What's the Best Wood Joint || Insanely Strong Joinery!
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- čas přidán 29. 04. 2022
- In this video we test to see what's the best wood joint and find some insanely strong joinery! Get Honey for FREE today ▸ joinhoney.com/bourbonmoth
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You also have to consider what the joint is for. A dovetail joint is designed to be strong in a particular direction - resisting pulling apart against the wedge of the dovetails. It's not as strong when being pulled in the other direction, and the wedge shape of the tails and pins may even make it easier to collapse in the diagonal force direction that you applied. If you were to retest with a 90° pulling force instead of a 45° pushing force, your results would definitely change because the mechanical advantage of the dovetail would actually play a factor.
You remind me of when I pointed out to the one gentleman he tried to Say end grain to end grain glue up with stronger than long grain to long grain. But his test was flawed by the direction he was applying the force. As I explain to him if you were making a stool that was 1‘ x 2‘ you would put the grain running the 2 foot length. Now if you cut that stool and a half across the grain and just glued it up would you trust the stool to stand on? I wouldn’t now cut that stool instead of across the grain with the grain and then glue it back together now would you trust the stool? Yes I would. Which direction the grain runs is part of Woodworking that makes your end project strong if you do it right but weak if you do it wrong.
I say the same for the box joints, more glue surface more pulling strength
I would like to see the results of the pushing force.
I think dovetails that are more equally sized may contribute to extra strength as well.
Two women in a thread in a male dominated job subject, and being smart and relevant - my toxic masculinity is triggered and offended.. Keep it up ladies. ;)
Ordered as presented (breakage) in the video:
1. Butt Joint 60 lbs
2. Lamello 70 lbs
3. Domino 100 lbs
4a. Pocket Hole Inside 110 lbs
4b. Through Dowel Pins 110 lbs
4c. Dovetail 110 lbs
5. Pocket Hole Outside 170 lbs
6. Miter Joint 210 lbs
7. Box Joint 220 lbs
8. Miter with splines 270 lbs
omg ty so much
Strongest joint I've seen is also a type of miter joint. The lock miter joint, machined on the shaper, has outstanding strength due to the glue surface area.
I also couldn't help but wonder, would the tyloses in the white oak have made a difference by not allowing the glue to penetrate the pores?
I wonder how a pocket miter would do. I have often used those for small projects. Now that the miter and pocket were both pretty high on his list, what would combining them do?
I think the dovetail would have done a better job if it wasn't made so thin. My dad does wood work and his dovetail joints are much thicker than that.
Seriously, your dovetail was crafted by an expert. I'm sorry, the small contrasted with large dovetails is ignorant. The small dovetails will obviously break. Go back to structural engineering classes.
My theory on the dove tail is that the pins were just too small. Your box joint beats it just by having more glue area. I think you could get a significant boost with a 50 50 ratio of pin to tail
If you look closely the board actually split along the grain, spread, allowed the smaller ends to slide out
This.
It was a pretty bad example of a dovetail joint. I questioned it on first glance, and not surprise it failed spectacularly. The little details make a huge impact. Also you have to account of the same wood and same glue, which he didn't.
You can also cut dovetail joints in the trans-axis/dimension, which would decrease it's rigidity in the "pulling direction" but increase it in the "crushing direction". There's some interesting techniques in Ancient Japanese woodwork, and they occasionally used spines which really adds a lot of strength. That was no surprise to me.
Before the video here's how I expected it to go:
13- Butt Joint Glued
12- Lamello Attached
11- Domino Attached
10- Milter Joint
9- Dowel Pins Embedded
8- Pocket Hole Inside
7- Pocket Hole Outside
6- Butt Joint with nails
5- Butt Joint with screws
4- Milter with spines
3- Box Joint Proper
2- Dovetail proper
1- Dovetail 3D/spines
0 - Weld that sucker!
@@shadowanonymous3941 Dovetail joints present a lot of areas for stress concentrations. Stress concentrations in a linearly grained material can cause failures like this. I do agree that the small pin size may be a contributing failure factor, I would expect more equally sized pins/tails to be stronger in a situation like this.
Not so much the glue area, it simply slid . And with the angled cut it should have actually offered more surface area than a straight cut in a box joint. It most likely slid thru because of the angle of the cut and that was simply limited by the thickness of the pins (thinner material means you cannot increase your angle on both sides. The thicker box joint mainly offered a compression force distributed to both sides of each pin. The thin pins cannot simply be compressed on both sides to prevent it from sliding. That is, given that the pins have very tight fit. It could simply be that the dovetail pins were not as tight as the box joint. The fact that it slid instead of breaking at the shoulder means there is a problem with the fit. Of course, given the forces applied, the box joint will always defeat the dovetail in terms of preventing breaks at the shoulders since the grains are simply supported on all sides unlike the angles cut on a dovetail where the pins are smaller in diameter closer to the shoulder.
No, it's because dovetails are specifically strong against pulling pressure, not 45 degrees downward pressure. If it was a pull test, dovetails would be top.
You defined my life as a woodworker: I like to make things stronger than necessary and more complicated than they need to be.
As an engineer specifically in structures, the applied force and direction in relation to the joint have a huge impact on the results. The joint actually felt more force than the weight you put on top. This is called a moment arm between the joint and applied force. This is measured perpendicular from the joint and the applied force. I agree with you that more test would need performed as this is one case out of several cases and only measures the strength of these joints in a very specific instance. Still fun to watch and interesting.
Luckily, there's constants that can help determine just how much weight was applied on those joints as a result of the length of the lever.
And the test is valid for relative strength for the direction of stress it measured.
While true, the measurement of the force in pounds isn't really important here. What's more important is the comparative data - Having 5-10 of each joint would be helpful to take an average reading of the breaking-point of the joint. Also, instead of a levered arm with gym weights, using a hydraulic press with a more accurate digital readout would provide more accurate comparative readings. This is a good start, for sure.
Side topic from the video. Don’t have a degree in this field, but use moments, arm, and center of gravity (CG) all the time for work. If you would be willing to help us understand more. Wouldn’t you have to figure the moments being applied by finding the distance from the joint (arm) and then find the CG and multiplying them? You just used the term “moment arm” and I’ve always thought those as two separate things.
A better measure for the strength would be the torque in the joint. This depends on the force applied, the length of the lever and the angle between the direction of the force and the lever. Sometimes torque is also called moment which someone else here mentioned, so maybe we're talking about the same thing. Consider using torque to compare with new measurements or just keep the setup unchanged.
Great video and what a surprising result!
Regardless of strength, I think contrasting splines in joinery is a great way to add character to what could be a simple piece.
Except you get to add character AND strength. I always enjoy form + function.
I would love to see the follow up video to this with more tests:
• different sizes of dovetails/fingers
• different wood glue uses
• different woods and whether or not cross-hatching helps wood glue hold it tighter
I liked and subbed!
mechanical engineer: my take is that the way dovetails are hand cut left a stress concentration at the inner edge of the tail (see failure pic for where it split). this is where the saw stops when hand cutting the tails. routing the dovetail would likely do a little better job (similar to box joint). altho box joint would still be better since it is shearing the glue only and not exerting a force that is splitting the tails
I would love to see this test done a second time with the same wood and joints, but this time testing the breakage in a pulling direction. As several already mentioned in the comments, different joints are strong in different aspects, and depending on what you're constructing you may need some joint over other.
In physics, we call these different loads *compression* (what was tested in the video) and *tension* (if we pulled the ends apart). We also have *torsion* (by twisting the joint) and *shear loads* (by dislocating one board out from the plane of the ∟-shape), that would be interesting to look at.
The differences in these strengths are actually quite important in fabrication.
For example, if we were to construct a box (with no top or bottom) using only Miter joints we would now expect this box to be super strong from what we just learnt. But this is not necessarily the case.. If we try to crush this box (by for example by standing on its edge), only two of the box's joints will be under compression (the two joints on the side). The other two joints (the top and bottom joints) will actually be under tension. So if the Miter joint happen to be very weak under tension, then the box will break pretty easy, even though the Miter joints are super strong in compression.
Wouldn't every joint here actually be tension and / or shear though? The inside corner of the joint in each case provides a fulcrum around which the joint fails. The box joint is basically just a bunch of glue joints failing in shear.
I was thinking the same thing. He could just take the joined boards and rest them on a level, low-friction surface in an inverted vee (^) shape, then apply a straight-down vertical force to the joint.
You'd also have to repeat the experiment many times and have other people replicate it several times to make it truly scientific.
@@monsterchimp1669 yes, science is very boring and hard work
@@crackedemerald4930 This was the first thing I thought of - 1 sample per joint is suggestive but not definitive, and it would have been a lot better to have a whole bunch of each joint. But he has limited amounts of time and funds. It'd be great, though, for a senior thesis in woodworking engineering, to have repeated tests. He could also have tested other types of joints (that I just listed in a comment of my own).
As a completely non-woodworker I definitely guessed the splines and was pleased my guess was correct. My thought process was that the way your contraption was setup is that it emphasizes compression on the inside of the joint which translates to tension on the outside of the joint. So I assumed those splines would be best to resist that tension since they are full grain wood running the exact direction of the tension.
You grasped the essence of joint engineering better than most woodworkers.
well, this will teach me to read comments before I finish watching the video!
Excellent analysis! This is the type of logical thinking I wish I'd see more of in woodworking. As Donny P said, most woodworkers seem to have very little understanding of these things.
im 16 never done woodworking in my life randomly watching this. And instantly knew the splines would win because the wood is going the same direction as the force. Like its hard to tear a pice of wood by pulling on it or i n this case compresing. idk
Exactly, had he tested the expansion of the joint under the opposite load instead, then the joint would have failed earlier.
Its pretty rare that a drawer or box is stressed that way. I would love to see these tests repeated as a pull test instead (think the pulling action on a drawer).
Yes please! Although I suspect that the miter with splines may still come out surprisingly well.
I also wonder how much difference it would make if dowels and/or loose tenons (dominos) were perpendicular to the force applied to parallel to it. IOW which end of the box angle you pull on probably makes a difference.
Another interesting test would be sheering force. Make a T like a shelf attached to the side of a cabinet. Apply downward force close to the joint. How do pocket holes, dominos and dowels compare to a dado & rabbet? (Hint: I’m pretty sure I know the answer.)
Scott Walsh did a video with pulling for the test with opposite results. The miter with splines was the best and box was the weakest.
I'd like to see the test after the pieces have aged for a year or two. I suspect the miter would turn out to be one of the weakest joints. What we're seeing is the strength of fresh glue here, not of the joint.
Miter had me stunned! Thank you for running the gauntlet! Also, stray option that might help:
Drill into the narrow edges of the box-joint, and plug with wooden dowel (imagine if you were making a 'hinge' out of wood, dowel plugging through each 'tooth' of the box-joint) to prevent the two boards from tilting out of alignment; it should force the inner dowel to fail, first, which'd be difficult in that confined bore.
I think the idea of the dovetail being so superior is that as it begins to come apart or loosen up (say in a really old drawer that’s been opened and shut A LOT) it still functions whereas a miter, box, or pocket hole are basically shot the moment they start to loosen up
Ummm... sand and glue it again?
@@lisat9707 not very easy for someone who isn't a carpenter or doesn't have access to a workshop.
Super good point. It still holds together-do’n its job- even though it’s injured.
The dovetails we used when I was making furniture, were more like your box joins in size and spacing, just dovetail shaped. Maybe the size and number made a difference.
I think the big difference with this test is the amount of friction you can have versus tensile strength, maybe the ultimate joint would be the mitre with splines, but have the splines being evenly spaced and sized to the actual join wood, or at least increase the number of them. I have no idea really.
Its so funny that only you say it… we learned in school that it have to be in a specified ratio, so the gap cant be thin like in the video. Its look good but not as strong.
I don't understand the point of those dovetails where tails are thick and pins are thin.
tails and pins should be about the same thickness as the thickness of the board or slightly wider.
I'm not sure if it's done that way for esthetic reasons, but they don't look nice to my eyes.
Yeah, the thinnest part of the dovetails become the weakest link. Bigger splines don't do anything, they just add surface so more thin ones would be best, but not too many to make the wood in between them too thin.
I was surprised that he didn't include the typical routed dovetail joint that is the industry standard in cabinetmaking.
agree. Seems the dovetail was too thin and we can see on the video that it was the timber that failed (because it was too thin) and not the joint or glue.
this video rocks. the comprehensive study of basic woodworking joints is really useful for woodworkers of all skill levels. miter joint... wow.
I love this guy. It was funny, informative, scientific, it had everything, even a lab coat.
You sure know a lot of joint tricks. I would follow you anywhere sir!
The strength of the miter joint is really surprinsing. A few thoughts on that:
- Since your miter joint is 45 degree, and you placed it in a 45 degree angle, the strain is ideally angled, as the joint should "see" no to little shear stress. I wonder what happens, when you alter the force direction.
- The surface area is around 40% greater than that of a simple butt joint.
- The cutting surface is a mxiture of end grain and long grain. Could you do a test, where you presoak the endgrain in a mixture of water and glue, let it dry and then glue it?
Super interesting video! I feel like such videos really bring reliable knowledge to the community!
Its not so much the angle. Technically its an arm of momentum thing where the inner corner is the centerpoint.
Looking at that, it is important, that it is not only 40% more glue area, but the additional area is also at a larger distance to the center of rotation, giving it a much larger arm of momentum.
If you calculate effect, you'll find, that those 40% can hold the same weight, as the first 100%
So only from that effect, you could expect double weight.
Adding those splines improves even more especially at the longest arm.
Another interesting thing is, that this connection does not apply any stress onto the fibers, that separate them from each other (as happens in the butt joint) They are mainly and in a bunch pulled in their fiber direction.
Really would like to see how it would perform if the glue surfaces are prepared (pre glued).
You want sheer stress in a test like that. Lap shears can resist a lot of force. The main problem here is the glue being used or the bond line that is generated is insufficient.
@@wildeast66 I'm curious to see how things would change if a high strength epoxy was used instead.
@@MarkPryor1 Mee too.
Another interesting thing with the 45° miter is the taper of the wood to the point of greatest tension. This helps to minimize peak tension stresses. This turns out to be more effective than shear stress in the other style joints.
A lot of good suggestions in the comments. One thing I would add, it would be more beneficial to do multiple tests of each joint. It is entirely possible that one or more of the joints failed earlier than a typical example of that joint, and it is also possible that one or more were hero joints, holding on longer than a typical example of that joint. I know it is more work and cost to make and test multiples, but it would help to establish more reliable results.
I had this thought, too. He put so much effort into this, so I don’t want to seem flippant, and you don’t seem flippant to me, to be sure, but IMHO science would require multiple (at least 3) examples of each to test just because, like you say, any one of those joints could’ve been a lemon. This kind of research is absolutely awesome, though, and hats off to this guy for making it happen.
Agree. There's a video about glue strength that did 3 of each and sometimes there was pretty big sample to sample variance. Maybe he just got a bad dovetail :)
@@Bob.Silverstein I don't know if you remember this, but about 10 years ago, there was this meme floating around of a child's science experiment where she fed one plant tap water and the another plant water that had been heated in a microwave oven, then allowed to cool. The one watered with the microwave-heated-then-cooled water died while the other one flourished. So a lot of people started to avoid using the microwave!
Follow-up studies were significantly less viral, unfortunately, but they sampled a lot more plants and it turns out the kid just had a bad plant that wan't going to make it anyway - and it happened to be the one that got the microwave water.
So, anyway, I'm speaking to the choir here. It would triple the time and resources required for his experiment and if I was him, my eyes would be rolling, so I also want to emphasize - I really appreciate this video and the spirit in which it was produced.
@@sivacrom agree on the extra time taken being pretty steep. But perhaps it would be worth picking six of them: butt, miter, spline miter, box, dovetail, outside pocket screw. Another thing I didn't even think of is that it might differ for hardwood and softwood for a variety of reasons. Softwood might take glue better. Hardwood might support screws better. So one could get very different results with pine versus oak.
@@sivacrom also, I do remember experiments like the one you mentioned. Not surprising. You could even show that singing to a plant causes it to grow twice as fast, if you have an N of 1 :)
Testing under a tensile load and testing fatigue strength to cyclical loading would probably have very different results and would be interesting to see
Credit where it's due - these videos are both informative and amusing - and also nicely put together - Good Work Sir! Good Work
I'd like to see a joint I have used a lot: a rabbet joint both glued and nailed as well as glued and screwed. Really enjoying this content.
I was really hoping he would do butt joints with brad nails, structural nails, and screws.
I would like to see a Greene & Greene style box joint tested, one with dowels and one with screws. It's probably not as strong as a conventional box joint but I would like to see how it holds up compared to the others.
An excellent video that triggered a storm of responses and professional opinions. Wow! IMO, your practical experiments taught us all a helluva lot ... grain, surface area, geometry, glue, the value of trial and error ... a thoughtful human effort. Thank you for your hard work!
Thank You sir, this was not only educational but very pleasant to watch as well
Cheers
Thank you for your videos. I get a lot of enjoyment (and woodworking knowledge) watching your content. Love your humor! Great job and keep it up!
An interesting thing is that the splines can be added to a miter joint after the fact.
One part of the strength of the miter is that it is end grain to end grain, and wood glue generally works best that way - as it seeps into the pores, it effectively makes tons of tiny glue dowels in every pore of the wood.
Nice
As a structural engineer that designs wood connections all the time, it would be really interesting to test the strength of something other than the glue. Some of those connections seemed quite strong if it weren’t for the “snap” of the glue bond failure. I’d love to see just how high you can go with things like truss plates, angles, and structural nails and screws. Obviously a carpenter isn’t making a cabinet to withstand an earthquake, but I think it would be fun either way.
All my cabinets and shelves seem to have withstood multiple earthquakes. Perhaps not good for their structural integrity but nothing has fallen apart,not even the antiques.
As interesting as that may be, I think it would get really silly really fast. Heck even this test showed that steel vs glue is no comparison. The pocket holes had 2 screws and it put them in 4th place even though there wasn't a lot of wood to hold them. Something like a truss plate, you instantly get to the point where you pretty much just find the weak spots in the wood. Which if you think about it makes sense. Its kinda why we invented truss plates lol. The only reason miter was so high was the leverage gain of having that glued plane being level.
Yup. That's why I just use glue, maybe pin joints if it's a bookshelf but most modern glues can handle what I can throw at it. Worst comes to worse yoy can always add support.
Need too much weight. You would be looking at thousands of pounds unless you are using quarter inch stock.
Sounds like you have a plan for a CZcams video in the making
That was a great experiment. I have to admit that I had the miter joint not lasting much longer than the butt joint, which I di have as the weakest. I also thought the dovetail with all of it's glue surface, and the cuts at angles would be stringer than the box joint. You learn something new everyday. Thanks for doing this!!
I Loved the perspective, analysis, and tongue in cheek stuff!!! I am subscribing!
A point on dovetails, I've notice from looking at my late Grandma's 100 yr old furniture. Dovetails are everywhere, but there is zero glue. Seems to me that dovetails were not developed to be a strong joint that stands up to compression force, but to stay together along a specific direction of force before glue was a thing that saved all mediocre wood workers (
tension strength of most wood is insane. straight grain fir is like a million pounds per sq inch. try pulling a toothpick apart.
@@victorhopper6774 You are correct, but tension strength of the joints is not the same as the wood.
Yes that is why dovetails are used a lot in drawers.
There was definitely wood glue 100yr ago. Humans have been using glue for 70,000 years. Egyptians used glue for wood furniture 4,000 years ago.
Your grandma just bought some junk, either missed the glue or used something low quality that deteriorated. Dovetails are definitely traditionally glued.
Yes glue made from bones for example
As a full time engineer and hobbyist wood worker this is a fantastic video. I will say that by applying the weight to a lever arm you're testing the torque on the joint rather than the weight that it can hold. But because each test piece is consistent you do get reliable results and eliminate quite a few variables. Great to see you invested in a lab coat as well for science!
Great comment! Lol. Lab coat! Most "Doctors " are the same. They just google what pills to give you for the symptoms NOT the actual cause. But that is for a different discussion. 😜😊
Yes, it's actually the law about force and lever action that applies.
The cross-product of force and distance is torque. So what we needed in this experiment was the distance from the end of the board to the center of the joint thus calculating the actual force applied to that joint. The result would be a figure in Newton meter or Nm, not in pounds or kilogram.
However, I think we should leave all the complications out of this equation and see it as a practical experiment or proof of concept. ;)
Yeah nah I wouldn't say it's torque. Because if you put the same weight further out from the pivot point it would still put the same force acting down on the joint.
Or are you talking about the wood joint being the fulcrum? In any case, as you say, the experiment is consistent. It's comparing different joints under the same test conditions, and using the amount of weight on top as the variable.
@@JebediahKerb it entirely is torque. this is a textbook example of a 2D moment of force. statics 101.
@@Pan_Galactic_Gargle_Blaster it would only be torque if it was driven from a motor at the axis, or if a constant weight was at a constant distance and the force on the joint was at a different distance. Then you would talk about torque. But the weight is directly above the joint. It's always going to be the same amount of weight on the join if you have the weight directly above it, no matter how long the arm is. You could measure torque on the hinge, and that would change based on the arm, but the weight on the join is always going to be the amount of weight you put above it. He even showed this in the video.
Would be cool to see how miter-lock joints would hold! Incidentally, I make my bee boxes with splined miters and they hold up better outdoors in the sun than the traditional box joints that most use. I didn't know it would be stronger but less end grain exposed to the elements seems like a good idea.
Wish more people were doing something similar, and see the results ^^
Thanks a lot for providing this video and help us understand more about the joinery techniques.
I am new to the subject and I wana do my first box.. So it help me a lot! :)
One thing I'd add that I haven't seen mentioned yet: testing for max strength doesn't necessarily account for the effect that cyclic loading will have on a test joint - the goal with a drawer isn't to withstand a single incredibly forceful push/pull, it's to withstand pushes and pulls over the lifetime of the piece, as the materials age and as the piece undergoes varying environmental conditions.
That's not to take anything away from this testing methodology. But rather, to point out that this test isn't going to give someone all the information they might need to select a joint design for a project. More specifically, I don't think it's reasonable to conclude from this test alone that dovetails are mostly for aesthetics.
Beyond that, other people already mentioned the difference between static and dynamic loading, and I would emphasize that: it would be good to control for _how_ you apply the weight, to make sure that you're not (for instance) dropping the weight more when you're worried about a high stack of weights toppling onto your foot.
Someone else has mentioned using a forcing screw, and I know Matthias Wandel already uses one for his experiments. Something like that would be a much more repeatable way to load the joint.
Dear Wendel, thanks for doing this test. It certainly revealed some surprises, particularly the dovetail joints. I built a bedroom suite 40+ years ago using veneered chipboard for the walls of the furniture modules. The only joint I could make easily was a mitre joint with glue. Despite decades of abuse, no sign of breakdown. I got it right way back then before your video {or computers or internet etc}. Cheers.
The dovetail is strong against pressure being pulled on the structural side of the joint. I'm definitely going test! Awesome results!
This was fun to watch, and informative. Thanks!
Wendel did these tests a decade ago and determined with some confidence that the only thing that matters is total joint surface area with glue. The strongest joint will be a box joint with many, many cuts to produce a lot of surface area.
A tight fitting box joint with skinny fingers, lol.
@@collina.7336 giggity
How about a mitered finger joint.
That was really cool. Now that I’ve seen it I can see several variables to consider. For the dovetail and box joints the strength would be affected by how tight the joints are. William Ng has talked about this in some of his videos. For wood glue to perform at its optimum strength it can’t be too tight or too loose of a joint. For the tenon, dowel, and spline joints the walnut splines likely we’re stronger than the dowels and tenons assuming those were just pine. And for any joints using end grain my high school shop teacher taught me a trick to make them stronger. I was building my Mom a bookcase out of hickory and due to time constraints I didn’t have time for fancy joinery to attach the top so it is just a butt joint where the top sits on top of the sides. He had me thin the wood glue with water and apply that to the end grain a couple of times and let it soak in without assembling the top, then after it was dry I came back with just glue and put it together and clamped over night. That was in 1975 and it has never failed in spite of being moved many times by lifting it by the top while fully loaded with books.
literally thank you so much. i was able to use the info in this video for my physics project
I love the approach, this has been a fantastic ride. I am amazed by your findings and yes the lowly butt joint and his buddy the miter joint are far stronger than we need for most things. As you mentioned, I wonder if the advancement in our current glues has helped the “weak” joints be much stonger.
One thing that is bothersome in my mind is that I don’t see dovetails used with stresses like this. Think of a drawer front. The dovetails are pulled on in line with the sides of the drawer. What I getting at is we have different types of joints for different applications.
I really enjoy your presentation thanks for all you share with us.
I love how you can make something educational really entertaining. That’s a skill not everyone can pull off. I thought it was funny when said you built a contraption to hold the joint for the test but it’s just the spline jig. Great Video!!! Keep them coming
Thank you so much, Bourbon Moth Woodworking.
If you are still doing this.. try angling the outside splines in your mitre joint instead of all of them being parallel with your downward force. It could be as little as 10 degrees. Also, try some angled dowels as splines toward the inside of the joint. My theory is that the angles will transfer some of the downward force into other directions (namely into the wood itself) which would weaken the overall downward force applied to the joint. I also believe that there is an optimal degree of angle for maximum strength. Too high would be much less effective and would probably weaken the joint.
Also would be interesting to see how much the material used for the splines/dowels matters.
It‘s likely that in softer/weaker woods, dowels and splines made of strong woods would have a greater impact on joint strength.
I recently saw a gizmo for drilling dowels at opposite 45 degree angles (I think on 731 woodworks‘ channel?) which locks the joint together. Thought that was interesting. I‘ve seen many finish carpenters take that approach with moulding and brad nails, angling them opposite to lock it in, but hadn‘t seen it previously with dowels.
Longer dowels too.
Great suggestion
That was an awesome and very thorough test! Thanks for doing the hard work figuring that out. :)
I've found that while butt joints offer more than enough strength in a single instance, the repeated strain of opening and closing the drawer tended to cause failure over time... but this was still a valuable and interesting video, thanks as always for posting!
Indeed, impact strength is not the same as tensile strength!
Pocket screws seem to do that over time also.
The glue surface area is part of it, you're getting (I think) 1.4x the surface area.
There's also the question of leverage. The inner corner of the joint is the fulcrum, with the board is one side of the lever and the outside corner is the other side of the lever. By using the 45 degree cut, the short lever (the joint) is lengthened by 1.4x.
I was surprised it made that much of a difference, though.
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Agreed, this is the way I would flex the joint to break it but also not how mitered joints on a drawer are used so I'm not sure the examples are applicable to the the intended end use they were designed for. Also all joints were glued and some designs were developed to be used without glue at all. I'd like to see that basic mitre joint hold up to its own weight even without glue! The other problem with using glue is that this just becomes a test of which joint has the most surface area along the long grain of the wood. And for that it could have been simply mathematically calculated without even testing and probably predicted fairly close results to this.
The miter joint is surprisingly strong in this direction for both of the reasons you listed, and two additional ones:
1) It's actually more like an edge-grain bond than you'd expect. And edge grain bonds are all about surface area.
2) Wood glue is stronger than many woods IN TENSION, not in shear - this is why the miter out performed the box joint - it's all about how much glue you can get in tension when you load the joint up.
Rad 2? He's a witch!
Mathematically the leverage effect amplifies the whole thing to hold factor 2 instead of 1.4. so there must be something more.
And I guess that is the direction of load on the fibers.
A butt joint with that "leverage" load, actually pulls the fibers of the long grain wood apart from each other. In that direction the wood is very weak.
If the force had a direction parallel to the fibers (which would be typical for that type of joint) they would have hold much much more.
For that specific load shown here (which you try to avoid in ANY construction by creating triangles) the miter joint loads all fibers in their strongest direction, which gives the additional strength compared to others.
That is, why the test is on one hand very interesting indeed, but of limited help to woodworking, as the direction of the force is very important. Even a butt joint has two different strengths depending on the direction you load them (parallel or perpendicular to the glue surface)
Greetings from Germany. Thanks for this great video. I really love the simple woods. Your test made me think twice.
Thanks, that was mind expanding for me. I'm blown away
I love videos like this. Yeah there were a few things that could have been done better as mentioned in other comments, but in general, I learned something new. And that knowledge will come in handy when I go to do my own projects. Thank you for the informative video.
it'd be interesting to do a test on joints 1 year after they're glued, to see what kind of effect time has on the glue/joint integrity.
Glued? My joints get me only hammered. Where's the glue coming from?
Time is one thing, I would be more interested in repeated loading. I doubt that box joint would hold up well if you put 30 pounds on it 100 times.
Ya, hopefully people don't start making drawers with miters because of this, lol. While this video was cool, the test was more or less irrelevant. The vector of the force was different than a push/pull force a drawer would receive. For a miter join, the glue would take all that repeated force over years which would inevitably lead to a failure. The dovetail, however, is distributing that force to wood-on-wood contact. Meaning, for the joint to fail the wood itself *must* break. You don't even need glue for a solid dovetail join. Fun test, fun video, but ultimately "wrong" and misleading.
@@JustinSmith1287 I don't see the miter joint failing at all on a drawer if you add splines. The joint is so simple it shouldn't work so good, but apparently it does.
@@sh0cktim3 I dont see it failing anyway since decent wood glue is stronger than the wood its holding together.
Unbelieveable! Virtually every drawer in my shop is made with box joints. 1000's of cuts. I am going to switch to the splined miter for all my future drawers. I need about 50 in the kitchen remodel I am doing and this will save me HOURS of time. Great test.
I made a diploma frame for my son and did miter with splines. I wasn't sure if the splines would add much, but they looked pretty and I wanted to learn how to do it. Glad to know it might actually survive the inevitable dropping off the wall. I mean, he hung it right at the edge of his VR space. Thanks for opening up this Pandora's box of joinery.
I wonder what kind of joints Pandora's box has.
Fascinating video. I was not at all surprised with the miter/spline joint coming in first. I make these fairly regularly and are not only strong but give a nice modern look as well.
Also to consider, although they wont live at 90 degrees, miters with steeper angles. Increasing the surface area of the connected materials and making incredibly strong joints.
Redo the dovetail. I'll explain. Yes it's the pin size to tail size. That style of dovetail is made for strength in pulling a drawer. Equal pin/tail sizes will be much stronger for the test you ran.
Edit: also, increase the angle of slope to about 9° or 10° and make them half blind. You'll be suprised at where they end up. Probably top spot.
Nice vid. Very informative.
I knew the miter joint would be in the top 3 because it increases the surface area by the greatest amount AND in the same direction, i.e. in line with the grain. In 3/4" wood it's about 1" high by whatever the width of the wood is. I use this for building speaker cabinets, and I was originally surprised at how strong it is - especially when it's a box and not just two boards. The dovetail and box joints actually reduce the effective surface area quite a bit; in the context of this test, the sides of the fingers provide little to no structural integrity because the force would be torquing on them rather than pushing or pulling.
Loved this demonstration. Sent it to friends to watch.
The dovetail wedge shape splits the wood in half due to the loading, that's why it's weaker than the box joint. It's strong in tension, not rotational loading
The thickness of the top of the pins and the angle of the dovetails matter alot as well. I always make my dovetails with half an inch at the tap of the pins if structure matters at all.
I'd like to see a dovetail angle shootout one of these days.
The thin pins is what had the dovetail fail .. someone should recreate this test with a dovetail /pin 1:1 size ratio ..those thin pins looked nice but didn't provide strength .
Thanks!, this made me feel better about my picture frames (especially the ones with splines).
Also, no one ever sits on my picture frames, so I have that going for me
Terrific work. As as physics teacher, I’ve seen a good experiment often leads to others. Some great suggestions in the comments. Thanks for a great job!
Great test, would like to see a mortise and tenon joint test against the Domino joint.
Yes I was very surprised too of the results but some joints are made to withstand pressure from a different direction.
Love your videos keep up the great work 👍
I'd like to see a mortise and wedged through-tenon setup (not dominoes) for the next go around. I suspect it would out-perform the dominoes and dowels, but it would be interesting to see the results. With that joint, the wood should break before the joint, if done correctly. That's been my experience with them anyway.
Also, how do you NOT have a dovetail jig in that shop? Seriously. You literally have all this stuff nobody has ever heard of, but you have to outsource a dovetail? That alone may have blown my mind more than the test results.
Anyway, really enjoyed this. Looking forward to round 2!!
A corner joint such as being tested here, is not the correct application for a through mortise and tenon. It would not be strong at all. The end grain of the one piece of wood would just blow out.
Awesome test and wonderful neutrality. I guessed it right! I figured the splines would essentially act as struts for a triangulated joint.
Right, my pick a stronger joint would be: Box, with a dowel run longitudinally through the assembled joint. So visually it looks like a hinge pin. Just need a long drill bit! (I just made that joint up in my head.)
This is my second favourite type of joint testing
Thank you. I am truly amazed
As far as I can tell, the boxjoint (fingerjoint) was stronger than the dovetails, cause they were too delecate and thinn. If you’d made them more even in width or made more dovetails (5/4 or more instead of 4/3), like on the boxjoint it would have held more lbs.
Would have been interesting to see the box joint compared to one with more, narrower fingers, and even more glue surface area!
Dovetail is a fundamentally flawed joint type. Reguardless of the size or amount of em. All the pressure from the weight ends up on that small short "triangle" shape at the sides of each dovetail. So just as you saw, the wood will break on that triangle line leaving one side looking as if it was a box joint because that small wood section ends up as the weakest part of it making it much weaker than a normal box joint.
Great video!!! When you redo the video, use Titebond III, it supposedly has a higher strength rating. Also TB1 & TB2 both tend to be far more brittle when fully cured, while TBIII can flex when cured which means it 'should' hold better & longer.
As soon as I saw the thin pins on the dovetail, I immediately thought that it would not perform well. Looked to me like the dovetail board cracked then just separated, though honestly, I expected those thin pins to break off instead.
I don't know how I ended up here but instant subscribe; love your humor! I have no use for this information (I WISH I had woodworking tools!) but very entertaining and one day, who knows =) Thanks again for the video, looking forward to learning more!
In wood aircraft construction, where the least wood / lightest weight, and greatest strength, are essential, joints are made by using glued internal corner blocks and exterior glued thin plywood plates that cover the joint. Nailed together. This gives tremendous resistance to the rotational force that you are applying.
Wow, it's shocking to me how well the miter joint did! I was also surprised by how much weight the butt joint held; definitely strong enough for a picture frame or something that doesn't bear much weight. Great video, thanks for sharing!
Great video. I almost had the order right. The mitre surprised me for sure. I make cabinets everyday and only use box joints. Making sure to get a lot of glue on all surfaces...most will het squeezed out as you know on those tight fingers.
I think the angle that the weight is applied to each joint could have an effect on the outcome. Hence the mitre would maybe be stronger or weaker depending on the direction the weight is pushing on the joint.
Anyway thanks for the great video, I always wondered about different joints.
I'm learning so much! Thank you!
Badass experiment , thanks for the work you do!
One more consideration is the impact of the joint ‘failure’. Some of these options fail catastrophically, others (particularly the pocket screws) would hang on as a kind of hinge.
Also the ease of repair though. If a glue but joint fails, you can often just reglue it and you‘re good to go (after sanding off the remaining glue, provided it broke on the glue joint and didn‘t destroy the wood too much). With failing pocket screws, it can really tear up the wood.
I was buying wood at an Amish place once and they mentioned that mitered cuts almost acted like edge grain to edge grain. I was still surprised to see your results and still feel like a miter needs a spline.
A very entertaining and helpful video. I am now enamored with the miter + spline joint. I thought your testing was thoughtful and fair. I am sure someone else has already made the comment about the dovetail joint possibly having different results with different (equal) dimensions, but whatever. Splines... WOW! Who knew?! Thankful that you did this... as a woodworking hack, this is something I don't need to obsess over -- I will thank you from my wife in advance.
Thanks for sharing this information with us, I am going with the miter joints and the biscuits, making a new case for my fishing poles, then I will make a case for my O/U shotgun, Thanks Again, and keep it going!
Given the options for different spline counts and orientations, ie. angled, a follow-up video is required. All hail the splined miter!
Loved watching thee tests and the method you used. The dovetail could have been starved of glue. To many people make an ultra tight joint. No room for adhesive. I spent a good part of my life as a Cabinetmaker. And made hundreds of dovetail drawers via a dovetail jig I made in the shop. I found that I needed a certain amount of slop so that there could be proper glue joint allowance. Too tight and I squeezed out all of the glue.
I imagine the same is true for box joints
@@tomruth9487 Exactly.
It very much looked like it broke on the glue edges (which are long grain to long grain) - I think you're right.
Dam good future plan, a joint stronger than the wood itself. Go ahead. Very informative Bro.
Love video. Very informative. Would like to see Lap joint. Thanks for your time.
This was surprising, hope you will do a part two. After seeing the difference between the boxjoint and the dovetail, maybe wider pins would do the trick.
I'm looking forward to the follow-up video!
Also, I think the dovetail joint would have outmatched the finger joint if there were the same number of dovetails as there were fingers on the finger joint, and if the pins and tails were of similar size, instead of tiny pins and huge tails.
I love people experimenting and discussing, this is the way to go! We need to take all power into our own hands, and take care of these horifically uneven levels of power between "normal" people and the rich.
And yes, the outcome is very interesting! Thanks for doing this test. At the same time though, the question Megan and others discussed is valid - is this the right way of testing these types of joints? In woodworking, not only the power of something is relevant, but also the looks, the fun of making it, and so on and so forth. A joint just needs to be strong enough to do its job!
Thank you for the video, I have learned much!
Quite an imaginative testing routine! I wonder how a more traditional "finger joint" might fare. Also I wonder at the lever action of pressing down on that 90 D joint. I dunno, but am not sure that most such joints are subjected to that sort of vectored and leveraged force. Might it be a more indicative test, to possibly subject the joints to lateral pulls - or possibly constructing a complete box using the same joint at all 4 locations, and then putting the pressure to the entire box with your inventive rig? Still and all, you've gotten my mind reconsidering what I thought I knew about the construction of various wood joints and joinery, which is what I think you intended in the first place. Many thanks!
I always found that applying a layer of glue on end grain and allowing it to dry to tacky then apply a second layer and affixing the joint it results in a much stronger bond. The initial layer will absorb into the end grain and the second layer will bond to the first and both boards. You then have a very deep glue bond to the end grain board.
It would also be interesting to do the same round of tests using two part epoxy resin and see the performance difference compared to wood glue.
While I know it’s generally not feasible to use epoxy for most wood projects nor is it necessary to have that much strength, I think the results would be surprising.
I used to make custom knives and used Smooth On epoxy for handle retention with dowel pins as the mechanical connection. Since most of the knives I made were bushcraft knives and would be put under serious use, from chopping and batonning and occasionally throwing, the handles needed to withstand enormous amounts of shock force.
Thank you good sir for this demonstration, goodwill to you.
🤯 Wow! Absolutely insane! I was not expecting this result whatsoever. I love pocket holes and dowels. I thought a simple miter would have been the weakest. Thank you for taking the time to show us all of this. I've seen the splines before and just thought it was esthetics only. Now that I have a table saw, I really want to do splines. They are so pretty and now I've learned are strong too. I also learned that outside pocket holes are stronger. Did not know that. I thought they would have been the same result. Love your channel. Keep up the great work.
biscuit jointer works great too
Also, throwing a rabbet joint into the mix might be informative, too!
This is also a test of the glue, all joints have an increased glue surface over the previous one. Excluding the dovetail, even though the joint was well executed the ratio was a bit off for this test. Spacing the dovetails more like the box joint would have helped increasing its odds.
There are so many different joints because they all serve different purposes.
This. The dove tail needed at least as many tongs as the box joint to be compared like this.
The last sentence is the most important. Joints are meant to be strong at specific direction(s) and also handle twists, not just wait, and also to look nice.
Every single joint caused the glue to fail. His glue is the weak point in every single joint. He needs to try this with better glue to compare the difference in strength caused specifically by the joint.
@@caleb186 yeah but if thats the glue he uses regularly then it gives him an idea as to the items he builds. Plus many wood workers use titebond II
I’ve always been lead to believe glue works best when cured under pressure. It would be interesting to see, glue under pressure vs. not.
Dale Zimmerman of Franklin International, maker of Titebond woodworking glues, recommends 100 to 150 pounds per square inch (psi) for clamping softwoods and 175-250 psi for hardwoods.
I would like to add , that the type & quality of the adhesive is an important & major factor in determining the strength of the joint. On the other hand, your demonstration is very impressive. As always, thanks.
Awesome job thank you for sharing
That was extremely educational. I make mother joints all the time. I mostly put through dowels across the miter. That would be one to try. Oh and I use 1/4” dowels. I think that would be a good one for your next test. Great video as always
I love a good mother joint.
@@sirbrewzalot 😆
My ideas for a strong joints:
-The 45° angle with thicker splines (similar to a box joint). Reason: It appeared as if the splines were actually the weak point.
-Box joint but with a pin going through all of the pieces. The weak point of the box joint seemed to be the glue. So a pin should increase the strength by taking some of the load away. Another option would be to make the boxes narrower so the glued surface increases. That would of course combine well with the pin. If you want to be really fancy, you could try to reinforce that even more with some pocket hole screws. I think the possible strength of this is really just limited by the strength of the wood itself.
-The spline thing but with deeper cuts so the splines actually go into the inside a bit. Another fancy way of doing this eould be to have bent splines so you are not dealing with pulling the grains apart.
The most important ingredient of strength & Power , beyond any doubt , is ,definitely, Knowledge. Thanks always.
Perfectionism - starting from the beard - entangle every piece of workshop and work. As well as jokes. Admiring 🙏
I'd love to see this test done in the sheer/torsion direction - 90 degrees from how you had it. And see how the joints stack up there. Some might be better in that orientation.
The other great thing, you’re never going to be putting that kind of pressure on those joints at that kind of angle. But all around super surprising. I thought the miter would be SO much weaker!
By the way.... I love your video! You are funny and informative! Great combination. Thanks 😍
Nicely done. Very informative