The Shocking Truth About Glued End Grain Joints

[@WoodomainJeremyBroun]

I am happy to discuss Mr Sullivans video but please do not tell me I have missed the whole point of his video. And comments are welcomed about my video of course.

[@patrickboyle5860]

Hi Jeremy, great video. I had just watched the video you mentioned earlier this week. Is the take away simply that in a situation where leverage can be applied - an unreinforced joint is just not up to the job. For example, no one would make a table leg out of cross-grained wood as it would just be too weak. While glue may be stronger than lignum, we don't rely much on lignum for structural strength. The biggest design flaw in the Gibson Les Paul is that headstock break angle means that the strength of the lignum becomes structural. Thus Les Paul necks all snap in the same place. Newer versions of the same guitar rely on scarf joints or less of a break angle. Thanks again for the video, I feel that the earlier video you mentioned was interesting, but just dodged around the true reason that people don't glue end grain joints.

[@WoodomainJeremyBroun]

Somebody restoring my sanity - discussing guitars and wood strength in the real world! I dont personally know the Gibson Les Paul but have a PRS which is syled on the Les Paul guitar and I have built nearly two dozen guitars so I know a little about woods and the stresses put on a neck. Headstock angle is crucial of course and the steeper it is the shorter the short grain. In general woodworking terms short grain is a weakness and to be avoided when designing. Instead of splicing necks I laminate my necks from thin vertical sections and depending on whether steel strung (more stress) or nylon strung, I interlock the laminates at the headstock juncture to spread the strength - minimize short grain. This video showing a glimpse of how I made the walnut neck should show the laminates: kzbin.info/www/bejne/hpXEnZmon71-m80 My PRS guitar has a mahogany type one piece neck and doesnt look vulnerable than other if it were dropped and landed at the wrong angle no doubt the headstock would snap because that is where the short grain is. Hope this helps.

[@Casiomidi1]

It's interesting that plywood achieves it's amazing strength by gluing the direction of the grain of the layers together in an approximate 90 degree to one another

[@WoodomainJeremyBroun]

You have put your finger on it - this gluing configuration of massive glue surface area of adjacent grain bonding is a feature of one of my 1973 furniture designs I have sold all over the world and that touch wood is still holding up after nearly 50 years. Early examples in pine are selling in auction houses. I'm a little reluctant to share my trade secrets of construction as proportion and geometry is absolutely crucial in the glue only scenario but it totally blows away Mr Sullivans claim that end grain gluing is twice the strength of side grain, certainly in the real world. Your example of plywood is perfect and the thickness of laminates is crucial in its bonding longevity. In theory adjacent fibres glued together are fighting against each other in the way the wood wants to move.

[@Casiomidi1]

@@WoodomainJeremyBroun Thanks Jeremy -Opposites attract like in magnetism

[@Eweber007]

I had written a comment earlier but it seems to have gone missing. I just wanted to say thank you. I felt as if I was a lone voice or at least severly outnumbered voice in all of this controversy. The KZbin woodworking community is not doing anyone, especially young woodworkers any favors by promoting these "glue myth" videos and then attempting to explain to us what we should have understood. Young and/or inexperienced woodworkers are viewing all of this as some sort of revalation, it is not. The "results" that came in Mr Sullivans video/s were to some of us, quite predictable. although they are not reflective of real world scenarios in any way. Judging by the comments, many seem to think that this is an "absolute" finding and applies everywhere. Thees tests were done in a controlled manner for one specific type of joint (a butt joint). In the thousands of years of known woodworking history we have always avoided glue only end grain joints, not because they're weak but because they break in practical use, just like Jeremy's table. Strong and weak are both relative terms, you need to know the context of how they're being used. I would hope that more woodworkers will come forward to try and stem this tide of misunderstanding, to put ias politely as I can.

[@WoodomainJeremyBroun]

Edward I saw your comment on Rob Cosman's video about my voice not being entirely alone, thanks for that. Maybe you are referring to another comment here, but sometimes technology plays up and things disappear. Yes we are probably in a minority but that doesn't mean we are wrong or shouldnt speak out. I've gone against the grain for most of my life and not been afraid of independent thought. In one sense its good that tradition is being challenged but they are picking the wrong fight over end grain! Yes I agree with you, to many of us - we already knew what Mr Sullian suggested would be surprise outcomes in the rather one dimensional experiment. I think the vast viewing numbers has resulted from a sophisticated confident visual presentation using tabloid psychology! I think his latest mitre joint video has some intriguing methodology but actually has more obvious flaws in it which you will undoubtedly spot. Incidentally I took a big risk in sharing my crazy but true story of the table with no joints as I could be roasted for it on KZbin and so far viewers have been understanding or at least refrained from comment, but I honestly thought it was a perfect demonstration and I risked my reputation (amongst those who know my pre KZbin history) for what I believe to be true. But of course we are being told that Mr Sullivan is not advocating not using joints.

[@Eweber007]

One way to look at it is this, When you build a house frame using only nails and mostly butt joints the orientation of the joints needs to be correct first, the nails are only there to restrain the wood from moving, the wood bears the brunt of the force the nails simply keep things aligned. ( we used to use wooden dowels) Glue is used in much the same way, the joint should first be as mechanically sound as it can be, the glue has only a supporting role of keeping the mechanical joint together but should not be subjected to the majority of the stresses of the joint, thats the woods job With butt joints there is no mechanical connection, the chemical bond of the glue is the only thing keeping the joint aligned and proviiding structural support. Glue is not designed for this and neither is the natural stucture of the wood and this is why end grain joints fail.

[@WoodomainJeremyBroun]

This is a good script for a video on what has to be the essence of woodworking - jointing, as you put it very consisely. Sadly, the way KZbin is evolving and the kind of mentality of mass audiences in the pocket of a few of the 'Big Boys' who are predominantly salesmen, is echoing a malaise in society where cultures are cancelled and in our subject the proper teaching of fundamental woodwork in schools was cancelled some time ago and I understand this has happened in the USA which maybe explains why this end grain myth has been invented. I recall in my eartly furniture making career (circa 1973) contacting TRADA (Timber Resarch And Development Association) about the way I was gluing huge blocks of wood together to make a sculptural desk clock and asking them how the glue would behave and hold the sections together over time. Bear in mind I had aligned the grain direction so all the segments would move together. I did not get a definitive answer which was a wise response because I still have the prototype clock and very recently repaired the clock movement on one of the clocks I sold to a local client. If you have the time take a look at the video: kzbin.info/www/bejne/omqko2BuoMiglck

[@stone.dayton]

Enjoyed the video, thank you. I think the only ‘revelation’ from Mr Sullivan’s video concerns which members of the youtube woodworking community are and aren’t pigeons.

[@WoodomainJeremyBroun]

I guess the pigeons are currently outnumbering the eagles!

[@rolanddrewinski2295]

In one of your comments: "Why on earth would anybody NOT put glue on all surfaces of a joint?" (-:

[@WoodomainJeremyBroun]

I think I made that comment on Rob Cosman's channel and I was of course referring to the revelation that in the USA and Canada the practice is not to add glue to the end grain sections of a joint, eg tenon shoulders and mortice bottoms. I thought it was a given that glue adds some strength to end grain but on its own is not structurally sound. Of course the argument Mr Cosman put up is that glue is messy to remove around the shoulder but its no different to cleaning up glue from anywhere else and is done in different ways either pre or post lacquering. What a fascinating subject woodworking is. Thanks for commenting. Its being taken to a whole new level now of fantasy!

[@cschlater]

As so many others, you fail to grasp what Mr Sullivans experiments show. When you are adding reinforcement in the comparison, you compare pears and apples. If you ever have restored old furniture where the joints have came apart, then you would know that it is not the glue that fails, but the wood. The wood fails parallell to the fibres, showing that Mr Sullivans conclusions are correct. If you are going to compare reinforced joints, then compare the same type och joint, with the same type of reinforcement and shift the grain directions in the boards used in the joints you're going to compare. No matter if you reinforce the joints, you will get the same results as Mr Sullivan did.

[@WoodomainJeremyBroun]

Sounds like an echo chamber comment (comparing pears and apples). No I dont think I have failed to grasp what Mr Sullivans video was about and the message it clearly conveys and I think if you watch my video you will see that not once I have claimed the glue fails! Yes I have repaired and restored furniture including a Chippendale chair that was almost beyond repair and you may learn something about wood, grain and glue if you watch it: kzbin.info/www/bejne/nn3Fh6CjjrOpmsk And maybe to answer your last question you would like to view the comparable strength tests I did on end joints and glues back in 2013: kzbin.info/www/bejne/e4OUnGeGmN6hZq8

[@cschlater]

@@WoodomainJeremyBroun obviously, you fail to grasp what Mr Sullivans experiments show. Still comparing pears and apples.

[@Eweber007]

@@cschlater What is it that we are supposed to have "grasped" from Mr Sullivans video? The fact that modern PVA glue is stronger than wood lignin? Many of us have know this for decades. Should we have learned that a glue only bonded butt joint is weakest along the glue line? I submit the same annswer. None of this is new or revelatory in any way. Naming a video Glue Myths and then later posting accross the screen "End grain joints were the strongest joints of all" what do you think people will take away. From the numerous comments he's recieved, far too many seem ato be of the mind that this applies in a real world scenario, it does not and can be dangerous. Not to mention striking a blow against woodworking in general.

[@WoodomainJeremyBroun]

@@Eweber007 Well put. Its about time the word 'dangerous' appeared in the discussion over Mr Sullivans video, especially in chair joints or even the kind of table I demonstrated if somebody stood on it to change a light bulb!

[@WoodomainJeremyBroun]

Christian - on your KZbin channel I see you have a video about your introduction to woodworking. I am curious to know why you block people from making comments?!!