There is another important factor. Wood expands and contracts according to the moisture content of its environment and screws expand and contract according to temperature. The combination of these means that screws work themselves loose over time, often wearing the threads out of the wood.
In the UK, stair handrails (for instance) used to be mortice and tennoned with a drawbored peg. This is where an offset holde is drilled through the tennon and a peg driven in to pull it tight. A fashion for cheap construction has seen this replaced by screws in many cases. The problem is that uk houses tend to have wet plaster (or at least a skim on drywall) and high moisture levels at the time of installation. This means that the wood will shrink once installed... and your handrails come loose, the screws are hidden by this time!
In a very damp situation, say a wooden gate, this gets a cyclical drying and wetting, yet properly made oak gates can last many years due to their pegged tennon joints.
Edit: clarity
In addition to wood movement, there's another important factor when it comes to hobbyist woodworkers: accuracy.
With modern adhesives and precision machining like Mathias' work will make mighty strong joints even out of the simplest joinery method. A precision made box joint glued with wood glue is stronger than a finely made dovetail joint.
But when it comes to me bodging away in my garage with hand tools, that kind of precision is not going to happen. But historical "strong" joints like dovetails and mortises and tenons with wedges and drawbores are very forgiving joints and are quite strong even when they're not made to sub-millimeter accuracy. I can join a decent box with dovetails in about 30 minutes, put it together with a few drops hide glue and fill the gaps with sawdust and it'll work great.
But someone with a table saw and a simple box joint jig could join 10 boxes in the same 30 minutes it took me to make one.
Modern hand tool woodworking can match or exceed the accuracy of machine woodworking, albeit with a higher skill threshold. You can achieve very fine results with very basic tools. Machine woodworking is undoubtedly faster, however.
Tight tolerances are often completely counterproductive because of wood movement. Even with an impermeable polyurethane finish, you'll get significant seasonal movement. Effective fine woodworking is about designing to account for that movement - building drawer runners slightly undersized so they don't bind up, allowing door panels to float in the groove so they don't bow or split etc. One of the key skills of cabinet-making is developing an intuition for wood movement.
You can't really stop wood movement or even reduce the amount it moves. It can be slowed down a little with some finishes (then you have a "wood-plastic composite"). Kiln drying (do you mean this by "torrefying"?) will make the wood dry for a while, but when the temperature and (absolute) humidity will rise on the summer, the wood will absorb moisture from the air and expand and shrink again next winter.
Torrefaction (more properly, thermal modification) involves higher temperatures than kiln drying, causing chemical changes to the wood that result in permanently lower equilibrium moisture content and hygroscopicity. It improves the stability of wood and drastically improves the resistance of softwoods to decay, but it isn't a complete solution to wood movement. There is a significant tradeoff between stability and strength.
It also changes the color, which in many cases is inappropriate for the project. However, if it were being painted I would definitely consider it. I bought some Torrefied ash recently - it's weird stuff. Kind of like working with toast instead of bread. the sawdust smells odd, too.
In the acoustic guitar world, torrefication has become popular for some guitars. The main idea is that the end result of the spruce (commonly used for top wood on an acoustic guitar) is closer to a piece of spruce that is many years old which affects the tone and "improves" it to some ears. The other benefit is the wood is less likely to crack which is an issue with acoustic guitars, especially in dry climates where humidification is an issue. Some say the wood is more resistant to cracking but more brittle in other ways which aren't too important to how an acoustic guitar applies tension. the main idea is the wood won't change with respect to humidity as much as untreated wood.
But yes, especially when luthiers started using this technique there were all sorts of issues with the end result in terms of superficial results/coloring. However, they've gotten better at this and now we see the wood being a bit darker but without all the other cosmetic issues from past years.
>The main idea is that the end result of the spruce (commonly used for top wood on an acoustic guitar) is closer to a piece of spruce that is many years old which affects the tone and "improves" it to some ears.
Torrefied tops can definitely make an instrument sound better. With the right thermal treatment, you get a slight increase in stiffness and a fairly significant reduction in damping due to the lower equilibrium moisture content and the depolymerisation of hemicelluloses. If the top is properly braced to account for the different properties, you get a more open-sounding instrument with more volume and/or sustain. Torrefied necks are substantially more stable, particularly for the flatsawn maple necks on most Fender-style electric guitars. The durability of tops is very much swings and roundabouts - you gain a fair bit of stability with respect to atmospheric changes, but the top becomes weaker and more brittle, so more prone to impact cracking.
>But yes, especially when luthiers started using this technique there were all sorts of issues with the end result in terms of superficial results/coloring. However, they've gotten better at this and now we see the wood being a bit darker but without all the other cosmetic issues from past years.
If anything, the caramel colour of torrefied maple or spruce has become a status symbol. We're starting to see a lot of roasted ash bodies on electric guitars and basses, which doesn't really do anything tonally but looks cool.
I agree, the slightly darker top is nice to my eye and gives it a fine head-start to the natural aging process of yellowing the guitar.
I think some of the issues that were out there with regards to coloring were things like "racing stripes" where there would be significantly darker stripes of darkened color an inch or more wide that would run up the tops, which many people disliked. It never really bothered me too much, personally.
I agree on the improved tonal characteristics - the reason I say "improves" in quotes is that this is entirely subjective. Some people are very sensitive about these types of proclamations for some reason. I believe it does make for better tone, which is why I have a guitar with torrification (red spruce top) being built currently. To my ear it is louder and more articulate than the same species of spruce that hasn't been torrified. As you've said, it's opened up right from the start rather than waiting years for the wood to change enough to create that open sound.
Of course when it comes to the tone of the top wood, besides the bracing (which is obviously unbelievable important), I believe that the finish matters a lot and as thin a nitro finish as possible is ideal. I've drank the kool-aid with regards to hide glue as well. At the very least, it makes a neck reset (dove tail, glued joint neck) or any other type of surgery easier in the future.
No, I do not. According to the strength tests I've seen (and my experience with joinery reflects this), there is hardly any difference in strength between a box joint and a dovetail when done with equal precision and glued with modern glue, given that they have roughly equal amount of glue surface area. But a box joint is much easier to cut with precision on a table saw with a simple jig.
Dovetails aren't usually used without glue (or wedges). A tightly cut dovetail will stay together just fine without glue, but it has relatively little resistance against shear stress. A small bump can turn a square box into a trapezoid even with good joinery.
When I do dovetails, I use a small drop of glue on the long grain of the pins and tails. That's enough to keep it from trapezoiding and allows me to plane the joint flush.
Plus the dovetail, mortice and tennon with wedges etc are still strong even after wood shrinkage has cracked the glue line. A simple glued joint just falls apart.
This is similar to current nails versus cut nails. Round nails help for sheer force, but after a while are easy to pull out. Cut nails are shaped different and work much better. I built two blanket chests using cut nails to hold it together, glue only to make a panel wide enough. Five years later it still is doing great, even with 5+ kids using it as a toy box. Screws would have worked themselves out by now.
Also built a workbench with pegged tenons, guess it weighs 100+ lbs, and if you bump it with enough force the whole things moves, but the tenons are still not loose.
Yes, for outdoor applications, the glue usually doesn't hold, though sometimes, for some joints, if its tight enough, the glue can keep the moisture out. See here: https://woodgears.ca/deck/repair.html
>> The combination of these means that screws work themselves loose over time, often wearing the threads out of the wood.
There are also dramatic differences between woods. Even if you use the same wood from the same tree, glues can impact moisture absorption rates. The only totally stable joints are those that don't use either fasteners or glues, the sort of stuff used to build Japanese temples, but these are complex and bulky. There is no perfect joint short of growing a tree in the shape you want.
Moisture expansion cycle creates incredible forces, especially when the construction is used outdoors with large seasonal temperature/humidity changes. Even a wood as soft as pine can easily rip of heads of the screws after a couple of years of use. (personal experience)
I find this interesting and somewhat in conflict with my experience.
I've been doing restoration work on an old home in the desert, and many of the nails in wood exposed to the elements had become quite loose and worked their way out enough to just grab and pull the rest of the way out without any tools.
But the nails with with a screw pattern on them which twist as they're hammered in have done much better than the smooth ones. None of these have backed out, and they're all still very firmly set, in the same wood, in the same environment, for the same duration. The builder had used these screw-style nails for hangers, but smooth nails for everything else.
I've been using SS deck screws of various length and gauge to do all my restoration work, in part because the reused wood is so old and brittle it's impossible to put new nails into it without splitting, and based on the screw-nails doing so much better than the smooth ones, I assumed the deck screws would be similarly more lasting.
If what you're saying is accurate, I would have expected the screw-nails to have backed themselves out. But it was the opposite situation.
My interpretation of what happens is the wood swells and contracts from both the temp and moisture changes. The metal fasteners don't change dimension much at all in these relatively insignificant (for metal) temp differences. When the wood swells up the first time, it compresses itself around the firmly held nail, and the nail doesn't budge. When the wood shrinks back down, the compressed wood around the nail stays compressed and now the bore is bigger than before. This cycle repeats itself over the years, and since the nail has a pointy tip, every time the wood swells up and closes in on the nail, it nudges the nail out a little bit before tightening until things shrink again.
Based on this model, I think the screw is superior because the depth of the threads is greater than the dimensional difference between swollen and shrunken. The wood is free to go about its seasonal cycles, and the screw doesn't move because the threads are always engaged enough to resist that little pressing force at the pointy tip.
I'm a noob when it comes to all this, but that's my impression and only time will tell if I've made a horrible mistake using screws for all these joints. Though it's not like I had many options.
I'd recommend NOT starting to watch Matthias Wandel's videos. I must have lost years of my life watching woodworking videos on youtube after he got me hooked. It also cost me several thousand pounds in tools and culminated in me buying a home requiring complete refurbishment (not quite finished).
At the very least, watch some Paul Sellers videos to inoculate yourself against the belief that you absolutely must give all your disposable income to Festool and Lie Nielsen.
His workbench tutorial is excellent, but for me, an absolute noob, it was still daunting to build a workbench as the very first project. What I ended up is building the Paul seller's Trestle [1] as my Hello World project, and it has been super handy. Even after that, I still think his workbench is too much work for me, and I eventually decided to build Christopher Schwarz's knockdown workbench [2].
That is where I first started out. Watching his videos helped build my first workbench, from there I found Wandel and others. I still go to Paul for tips and tricks.
Except for sanders. If you use one of them for a bit, you'll have no problem signing away an organ or two to Festool. And the dust collector, of course. Maybe a Domino joiner. But other than that, you don't have to give them all of your disposable income for your power tool needs.
Watch enough of hand tool videos and soon you will be hand planing and scraping instead of finish sanding.
Buying the sander and dust collector would probably be cheaper than all those hand planes, but there is something in that fine smoothing plane shaving that keeps you coming back.
Hi Matthias, I really enjoy your videos. I hope you didn't take my comment as a criticism of your work - it was really aimed at the broader culture of woodworking. Your videos are experimental, interdisciplinary and in many ways orthogonal to that culture.
The Sellers approach is obviously far more time-consuming than what I might call the New Yankee Workshop approach, but it has tremendous merits for new woodworkers. It's very easy to be intimidated by the huge workshops full of expensive machinery that you see on YouTube or in the magazines, but Sellers makes it absolutely clear that you can do fine woodworking with a tiny amount of space and a handful of cheap second-hand tools.
Other YouTubers promote a similar message - Rex Krueger springs to mind - but I think that Sellers offers a uniquely clear vision of how traditional skills and tools can make woodworking a more accessible and enjoyable pastime. For many amateur woodworkers, getting it done is almost besides the point - it's about the quietness and concentration of skilled manual work, the smell of the shavings, the satisfaction of a sharp tool and a neat dovetail.
That's fair, I think what is also fair is that a lot of folks simply enjoy spending the time on it rather than just getting it done, which is also the case when it comes to writing code.
He's an extremely interesting person. He was a longtime engineer for RIM and he holds several GSM-related patents [1].
He's also written a few neat pieces of software, my favorite of which is Bigprint [2].
As someone who dabbles in woodwork, I can highly recommend it as a hobby.
Exercising the brain in any new problem domain can often be rewarding in itself, but it's a nice opportunity to blend engineering, practicality, creativity, usefulness.
From TFA, I'm (also) surprised that end-grain screws worked at all well. I appreciate the author was trying to minimise variation between the components, but for end-grain I'd use a much deeper thread, as screwing into end grain is often compared to joining into the end of a bunch of drinking straws. Not that I'd ever screw into end-grain. ;)
Similarly, the makeshift pocket hole jointer isn't clear from the pictures how they got a recessed hole (commercial pocket hole devices use a t-shaped drill bit, and do not drill all the way through the piece). The recommended bits for pocket holes also have a threadless shaft near the head, so the two pieces pull tightly together.
Which leads to the lack of glue in many of those photos. I grew up hearing (but not really believing) phrases like 'the nails are only there to hold it until the glue dries'. Wood glue technology is amazing -- when they say on the bottle 'stronger than wood' they aren't joking. I'd expect to use a lot more glue than shown, and have it significantly affect the results.
> the nails are only there to hold it until the glue dries
This is a phrase my brother, a cabinet maker/ jointer, uses... And tests occasionally: Glue 2 pieces of timber together at 90 degrees and clamp it normally. When dry, break the join (by bashing it with a hammer is his general way) to see if it's the glue or the timber. Nearly all of the glue he tests are stronger than the timber (Oz, US and Asian hardwoods), as it's the timber that is ripped apart, and not the glue join.
A bottle of standard PVA-B (/ exterior grade) from the local hardware store is pretty excellent.
When you think about glue, it's everywhere these days. All timber laminates (eg kitchen bench tops, plywood, particle board, MDF, and finger jointed/laminated timber) are just 'glued'. A lot of this is structural timber (ie designed to last decades).
From the article:
> This joint failed by the wood in the post shearing along the growth rings
This is the most common place of failure when witnessing my brother's "tests", and makes a lot of sense it happens that way too. The glue should have been the strongest part of ALL of his tests. It looks like he 'over clamped' the timber (ie squeezed out all the glue) in few of his photos [0]: which is something my brother has warned me about, as it makes the join weak.
> the nails are only there to hold it until the glue dries
I'm only dabbling with woodworking on a very basic level, but realising how strong wood glue is one of the big aha-moments I've had. As the article author mentions, screws are simply not good enough for holding stuff steady, but when combined with glue it's simply redicilously strong.
Hey there! Big fan of your articles and videos. I've been building box joints recently and even though the forces they're subjected to are not nearly as pathological as what you tested, I enjoyed your box joints and dovetails strength testing article: https://woodgears.ca/dovetail/strength.html
Quick question: do you recall what wood you used for the box/dovetail article? It looks similar to the spruce from the earlier joint strength article. I suppose using a stronger wood would just get you closer to where the glue is failing more than the wood, but I'm just curious.
Less-quick question, feel free to punt/ignore: any thoughts on deliberately building in a very, very slight gap between box joint fingers? I would expect this to reduce joint strength (thanks to reduced force between fingers and surface area in contact) but potentially also mitigate wood stress from movement in service due to humidity. Though I imagine if a work piece is big enough for me to be concerned about movement in service, I probably shouldn't be using box joints!
A small gap actually helped. Probably because the glue soaks into the wood, so a joint without any gap sort of runs out of glue too quick (my theory). But it suggests that putting glue on and leaving the joint open for a minute may be beneficial.
I enjoyed the linked write-up, and also the "M&T vs dowel" and "M&T vs dowel revisited".
Have you ever used your joint-strength rig to determine the minimum M&T geometry or dowel configuration required to make the joint fail before the surrounding wood fails? It seems to me that if all the joints are stronger than necessary anyway, your tests were really testing the joint, plus the wood (which you tried to control), plus your own assumptions about the equivalency of different joinery techniques, rather than just the joints.
I'd also be interested to see a test of hybrid joints, such as a screw at the end of the joint under compression, and an M&T or dowel at the end of the joint that's under tension. A screw-head won't pull out through the wood, if it's mostly being pushed and sheared rather than pulled. I'm thinking a dowel at 45 degrees on the tension side, and then drive a perpendicular screw into the end grain through the compression side.
Your tests also suggest that, since the joints tended to fail along the glue line, dimpling the tenons, or adding ring-shaped grooves to the dowels--rather than the grooves parallel to the long axis or slightly helical that are typical in pre-cut dowels--would increase the joint strength. The interior surface of the mortise or dowel hole would have to be similarly roughened. Perhaps thread the dowel hole, as if for a larger bolt, and thread the dowel rod, as though for a smaller hole, and let the wood glue bite into both like the threads of a screw?
I haven't tested it explicitly, butI consider the magick mortise and tenon (or dowel) ratio to be around 4:1 or 5:1. A tenon longer than that will break off (wood failure), shorter than that, and it will pull out (joint failure). I suppose grooves on the dowel would help the glue a bit, but they also weaken the dowel.
But your failure analysis showed that the point of failure was not the dowel, or the glue, but the wood near the wood-glue interface. The wood failed at planes parallel to the glue plane, such that the glue was left holding on to little splinters. If the glue did not form a plane, whenever the wood cracked parallel to the glue, those cracks would be misaligned, such that they would not immediately lead to joint failure by forming a shear plane. But it still has to be close enough to a plane that you can make the join in the first place. Grooving or dimpling one of the surfaces would be like nailing the dowel to the hole from the inside of the dowel as the glue dries, or adding o-rings that prevent lateral movement to a piece that requires lateral movement for assembly. The glue spikes/rings would have to shear off, or the wood would have to crack from the outermost extent of the spikes/rings.
Weakening the dowel is okay, since it wasn't the dowel that failed. It's probably more important to rough up the inside of the hole anyway, since the failure photos mostly showed that the glue was still stuck to the dowels, and it was wood from the inside surface of the hole that broke away. And the end-grain in the rail somehow frustrated the cracks better than the grain in the post.
These questions are completely tangential, and may be a bit too personal, but I can't help but be curious...
1. After you moved out to the country, and discovered you did not want to handle the lifestyle of maintaining all that land (esp. w/ tendonitis + family health issues), did you take a financial loss selling the land? I could see that experience being frustrating.
2. Would you be financially independent regardless of your youtube income and other income (selling plans) from your website?
I have an idea for a build, hereby up for grabs for Matthias or anyone. Inspired by your copy carver. Thanks for all the great videos! You started my interest in woodworking :-D
3D 'Tracing at Scale' with light
Apparatus is two rotationally-locked turntables and a can light (fairly directional), all mounted in a line. A model is placed on the center table, working material is placed on the table further from the light. The light and model are aligned so a shadow of model is cast on the working material. Remove everything that is illuminated, rotate, repeat, until you've created a copy of all (convex) curves of the model. Because the tables are rotationally locked, you can reliably reproduce the corresponding shadow for any rotation - can work your way around multiple times or easily come back to tricky angles. Distance between light and model can be adjusted to change scale resulting shadow.
Could be fun way to guide yourself with modeling additive materials like clay as well as woods and such.
I miss working with other engineers. But overall it’s been fun. But with changing trends and so many people making videos now, it may be the right time to get out and get a real job again.
A problem is that "strength" isn't a scientific term. You have tensile strength, shear strength, torsion strength, and compression strength.
Screws have incredible tensile strength, which this article was testing. Shear strength? Not so much. Hit the joint with a hammer from above, and most screws will just snap. Nails are the opposite -- great shear strength, and no tensile.
Glue is stronger than wood, as several comments indicated, but for how long? I've had many glued pieces of furniture fail after a decade of use.
In a lot of woodworking, I use multiple types of fasteners. It's overengineering, but it doesn't fail.
Most of the glued pieces I'll see fail after a decade were using your standard yellow carpenter's glue. It's fine, strong stuff that lasts a while, but it will still soften if it absorbs some water. Some older glues will also brittle over time. There's been a big push recently to waterproof glues that fully cure and can't be re-wet. While it's disheartening to throw out a bottle of clumpy glue (when I've had bottles of the yellow stuff sit around for over a decade and are still good), glues like titebond 2 or 3 should last as long as the wood itself.
I'll still use the yellow glue for anything that doesn't hold a load, like thin panelling. These days my yellow glue mostly gets used to repair pop up books my toddler tore apart.
On the other hand, if you build heirloom pieces with nice joinery, you want the glue to fail before the wood does. When that happens, it's an easy repair. If there's damage to the wood, it's a much more complex affair.
I use hide glue liquid, which is not very strong and not moisture resistant at all. But it's a pleasure to work with and I know that if it fails, I can put it back together again (doesn't even need the old glue to be cleaned up).
If anyone wants to geek out about historical adhesives for woodworking and other craft, I'll gladly share my experiences about DIY glue cooking at home.
It usually is, but that depends on the additives used and the gram strength of the flakes used to cook the glue and the quality of the glue job.
E.g. I cooked a batch of 192 gram strength glue with 50% table salt additive to keep it liquid at room temperature, and I had half of the failures at glue seams in destructive testing. Made an excellent glue for cold winter days, though.
In glue strength tests (like James Wright on YouTube and FWW magazine both), hide glue compares favorably to modern glues.
But all it takes is a few drops of additives to drastically change the qualities of the glue.
If you absolutely need a joint to not fail before the wood, use epoxy, mix in some glass fiber cuttings. It's indestructible to the point I wasted considerable amount of sandpaper sanding off a joint I needed to remove. Nothing else would so much as cut it.
PVA ("standard yellow carpenter's glue", titebond, etc) is much weaker and moisture kills it over time.
2) Everything you apply it with is ruined within minutes
3) It can cause terrible dermatitis (always wear multiple pairs of nitrile, not latex, gloves). You can become sensitised to the point that you cannot share a room with sanding dust from it!
4) It's open time is short and varies according to the batch size due to the heat it produces. This means you have to spread large batches out in a tray to lose heat or it goes suddenly hard, or indeed melts your tray!
5) Clean up is nigh on impossible. Normally you are left chipping and sanding what is left
6) It has poor resistance to UV light
7) It leaves a residue that can stop paint sticking
8) It is unsuitable for thin glue lines like are used in furniture and traditional joints
But yes it is phenomenally strong and water resistant.
A better glue for joinery is polyurethane, especially the titebond stuff.
I'd say multiple pairs of gloves is overkill, plain medical latex ones do just fine for me. Just don't mix or apply it with a finger.
Open time of modern ones is acceptable, Many times I found myself waiting for it to get more sticky than otherwise. And heat is of no concern for joints.
For point 8 I'm not sure what are you talking about. It's great for thin-layer joints, that's where it actually excels.
Never had any problems with UV, but maybe because it was always painted over (and what's the problem with painting? sand it a bit, that's taken as granted as even epoxy itself won't stick to unsanded epoxy)
Besides, knowing you won't be able to get it off once it gets on something trains concentration and fine motor control :)
As for $ well, it costs a bit more, and time spent on weighing and mixing is well over any cost difference in raw materials. Still in the end you get a joint that'll be the last thing that fails.
I used to work in a chemical factory and the head buyer wouldn't have latex gloves in the building, because they are so porous, so no use nitrile or neoprene. Maybe this link will change your mind about the risk of epoxy exposure[0]. There are loads more if you google it. I read an article once about a poor chap who had to wear an NBC suit to finish his boat.
Open time is not an issue if you are mixing enough for a chair leg, but if you were mixing enough to glue a large lamination it kind of sucks when it smokes in the pot and then goes instantly hard or melts your glue pot[3]. Equally if you were trying to glue up a set of stairs, for instance, you would need a helper just to mix the glue fast enough.
point 8. It shows a glue line in thin laminations [1]. I struggle to get where you are saying it 'excels' at thin joints, in fact the main selling point with epoxy is that it is the only wood glue that is strong across a gap. That is where it excels, loose joints and fillets.
> and what's the problem with painting?
It is called amine blushing.Sanding won't do, it has to be washed off [2]
> Besides, knowing you won't be able to get it off once it gets on something trains concentration and fine motor control :)
Buying new rollers, brushes, tubs for every single joint gets old really quickly if you are a pro user. Again fine if you are gluing a chair leg, a pita if you are glueing large joints.
> it costs a bit more,
It costs a lot more! Titebond in bulk is £10 a litre. West system large packs are nearly £50 a kilo!
> Still in the end you get a joint that'll be the last thing that fails.
Is that always a good thing? Wood moves around a lot and sometimes it can crack a glue line that can just be reglued. With epoxy your wood will split instead.
Epoxy has some amazing qualities, gap filling and water resistance in particular. In a hobby shop it might be worth the hassle, in a pro-shop almost never.
Well, we must have completely different applications in mind then.
My experience with epoxy is building boats. Mostly spruce stock and birch plywood, fibergrass all around for surface protection and stiffening; 12-16 meters length.
Can't call this a pro operation, there's that.
Still in my experience, thin epoxy joins are the strongest.
We've tested spliced plywood to destruction - not once did it fail along the joint; delamination across factory glue was always the case.
If screws snap from shear, you used the wrong fastener. A bigger screw isn't the right solution. It costs more, makes a bigger hole, and doesn't work as well as the right fastener.
Screws are generally harder steel so that the threads can cut into the substrate. That makes them brittle. Try bending a screw; it won't bend. It will snap.
There are engineered screws designed for high shear strength which I use quite often. They're much more expensive, but I find them worthwhile.
Nails are made of softer, tougher steel. If you try to bend one, it will bend. It won't break.
Conversely, from the video linked, you can see that even a basic screw will handle several times more tension loading than a barbed nail.
It is amazing to find woodworking is such well received topic on HN. I don’t remember how I stumbled on a woodworking video on YouTube about a year ago, and last week I just finished building the Christopher Schwarz knockdown workbench. This hobby is truly addictive, to me, it resembles a lot aspects of software engineering, but in a more vivid and interactive fashion.
I think this is particularly true in the sense that woodworkers (like software people) can make much of their own tooling in their native media. Nothing I've seen on youtube is a better example of that than Matthias Wandel. Need to make a bandsaw out of wood? Here, hold my beer. The Pantorouter... really? Even dust collection! This makes wooden stuff out of wooden stuff out of wooden stuff. Three levels deep, inception style.
The thing that draws me to woodworking, as a software engineer, is that it resembles many aspects of software, but has a wonderful imperfection inherent to it.
The more skilled at woodworking I become, the more I learn that every piece of wood is unique, and does not care about systems and methods. The grain will happily explode in your face if you try to work with it the wrong way. =)
It all makes me appreciate the physical aspects of things much more.
Why didn't he join the screwed pieces with glue? I was always under the impression the whole point point of screwed joints is to stress the glue, not to actually bear load (Because of the small surface area and hardness difference of the materials)
Cool article! I've made a few very simple pieces of furniture and have always used screws, so I was surprised to see they were the weakest joint. Guess I'll need to learn how to mortise and tenon!
At right angle means the screw is loaded in shear rather than tension right?
And that's why screwing in deck boards is good, but not for joists. Use nails for that instead, unless using engineered screws.
So I'd be curious if you'd do the same strength test but with nails: end nailing and toe nailing. After all you did end screws and pocket screws...
I'll add that your "Smashed deck repair hack job" is very interesting... the deck is attached by mortise and tenon joints? I keep reading about ledger boards and joist hangers, so I'm just... surprised? And you replaced posts in hole with essentially deck blocks! Very interesting... Thanks!
Your failures mostly amounted to the joint pulling apart along the glue interface rather than breaking, I suspect adding a transverse retaining pin will make the failures more interesting with significantly higher loads.
Did you consider doing any tests with a retaining dowel or some nails/screws through the mortice and tenon joint?
The transverse pin weakens the tenon and the piece of wood it goes into. If the joint is well designed (so that the glue strength and wood strength are balanced), the tranverse pin only weakens the joint.
Lost Art Press is great, but not exactly for the beginner. I'm a huge fan of The Wood Whisperer aka Marc Spagnuolo (https://www.youtube.com/user/TheWoodWhisperer). He has a lot of content on YouTube that's significantly higher production quality than everyone else, and most importantly he's very good at teaching.
He has two books that are great for the beginner:
-Essential Joinery
-Hybrid Woodworking
His Shaker Table project was my first "real" piece of furniture that I built. I've since graduated to designing and building my own furniture. Highly rewarding, and I owe a lot of my skills to Marc's wonderful teaching methods.
I've worked with wood for a few years now, and I wish I would have found Rex Krueger's channel earlier (https://www.youtube.com/channel/UCj4SLNED1DiNPHComZTCbzw/vid...). I'd say his primary intent is to get you started with the minimal amount of cost, and his videos get to the point faster than many other instructional videos.
In the UK, stair handrails (for instance) used to be mortice and tennoned with a drawbored peg. This is where an offset holde is drilled through the tennon and a peg driven in to pull it tight. A fashion for cheap construction has seen this replaced by screws in many cases. The problem is that uk houses tend to have wet plaster (or at least a skim on drywall) and high moisture levels at the time of installation. This means that the wood will shrink once installed... and your handrails come loose, the screws are hidden by this time!
In a very damp situation, say a wooden gate, this gets a cyclical drying and wetting, yet properly made oak gates can last many years due to their pegged tennon joints. Edit: clarity