Name-vu1kn]

I was assigned a project at work to compare the holding power of screws Vs. rivets and roves in ship building. I searched for weeks for a published standard and mostly just found conflicting numbers published by screw manufacturers. I wasn’t quite at the bottom of the internet (but I could see it from there) when I found a study published by the Montana school of forestry for the construction industry that laid out pull strength of screws in wood. The interesting part of the study was that the moisture content of the wood played a huge factor in the screws holding power.

[@jeffcostello6747]

I would love to see these tests performed in isotropic engineering materials like HDPE, nylon, or acetal plastic. Each plastic with a unique, known yield strength and ultimate strength. I've wondered if the results would be more consistent. Then, I'd also be very interested to see if the results from the engineering materials could be generalized for many different wood species, hardness levels, and grain directions.

[@Xtian982]

I would agree, that would be a good one for the Mathias “bullsh*t detector” test 🤣

[@MordecaiV]

Plastics aren't super great for "unique, known half and ultimate strength" ... They can be a little tricky to pin down with creep and plastic deformation

[@TizonaAmanthia]

I really like how you spent almost half the video explaining the original need for this test. sometimes tests feel....disjointed from reality...so having this one start out with "I'm doin' a thing, and then had a question, and decided to test it to get more info. so this is why I"m yanking screws out and measuring the forces. "love your videos, Matthias."

[@ChristopherBotelho3052]

i wish we could see all the math for that (including the math for even the reasoning and suggested ideas he gave)

[@ErinJayEldridge]

I'm an aerospace engineer whose knowledge of wood is practically limited to things I can remember from your videos. This was really fascinating to me, especially the bit at the end about how little additional threads changed the pull-out force and the negative trades that go along with driving it in the first place. I wish that had been a little more prominent in the video, honestly, to help reinforce it in my brain, but I'm glad you got it in there.

[@matthiaswandel]

I just got tired of filming, so it was just a quickie test. And nothing overly interesting.

[@markm0000]

Woah that’s cool. Would you be so kind as to share some of the channels you find interesting? I work on transport refrigeration systems. There’s a little overlap between our fields. My background is in IT infrastructure. Thanks 😊

[@Squibbleses]

I'd be quite interested to see the results for nails. Especially those cut or square nails that are supposed to get their hold by bending the fibres down sort of like a feather board

[@EvgenyPakhomov]

I'm a software engineer and practically never work with wood, but it's always interesting to watch your videos.

[@nobodycares85]

As a matter of fact, I think this information is very useful in meaningful and practical ways. Your videos of shown that many practices actually weaken projects. For example, threaded inserts failing before bolts or screws directly screwed in.

[@mspacone]

I love this kind of testing - you answer all of the questions that I wonder when I build things, but don't want to put in the effort to test. Thank you!

[@fxm5715]

This is great. I love this kind of testing because it helps me understand what's actually happening, not just the results. That's a far more useful tool to carry around in my head, since it is much more broadly applicable. Thanks, Matthias!

[@deanrambler9006]

I found this very fascinating about the pilot hole size versus pull-out strength. With no pilot hole being not much stronger than minor thread diameter, I will be putting pilot holes in to prevent splitting even more than I had been. Thank you so much for sharing these strength test videos. Very informative!

[@chrisoddshoes]

I think these sort of tests help with a general understanding, or feel, for how materials perform and can thus influence design of personal projects. So thanks Matthias.

[@oskimac]

what i love about these channel is that it is most about the tools and the procedure of making them than the test itself. really loveit

[@andyandnancy]

I love the experiments that you run and how you share both your mental and the physical process. Thanks!!!

[@Sludgepump]

That was fascinating, Matthias. I wonder about this every time I drill a pilot hole. Would be interesting to see you continue these experiments with sheer strength. I'm always wondering how well my drywall screws will hold up to side loads. Great video... Really enjoyed that!

[@zoharflax6363]

You're the best experimenter I've ever come across. Nice work!

[@freedomofmotion]

I do love it when one of your videos turns up in my feed. Its a rare occasion but i always watch.

[@bobd5119]

These tests are truly useful. In soft wood, I drill 1/64 smaller than the screw's inner diameter. That makes me feel better...

[@HenryKamp]

these tests are great - i love seeing the evolution of your rig too! keep up the good stuff, Matthias!

[@MCsCreations]

Fascinating results, Matthias! Thanks a bunch for the testing and comparison! 😃 Stay safe there with your family! 🖖😊

[@JPWack]

WOW! Those drywall comparison at the end was interesting AF

[@DonMohle]

Mattias is a dispeller of unfounded notions, questioning and measuring and clarifying what the rest of us just gloss over with assumptions, presumptions, and "gut feel." As a retired engineer myself, I see the difference between real facts and imagined ones like the difference between bedrock and sandbank.

[@DJRockinRob]

I LOVE THESE TESTS!!! I also super enjoyed that co-lab you did testing clamps. That was lots of fun! I cant wait for your next experiment!!

[@TgWags69]

Very interesting, I like these videos. Nobody else would bother, and if they did, they probably wouldn't do it in a way that shows valid results like you.. Thanks for bringing this to us.

[@OneManBandWoodworks]

Thank you for doing that test, I find your tests extremely helpful and I have actually won arguments with architects and engineers on jobsites using your videos as the only evidence

[@gericstewart]

Thank you for taking the extra time to film and share the experiments you run.

[@JayBates]

Thanks for taking the time to do these tests. Always interesting.

[@tracybowling1156]

I mainly watch your channel so I can watch your genius in action.

[@jamisonlm3]

Thanks for doing these tests. I usually eyeball drills to use for pilot holes. I try and get one the minor diameter or just slightly larger. One slightly larger will be easier to drive and lower the chances of splitting the wood. It's also interesting how the number of screw threads didn't impact pull force that much. Looking forward to seeing you test different fasteners.

[@hazza2247]

drilling a pilot that is larger than the minor diameter will reduce the holding strength by a massive amount tho

[@Xeroxorex]

Matthias, please keep doing your thing, it directly adds to the collective of all our living engineering knowledge!

[@antraxxslingshots]

Your contraption is a gift that keeps on giving.

[@tomdenny8507]

Awesome. Loved this and am looking forward to some sort of series. Thank you for the videos you produce.

[@IvoTichelaar]

Epic video! I don't know about most people in garage shops, but 90% of what I make are more or less experiments in engineering and reduction. But yours are much more comprehensive and structured.

[@wholesomeengraving]

Glad to see there's so little difference, because that's something I've always eye balled. I try to make my pilot hole the size of the screw core, or slightly smaller. And I've always prefered screws with less threads because they tend to strip less easilly when I drive them in. Especially in softwood.

[@tf1354]

Interesting test. However, I don’t think that just pulling on the screw is correct. You need to pull on the joint. It’s a bit complicated to explain in a comment but it has to do with compression of the clamped piece

[@thefack149]

thanks for making this. looking forward to more! I found a load table for pullout force of various sized lag screws years ago, but other screws, too!?! that is so great

[@jmig1021]

I find this all to be very useful. Keep it going Matthias! Thank you

[@esepecesito]

That was definitely not more that I wanted to hear about it! Thanks a lot for sharing these tests

[@JeremyMcMahan]

Fantastic testing Matthias, and I appreciate this empirical information!

[@simonhopkins3867]

Always fascinating experiments when your testing machine comes out. I'm going to have a look for your video on building it.

[@javbw]

I love your testing videos! Thanks ☺

[@TheAxecutioner]

Thoroughly interesting, thanks for taking the time to make this !!

[@PeteLewisWoodwork]

The kind of stuff we never learned as trainees over 40 years ago, so very interesting. I'll be using smaller pilot holes from now on...!

[@truckguy6666]

I would be interested to see a video on the force required to sheer off a 16d and 8d nails. A lot of times in the trades you nail a cleat to a wall or something you want to move with a crane, and I have always considered a 16d to reliably hold around 200lbs in the sheer direction. Sheer paneling on modern engineered structures usually requires a very specific number of 8d common ("common" being a specific diameter) nails for a reason. Commerical or school wall framing requires 16d common nails for nailing studs, etc. I always prefered to use a smaller diameter nail because there is less splitting especially in dry lumber.

[@jinto_reedwine]

These tests are very interesting, keep them coming!

[@Bob_Adkins]

I always made my pilot holes the same size as the minor diameter, now I know that a skosh larger won't matter that much. Thanks Matthias!

[@CDP135Z]

If you think this isn’t interesting, you are dead wrong. I love this sort of stuff! And now I know exactly what drill bit to grab! Thank you so much!

[@ScramblerUSA]

As always, very informative content! Thank you. It would be interesting to see the difference between end grain and long grain, and also difference between long grain and long grain (by driving screw radially vs tangentially to the wood rings). And maybe something in between (45 degrees?).

[@carfreak201047]

Since the beginning of watching all the force tests became a big fan of the screw jacks that are used in case of an emergency to change a tire on gm pickup trucks. Can really move alot with just finger strength.

[@hdwoodshop]

Pilot hole at minor thread diameter makes sense and easy to do with calipers and a good drill bit set. Thanks for doing this.

[@WoodcraftBySuman]

Those wood tapped threads holding it down like a champ! 🙌

[@YouPlague]

This was perfect, please do more of these.

[@jackle7913]

Thank guy, i whatched your channel for years! Almost videos

[@nealkonneker6084]

Thank you for doing this. We need more hard data about this kind of thing.

[@akiriwas]

This is top notch work. Doesn't matter if it's for wood working screw strength measurements, Matthias' methodology is wonderful. I've seen less quality from a real life rocket engine analysis presentation.

[@MrThetaphi]

Great DIY tensile testing machine!

[@markm0000]

This kind of content is like wood science. I love it.

[@Xtian982]

I really enjoy these tests. Especially the insights into minor pitch and pilot hold etc. Would be great to see same/similar tests on hanger bolts and anchor screws (don’t know if they’re called something different overseas) considering the application claims behind their design. Keep up the great work!

[@jcr723]

I've been wondering about these exact things. Not kidding. Great video

[@Dcvmnaturalist]

This was fascinating- thanks for another great video!

[@jshet]

These test videos are the best.

[@kylehadden7294]

I found this beyond interesting, I would love to see more

[@Kevin.L_]

Absolutely great and useful information. Thank you sir!

[@mahmoudomara5421]

Great and eye opening video. Thanks for sharing!

[@Lucas_sGarage]

I love CNC kitchen and I love this kind of videos

[@amielgiloni7302]

Great video! It would be interesting to see the effect of adding a washer and torquing the bolt with different values.

[@naher1277]

This was not at all more than I ever wanted to know about pilot hole size, but instead very interesting and informative.

[@rodsilva80]

Thanks for doing these tests

[@alanheady7982]

No, not way too much to know about pilot holes. Always wondered what the optimum pilot hole diameter was. Very interesting. This reminds me of Materials Testing class I had is college. Thanks!

[@BenMitro]

i wonder if treating the holes with cyanoacrylate or wood glue will make a difference to the yield strength of the wood?

[@F0XD1E]

Would be cool to see. My prediction is that the glue actually makes the wood more brittle and will fail sooner.

[@JB-fh1bb]

@@F0XD1E You make an interesting point. You’ve got me thinking that there could also be a “sharp edge” between the CA glue and the unglued fibres which would lead to an additional failure point

[@BenMitro]

@F0XD1E Interesting. I was thinking it would permeate into the wood and make a few mm of hardened wood around the hole. Hopefully our gracious host will see fit to try this for us on his testing apparatus and let us all know.

[@nicktecky55]

@@F0XD1E I'll stick my three ha'pence worth in. The glue is fluid, and so soaks into the soft wood fibres. That forms a composite material that is hard and flexible. In addition the glue only sets fully under pressure, so the junction between the screw's hole and the clean wood is gradual. When the glue is fully dry, there's now a plug of the composite material maybe a half inch in diameter intimately bonded to the structure of the wood. Hard wood? Meh, not so much. Time for an experiment, now I wonder who might be interested enough to do that?

[@davidt8438]

You are the living definition of a mad genius. For years you’ve built countless machines, jigs and apparatus that have either proven or disproved a theory utilizing wood or wood products. And after all of this what have we learned? We’ve learned that wood varies in strength and hardware varies in strength. Use your talents to improve products that exist already and help the woodworking community and maybe even make a couple million bucks in the process. I for one would love to hear you’ve built a better mousetrap.

[@TimothyJesser]

Actually, exactly what I wanted to know! Not too much! ha ha. I've always wondered about this exact subject, especially the effect of different pilot holes. Great video.

[@jdl3408]

Great video. I look forward to more tests!

[@zweg1321]

As always cool video Can’t wait for more on this topic

[@85krink]

I love this type of content!

[@thecasualcitizen492]

Very interesting to learn that what I assumed to be correct about pilot hole size is more or less correct. Thank you.

[@johnfreiler6017]

Glad you found the most common failure mode: the wood is collapsing. I suspect that's why no pilot hole showed a slight increase in one of your tests: that pre-loaded the wood fibers and the preload is what resisted failure for a little bit more.

[@celivalg]

actually, those tests are really interesting, helps a lot in trying to select which screw to use for which task. I usually go by gut, or try to follow some arbitrary recommendations, which were already proved wrong with your experiment on the thread count (although I suppose they are a bit stronger, but not by enough to be worth it)

[@Lizlodude]

This is so useful. I'm used to just using whatever is laying around, which is usually drywall screws, but whenever it's actually under some load I'm always wondering what are actually the right screws to be using here.

[@englebig]

When reading the title of the video, I thought it'd be about testing the difference between screws that had been screwed in, and screws that had been hammered in, like you did in your teenage years on roofing... I'd be really curious to see some hard data on that! Very interesting, though!

[@messaoudkrioua5002]

I don't think you're making a lot of money from these test videos... but I'm sure you're having fun doing them... Thank you very much Mathias

[@AaronHendu]

I just built a bike camper and was just thinking about this...also sheer strength between two pieces of wood screwed together. Perfect timing! This literally helps me decide how many screws are are actually necessary. I know the screws will usually break if you try to pull em out with a cat's claw or crow bar. So pull strength seems far greater than sheer strength, but I really dont know.

[@nasonguy]

Intuitively I would think you’d get tear out way before actually shearing the screws themselves. Would be fun to see it tested though!

[@jcortese3300]

That countersink screw's going to have some epic war stories.

[@riba2233]

we want more, this testing is gold :)

[@MrLiveEra]

Very interesting, Lots of scope in this kind of testing, Reisser make some great screws , They are touted as high performance and I can vouch for that, they are the best screws I have used,

[@piconano]

I would be very interested to see what would happen if you squeezed a drop or two of epoxy into the pilot hole, before screwing the screw in and let it cure overnight, before pulling. Very interesting experiments and test fixtures you come up with.

[@mckenziekeith7434]

Let it cure for 3 days.

[@TimPiggott]

Really useful to know. Thanks Matthius

[@rl3898]

Very useful, thanks for the effort.

[@dabj9546]

I love it, please more!

[@Satelitko]

"Yanking for science." "Pulling out for science."

[@nastyevilbunny]

Thanks. You made a dry subject interesting, as usual.

[@joerosburns5639]

Thank you Mr. Wizard!

[@MurcuryEntertainment]

Please continue with this sort of testing, and publish your findings in a guide. I'd be very interested in the development of holding force based on the angle of the screw relative to the grain.

[@ikocheratcr]

Super cool testing. I wonder how pull force is affected if you screw in, then screw out (like making the threads), and then screw in again the same screw and "tight it enough". Also how much pull a regular bolt of same external diameter will hold compared to an screw.

[@wilcojuffer5940]

Hello Matthias I like this kind of test very much make more of this test 😊👍👍

[@Itslvle]

I just love this type of stuff; actual knowledge. Too bad it's not a view-winner, but please do note Matthias that even though you would get more viewers talking about vapid stuff like the Kardashians, this is the type of stuff that has real value and is highly appreciated by those who have the appetite for it.

[@arcrad]

What a coincidence I just rewatched your old video testing drywall screws vs deck and wood screws.

[@joelhollingsworth2374]

It would be great to see smooth joinery vs. surfaces textured to retain some glue during assembly. I think this would be easiest to test regarding dowels, but I have seen some commentary that box joints are often glue-starved, so I'd be interested to see that sort of test too.

[@36736fps]

Another interesting and useful video. I would like to see this repeated for solid softwood, softwood plywood and Baltic birch ply; both into face and edge.

[@TheSuperBanana1000]

I needed this video!

[@GERntleMAN]

Basically that's exactly what I someone's want to see. Real in depth information, not what most people can in depth information