Rob, I can't help it. The Engineer in me wants to know how long an end grain joint will last compared to a dovetail joint. Remember a glue joint is a chemical reaction that can be affected by time and temperature. I would suggest sending both of your example joints to Texas and let them stay in an attic for a year. My attic can hit 120F easily on most summer days. I know you have a friend in San Antonio who would probably be willing to help. If not, I would gladly do the experiment here in Austin.
Keep making stuff with old world craftsmanship joints, but for items used for shop space you always have the shortcuts. Its kinda no different then people swearing by pocket holes and screws. Most tradesmen use pocket hole joints because they are fast and stand up fairly well. But you won't see a pocket hole jig in my shop. Its a shortcut. I have a 16x7 garage door all wood but its finger jointed short pieces. The glue joints over the 22 years have failed on the finger joints I think had it all been 1/2 laps they would not have failed or the bottom Rail is 1 1/2 × 16' x4" if it had been made out of a stack or wood plywood and wood with stager joints it would still be a solid beam. But no over its 22 years it smiles from tension of the lift springs. The only reason it doesn't pull apart is the metal brace. One of these days i remake each panel out of better wood.
I have to agree with Rob that cleaning up squeeze out needs to be considered in all cases. There's few things worse than squeeze out glue that defies cleaning up, in how it affects the appearance of the piece after being finished. Perhaps you're better at glue clean up than I, though, but I just haven't had much luck, regardless of the various methodologies I've tried over the many years I've been doing this.
Excellent and useful video, Rob! I really appreciate how, as experienced as you are, you’re still able to be “blown away” by new evidence. You are a great craftsman with great character.
As a segmented woodturner I have always had to glue end grain to end grain to make my rings. Woodturners always thought the strength was in gluing the long grain of the rings together and using a brick lay pattern. Patrick's video demonstrated to me that my segmented bowls were very strong if the glue was applied correctly and the rings are flat. I shared his video with my woodturning friends because it just verified what we're doing on a segmented turning. With flat work the issues are different and you've done a great job of demonstrating the impact to your joinery. Thanks Rob!
It's really just a testament to how far glue technology has come over the years.. easy to forget how much chemistry and science has gone into these products.
No, hide glue is stronger than any of the glues we regularly use in woodworking, some of it is used to chip glass to make fancy designs, try that with titebond.
But dont be fooled by a scientific experiment tailored to get a result that bears no meaning on practical woodworking! . It doesnt matter how superior the wood glue is today, the lignum that bonds wood fibres together is the key factor in strength (demonstrated by Mr Sullivan) and centuries of wood jointing respect that overlapping/extending fibres give strength. Wood is not like metal.
I first encountered this phenomenon in 1970, when white glue was still commonly used in woodworking, even by professionals. Titebond glue was a revelation to me, as the breaking strength of the glue was so much higher than that of white glue. I bet that performing these tests with older glues will that end grain joints are indeed inherently weak, depending on the kind of glue used.
An interesting point, and that would make sense to be true. White glue is significantly different, and it may even be that the end grain wicked out the moisture from the glue so fast that it didn't properly polymerize as it set?
Funnily enough I started woodworking when I retired and made some cabinet drawers with glued rebated corners not knowing that this was not a thing to do. My drawers are still hanging together solidly so my estimated necessary rigidity for my drawers is now borne out scientifically. Thanks Rob, Stumpy and Patrick.
Rob, I always say that the best thing that can happen to me is to find out I have been wrong about something, because two wonderful things have happened. I have learned something new and I have been given the opportunity to stop being wrong. I love both. I watched all three of the other videos before I watched yours-I actually sent you an email about the issue. Other than the original, your was the most useful.
Thanks Rob, I watched Patrick's video and his reasoning made sense, the tests he did fortified the reasoning. You've added to it with real project application. Pretty cool.
Someone showed me years ago a wonderful trick for cleaning wet glue out of those tight corners. The opening of a regular plastic straw can be easily pressed tightly into the corner edge and scoops the glue out cleanly. When the opening fills up, snip the end off and repeat. A single straw will remove a lot of squeeze out glue.
Everyone's been talking about glue surface and wood properties, glue properties the science of wood joints. Throwing around terms like strong, stronger and strongest. Rob is the only woodworker to post a video checking on strong enough.
Just be careful of your first test with the dovetail and rabbet joint, if you hit the rabbit joint with a mallet (like the dado test) it does in fact fail. The dovetail does not. I was after something that was consistent so the test I performed was as follows: 1) Clamp the job to a post so that the part to be put under load is poking out. 2) Using two house bricks taped together drop them onto the section poking out as the same distance out from the job and at the same height (I used 8 ft). 3) Record results. My result may be slightly different to yours but you could very well find that the weakest joint is not the dado.
You are great Rob. You did this video, challenging yourself and investing your valuable time and materials. The Best of this, is that you did not do the video trying to "explain" Mr Sullivan's work. You earned my subscription Rob!
Another great response to Patrick's great video. If anything it just shows how lucky we are that we have the glues that we have that are stronger than the wood and it is just sitting on your shelf ready to be used whenever.
Rob, for me the critical problem is “TIME”. I’m Italian, in my home I have some 16th and 17th century pieces of furniture. Dovetails, dovetails and dovetails. Sometimes some rabbet or dados with forged nails. Do you think that in the centuries the rabbet joint that you tested can resists? Large pieces like these have a big tendency tu cup and no way for the glue joint. Dovetails last forever.
The benefit of dovetails is that they function even without glue. The rabbet lasts only until the glue fails, so it really just depends on how long we think the glue will hold before it becomes brittle and breaks.
@@nickglover exactly. Sincerely I have no idea how long glue can performs. I suppose it depends on the environment, moisture, exposure particular situation...a chest of drawers near a fireplace can be stressed a lot in the wintertime. UV is another important fact in some regions.
This whole knowledge of connecting the long grain end to the long grain end is actually incorporated into some Japanese joinery like a sleeve I think is the name of what I'm thinking of it's a long cut construction joint to connect two beams together then forced into each other with a wedge but it's connecting end to end and it's one of their strongest joints used in traditional construction edit:after thinking about it then finally just googling they use a ton of end to end joinery in traditional Japanese wood work they even have wats of turning a joint into ends touching ends when it doesn't have to be they go out if the way to join end grain I had never thought about it before. I know their whole culture and mindset in making anything is to use physics and nature to your advantage and work with it instead of fighting against those forces as we see it in the western world and those two different schools of thought are so obvious in everything we do honestly. I can help but look at some of their incredibly complex end to end joints and think God that's smart but it mimicks the tree itself by joint a long grain interlocking with another long grain then forcing them into each other as gravity would and giving them some flexibility you've mimicked the tree and maintained it's strength. We cut stuff apart then try to force it to have some strength again by glueing it to a strong piece we haven't cut through yet. We fight nature they use it.
Nice to see you make this video Rob....three of my favourite youtube woodworkers all giving comment and now a practical application test too.....best thing to see here?.....you still being able to be surprised by a result you in all honesty did not expect....a day with learning something is always a good day :)..weldone mate and thanks for taking the time to do this :)
Hey Rob, regarding glue cleanup from difficult places: a little bit of diluted shellack (or any other finish that is planned) on potential squeeze out areas will make cleanup a breeze. A plastic pick or something will make glue just pop off. The downside is a very careful application is required so that glue surfaces are not affected, but after a bit of practice padding some shellack is quick. Shellack is also easily removed, almost completely.
It always amazes me the way Rob attacks woodworking with the skill of a heart surgeon. I know tools can play a part, but his skill is the main tool in his arsenal.
I am with you if i didn't see it i wouldn't have believed those 2 joints could withstand that force of you standing on them. I am as stunned as you, tthey didn't even appear to flex at all. I know Dovetails are strong but the rabbet as well!?
Thanks Rob. A great video which wonderfully complements the videos from Stumpy Nubs and the Wood Whisperer. Between the three of you, you have covered the topic comprehensively.
As a Materials Engineer, I remain skeptical. In my opinion these one time static tests are only part of the equation. We need to assess this in a more comprehensive scenario by including cyclical racking and fatigue to see if the durability of these joints across the system of joints used in a piece is sufficient long term. Mechanical locking combined with glue surfaces of all types has the best chance of surviving long term use, wood movement, and the ubiquitous moving of furniture from room to room and house to truck to house over the course of generations. In the design of a piece use this knowledge appropriately by having critical joints absorb the racking forces with mechanical aid and other joints that typically do not see raking to use only glue surfaces (i.e. outside corners of a book shelf using dovetails and all the non-moving shelves using dados only). I am also one of those people who spends way too much time scraping glue out of my damn corners...
Of course you will also have to test several differnt types of glues. Looks like Rob is using something other than Titebond III which is very popular with many other woodworkers.
I like the application of his testing. Nice work! Patrick’s testing showed the end grain glue joint is a bit stronger than wood in its weakest direction. This gives a practical application of this. I have always glued end grain since it did add some strength and is easy to do. I was surprised with the results that it is stronger than I had assumed. As you indicate it doesn’t change most joinery methods but it’s good to see there is some change in applications and this bit of joining knowledge makes us all a little better.
Rob, thanks for sharing this important revelation with us. I think that it would be unrealistic to believe that the 1/4" deep dado joint could be as strong as the much more complete glueing surface of the rabbet joint. Very well done, Sir.
Mr. Sullivan blew up woodworkers youtube! This has been informative and entertaining. I think Mr. Sullivan has explained why scarf joints are so strong
That's what Luther said too!!!! I wont be throwing out dovetails for rabbets.....There is just something about the pleasure of cutting dovetails and the look of quality about them
Hi Rob I have great respect for you and now your willingness to adapt. I discovered your channel sometime maybe 2 years ago and without a double you have changed my woodworking skills more than any other one person. This video has gone most of the way to close the gap on the few things that I have disagreed with you about. 1) End Grain gluing 2) That two pieces of wood need to perfectly touch in order for a joint to succeed. I am not advocating poor workmanship. I am advocating that at the bottom of a joint if it hollows out a bit that that joint will actually hold better than a perfect joint. I know this sounds crazy but from some testing I have done in the past a joint with a small glue hollow will hold better than a perfect joint. There is another channel that did some glue experimenting that also seemed to agree with my theory. The primary reason I bring this up is your dovetail hollow, not that that joint needs more strength. Not asking you to prove me right or wrong or that you should change your practices. Thanks again for all that you have done for my skill level.
That rebate joint was a surprise. I was surprised as you Rob. I have restored antique and period furniture for 40 plus years and know that time is a big factor that is rarely factored into the equation of these tests. Can I suggest you retest the dovetail and rebate joints periodically over an extended period of time. Regards, Terry Gleeson. Sydney
I wonder if Patrick Sullivan realised when he uploaded that video what effect it would have. I’ll still be reinforcing my glue joints when dealing with end grain.
I suggest he is beginning to realize this as he states clearly and emphatically that end grain bonding is about twice as strong as side grain bonding (which is clearly click bait!) and then he and others now are trying to say he didnt actually mean this! How can a guy who is in a league of his own in filming and presenting such micro analysis in such a graphically convincing way , then say he may have confused some people? Thousands (who now think the experts are wrong)? His presentations are full of flaws and contradictions! But captivating viewing!!
Like most, I've always believed end grain glue joints to be weak. I think what Patrick's video (and the subsequent follow up videos such as yours), has emphasized is that a joint is only strong as it's weakest link. What's become apparent is that most of the time, It's not the end grain glue joint itself that's weak, it's the lignin bond that hold the fibers together. In cases where an end grain glue joint does fail, it's only because cross grain is incredibly strong.
Being a mechanical engineer I have to rise some doubts about the forces applied to the pieces with leverage and hits and loads. Sullivan used a more standard testing method that is the core of his research. I don't know if the two results could be comparable. After all, this video reason was different. I'll ease up things by doing the easiest joint next time and see how much it lasts. Anyway glues has improved a lot. Thanks to all the contributions on this task!
With the dado / housing: When cutting these by hand, you cut the sides, clean the middle, and refine with a router. If when cutting the sides, you go past the depth by even the smallest amount, then the bottom of the housing will be short pieces of face grain only as long as the width of the housing because of the fibers being scored along the length of the sides of the housing. Maybe this might be what is limiting the strength in your test? It looked like you had a clean line of torn out face grain fibers adhered to the end grain of the shelf...no ragged edges. That's what made me wonder if the bottom of the housing was really short (face) grain. The torque on the side walls was clearly enormous because it just pried off those pieces below the shelf. Thank you for sharing all these tests. Very interesting. I was sure that rabbeted corner would fail. I'll bet that if you do a pure tensile test on the housing, it is strong enough for tensile loads. The back of the cabinet could take care of the racking loads, perhaps?
One thing to consider with the rabbet joint though is that the glue is in the place where the wood will move seasonally. So if the glue doesn't flex it may separate from the wood itself, and that may cause the joint to fail earlier than the dovetail joint, which will stay strong longer since the way the glue is positioned moves way less.
Thank you very much, watching this video was a pleasure. It would be nice if you broke two similar-sized joints (rebate and dovetail) and compared their strength (simple lever and a water can works just fine for this).
I think it is very important to remember how pathetically rubbish wood glue used to be! If I had made that exact joint in my woodwork classes at school, it would have broken just by picking it up and shaking it. LOL So the wisdom of that era was correct and undisputed. But now with glue’s being stronger than the wood itself, it stands to reason that it can make a better joint than back then. How long that joint remains strong and reliable is to be seen, especially if you take into account environmental conditions and cycles of work or loading, and the position of the joint. I’d like to thank Mr Sullivan, Stumpy Nubs, The Wisperer and yourself Rob for all the videos and the integrity and character of all of you. For now at least I will still be reinforcing my joints or using dovetails.
This video is delightful. Everyone should be as open to new information and to empirical evidence. The thing I most appreciated, though, was the thoughtful analysis of the practical meaning - yes everyone has been wrong about end-grain glue strength, yes it has a few meaningful ramifications for actual work, but no it doesn't mean joinery is obsolete. When we learn, we adapt - we don't simply throw away what we've learned before. My takeaway from Mr. Sullivan's original video was "PVA glue is stronger than lignin but much weaker than wood grain. If maximum strength is needed (and due to leverage it often is), try to make a joint failure force a failure of the wood grain rather than accept a failure of the glue OR the lignin. That said, stop worrying so much about face grain vs. end grain for glue surfaces - that's not really what matters."
The dado joint (last piece in your video) is failing along fibers but not on fibers. The details are a matter of forces and its distribution inside the wood. That's part of stress calculation in direction of the fibers and perpendicular by an engineer. If you angle the glue surfaces to equalize stress along and perpendicular to the fibers proportional to the wood strength of both directions you're getting the maximum strength for a joint ... that's what makes finger joints so strong.
Rob, one idea. You should clamp(or fasten) the rabbet joint and the dovetail joint on the one side together and then apply force to the other arms until one of them breaks. I bet that will be the rabbet joint.
Yes, that would have been a far more accurate test. You could put a couple screws in that rabbit/rebate and no glue and on an angle like that it probably would give the same results. The forces on the joint surfaces at that angle, hold the boards up. We don't stand a cabinet or case on edge, but we do put weight at 90 degrees angle to the joint. Also, there are raking forces on the joint that standing on it doesn't really test.
Hey Rob. I actually make all my drawer boxes with that rabbit joint and they stay together forever. I have many draws that are 40 years old that haven’t moved at all.
The stresses and strains expected in furniture use are taken into consideration at the design stage. It is called joinery for good reason. All the main stresses are covered even if no glue was used at all. In most construction all the glue is needed for , is to provide enough strength to stop the joints coming apart. All the main tresses are carried by the wood alone. We have known for a long time that glue is usually stronger than the wood, what ever the direction of the grain. However there is no actual gain in this if the wood fails first. More important is choosing the right glue for the expected conditions. A beautiful veneered desk will soon delaminate if left out in the rain, or in a damp cellar. Not all glues are suitable for all purposes, and in the toughest conditions such as timber framing no glue is usually used at all. End grain to end grain is not something any one needs to use or even worry about very often and in most cases is best avoided. However commercially available timber and boards are now often spliced end to end. And are exceptionally strong.
I saw the Wood Whisperer's video, which was interesting and informative, and seeing your methodologies and explanations were just awesome as always! Interesting results, for sure.
The only question I have is, 'does the strength of the end-grain joints hold up the same after a few years when the glue has aged? Typically, after 25 years or so, glue deteriorates and starts to fail so the end-grain glue-ups would fail drastically whereby the dovetail ends would still hold fast after 25 years even if the glue deteriorates or even without glue sometimes. All this is good to know , thank you for showing this test.
The strength of the rabbit it's nice to know in a situation where you plan to paint. Dovetails or even finger joints would be a lot of work. To do if you don't need it and your painting over it anyway.
Rob, I was taught in gluing end grain, to first prime the end grain with glue. As end grains make up is as porous as it is, this technique allows the wood to absorb the initial glue. Wait a couple minutes after priming, then glue as you would ordinarily. This no doubt will strengthen even further the end grains ability to adhere to its mate. I've found this to be true more than expected. What are your thoughts?
Thanks for a sincere and through video. I'm impressed you are so thoughtful which faces get glue in a joint. A true master is in the details. It seems you'd have to intentionally not glue the end lap. Was there ever any reason not to glue it?
Hi Rob, this is an excellent "end" to Patrick's video then followed by The Whisperer, then Stumpy, then you. While Patrick's demonstration is to show that if glue is stronger than wood (long-grain seal), than glue is stronger than expected on end-grain wood. But, as Mark points out, Patrick's video doesn't say "don't do joinery," and Stumpy continued that thread. Where your video bumps the point by making and discussing that Joinery. However, (noticed that there's always a "however" after a compliment? :>)), I do take a small issue with your dado "shelf" joint test and conclusion. If you are working at impact force at an angle, I think that most joints will have issues. As you observed, once again in your test piece, the glue was stronger than the wood. But if that is going to be one side of a shelf, is that a fair test? About 35 years ago I made a "unit" to hold records, the stereo, a record player, books, etc. that wrapped over/around a desk. Since, at the time, I didn't know for beans about end-grain versus long-grain or proper joinery (etc.), I glued some home depot pine 1 x 12 boards at right angles. I did add 3 counter-sunk screws from the outside face into the (end-grain) boards mostly for keeping them in place for gluing. Each shelf is 24" wide and each shelf is holding about 180 vinyl phonograph albums. That's a LOT of weight on those shelves that are only (really) being held by glue and three screws. There is no joinery going on here at all. I should add that these shelves have had one major move and have gone through 3 major earthquakes (I live in Southern California). As far as your impact test. I suggest you try your hammer on your rabbet joint and maybe even your dovetail joint and see how they hold up. Alternatively, attache/clamp a cleat on the backside so you can safely stand on that shelf and see if you can do the non-impact "stand" test on it. My money says that it should be able to support your weight as did the corner joints. Meanwhile, I do love your work and your teaching technique and approaches. Continue to do your wonderful work.
A demonstration of end grain glue strength is very interesting and something to pay attention too, but it really should not change the way a craftsman approaches their woodworking very much at all. Those through mortise and tenon joints being considered for elimination in favor of a simple glued dado are part of the Rob Cosman mystique, not everyone can do those joints. Love your work, love and respect the PHP, thank you for staying on UA-cam. May you and your loved ones receive many blessings.
I think the impact test on the dado probably induced more forces than any normal piece of woodwork would suffer in regular use, plus how many completely cantilevered parts do you see. Of course, all of the joints are brand new and haven't flexed with seasonal movement over years which would surely stress the end glue joints.
Prime the end grain first with glue. Wait til it's been just absorbed, then glue as you normally would. This will guaranteed make even more of a difference, especially with the dado. david
I have watched all of the videos and yours by far is the most comprehensive with real world aplications. While I am just as suprised as you and everyone else about the rabbet. I am curious as to the racking strength, if a carcas were to be assembled with these joints. Obviously most cases gets some strength from either shelves or a static back. But dovetail corners can keep the carcas square with out relying on these. I would like to see an assembled carcas with rabet joints and just have someone sit on it and move side to side a bit.
The carcass gets ALL of it's "racking" strength from the back, not the corner joints. That's why backs are fitted onto furniture, even though they are hidden.
@@johncoops6897 But dovetails give mechanical racking strength with out the back, that is my point. There are examples of light weight furniture that do not have backs. These pieces my also derive strength from a dadoed shelf. Thus the toe nailed nail that was discussed. However if the endgrain glueing of the shelf removes the need for the toenail then hazaaah. But dovetails can prevent racking with out the additional components, just sayin.
@@charlesagby6662 - the glue cannot make tbe joint stronger than the material itself. So it is still important to consider the stresses that are applied to any joint and design accordingly. The point of Patrick's tests is not that the glue suddenly makes all such design decisions instantly irrelevant, but rather that adding (suitable) glue will add much more strength than (some ignorant) woodworkers think.
@@charlesagby6662 - I must clarify... the point is that if there is no triangulation (back fitted) and the end product will be subject to racking forces, then you need a VERY inherently strong corner joint like a dovetail. However if there is a back fitted that will add FAR more racking strength than any dovetail joint, the the corners will only need to be glued butt joints. So, its about applying the (new) knowledge properly, rather thsn ignoring it and using dovetails everywhere just because certain elite woodworkers said they are better.
Great video to add to the analysis by showing practical implications. I dont think this will be a game changer, but it may change how we play some matches. Loved those ultra thin half blinds.
As always, a great video presentation. The proof is in the demonstrations and those were great. Having personally committed the error of moving large bookshelves around on the floor, fully loaded with books (I'm talking about 3 ft. wide x 5 ft. high x 11 1/2 deep ones) by pulling them around I have wonder if doing what is shown at time stamp 27:46 would actually work long term. My intuition says repeated moves like that might cause things to come apart. Removing books first would most likely be the best thing to do before moving such a case. But I do think the demonstration where standing on the rabbet and dovetail joined examples was really something. I do think the tensile strength in a stationary wall mounted cabinet fully loaded ceramic dishes would work, but I'm not sure I'd want to test it on a wall-mounted cabinet fully loaded with famiy heirlooms 😀As always, thanks for the great ideas. The videography and demonstrations are so great they're worth watching just for the entertainment alone! Many thanks to you and all those involved in the production of these and all the best to you, yours and the team.
I think standing on the joint puts less pressure on glue and more on the woods fibers. I think putting weights only on one board will show the glue's strength vs the wood fibers.
If I glue endgrain to longgrain or endgrain to endgrain, I wouldn't worry about the strength of the glue joint since it's often stronger than the wood. BUT I would worry about wood movement and long-term stability. If the glue fails at some point in the future due to repeated wood movement or repeated stress, a tenon will keep the loose parts in place that would otherwise fall apart. Or am I missing something?
Rob, your comment is needed about glueing up the full length of the dado. In my work I only glue the first third of the dado, which allows the back two-thirds to move (as wood does). What are your thoughts here? One might argue that the grain direction of the two pieces is consistent, and they could move in a similar way. Or do they? Regards from Perth, Derek
I can’t help but wonder if the concern over endgrain glueing might have had to do with older kinds of glue. For instance, maybe hide glue didnt preform well. The glues we use today are pretty amazing concoctions.
I think the main problems with the shelve is the leverage you used and the way the dado is cut. You're very likely to cut the dado deeper on the sides than the middle, leaving only a very short piece of long grain attached to the upright board. The most likely failure of a bookcase is when the shelves are so loaded they either sag so much they pull inside, or there's so many books stuffed on the shelves they wedge the sides apart. Just gluing end to long will not be strong enough for those scenarios, but dado's or shelve supports will prevent a large part of those failures. Besides, you usually have 2 sides supported, making the leverage issue non-existent.
Rob, one thing to consider is the glue will fail with time. 100 years from now the glued only joint verse the dovetailed or locked mortise joint the glued only will be more likely to fail because the glue will become brittle. Well at least that has been my experience with glue that is only 20 years old. What are your thought when you consider long term results of a glue only joint?
@@RobCosmanWoodworking my big question is will time and changes in climate affect change the results? Will those glue joints be just as strong in 100 years.
my experience has been with glue drying out over a period of years along with wood movement. a year or 2 with but joints and up to 5 to 10 years for mortise joints. but with a mortise joint there is the mechanical connection.
I always reinforce my mitered picture frames with V nails but the glue joints are of course, all end grain. In my experience they have bee surprisingly strong. I also glue up pocket hole joints and have noticed the are much stronger.
Wow. I'm really, really impressed, @RobCosman.com. That's one of the most difficult character traits for a human to espouse: "When a rational man is faced with new data and he actually allows it to change his mind/position." One of the fundamental tenets of the Scientific Method is just that: when presented with novel, verifiable, peer-reviewed information that partially or entirely conflicts with the accepted understanding, it is incumbent upon we, as men of science, to adjust our position, even when it flies in the face of everything we have hitherto known or understood. This is, as one might (correctly) surmise, extremely difficult for many/most (all?) people. Imagine the reaction of a staunch atheist in the presence of a god, a born-and-raised Flat-Earther looking out the porthole of a shuttle, a lifelong devotee of Budweiser trying a real beer for the first time... huge, fundamental worldview shifts that rock ones foundations to their core (that burning smell is that of a paradigm shifting without the use of a clutch). It is to Rob's great credit that, although surprised, he calmly reflects on the impact and gravitas, then, with equal aplomb, simply shrugs, smiles, incorporates the upheaval into his greater understanding... and gets back to the bench. ...I don't know there's a more admirable quality in a human being.
But still I just wondering that how good the end grain glue join is in the long run, when the grains straws swells and shrink in seasons, but the glue wont? How good is that end grain joint is after 2 years or 10 years?
Thanks Rob and I agree Patrick did a good job. When we make something we hope it will last, and many of the early craftsman made things with nails that have lasted more than there life span. It may be that the glue will out last the wood, but it will never replace the beauty of your wedged mortis and tenon joints (or even mine and they don't look as good as yours). This year I will try to make a couple of jewellery boxes for my grand daughters 21st birthdays. I have little little hope of being there for the party but I hope they may see in the simplicity of my efforts a small part of what I have seen you and Patrick make. Some time ago Patrick made a Keep Sake box and alto I could not make anything as beautiful I did make a more simple box that will last for a life time the thoughts were Patrick's and the dove tails were yours. Please don't tell the grand children. A big thank you to James at Stumpy Nubs and thank you Patrick and Rob
I’ve now seen all four videos, starting with Patrick Sullivan and found them all very interesting. As my French daughter in law has taught me, each time I have gone to bed less stupid 🌞
Perhaps we should not forget that scarf joints do exist. Patrick's video was excellent, but many people have missed the point somewhat. In Patrick's data, what really mattered wasn't comparing the side grain to end grain glue joints, but rather the end grain glue joint to no joint at all.
What I'm curious about is how an end grain glue-up would hold up using hide glue. The "myth" has been around a very long time, but PVA glue is more recent and it makes me think the myth may have been true when earlier glue technology was commonly used.
I wonder how many people have thought about glue-sizing the end grain (literally pushing glue into the end grain) and seeing if that might improve the joint strength even further?
It simply means the glue is stronger than the wood resin but weaker than long grain so it doesn’t change much really. A proper joint is still always stronger than end grain glue joint period. No problems gluing m&ts with squeeze out. Using pva I just clean up with a damp cloth then use ply strips with 240 grit glued to them to clean up when dry.
People rushing out crazy do not fully understand what was tested and what was not. It was only about glue vs grain direction. No mechanical joints were tested, but he said more tests are coming. I never rely on glue for strength but on mechanical joints. I have never used butt joint with glue for structural pieces.
Another good video as always Rob! I have a question that would to hear your response to. The other day I was watching “Blacktail Studio”. He was talking about glueing up some walnut/black walnut up with “Tite 3” that several people have told him not to use Tite Bond 3 or Tite Bound 2 on walnut! I have never heard anything like the but I seem it might have been “Franklin Glue Company or even Tite Bond glue themselves. Can you please comment on any of the above as to what you would do about the information I relayed? Thank you in advance for your time and any information you may provide. Sincerely, Ron Hatcher
If you have not seen the other videos on this subject the links are in the description section of this video.
Rob, I can't help it. The Engineer in me wants to know how long an end grain joint will last compared to a dovetail joint. Remember a glue joint is a chemical reaction that can be affected by time and temperature. I would suggest sending both of your example joints to Texas and let them stay in an attic for a year. My attic can hit 120F easily on most summer days. I know you have a friend in San Antonio who would probably be willing to help. If not, I would gladly do the experiment here in Austin.
Great idea
end grain gluing for the win.
Keep making stuff with old world craftsmanship joints, but for items used for shop space you always have the shortcuts.
Its kinda no different then people swearing by pocket holes and screws. Most tradesmen use pocket hole joints because they are fast and stand up fairly well.
But you won't see a pocket hole jig in my shop. Its a shortcut.
I have a 16x7 garage door all wood but its finger jointed short pieces.
The glue joints over the 22 years have failed on the finger joints
I think had it all been 1/2 laps they would not have failed or the bottom
Rail is 1 1/2 × 16' x4" if it had been made out of a stack or wood plywood and wood with stager joints it would still be a solid beam.
But no over its 22 years it smiles from tension of the lift springs.
The only reason it doesn't pull apart is the metal brace.
One of these days i remake each panel out of better wood.
Very interesting! My methodology, whenever using glue, has always been that any surfaces that touch should get glue on them. 👍
In most cases I agree with you
I have to agree with Rob that cleaning up squeeze out needs to be considered in all cases. There's few things worse than squeeze out glue that defies cleaning up, in how it affects the appearance of the piece after being finished. Perhaps you're better at glue clean up than I, though, but I just haven't had much luck, regardless of the various methodologies I've tried over the many years I've been doing this.
@@ApexWoodworks Clean up can be a pain, yes!
Excellent and useful video, Rob! I really appreciate how, as experienced as you are, you’re still able to be “blown away” by new evidence. You are a great craftsman with great character.
Life long learner - right? Thanks for the comment
When the teacher is willing to become the student it shows tremendous quality in character. Thanks Rob.
I also love how after all his decades of experience, he still gets excited and amused by new discoveries.
As a segmented woodturner I have always had to glue end grain to end grain to make my rings. Woodturners always thought the strength was in gluing the long grain of the rings together and using a brick lay pattern. Patrick's video demonstrated to me that my segmented bowls were very strong if the glue was applied correctly and the rings are flat. I shared his video with my woodturning friends because it just verified what we're doing on a segmented turning. With flat work the issues are different and you've done a great job of demonstrating the impact to your joinery. Thanks Rob!
It's really just a testament to how far glue technology has come over the years.. easy to forget how much chemistry and science has gone into these products.
No, hide glue is stronger than any of the glues we regularly use in woodworking, some of it is used to chip glass to make fancy designs, try that with titebond.
But dont be fooled by a scientific experiment tailored to get a result that bears no meaning on practical woodworking! . It doesnt matter how superior the wood glue is today, the lignum that bonds wood fibres together is the key factor in strength (demonstrated by Mr Sullivan) and centuries of wood jointing respect that overlapping/extending fibres give strength. Wood is not like metal.
I first encountered this phenomenon in 1970, when white glue was still commonly used in woodworking, even by professionals. Titebond glue was a revelation to me, as the breaking strength of the glue was so much higher than that of white glue. I bet that performing these tests with older glues will that end grain joints are indeed inherently weak, depending on the kind of glue used.
An interesting point, and that would make sense to be true.
White glue is significantly different, and it may even be that the end grain wicked out the moisture from the glue so fast that it didn't properly polymerize as it set?
Funnily enough I started woodworking when I retired and made some cabinet drawers with glued rebated corners not knowing that this was not a thing to do. My drawers are still hanging together solidly so my estimated necessary rigidity for my drawers is now borne out scientifically. Thanks Rob, Stumpy and Patrick.
Thanks....how old is that joint that is still holding up?
Rob, I always say that the best thing that can happen to me is to find out I have been wrong about something, because two wonderful things have happened. I have learned something new and I have been given the opportunity to stop being wrong. I love both.
I watched all three of the other videos before I watched yours-I actually sent you an email about the issue. Other than the original, your was the most useful.
Wow. Thanks. I love your philosophy
Thanks Rob, I watched Patrick's video and his reasoning made sense, the tests he did fortified the reasoning. You've added to it with real project application. Pretty cool.
That was my goal. Glad you liked it
Someone showed me years ago a wonderful trick for cleaning wet glue out of those tight corners. The opening of a regular plastic straw can be easily pressed tightly into the corner edge and scoops the glue out cleanly. When the opening fills up, snip the end off and repeat. A single straw will remove a lot of squeeze out glue.
Everyone's been talking about glue surface and wood properties, glue properties the science of wood joints. Throwing around terms like strong, stronger and strongest. Rob is the only woodworker to post a video checking on strong enough.
Just be careful of your first test with the dovetail and rabbet joint, if you hit the rabbit joint with a mallet (like the dado test) it does in fact fail. The dovetail does not.
I was after something that was consistent so the test I performed was as follows:
1) Clamp the job to a post so that the part to be put under load is poking out.
2) Using two house bricks taped together drop them onto the section poking out as the same distance out from the job and at the same height (I used 8 ft).
3) Record results.
My result may be slightly different to yours but you could very well find that the weakest joint is not the dado.
You are great Rob. You did this video, challenging yourself and investing your valuable time and materials. The Best of this, is that you did not do the video trying to "explain" Mr Sullivan's work. You earned my subscription Rob!
Another great response to Patrick's great video. If anything it just shows how lucky we are that we have the glues that we have that are stronger than the wood and it is just sitting on your shelf ready to be used whenever.
Yes I am so glad the only option is just hide glue!
The fact you give a fair thought is what I really apreciate, old habits or ways we use to work are hard to disregard or change, nice done Rob!
Thanks, I really didn't expect the rabbet to hold. I would have bet anything it would have broken under my weight
Rob, for me the critical problem is “TIME”. I’m Italian, in my home I have some 16th and 17th century pieces of furniture. Dovetails, dovetails and dovetails. Sometimes some rabbet or dados with forged nails. Do you think that in the centuries the rabbet joint that you tested can resists? Large pieces like these have a big tendency tu cup and no way for the glue joint. Dovetails last forever.
Well I will still be using dovetails in my carcasses. I will now just put glue on some end grain to gain extra strentgh
This was my thought too.
The benefit of dovetails is that they function even without glue. The rabbet lasts only until the glue fails, so it really just depends on how long we think the glue will hold before it becomes brittle and breaks.
@@nickglover exactly. Sincerely I have no idea how long glue can performs. I suppose it depends on the environment, moisture, exposure particular situation...a chest of drawers near a fireplace can be stressed a lot in the wintertime. UV is another important fact in some regions.
This whole knowledge of connecting the long grain end to the long grain end is actually incorporated into some Japanese joinery like a sleeve I think is the name of what I'm thinking of it's a long cut construction joint to connect two beams together then forced into each other with a wedge but it's connecting end to end and it's one of their strongest joints used in traditional construction edit:after thinking about it then finally just googling they use a ton of end to end joinery in traditional Japanese wood work they even have wats of turning a joint into ends touching ends when it doesn't have to be they go out if the way to join end grain I had never thought about it before. I know their whole culture and mindset in making anything is to use physics and nature to your advantage and work with it instead of fighting against those forces as we see it in the western world and those two different schools of thought are so obvious in everything we do honestly. I can help but look at some of their incredibly complex end to end joints and think God that's smart but it mimicks the tree itself by joint a long grain interlocking with another long grain then forcing them into each other as gravity would and giving them some flexibility you've mimicked the tree and maintained it's strength. We cut stuff apart then try to force it to have some strength again by glueing it to a strong piece we haven't cut through yet. We fight nature they use it.
Nice to see you make this video Rob....three of my favourite youtube woodworkers all giving comment and now a practical application test too.....best thing to see here?.....you still being able to be surprised by a result you in all honesty did not expect....a day with learning something is always a good day :)..weldone mate and thanks for taking the time to do this :)
Thank you for watching and commenting
Hey Rob, regarding glue cleanup from difficult places: a little bit of diluted shellack (or any other finish that is planned) on potential squeeze out areas will make cleanup a breeze. A plastic pick or something will make glue just pop off. The downside is a very careful application is required so that glue surfaces are not affected, but after a bit of practice padding some shellack is quick. Shellack is also easily removed, almost completely.
What I most like about your videos is that you are one of the most real-world woodworkers if not the most of any on UA-cam.
Wow thanks so much. Thats where I want to be
It's an old tale, based on older glues. Modern PVA glues are exceptionally strong on end grain.
It always amazes me the way Rob attacks woodworking with the skill of a heart surgeon.
I know tools can play a part, but his skill is the main tool in his arsenal.
I am with you if i didn't see it i wouldn't have believed those 2 joints could withstand that force of you standing on them. I am as stunned as you, tthey didn't even appear to flex at all. I know Dovetails are strong but the rabbet as well!?
"Almost speechless" is not a term I've heard you use before. Great demonstration Rob, thanks.
Thanks Rob. A great video which wonderfully complements the videos from Stumpy Nubs and the Wood Whisperer. Between the three of you, you have covered the topic comprehensively.
Yes I think so too. I was a little worried about piling on, but I think mine was different enough to be additive verses repetitive
Thanks Rob, I had watched all the other videos earlier but I admire your honest, unbiased demonstration on practical applications.
Thanks Stan and thanks for the comment
As a Materials Engineer, I remain skeptical. In my opinion these one time static tests are only part of the equation. We need to assess this in a more comprehensive scenario by including cyclical racking and fatigue to see if the durability of these joints across the system of joints used in a piece is sufficient long term. Mechanical locking combined with glue surfaces of all types has the best chance of surviving long term use, wood movement, and the ubiquitous moving of furniture from room to room and house to truck to house over the course of generations. In the design of a piece use this knowledge appropriately by having critical joints absorb the racking forces with mechanical aid and other joints that typically do not see raking to use only glue surfaces (i.e. outside corners of a book shelf using dovetails and all the non-moving shelves using dados only). I am also one of those people who spends way too much time scraping glue out of my damn corners...
Sounds like you are the right guy to do all that testing and it would be interesting to see the results
"I am also one of those people who spends way too much time scraping glue out of my damn corners..."
What about masking tape?
Of course you will also have to test several differnt types of glues. Looks like Rob is using something other than Titebond III which is very popular with many other woodworkers.
You better get working on it. Cant wait to see the video
I like the application of his testing. Nice work!
Patrick’s testing showed the end grain glue joint is a bit stronger than wood in its weakest direction. This gives a practical application of this. I have always glued end grain since it did add some strength and is easy to do. I was surprised with the results that it is stronger than I had assumed. As you indicate it doesn’t change most joinery methods but it’s good to see there is some change in applications and this bit of joining knowledge makes us all a little better.
Rob, thanks for sharing this important revelation with us. I think that it would be unrealistic to believe that the 1/4" deep dado joint could be as strong as the much more complete glueing surface of the rabbet joint. Very well done, Sir.
I have to wonder if a 1/2” or even 3/8” deep dado would make a difference. If you look at his rabbet, it was effectively at least 1/2” deep.
Mr. Sullivan blew up woodworkers youtube! This has been informative and entertaining. I think Mr. Sullivan has explained why scarf joints are so strong
Thanks for the comment
All that time wasted learning how to cut dovetail joints.... seriously cracking video Rob, very informative and real world applications. Many thanks.
That's what Luther said too!!!! I wont be throwing out dovetails for rabbets.....There is just something about the pleasure of cutting dovetails and the look of quality about them
Hi Rob
I have great respect for you and now your willingness to adapt. I discovered your channel sometime maybe 2 years ago and without a double you have changed my woodworking skills more than any other one person. This video has gone most of the way to close the gap on the few things that I have disagreed with you about.
1) End Grain gluing
2) That two pieces of wood need to perfectly touch in order for a joint to succeed.
I am not advocating poor workmanship. I am advocating that at the bottom of a joint if it hollows out a bit that that joint will actually hold better than a perfect joint.
I know this sounds crazy but from some testing I have done in the past a joint with a small glue hollow will hold better than a perfect joint.
There is another channel that did some glue experimenting that also seemed to agree with my theory.
The primary reason I bring this up is your dovetail hollow, not that that joint needs more strength.
Not asking you to prove me right or wrong or that you should change your practices.
Thanks again for all that you have done for my skill level.
That rebate joint was a surprise. I was surprised as you Rob. I have restored antique and period furniture for 40 plus years and know that time is a big factor that is rarely factored into the equation of these tests. Can I suggest you retest the dovetail and rebate joints periodically over an extended period of time. Regards, Terry Gleeson. Sydney
Keep those around the shop for the next 30 years and keep testing them??? I am not that committed...Besides I am not giving up dovetails
I wonder if Patrick Sullivan realised when he uploaded that video what effect it would have. I’ll still be reinforcing my glue joints when dealing with end grain.
Interesting question, my guess is no, but its all good and we have all learned a lot.
I suggest he is beginning to realize this as he states clearly and emphatically that end grain bonding is about twice as strong as side grain bonding (which is clearly click bait!) and then he and others now are trying to say he didnt actually mean this! How can a guy who is in a league of his own in filming and presenting such micro analysis in such a graphically convincing way , then say he may have confused some people? Thousands (who now think the experts are wrong)? His presentations are full of flaws and contradictions! But captivating viewing!!
Like most, I've always believed end grain glue joints to be weak. I think what Patrick's video (and the subsequent follow up videos such as yours), has emphasized is that a joint is only strong as it's weakest link. What's become apparent is that most of the time, It's not the end grain glue joint itself that's weak, it's the lignin bond that hold the fibers together. In cases where an end grain glue joint does fail, it's only because cross grain is incredibly strong.
Being a mechanical engineer I have to rise some doubts about the forces applied to the pieces with leverage and hits and loads. Sullivan used a more standard testing method that is the core of his research. I don't know if the two results could be comparable. After all, this video reason was different. I'll ease up things by doing the easiest joint next time and see how much it lasts. Anyway glues has improved a lot. Thanks to all the contributions on this task!
I was more interested in “real world” happenings that my furniture would endure. Blunt force would be a big part of that.
With the dado / housing: When cutting these by hand, you cut the sides, clean the middle, and refine with a router. If when cutting the sides, you go past the depth by even the smallest amount, then the bottom of the housing will be short pieces of face grain only as long as the width of the housing because of the fibers being scored along the length of the sides of the housing. Maybe this might be what is limiting the strength in your test? It looked like you had a clean line of torn out face grain fibers adhered to the end grain of the shelf...no ragged edges. That's what made me wonder if the bottom of the housing was really short (face) grain. The torque on the side walls was clearly enormous because it just pried off those pieces below the shelf. Thank you for sharing all these tests. Very interesting. I was sure that rabbeted corner would fail. I'll bet that if you do a pure tensile test on the housing, it is strong enough for tensile loads. The back of the cabinet could take care of the racking loads, perhaps?
One thing to consider with the rabbet joint though is that the glue is in the place where the wood will move seasonally. So if the glue doesn't flex it may separate from the wood itself, and that may cause the joint to fail earlier than the dovetail joint, which will stay strong longer since the way the glue is positioned moves way less.
Add this to the most shocked I've ever been.
You stood on those 2 corners, and I thought for sure you would break the Non-Dovetail one.
Holy crap
I absolutely thought it would break
Why? I thought that the dovetail would break, since the "pins" are much smaller.
Thank you very much, watching this video was a pleasure.
It would be nice if you broke two similar-sized joints (rebate and dovetail) and compared their strength (simple lever and a water can works just fine for this).
I always respect experts, especially in industries with literally ancient wisdom that works, willing to try something different.
You have to be open to new ideas
I think it is very important to remember how pathetically rubbish wood glue used to be!
If I had made that exact joint in my woodwork classes at school, it would have broken just by picking it up and shaking it. LOL
So the wisdom of that era was correct and undisputed. But now with glue’s being stronger than the wood itself, it stands to reason that it can make a better joint than back then.
How long that joint remains strong and reliable is to be seen, especially if you take into account environmental conditions and cycles of work or loading, and the position of the joint.
I’d like to thank Mr Sullivan, Stumpy Nubs, The Wisperer and yourself Rob for all the videos and the integrity and character of all of you.
For now at least I will still be reinforcing my joints or using dovetails.
This video is delightful. Everyone should be as open to new information and to empirical evidence. The thing I most appreciated, though, was the thoughtful analysis of the practical meaning - yes everyone has been wrong about end-grain glue strength, yes it has a few meaningful ramifications for actual work, but no it doesn't mean joinery is obsolete. When we learn, we adapt - we don't simply throw away what we've learned before.
My takeaway from Mr. Sullivan's original video was "PVA glue is stronger than lignin but much weaker than wood grain. If maximum strength is needed (and due to leverage it often is), try to make a joint failure force a failure of the wood grain rather than accept a failure of the glue OR the lignin. That said, stop worrying so much about face grain vs. end grain for glue surfaces - that's not really what matters."
great comment, thanks
The dado joint (last piece in your video) is failing along fibers but not on fibers. The details are a matter of forces and its distribution inside the wood. That's part of stress calculation in direction of the fibers and perpendicular by an engineer. If you angle the glue surfaces to equalize stress along and perpendicular to the fibers proportional to the wood strength of both directions you're getting the maximum strength for a joint ... that's what makes finger joints so strong.
Rob, one idea. You should clamp(or fasten) the rabbet joint and the dovetail joint on the one side together and then apply force to the other arms until one of them breaks. I bet that will be the rabbet joint.
To tell you the truth, as amazing as this sounds, when I was standing on them the dovetails felt weaker!!!!!!
Yes, that would have been a far more accurate test. You could put a couple screws in that rabbit/rebate and no glue and on an angle like that it probably would give the same results. The forces on the joint surfaces at that angle, hold the boards up. We don't stand a cabinet or case on edge, but we do put weight at 90 degrees angle to the joint. Also, there are raking forces on the joint that standing on it doesn't really test.
Squeeze out is easy to get around. i always put painters tape at the joint. When it dries a bit, you peel off the tape and there is no clean up.
great video.
Try keying or cutting into the joint contact to make them stronger
Thanks for watching and commenting
Hey Rob. I actually make all my drawer boxes with that rabbit joint and they stay together forever. I have many draws that are 40 years old that haven’t moved at all.
Thnaks for that info. Lots of folks wondering if the rabbet would hold up over time...I think you just answered the question
Another useful and enjoyable video. It was intriguing to see you gobsmacked at the end.
The stresses and strains expected in furniture use are taken into consideration at the design stage. It is called joinery for good reason. All the main stresses are covered even if no glue was used at all. In most construction all the glue is needed for , is to provide enough strength to stop the joints coming apart. All the main tresses are carried by the wood alone.
We have known for a long time that glue is usually stronger than the wood, what ever the direction of the grain. However there is no actual gain in this if the wood fails first.
More important is choosing the right glue for the expected conditions. A beautiful veneered desk will soon delaminate if left out in the rain, or in a damp cellar.
Not all glues are suitable for all purposes, and in the toughest conditions such as timber framing no glue is usually used at all.
End grain to end grain is not something any one needs to use or even worry about very often and in most cases is best avoided.
However commercially available timber and boards are now often spliced end to end. And are exceptionally strong.
That was completely unexpected!
Excellent on many levels. Thanks. 👍
I saw the Wood Whisperer's video, which was interesting and informative, and seeing your methodologies and explanations were just awesome as always! Interesting results, for sure.
Awesome, thank you!
The only question I have is, 'does the strength of the end-grain joints hold up the same after a few years when the glue has aged? Typically, after 25 years or so, glue deteriorates and starts to fail so the end-grain glue-ups would fail drastically whereby the dovetail ends would still hold fast after 25 years even if the glue deteriorates or even without glue sometimes. All this is good to know , thank you for showing this test.
Yes that's a really good question. Someone should test that
Love it. Thank you Rob.
The strength of the rabbit it's nice to know in a situation where you plan to paint. Dovetails or even finger joints would be a lot of work. To do if you don't need it and your painting over it anyway.
If I am painting over it glue it, screw it paint it. I dont use paint
Rob,
I was taught in gluing end grain, to first prime the end grain with glue. As end grains make up is as porous as it is, this technique allows the wood to absorb the initial glue. Wait a couple minutes after priming, then glue as you would ordinarily. This no doubt will strengthen even further the end grains ability to adhere to its mate. I've found this to be true more than expected. What are your thoughts?
Thanks for a sincere and through video.
I'm impressed you are so thoughtful which faces get glue in a joint. A true master is in the details.
It seems you'd have to intentionally not glue the end lap. Was there ever any reason not to glue it?
I really enjoyed this video. Very informative. A big thanks to Patrick and yourself for an eye-opening tests.👍❤
glad you found it useful
Hi Rob, this is an excellent "end" to Patrick's video then followed by The Whisperer, then Stumpy, then you. While Patrick's demonstration is to show that if glue is stronger than wood (long-grain seal), than glue is stronger than expected on end-grain wood. But, as Mark points out, Patrick's video doesn't say "don't do joinery," and Stumpy continued that thread. Where your video bumps the point by making and discussing that Joinery.
However, (noticed that there's always a "however" after a compliment? :>)), I do take a small issue with your dado "shelf" joint test and conclusion. If you are working at impact force at an angle, I think that most joints will have issues. As you observed, once again in your test piece, the glue was stronger than the wood. But if that is going to be one side of a shelf, is that a fair test? About 35 years ago I made a "unit" to hold records, the stereo, a record player, books, etc. that wrapped over/around a desk. Since, at the time, I didn't know for beans about end-grain versus long-grain or proper joinery (etc.), I glued some home depot pine 1 x 12 boards at right angles. I did add 3 counter-sunk screws from the outside face into the (end-grain) boards mostly for keeping them in place for gluing. Each shelf is 24" wide and each shelf is holding about 180 vinyl phonograph albums. That's a LOT of weight on those shelves that are only (really) being held by glue and three screws. There is no joinery going on here at all. I should add that these shelves have had one major move and have gone through 3 major earthquakes (I live in Southern California).
As far as your impact test. I suggest you try your hammer on your rabbet joint and maybe even your dovetail joint and see how they hold up. Alternatively, attache/clamp a cleat on the backside so you can safely stand on that shelf and see if you can do the non-impact "stand" test on it. My money says that it should be able to support your weight as did the corner joints.
Meanwhile, I do love your work and your teaching technique and approaches. Continue to do your wonderful work.
A demonstration of end grain glue strength is very interesting and something to pay attention too, but it really should not change the way a craftsman approaches their woodworking very much at all.
Those through mortise and tenon joints being considered for elimination in favor of a simple glued dado are part of the Rob Cosman mystique, not everyone can do those joints.
Love your work, love and respect the PHP, thank you for staying on UA-cam.
May you and your loved ones receive many blessings.
Thank you so much. As long as you keep watching we will keep filming
Rob did you ever try to rip a cut up the side of the tenon allowing you to glue both sides with a relief space as well .
Rob I love your content. I really love your tools. Thank you!
I think the impact test on the dado probably induced more forces than any normal piece of woodwork would suffer in regular use, plus how many completely cantilevered parts do you see.
Of course, all of the joints are brand new and haven't flexed with seasonal movement over years which would surely stress the end glue joints.
Prime the end grain first with glue. Wait til it's been just absorbed, then glue as you normally would. This will guaranteed make even more of a difference, especially with the dado. david
I have watched all of the videos and yours by far is the most comprehensive with real world aplications. While I am just as suprised as you and everyone else about the rabbet. I am curious as to the racking strength, if a carcas were to be assembled with these joints. Obviously most cases gets some strength from either shelves or a static back. But dovetail corners can keep the carcas square with out relying on these. I would like to see an assembled carcas with rabet joints and just have someone sit on it and move side to side a bit.
Good point. And dovetails and mechanical strength the rabbet does not
The carcass gets ALL of it's "racking" strength from the back, not the corner joints. That's why backs are fitted onto furniture, even though they are hidden.
@@johncoops6897 But dovetails give mechanical racking strength with out the back, that is my point. There are examples of light weight furniture that do not have backs. These pieces my also derive strength from a dadoed shelf. Thus the toe nailed nail that was discussed. However if the endgrain glueing of the shelf removes the need for the toenail then hazaaah. But dovetails can prevent racking with out the additional components, just sayin.
@@charlesagby6662 - the glue cannot make tbe joint stronger than the material itself. So it is still important to consider the stresses that are applied to any joint and design accordingly. The point of Patrick's tests is not that the glue suddenly makes all such design decisions instantly irrelevant, but rather that adding (suitable) glue will add much more strength than (some ignorant) woodworkers think.
@@charlesagby6662 - I must clarify... the point is that if there is no triangulation (back fitted) and the end product will be subject to racking forces, then you need a VERY inherently strong corner joint like a dovetail.
However if there is a back fitted that will add FAR more racking strength than any dovetail joint, the the corners will only need to be glued butt joints. So, its about applying the (new) knowledge properly, rather thsn ignoring it and using dovetails everywhere just because certain elite woodworkers said they are better.
Great video to add to the analysis by showing practical implications. I dont think this will be a game changer, but it may change how we play some matches. Loved those ultra thin half blinds.
I agree....good analogy with matches
As always, a great video presentation. The proof is in the demonstrations and those were great. Having personally committed the error of moving large bookshelves around on the floor, fully loaded with books (I'm talking about 3 ft. wide x 5 ft. high x 11 1/2 deep ones) by pulling them around I have wonder if doing what is shown at time stamp 27:46 would actually work long term. My intuition says repeated moves like that might cause things to come apart. Removing books first would most likely be the best thing to do before moving such a case. But I do think the demonstration where standing on the rabbet and dovetail joined examples was really something. I do think the tensile strength in a stationary wall mounted cabinet fully loaded ceramic dishes would work, but I'm not sure I'd want to test it on a wall-mounted cabinet fully loaded with famiy heirlooms 😀As always, thanks for the great ideas. The videography and demonstrations are so great they're worth watching just for the entertainment alone! Many thanks to you and all those involved in the production of these and all the best to you, yours and the team.
I think standing on the joint puts less pressure on glue and more on the woods fibers. I think putting weights only on one board will show the glue's strength vs the wood fibers.
Where were you when I Was testing these things? I was sure the rabbet would fall right apart
If I glue endgrain to longgrain or endgrain to endgrain, I wouldn't worry about the strength of the glue joint since it's often stronger than the wood.
BUT
I would worry about wood movement and long-term stability. If the glue fails at some point in the future due to repeated wood movement or repeated stress, a tenon will keep the loose parts in place that would otherwise fall apart. Or am I missing something?
Excellent Video
Rob, your comment is needed about glueing up the full length of the dado. In my work I only glue the first third of the dado, which allows the back two-thirds to move (as wood does). What are your thoughts here? One might argue that the grain direction of the two pieces is consistent, and they could move in a similar way. Or do they? Regards from Perth, Derek
You are correct in that last statement, Derek. Both pieces are the same thickness, and species, so I would expect them to move the same amount.
I can’t help but wonder if the concern over endgrain glueing might have had to do with older kinds of glue. For instance, maybe hide glue didnt preform well. The glues we use today are pretty amazing concoctions.
I think the main problems with the shelve is the leverage you used and the way the dado is cut. You're very likely to cut the dado deeper on the sides than the middle, leaving only a very short piece of long grain attached to the upright board.
The most likely failure of a bookcase is when the shelves are so loaded they either sag so much they pull inside, or there's so many books stuffed on the shelves they wedge the sides apart.
Just gluing end to long will not be strong enough for those scenarios, but dado's or shelve supports will prevent a large part of those failures.
Besides, you usually have 2 sides supported, making the leverage issue non-existent.
The bottom of the dado was trimmed with a router plane to provide maximum glue surface.
Rob, one thing to consider is the glue will fail with time. 100 years from now the glued only joint verse the dovetailed or locked mortise joint the glued only will be more likely to fail because the glue will become brittle. Well at least that has been my experience with glue that is only 20 years old. What are your thought when you consider long term results of a glue only joint?
I always like a back up, dovetail, mortise or even dowels.
Rob, would this change how you think about a mortise and tenon joint where the long grain tenon is mated to a short grain mortise?
I was waiting for your video on this!
How did you like it?
@@RobCosmanWoodworking my big question is will time and changes in climate affect change the results? Will those glue joints be just as strong in 100 years.
I remember assembling a cabinet with dadoes using just glue 30 years ago. To my knowledge it's still in use. I never heard back from the client.
It is probably still good
OMG! That rabbet joint bro!!!
A new day in the shop 👍
my experience has been with glue drying out over a period of years along with wood movement. a year or 2 with but joints and up to 5 to 10 years for mortise joints. but with a mortise joint there is the mechanical connection.
I always reinforce my mitered picture frames with V nails but the glue joints are of course, all end grain. In my experience they have bee surprisingly strong. I also glue up pocket hole joints and have noticed the are much stronger.
makes total sense to me
Excellent study and video! Thanks!
It's amazing how Patrick Sullivan (almost literally) set some people woodworking on fire (Ramsey's for sure)..
What does that say about the strength of miter joints which are probably the most likely to be end grain glue ups?
Wow. I'm really, really impressed, @RobCosman.com. That's one of the most difficult character traits for a human to espouse: "When a rational man is faced with new data and he actually allows it to change his mind/position."
One of the fundamental tenets of the Scientific Method is just that: when presented with novel, verifiable, peer-reviewed information that partially or entirely conflicts with the accepted understanding, it is incumbent upon we, as men of science, to adjust our position, even when it flies in the face of everything we have hitherto known or understood.
This is, as one might (correctly) surmise, extremely difficult for many/most (all?) people. Imagine the reaction of a staunch atheist in the presence of a god, a born-and-raised Flat-Earther looking out the porthole of a shuttle, a lifelong devotee of Budweiser trying a real beer for the first time... huge, fundamental worldview shifts that rock ones foundations to their core (that burning smell is that of a paradigm shifting without the use of a clutch).
It is to Rob's great credit that, although surprised, he calmly reflects on the impact and gravitas, then, with equal aplomb, simply shrugs, smiles, incorporates the upheaval into his greater understanding... and gets back to the bench.
...I don't know there's a more admirable quality in a human being.
But still I just wondering that how good the end grain glue join is in the long run, when the grains straws swells and shrink in seasons, but the glue wont? How good is that end grain joint is after 2 years or 10 years?
Thanks Rob and I agree Patrick did a good job. When we make something we hope it will last, and many of the early craftsman made things with nails that have lasted more than there life span. It may be that the glue will out last the wood, but it will never replace the beauty of your wedged mortis and tenon joints (or even mine and they don't look as good as yours). This year I will try to make a couple of jewellery boxes for my grand daughters 21st birthdays. I have little little hope of being there for the party but I hope they may see in the simplicity of my efforts a small part of what I have seen you and Patrick make. Some time ago Patrick made a Keep Sake box and alto I could not make anything as beautiful I did make a more simple box that will last for a life time the thoughts were Patrick's and the dove tails were yours. Please don't tell the grand children. A big thank you to James at Stumpy Nubs and thank you Patrick and Rob
I’ve now seen all four videos, starting with Patrick Sullivan and found them all very interesting. As my French daughter in law has taught me, each time I have gone to bed less stupid 🌞
Perhaps we should not forget that scarf joints do exist. Patrick's video was excellent, but many people have missed the point somewhat. In Patrick's data, what really mattered wasn't comparing the side grain to end grain glue joints, but rather the end grain glue joint to no joint at all.
Thanks for commenting
What I'm curious about is how an end grain glue-up would hold up using hide glue. The "myth" has been around a very long time, but PVA glue is more recent and it makes me think the myth may have been true when earlier glue technology was commonly used.
Great minds think alike, those are my exact thoughts. I might test it and do a video on it
Wonder if that half lap would hold into the winter.
Love your show and all you guy's do but Rob almost speechless Wow. LOL
I really was
2:38 you mean? James Hamilton, from Stumpy Nubs. Thanks for sharing :)
Yes, my buddy Stumpy.
I wonder how many people have thought about glue-sizing the end grain (literally pushing glue into the end grain) and seeing if that might improve the joint strength even further?
My guess is it probably does improve a little bit
It simply means the glue is stronger than the wood resin but weaker than long grain so it doesn’t change much really. A proper joint is still always stronger than end grain glue joint period. No problems gluing m&ts with squeeze out. Using pva I just clean up with a damp cloth then use ply strips with 240 grit glued to them to clean up when dry.
Awesome!
People rushing out crazy do not fully understand what was tested and what was not. It was only about glue vs grain direction. No mechanical joints were tested, but he said more tests are coming. I never rely on glue for strength but on mechanical joints. I have never used butt joint with glue for structural pieces.
100% agree with you
Another good video as always Rob!
I have a question that would to hear your response to. The other day I was watching “Blacktail Studio”. He was talking about glueing up some walnut/black walnut up with “Tite 3” that several people have told him not to use Tite Bond 3 or Tite Bound 2 on walnut! I have never heard anything like the but I seem it might have been “Franklin Glue Company or even Tite Bond glue themselves. Can you please comment on any of the above as to what you would do about the information I relayed? Thank you in advance for your time and any information you may provide.
Sincerely,
Ron Hatcher
I wonder how a proper scarf joint would behave.