Great video!! Here's my theory. When the clamps were removed after 30 minutes, the glue hadn't cured enough to compensate for the release of pressure. The boards pulled apart just a little bit on their own and messed up the glue. When you just pushed the boards together and left them, there was no change after 30 minutes, so the joint was stronger. Maybe?
Agreed, to look at it another way, the clamps squeeze out far more glue than the "hand pressed" version, so when the pressure relaxes to "clampless", there is less glue in the joint than the hand pressed version, but a wider gap than the long-term clamped version.
I was a research engineer for 10 years designing and carrying out experiments, and a woodworker since before that. This is one of the most complete and robust scientific woodworking experiment videos I've seen. Controlling for all sorts of variables via sensors that most others would ignore. Thank you for this video, I and countless others will benefit from your rigor! I'm about to glue up a large table in half a dozen glue ups and this will save me days!!
Thanks dude! I could have added more variables like letting each of the conditions dry 24hrs but it takes so much material and time to do this experiment as-is. I’m glad you appreciate the consideration that went into the setup.
@@WoodcraftBySuman There are always more variables! You seem proficient at identifying and appropriately accounting for the important ones to reach practical, useful conslusions which is what makes good science. Most videos like yours are woodworkers taking a stab at being scientists, with varying success. You strike me as a scientist first, applying yourself to woodworking. Do you have a background in research?
@@WoodcraftBySuman Not a lot of fields that have a future in research beyond academia, biologics seems like it would be a good one. I worked in metal product manufacturing research and applications. Very large lab with lots of fabrication, inspection and data collection equipment - lots of work with load cells, they are so incredibly valuable for experiments but unfortunately very expensive! Stuff I've always dreamed of applying to woodworking so your videos resonate strongly with me, I'll be binging them over the next few days.
@@FlyingMoose_ that’s super cool! And hope you like the videos. I only have a few on testing stuff as this has been a recent pivot for the channel. I will continue to make testing or testing adjacent videos going forward.
I worked in a furniture mill in the early 1980's. When making raised panel doors with standard stick and cope construction, our rule was to leave the doors in the clamps for at least 2 hours. After that time, they could be removed from the clamps and stacked if we needed the clamps for another batch of doors. (We typically made doors in batches of 50 to 100 doors.) We were using a typical PVA glue, something similar to Titebond Original, which we bought in 55 gallon drums. We let the doors cure for approximately 24 hours before doing any additional work on the doors (trimming to final width and length, putting an edge profile on them, sanding, etc.). I follow the same practice in my shop today. I leave a glue-up in the clamps for at least 2 hours and don't stress the joints for about 24 hours. I've never had a glue joint fail when following these procedures. (Except for the time at the Furniture Mill when someone stored a 55 gallon drum of glue outside, overnight, in sub-zero temps. None of the joints made with that glue held! PVA glue is ruined by freezing.)
Ruined by freezing, eh? Guess I should be throwing away all the bottles that sat in the garage over the winter and experienced repeated freeze thaw cycles. Not a lot of glue, but a couple of small bottles from when I couldn't find the last one and just bought new.
No. We confirmed with our supplier that freezing ruins PVA glue. If your glue freezes, simply throw it away. There’s nothing that can be done to make it work after that.
I can attest that frozen wood glue does not work that well after thawing. I’ve also accidentally let CA glue freeze and that stuff is worthless after that
My rule of thumb from a practical and time efficient standpoint was to clamp up in the evening and let dry overnight then release and carry on the next morning. Has worked for me for decades.
Great info. I think one important point was unstated or understated: the piece without clamps was not disturbed. We saw how little force was required to break the joints when the glue had not dried yet. Clamps hold the pieces together so that they don't come apart from something as minor as bumping the table that the glued pieces are on. Edit after watching again: the proper testing would have been to clamp for 1, 4, and 12 hours - then waiting to test until the glue had cured at 24 hours. While 30 minutes was shown to be too little, it was not shown what happens at 1, 4, or 12 hours. The assumption that 4 hours is enough is merely assumed.
I agree with you that a second subset of 1hr, 4hr, and 12 hr clamp time with full 24hr cure would have added better data for consideration on this video. Two reasons why I did not do that: 1) it makes the video longer and slightly more complicated to follow. I have to consider average view duration and retention times when making videos on youtube. 2) it would take a lot more wood and I felt bad wasting so much wood as-is. Because 4hrs is able to get strength that competes with the strength of the fibers itself, it is a reasonable conclusion to make that 4hr clamp time generates strong enough joint to remove clamps at room temps and 200psi. Tests like this are just that: tests. How I chose to break the joints is not necessarily analogous real world conditions. Some people glue up in 65F shops and others in 85F shops -- this will have a huge impact on clamp time needs. There are certainly other ways to test this topic and I may even explore it in future videos. Thanks for watching.
Jupp, this is how it should haven been tested. No need to leave a glue up for 12-24hours in the clamps. Clamp for 2-4 hours and let the glue dry for 24 hours before applying thr full expected load. Assembly can continue after the 2-4 hours, if you don't stress the glue line to much.
@@WoodcraftBySuman I can see that work and time and material has to be finite and you have to stop at some point. However your argument about "viewer retention" is unfortunate. Good methodology is like good workmanship quality: A bit of a pain to follow through with, but viewer retention through reputation is worth much more IMO. Compare for example to "Project Farm" testing. Always super meticulous. And look where it got him! (Just speak faster and edit more? 😁)
Testing that actually uses multiple samples and throws out the top and bottom? Here on TH-cam? Amazing! Seriously, I find it so refreshing to see a real effort to apply the scientific method. Thank you! (I've wanted countless woodworking videos here, but this is the first of yours. I subscribed.)
That is a pretty common approach to doing simple statistics. The idea behind throwing out the extremes is to remove the cases where something unusual happened, letting you focus in on the most common examples. When I googled it I mostly got examples of how to do it using tools used for such analysis (Excel spreadsheets, MATLAB) rather than WHY. Which supports the idea that it is common, since so many questions about how to automate it have been asked.
@@somebodypeculiar Thanks for looking into it! That's also what I found. I was hoping there was some statistical rule of thumb that outlined the why. To me, it seems like just lopping off the top and bottom gives an artificially high confidence in your data's consistency. I'm not good at statistics though, so that's why I ask.
Actually, removing the extremes is often a sign of a lack of confidence in the quality of the data. Measurements that are way off from the rest can be the result of a bad measurement. Or they can represent failure of an experimenter to repeat the process consistently. It is a rough-and-ready approach to trying to reach a good rule-of-thumb, rather than a rigorous statistical process. For that matter, the average (mean) isn't always the best measure to use; the median is often preferred, where half the samples are above that point and half below. Note that while the drop-on-from-each-end approach can change the average, it can not change the median.
@@somebodypeculiar So it's like a quick and dirty way to try to limit the influence of outliers without having to actually know how to identify true outliers. I think I understand why people use it better now, thank you.
As a mechanical engineer I applaud your approach and execution. As a long time wood worker I just found the answer to a question I have wondered about for 50 years. Congratulation, Suman, you deserve a big thanks.
As a full-time human for 32 years I was entertained by this video and at the same time I found the answer to the questions I asked myself when gluing wood.
For the 30 min clamp 24h dry --> The wood changed shape after unclamping, but the bond was not compete. The wood applied a separating force that the glue could not expand to fill. This is partially driven by the moisture from the glue entering the wood.
I'm glad that I can safely free up my clamps in shorter intervals, since I started woodworking I'd usually leave glue-ups for 8 hours. Great video! The pacing of information throughout was perfect.
I am so glad you did the hand test, because I cannot tell you how many times people have told me 'you should clamp that'. I usually just use tape on veneer repairs (small pieces) unless it may shift. Its always been fine. Thanks for the video!
This is a super helpful video ! I didn't realize how much risk I was taking unclamping my glue ups at 30 minutes. You've probably saved many people at least one project disaster. Very through analysis !
I second this nomination. I've always wondered that myself. But like Suman says, Im putting possibly too much glue, and relying my choking of my clamp handles to squeeze out what it doesnt need. I'm a drowner, but have found the only downside of this is cleanup time, and using more glue. But I'm a weirdo, and enjoy the glue scraping/cleaning process....its cathartic.
As a non-woodworker who frequently puts bits of wood together, I'd also like to hear/see the results of flood v's sparing. As well as that, what about the effect of lightly moistening the joint face with water (to open the pores) before applying the glue?
Love how thorough you were with this. You have saved me from the worry of "Have I clamped this long enough" I was at overkill with overnight glue-ups lol. Thanks Suman.
Great vid, I’m sure this will be very useful and informative to a lot of people including myself! My totally unscientific thought on the 30 min/24 hour surprise breakage is that maybe it could be that when the pressure is released before the glue is fully cured, the wood slightly ‘rebounds’ when the clamp is removed and causes a sudden shift in force that might upset the bond, whereas an even pressure scheme for the entire cure time wouldn’t experience such disturbance in the forces and glue line. Just a thought for future vids - it would be nice to have a text layover of the test conditions (clamp time etc) during the part of the video where the breakages occur in the testing. Good for easily distracted people like myself to see where we’re at. Keep up the great work, I love this channel!
Wow! No fluff, only the good stuff. Literally packed a 30 minute video into 10 minutes. Played at 1.5x that's less than 7 minutes! You won't find a video packed with more info per minute. Took me longer to write this comment than watch the vid - very well deserved. How could I not subscribe? Genius! Thank you man - been prayin for vids like this!
my hypothesis on the 30m clamp 24hr dry boards is that the clamps force much of the glue out, but the bond after 30m isn't enough to the adherants to maintain the joint and so it weakens. i've had this type of result when overclamping joints, wiping up the squeeze out and then backing off some of the pressure. i had a tabletop split right down the glueline this way and ended up doing some testing to figure out why it might have happened. i found it was pretty well understood that too much pressure can starve a joint and i suspect that backing off the pressure after clamping is creating a similar situation.
I have a video suggestion for your test rig. It would be cool to see testing done to compare fluted dowels, spiral dowels, regular dowels, and maybe miller dowels too for the fun of it. I'm curious if the friction of a regular dowel causes glue starvation, or if the different types of dowels cause any significant difference in strength in the joint. I've never seen anyone test this before and many woodworkers use dowels in their joinery.
Love the process you used, I'm 60+ years old and spent my life thus far as an engineer asking the questions you asked. Well done! About to retire and spending more time in the wood shop, been thinking about my glue ups, hum... and you just did 700% of the work. Thank you so much. Youre awesome, thank you. Honestly, I think you out engineered Tightbond on their instructions, and you were very graceful, well done.
The real question is not how strong the joint is after clamping for 5 minutes, 30 minutes, etc. but how strong is the joint 24 hours after clamping for 5 minutes
@@lustucrugf5591 Two variables make it anti-scientific? God forbid you read any study with statistics and see how many variables they have to deal with.
Dude I can’t begin to tell you how useful your mini split install video was for installing one in my shop. Appreciate all of your efforts as well! Thank you
As an owner of a WW business, (and an even smaller YT channel than yours...lol) this is very helpful information. I got into the habit of writing the time on my glue-ups and waiting about 3 to 4 hours with only enough clamping pressure to get squeeze-out along the entire edge. As to the LAST TEST...my theory would be that the initial pressure squeezed out most of the glue and then releasing that intense pressure left the joint a little "glue-starved" for final curing.
This males perfect sense. there may even have been air ingress once the pressure was removed from the glue starved joint. I'd love to see a magnified shot of the break
As an engineer myself I have to say: Perfect execution! 🤩I love how you put attention to all the details! And the results are also very helpfull ... thanx for investing your time. 👍
Excellent video! Two thoughts of mine you didn't ask for 😬 : - It would be helpful to see how all those clamping times fared with the recommended 24-hour unstressed period after removal from clamps (or perhaps a period that would add up with clamping time to 24 hours total to keep all the samples identical in total cure time). If the full day of curing took the 30 minute clamped batch halfway to the strength of the 24 hour clamped group, I'd be fascinated to see how, say, the 1 hour or 4 hour group would fare after the full 24 hours. Either case would still free up clamps much sooner then the common "clamp for a day" thing a lot of us do. -The hand-clamped results are fascinating! I'd love a comparison between those where you just pushed them together to a sample group you joined with rub joints. Would the atmosphere offer greater pressure in that regard? Would the joint be any noticably different from your first group? Again, amazing work, man! You more than earned this sub.
Thanks! I have had bosses insist on running things through the planer after 15 minutes, but I always had other thing to do in the meantime to let them sit for a while longer. About an hour into the glue up, when the glue is somewhat still soft What I have been doing is removing clamps one at a time to remove the glue and then replacing them from the panel. So instead of releasing any pressure is to keep the clamp about ½ an inch above the wood to be able to scrape the glue off. One thing I have been doing for years now is to let the panels sit for a week to allow any water from the glue to evaporate off the wood. When first glued the panels have a swelling like a mountain ridge and if you were to plane or sand it flat, it then dries leaving a valley.
Love the evidence-based approach to woodworking, Suman. Could you put error bars on your averages in future? It's important to see how much variation is caused by the test variable relative to uncontrolled variables.
This is an excellent video on glue ups. I usually wait at least 1 hour before handling or working with glued material on fast moving projects, but now will wait longer after seeing you video. Thanks a million
I'm a cabinetmaker. When I was an apprentice, and going to trade school, I was taught that a properly glued joint (not too much glue, not too little) needs to be in the clamps for at least 10 minutes. And properly clamped of course. So not too much force, where you're squeezing all the glue out, and not too little force, where it's not even doing anything. In practice, I like to keep clamps on at least one hour. If it's something big and complicated, I leave it overnight. It's also important to note that regular white PVA glue is perfectly strong enough to use for furniture, as long as the joints are put together as I've described. Yellow glue, or "carpenter's" glue, also known as aliphatic resin, is typically a stronger adhesive, as it's meant for structural purposes. Titebond III is an exterior PVA, but I've noticed it is thinner and runnier than regular PVA, and it definitely needs more than 10 minutes in clamps.
Congratulations on your very carefully controlled methodology, I hate testing videos that don't even care to make sure the samples and force applied are as equal as possible, it made me really happy to see all the care you put into this, it doesn't go unnoticed.
When PVA glue "dries" it is polymerizing. The solvent (water) evaporates, It was keeping the glue from polymerizing. It is analogous to a crystal without such a regular, repeating pattern. When the glue is drying and the polymers are accreting into a solid it forms up in a more or less orderly manner. If the pressure changes in the middle of that process, it will interfere with the orderly manner and introduce a defect in the glue. Any polymerization already finished cannot shift - it is already essentially solid. The glue that is still solidifying will be torn away from what it was trying to connect to, which creates a very tiny rift that is not mended by liquid glue. It is too small for that and surface tension prevents it from entering these tiny fractures. These tiny fractures will reduce the strength of the glue joint wherever they exist, and if there are enough of them it will significantly undermine the strength of the joint. They probably will be lined up because the evaporation happens more from where the glue line meets the air and less from inside. So there is a wave of hardening traveling through the joint, but not too orderly, probably. So when the pressure changes because you remove the clamps, you're introducing tiny fractures wherever the glue was not cured. This is better avoided by waiting long enough for the glue to cure. I don't know why TB would recommend 30 minutes. It isn't enough time if the pressure will change. The reason the hand-pressed or taped glue-ups work so well is because the pressure doesn't change.
Your joinery was very good and the extremely smooth surfaces obviate the need for high-pressure clamping. If you use wood that is less smooth, the clamping pressure helps the glue penetrate into the pores, cracks and defects in the surface of the wood. A rougher surface can result in a stronger glue joint because there is more surface area for the glue to touch, and the cured glue is physically locked into the pores. Glue is already stronger than wood, so the payoff isn't that great. But, it takes more work to make a super-smooth surface like you made, so you can save that effort for a glue up. Jointers often produce a less than furniture-quality edge, but it is ideal for glue--ups. So, the results you got were influenced by how smooth the wood actually was. That is not a problem, that is a feature, because it removed from the equation the "smoothness" or "roughness" of the wood, which is difficult to characterize. But, clamping pressure becomes more important when the wood is less smooth. To the extent that the glue is filling any gaps, clamping pressure matters more. Another reason clamping matters is that the project can warp or shift while the glue is drying. This can ruin a project. Clamping can prevent movement (if that is a goal and it is done right, of course). Clamping can also force the parts to shift, so extra clamps and/or cauls are needed to prevent any movement.
Wow, heck of a video on wood glue. You answered a huge number of questions I’ve asked myself, clamp time, fit, etc.. Great video, thank you. Looking forward to your next vid, you a great job at explaining what you’re doing, why, and the editing is very good. Thank you, a woodworker from Missouri.
I like this video very much because as an engineer, this is exactly the type of experiments I'm interested in to understand why we do things the way we do them and challenge tribal knowledge or rules of thumb. I'm writing my very first (and hopefully longest) youtube comment here because I'd like to make a few suggestions that may make your future experiments/videos even more valuable. 1. Include information about the spread of your samples Instead of bar charts, I suggest using "box plots" as they are a common way to display information about the average and the spread of the samples together. With few samples like here, you may also just overlay the individual samples over your bar chart, but I'd still prefer some of the statistics that a box plot has to offer. Why this is important: you concluded that 4hr clamping is sufficient for you, because in average the joint is just strong enough, without considering how consistently this is the case. But would you still make the same conclusion if half of your samples are very weak and half of them are very strong, resulting in a just strong enough average? 2. Validate your assumptions The underlying assumption you make here is that with 24hr of clamping, the joint is as strong as it gets and it is still weaker than just wood due to being stiffer. It would be interesting to see experiments with more than 24hr clamping time to validate (or invalidate) that the strength does not increase further. Why this is important: assuming after 48hr of clamping you can double the strength compared to 24hr clamping, would you still just clamp for 24hr if you have a project where strength matters more than clamping time? 3. Separate potential causes to make fair comparisons Your experiment with hand clamping and letting the piece dry clearly shows that there are at least two major causes for joint strength. One of them being the clamping time and the other being the total drying time. I think these can and need to be separated in that you test the strength after the same amount of total drying time for all the samples. If you can keep all the variables except for one fixed, you can show which has how much impact. Why this is important: what if the clamping time has almost no impact (as long as there was some) but it's really only the total drying time that matters? I.e. would you still do 4hr clamping if after 1hr of clamping and 24hr total drying time you get the same strength as with 24hr clamping/drying time (Your hand-clamping experiment potentially indicates that this could actually be the case)? When repeating such an experiment I suggest to first find the clamping time that results in maximum strength and take that as a reference. Then, try different clamping times but keep the total drying time the same as the one that reaches maximum strength before testing the samples. And in the analysis, also show the spread of the different samples ;)
Came over from Scott Walsh. Love your channel brother! You've definitely earned my sub. I know that these kinds of videos are very difficult to make and you need to take time to be with your family. No one on their deathbed is going to say, "I wish I had made one more YT video." Keep up the good work.
Excellent video! I shared it with my woodworking buddies. Great information! Thanks for doing all the footwork for this data. I know all the behind-the-scenes stuff is often forgotten when we watch these videos. For us, it's ten minutes. For you, it's a huge investment of time. Thank you, sir!!
I wonder if greater clamping pressure causes more glue to squeeze out, but then if that clamping pressure is released before the glue dries/cures enough to hold the joint tightly together, then there joint has an effective glue deficit. Less pressure means more space between fibers, which means more glue is needed.
Great testing video. That took a pile of time to pull off. I appreciate the 'woodworking science'. We need more clips like these on the net. Keep up the GREAT WORK, my friend.
I watched this after seeing the joint testing video you did with Scott Walsh, and you've definitely earned my subscription! I only own a few clamps and I'm definitely one of those who leaves them on overnight if not a full 24 hours so knowing this will help ease my anxiety about taking them off sooner. Thanks, and I look forward to seeing more of your testing videos!
I never leave my stuff in clamps for more than an hour or two, unless I am just going to bed and happen to leave them in clamps overnight. I also don't use excessive glue. like most people. Removing the clamps after an an hour doesn't make for a weaker joint, as long as you let the glue cure before you stress the joint. 30 mins may be a bit short, but you were also using titebond 3. Original has a quicker set time
Most of my glue-ups are segmented rings for wood turning. This is useful information to me, especially allowing the joints to cure for 24 hours. This will speed up my assembly process while still producing a strong, safe bond.
I've seen a couple of your stress tests and I have one compliment on your test setup. A lot of videos that I see people doing similar tests they use a luggage scale and try to capture the readout with a camera to find the frame with the highest reading. Your setup is much better because of the peak-hold feature of your scale. LCD displays, especially on inexpensive luggage scales have a fairly slow refresh rate so the actual peak reading may never show on the LCD. The peak hold of your scale will actually capture the peak reading even if it happens between LCD refreshes. Thank you for the quality of your test setup.
Yes! You make valuable, quality video, Suman. Doesn't matter if they don't come out often. Good stuff is worth waiting for, and it can only come as you are able, not as others wish. Very helpful to quantify the time effects of clamping glue-ups. Adequate clamping pressure, released at 4 hours but NOT disturbed for 24, and on to the next tasks. It would make sense to have left them all for 24 hours as directed, to see if it matters when the clamps were removed. I suspect it wouldn't matter so long as the glue lines were intact. You are so right that the quality of the edge match is most important. And that means you don't need a clamp every 3 inches either. I glued a 3 piece panel of cheap wood with jointed edges for a painted sign that rotted away after 15 years in the rain, snow & ice. But it never came apart. Thank you so much!
I think what happend in the last test is that when you released the clamps - the structure of glue was weakened by the released wood and when the glue hardened it was already damaged by this clamp-release movement.
What I find funny about this is that it tracks with my experience and practices. I always assumed cure time was the major factor, and clamping is mostly to ensure the most surface area for the glue is being contacted before it sets up enough to hold that pressure itself (how sprung joints work). I typically take my clamps off after 3-4 hrs as I only have a few, and unless the wood is particularly "featured" I really don't want to leave them overnight in those clamps.
By clamping you push excess glue from joint. When you remove clamps after 30 minutes you release pressure on wood so a little tiny gap can occur on joint, but there is no glue to fill that gap. So it doesn't matter that you leave it for 24 hours, joint is already weak. When you making joints using just hands or weak pressure, you don't push so much glue out from joint, you don't store tension in wood, so wood don't try to break that joint and glue can do the job. There is probably a little more glue in such joint but it doesn't matter.
I love Titebond III. However, I have believed - from my woodworking experience [I used to be a luthier] and am now a woodcraftsman - that it is weak unless it is left undisturbed for 24hrs. After then, it is an excellent bonding agent, and as you have shown, only 4hrs is necessary for reliable strength. But good to have your scientific experiments to draw from, really appreciate it. Great work, thanks.
I am pleased that I came across this video. It answered some of my questions about the strength of glue joints. I would like to see the exact same test on a series of boards with one difference. Instead of clamping for a time period and immediately testing the strength, I would like to see the boards set aside for a week, (and possibly other intervals of time) before testing the joint. It is my understanding that curing time is a crucial component in joint strength.I would be surprised if you found the differences to be the same after a week. I have restored furniture for years and have found that clamping for at least an hour works well enough for me to use the glued up pieces in further construction, yet it takes a long time for the wood joint to really cure properly. I wouldn't want to stress any joint that I had glued for a long time. The glue contains water or possibly another medium which does alter the moisture level of the wood. I have never seen any tests that determine the moisture content in the wood before and after a joint fails. You have definitely answered some of these questions. I am greedy for more.
Edit* I probably shoulda finished the video before commenting haha. In any case, I'd be interested to see the differences anyways! Amazing video! What I'd be interested to see is this same test, except instead of trying to break the joint immediately after the clamps are removed, let the glue fully cure To avoid confusion here's an example. Clamp the wood for 5 minutes, remove clamps, and let glue cure for 24 hours. Come back and test the joint.
@WoodcraftBySuman I edit my comment if you didn't see. I should be more patient and watch the full video before commenting haha. In any case, I completely understand. I have some limited content creating history and I know first hand the limiting factors of being small and just not having enough time to do everything you'd like to do! Still, amazing video. Youve just gained another sub for what it's worth 😊
Saved me a pile of testing , thank you. I am also sharing because I think someone who takes the time to do testing is a valuable asset to any wood workers out there.
To me the most interesting element of these tests is the no clamp test. I've seen some great videos discussing clamp pressure. Over time I've reduced my clamp pressure. I now clamp to achieve squeeze out and typically unclamp after 20 to 25 minutes and put the piece aside over night.
Agree, when releasing the clamps wood have a tendency to "swell" if I can put it that way. and well half dried glue the stretches and creates air pockets or pulls away from the micro bonds its made with the wood.
I've been making panels out of pallet wood. Planed faces, some bowing, heated but not too warm shop, Titebond 3. I have have a limited amount of clamps etc, so I can only do 1-2 panels at a time. I leave them in clamps for about 90min. After that they are pretty solid, but I can still easily scrape the squeezeout off. Next day they are good and ready to go in the planer. I have done about 30 boards like this and so far no problems.
Excellent tests! For decades I have suspected that clamping is mostly insurance of the tightest possible joint for a given glue up and this seems to confirm :)
Interesting! I can only guess that on that last one, when you removed the clamps, the connection was partly separated. The one you just "hand-clamped" was left to rest over night without any stress. Keep up the good work!
Great presentation!!! I agree that most woodworkers will opt for an overnight clamping. It is my understanding that your test method is to clamp for X amount of time and stress test shortly after unclamping. As the Titebond label states, “Clamp for a minimum of 30 minutes” and “Do not stress joint for 24 hours.” If possible, can you please do another test with the same clamp times but with a stress test after a total clamp and cure time of 24 hours.
Great video, thanks so much for taking the time -- very useful and interesting, but with a "real life" competing for your time, impressive you were able to do such thorough and careful testing, and then the video editing.
Nice well paced presentation with excellent test based info on glue/clamping strength relationships. First time on your channel, wil be back to learn more. Thanks for sharing.
The hand-clamped joints left more glue in the joint, which pulled the wood together as it shrank while drying. The clamping process squeezed most of the glue out and glue was wiped away. As that tiny amount of glue shrank, it was replaced by air, which is weak as you can get. Thanks for this excellent testing !!! 😊
Should have mentioned the spring-back / rebound of wood after removing clamp. With no force applied this rebound would suck in air, since all the glue had been squished away. Having excess glue would pull the wood together as it shrank, and because of extra glue, no air gaps.
I used wood glue couple times without clamp. I noticed glue has a tendency to pull itself together in thickness dimension and push the joint apart which leave the joint without fully glued after dry.
Love it! At some point, I have to test glue quantity and clamping pressure. There are some questions, especially on glue starving a joint that needs to be seriously considered. I think the 175-250psi recommendation by titebond is wayyyy too high.
I love the scientific approach you've brought to your channel. There are so many possibilities for things to test in the shop, I always look forward to what you'll test next!
Great testing. Another factor I have found (50 years since I was an apprentice) that you mention is glue line thickness. We used to do panels with no clamps - rubbed joint. It would interesting to compare - several panels clamped together and several with a rubbed joint. For those unfamiliar, take the 2 pieces with good glue joints, glue the edges and press the joints together to ensure glue spread and also squeeze out any excess glue (with experience you should be able to apply just the right amount of glue for a .003 to .006 thick glue line) then stand the “panel “ on edge allow to dry. For wide panels lean 2 sticks against the wall to support the panel at a nearly vertical angle.
I love these kinds of videos. I need to make a setup for testing like this. I've had some glue joints that I couldn't get apart after 10 minutes and the only reason I can think of that is because it was summer in Colorado and it was very dry. I realize the wood wasn't aligned properly and took a hammer to it and that sucker would not move. it always feels like I have 5-10 minutes, when there's low humidity, before there's no undoing the joint without breaking the wood. the hand-held joint was the coolest finding of this. I had seen some youtube video where the person would just hold two pieces together and that was it, no clamps. It seemed crazy, but now it doesn't seem so crazy. I had assumed the person had done it before and knew it'd be fine, but this shows it's fine with lightly used things.
Temperature is a huge factor. Also the jig was designed to really force these joints to snap in a hurry. I made it that way because I wasn’t sure if my scales would max out before joint faliure. And keep in mind, the test pieces are pretty small compared to most glueups with mich larger surface area involved.
I saw somewhere on TH-cam this tip: rub two small pieces of coarse grit sandpaper together, say 80 or 100 grit. Sprinkle just enough of this grit in a couple of areas where the clamping force is greatest. The idea is to compress the grit into the wood so that there is no gap created by the grit.
thanks. really well done. releasing clamps after 30mins releases pressure and weakens the glue. Personally I: put a few clamps on & leave them on overnight.
Great info, you saved a lot of extra glue time, and clamps. I always wondered about using tape on glued miter joints, now I see some proof thanks to you.
Great video!! Here's my theory. When the clamps were removed after 30 minutes, the glue hadn't cured enough to compensate for the release of pressure. The boards pulled apart just a little bit on their own and messed up the glue. When you just pushed the boards together and left them, there was no change after 30 minutes, so the joint was stronger. Maybe?
Was thinking the same thing
Hadn’t read your reply before my post, totally agree.
Agreed, to look at it another way, the clamps squeeze out far more glue than the "hand pressed" version, so when the pressure relaxes to "clampless", there is less glue in the joint than the hand pressed version, but a wider gap than the long-term clamped version.
Yep. My thought as well. Don't know for certain, but glad to be part of the majority consensus hah
Not even a question. The glue has not fully cured in less than 24 hours. It achieves a minimum working strength in 30 minutes.
I was a research engineer for 10 years designing and carrying out experiments, and a woodworker since before that. This is one of the most complete and robust scientific woodworking experiment videos I've seen. Controlling for all sorts of variables via sensors that most others would ignore. Thank you for this video, I and countless others will benefit from your rigor! I'm about to glue up a large table in half a dozen glue ups and this will save me days!!
Thanks dude! I could have added more variables like letting each of the conditions dry 24hrs but it takes so much material and time to do this experiment as-is. I’m glad you appreciate the consideration that went into the setup.
@@WoodcraftBySuman There are always more variables! You seem proficient at identifying and appropriately accounting for the important ones to reach practical, useful conslusions which is what makes good science. Most videos like yours are woodworkers taking a stab at being scientists, with varying success. You strike me as a scientist first, applying yourself to woodworking. Do you have a background in research?
@@FlyingMoose_ haha. Pretty solid deductions there. Yes I am a scientist - though in biologics.
@@WoodcraftBySuman Not a lot of fields that have a future in research beyond academia, biologics seems like it would be a good one. I worked in metal product manufacturing research and applications. Very large lab with lots of fabrication, inspection and data collection equipment - lots of work with load cells, they are so incredibly valuable for experiments but unfortunately very expensive! Stuff I've always dreamed of applying to woodworking so your videos resonate strongly with me, I'll be binging them over the next few days.
@@FlyingMoose_ that’s super cool! And hope you like the videos. I only have a few on testing stuff as this has been a recent pivot for the channel. I will continue to make testing or testing adjacent videos going forward.
I worked in a furniture mill in the early 1980's. When making raised panel doors with standard stick and cope construction, our rule was to leave the doors in the clamps for at least 2 hours. After that time, they could be removed from the clamps and stacked if we needed the clamps for another batch of doors. (We typically made doors in batches of 50 to 100 doors.) We were using a typical PVA glue, something similar to Titebond Original, which we bought in 55 gallon drums. We let the doors cure for approximately 24 hours before doing any additional work on the doors (trimming to final width and length, putting an edge profile on them, sanding, etc.).
I follow the same practice in my shop today. I leave a glue-up in the clamps for at least 2 hours and don't stress the joints for about 24 hours. I've never had a glue joint fail when following these procedures. (Except for the time at the Furniture Mill when someone stored a 55 gallon drum of glue outside, overnight, in sub-zero temps. None of the joints made with that glue held! PVA glue is ruined by freezing.)
Ruined by freezing, eh? Guess I should be throwing away all the bottles that sat in the garage over the winter and experienced repeated freeze thaw cycles. Not a lot of glue, but a couple of small bottles from when I couldn't find the last one and just bought new.
Could be that the glue was still cold when applied
No. We confirmed with our supplier that freezing ruins PVA glue. If your glue freezes, simply throw it away. There’s nothing that can be done to make it work after that.
Dang iI ust glued up a bunch of things with my titebond that was stored in my non heated garage. Great now I have to find a new spot to store my glue.
I can attest that frozen wood glue does not work that well after thawing.
I’ve also accidentally let CA glue freeze and that stuff is worthless after that
My rule of thumb from a practical and time efficient standpoint was to clamp up in the evening and let dry overnight then release and carry on the next morning. Has worked for me for decades.
That's the overall best way to do it.
I try and plan my glue ups the same way.
Great info. I think one important point was unstated or understated: the piece without clamps was not disturbed. We saw how little force was required to break the joints when the glue had not dried yet. Clamps hold the pieces together so that they don't come apart from something as minor as bumping the table that the glued pieces are on.
Edit after watching again: the proper testing would have been to clamp for 1, 4, and 12 hours - then waiting to test until the glue had cured at 24 hours. While 30 minutes was shown to be too little, it was not shown what happens at 1, 4, or 12 hours. The assumption that 4 hours is enough is merely assumed.
I agree with you that a second subset of 1hr, 4hr, and 12 hr clamp time with full 24hr cure would have added better data for consideration on this video.
Two reasons why I did not do that: 1) it makes the video longer and slightly more complicated to follow. I have to consider average view duration and retention times when making videos on youtube. 2) it would take a lot more wood and I felt bad wasting so much wood as-is. Because 4hrs is able to get strength that competes with the strength of the fibers itself, it is a reasonable conclusion to make that 4hr clamp time generates strong enough joint to remove clamps at room temps and 200psi.
Tests like this are just that: tests. How I chose to break the joints is not necessarily analogous real world conditions. Some people glue up in 65F shops and others in 85F shops -- this will have a huge impact on clamp time needs. There are certainly other ways to test this topic and I may even explore it in future videos. Thanks for watching.
@@WoodcraftBySuman Thank you for your tests. They are not only entertaining, but do give us more data.
Jupp, this is how it should haven been tested. No need to leave a glue up for 12-24hours in the clamps. Clamp for 2-4 hours and let the glue dry for 24 hours before applying thr full expected load. Assembly can continue after the 2-4 hours, if you don't stress the glue line to much.
When you get to the point where the wood fails instead of the glue, that's all the testing you need.
@@WoodcraftBySuman I can see that work and time and material has to be finite and you have to stop at some point. However your argument about "viewer retention" is unfortunate. Good methodology is like good workmanship quality: A bit of a pain to follow through with, but viewer retention through reputation is worth much more IMO. Compare for example to "Project Farm" testing. Always super meticulous. And look where it got him! (Just speak faster and edit more? 😁)
Testing that actually uses multiple samples and throws out the top and bottom? Here on TH-cam? Amazing!
Seriously, I find it so refreshing to see a real effort to apply the scientific method. Thank you!
(I've wanted countless woodworking videos here, but this is the first of yours. I subscribed.)
Do you have a reference for where the "throw out max and min, average the rest" approach comes from?
That is a pretty common approach to doing simple statistics. The idea behind throwing out the extremes is to remove the cases where something unusual happened, letting you focus in on the most common examples. When I googled it I mostly got examples of how to do it using tools used for such analysis (Excel spreadsheets, MATLAB) rather than WHY. Which supports the idea that it is common, since so many questions about how to automate it have been asked.
@@somebodypeculiar Thanks for looking into it! That's also what I found. I was hoping there was some statistical rule of thumb that outlined the why. To me, it seems like just lopping off the top and bottom gives an artificially high confidence in your data's consistency. I'm not good at statistics though, so that's why I ask.
Actually, removing the extremes is often a sign of a lack of confidence in the quality of the data. Measurements that are way off from the rest can be the result of a bad measurement. Or they can represent failure of an experimenter to repeat the process consistently. It is a rough-and-ready approach to trying to reach a good rule-of-thumb, rather than a rigorous statistical process. For that matter, the average (mean) isn't always the best measure to use; the median is often preferred, where half the samples are above that point and half below. Note that while the drop-on-from-each-end approach can change the average, it can not change the median.
@@somebodypeculiar So it's like a quick and dirty way to try to limit the influence of outliers without having to actually know how to identify true outliers. I think I understand why people use it better now, thank you.
As a mechanical engineer I applaud your approach and execution. As a long time wood worker I just found the answer to a question I have wondered about for 50 years. Congratulation, Suman, you deserve a big thanks.
As a full-time human for 32 years I was entertained by this video and at the same time I found the answer to the questions I asked myself when gluing wood.
Love your scientific approach to woodworking. We need more channels like yours. Great info with practical uses. Thanks for your content.
For the 30 min clamp 24h dry --> The wood changed shape after unclamping, but the bond was not compete. The wood applied a separating force that the glue could not expand to fill. This is partially driven by the moisture from the glue entering the wood.
I'm glad that I can safely free up my clamps in shorter intervals, since I started woodworking I'd usually leave glue-ups for 8 hours. Great video! The pacing of information throughout was perfect.
I am so glad you did the hand test, because I cannot tell you how many times people have told me 'you should clamp that'. I usually just use tape on veneer repairs (small pieces) unless it may shift. Its always been fine. Thanks for the video!
Honestly that was also my biggest takeaway from the video.
I feel so much better about my projects held together by painters tape.
This is a super helpful video ! I didn't realize how much risk I was taking unclamping my glue ups at 30 minutes. You've probably saved many people at least one project disaster. Very through analysis !
Id like to see a follow up on this video on what is the minimal amount of glue needed to secure a joint vs drowning a joint.
I second this nomination. I've always wondered that myself. But like Suman says, Im putting possibly too much glue, and relying my choking of my clamp handles to squeeze out what it doesnt need. I'm a drowner, but have found the only downside of this is cleanup time, and using more glue. But I'm a weirdo, and enjoy the glue scraping/cleaning process....its cathartic.
As a non-woodworker who frequently puts bits of wood together, I'd also like to hear/see the results of flood v's sparing. As well as that, what about the effect of lightly moistening the joint face with water (to open the pores) before applying the glue?
Love how thorough you were with this. You have saved me from the worry of "Have I clamped this long enough" I was at overkill with overnight glue-ups lol. Thanks Suman.
Great vid, I’m sure this will be very useful and informative to a lot of people including myself!
My totally unscientific thought on the 30 min/24 hour surprise breakage is that maybe it could be that when the pressure is released before the glue is fully cured, the wood slightly ‘rebounds’ when the clamp is removed and causes a sudden shift in force that might upset the bond, whereas an even pressure scheme for the entire cure time wouldn’t experience such disturbance in the forces and glue line.
Just a thought for future vids - it would be nice to have a text layover of the test conditions (clamp time etc) during the part of the video where the breakages occur in the testing. Good for easily distracted people like myself to see where we’re at.
Keep up the great work, I love this channel!
I agree, in fact releasing multiple clamps one by one causes serious unbalanced pressure on the joint line.
I came here to say the same thing. This absolutely what happened.
+1
+2
Well worth the $5 awesome video keep them coming
Wow! No fluff, only the good stuff. Literally packed a 30 minute video into 10 minutes. Played at 1.5x that's less than 7 minutes! You won't find a video packed with more info per minute. Took me longer to write this comment than watch the vid - very well deserved. How could I not subscribe? Genius! Thank you man - been prayin for vids like this!
my hypothesis on the 30m clamp 24hr dry boards is that the clamps force much of the glue out, but the bond after 30m isn't enough to the adherants to maintain the joint and so it weakens. i've had this type of result when overclamping joints, wiping up the squeeze out and then backing off some of the pressure. i had a tabletop split right down the glueline this way and ended up doing some testing to figure out why it might have happened. i found it was pretty well understood that too much pressure can starve a joint and i suspect that backing off the pressure after clamping is creating a similar situation.
I have a video suggestion for your test rig. It would be cool to see testing done to compare fluted dowels, spiral dowels, regular dowels, and maybe miller dowels too for the fun of it. I'm curious if the friction of a regular dowel causes glue starvation, or if the different types of dowels cause any significant difference in strength in the joint. I've never seen anyone test this before and many woodworkers use dowels in their joinery.
Love the process you used, I'm 60+ years old and spent my life thus far as an engineer asking the questions you asked. Well done! About to retire and spending more time in the wood shop, been thinking about my glue ups, hum... and you just did 700% of the work. Thank you so much. Youre awesome, thank you. Honestly, I think you out engineered Tightbond on their instructions, and you were very graceful, well done.
The real question is not how strong the joint is after clamping for 5 minutes, 30 minutes, etc. but how strong is the joint 24 hours after clamping for 5 minutes
Exactly. Two variables make it anti scientific
Bingo.
@@lustucrugf5591 Two variables make it anti-scientific? God forbid you read any study with statistics and see how many variables they have to deal with.
Super informative! I appreciate all the work you put into this video and will be watching more from your channel!
Dude I can’t begin to tell you how useful your mini split install video was for installing one in my shop. Appreciate all of your efforts as well! Thank you
As an owner of a WW business, (and an even smaller YT channel than yours...lol) this is very helpful information. I got into the habit of writing the time on my glue-ups and waiting about 3 to 4 hours with only enough clamping pressure to get squeeze-out along the entire edge. As to the LAST TEST...my theory would be that the initial pressure squeezed out most of the glue and then releasing that intense pressure left the joint a little "glue-starved" for final curing.
Hand-clamping kept enough glue in joint so it was not replaced by air (spring-back / rebound of wood sucks in air). You're right about "glue-starved".
This males perfect sense. there may even have been air ingress once the pressure was removed from the glue starved joint. I'd love to see a magnified shot of the break
As an engineer myself I have to say: Perfect execution! 🤩I love how you put attention to all the details! And the results are also very helpfull ... thanx for investing your time. 👍
Excellent video! Two thoughts of mine you didn't ask for 😬 :
- It would be helpful to see how all those clamping times fared with the recommended 24-hour unstressed period after removal from clamps (or perhaps a period that would add up with clamping time to 24 hours total to keep all the samples identical in total cure time). If the full day of curing took the 30 minute clamped batch halfway to the strength of the 24 hour clamped group, I'd be fascinated to see how, say, the 1 hour or 4 hour group would fare after the full 24 hours. Either case would still free up clamps much sooner then the common "clamp for a day" thing a lot of us do.
-The hand-clamped results are fascinating! I'd love a comparison between those where you just pushed them together to a sample group you joined with rub joints. Would the atmosphere offer greater pressure in that regard? Would the joint be any noticably different from your first group?
Again, amazing work, man! You more than earned this sub.
Thanks! I have had bosses insist on running things through the planer after 15 minutes, but I always had other thing to do in the meantime to let them sit for a while longer.
About an hour into the glue up, when the glue is somewhat still soft What I have been doing is removing clamps one at a time to remove the glue and then replacing them from the panel. So instead of releasing any pressure is to keep the clamp about ½ an inch above the wood to be able to scrape the glue off. One thing I have been doing for years now is to let the panels sit for a week to allow any water from the glue to evaporate off the wood. When first glued the panels have a swelling like a mountain ridge and if you were to plane or sand it flat, it then dries leaving a valley.
Love the evidence-based approach to woodworking, Suman. Could you put error bars on your averages in future? It's important to see how much variation is caused by the test variable relative to uncontrolled variables.
Yup- I’ll need to include error bars in the future bc folks are really interested in the spread.
and do you suppose that information would at all impact your decision when it comes to gluing? I doubt it.
This is an excellent video on glue ups. I usually wait at least 1 hour before handling or working with glued material on fast moving projects, but now will wait longer after seeing you video. Thanks a million
A lot of woodworkers suggest clamping for 1 hour, but then not stressing it for 24 hours. Curious how those results might fair
But from this - I guess it'd be not much different from the hand clamp test! Interesting
You mean the directions on the bottle that he quoted and then summarily ignored?
I'm a cabinetmaker.
When I was an apprentice, and going to trade school, I was taught that a properly glued joint (not too much glue, not too little) needs to be in the clamps for at least 10 minutes. And properly clamped of course. So not too much force, where you're squeezing all the glue out, and not too little force, where it's not even doing anything.
In practice, I like to keep clamps on at least one hour. If it's something big and complicated, I leave it overnight.
It's also important to note that regular white PVA glue is perfectly strong enough to use for furniture, as long as the joints are put together as I've described.
Yellow glue, or "carpenter's" glue, also known as aliphatic resin, is typically a stronger adhesive, as it's meant for structural purposes.
Titebond III is an exterior PVA, but I've noticed it is thinner and runnier than regular PVA, and it definitely needs more than 10 minutes in clamps.
Great video quality
Amazingly detailed video. This is going to save me so much time (and clamps) for future projects. Thank you Suman!
Thanks Blake! I can’t wait to see the bull weave sculpture!
Really love your channel. I personally believe that curing time matters more than clamping time. Another video perhaps? 🙃👍
Your videos mix engineering and woodworking in a way I haven't seen done on youtube before, really enjoyed this. Keep it up!!!
Congratulations on your very carefully controlled methodology, I hate testing videos that don't even care to make sure the samples and force applied are as equal as possible, it made me really happy to see all the care you put into this, it doesn't go unnoticed.
As a beginner woodworker, I found this to be one of the most useful videos. Great work!
Your attention to detail when performing scientifically repeatable tests is commendable. Well done, and keep it up!
When PVA glue "dries" it is polymerizing. The solvent (water) evaporates, It was keeping the glue from polymerizing. It is analogous to a crystal without such a regular, repeating pattern. When the glue is drying and the polymers are accreting into a solid it forms up in a more or less orderly manner. If the pressure changes in the middle of that process, it will interfere with the orderly manner and introduce a defect in the glue. Any polymerization already finished cannot shift - it is already essentially solid. The glue that is still solidifying will be torn away from what it was trying to connect to, which creates a very tiny rift that is not mended by liquid glue. It is too small for that and surface tension prevents it from entering these tiny fractures. These tiny fractures will reduce the strength of the glue joint wherever they exist, and if there are enough of them it will significantly undermine the strength of the joint. They probably will be lined up because the evaporation happens more from where the glue line meets the air and less from inside. So there is a wave of hardening traveling through the joint, but not too orderly, probably. So when the pressure changes because you remove the clamps, you're introducing tiny fractures wherever the glue was not cured. This is better avoided by waiting long enough for the glue to cure. I don't know why TB would recommend 30 minutes. It isn't enough time if the pressure will change. The reason the hand-pressed or taped glue-ups work so well is because the pressure doesn't change.
Your joinery was very good and the extremely smooth surfaces obviate the need for high-pressure clamping. If you use wood that is less smooth, the clamping pressure helps the glue penetrate into the pores, cracks and defects in the surface of the wood. A rougher surface can result in a stronger glue joint because there is more surface area for the glue to touch, and the cured glue is physically locked into the pores. Glue is already stronger than wood, so the payoff isn't that great. But, it takes more work to make a super-smooth surface like you made, so you can save that effort for a glue up. Jointers often produce a less than furniture-quality edge, but it is ideal for glue--ups. So, the results you got were influenced by how smooth the wood actually was. That is not a problem, that is a feature, because it removed from the equation the "smoothness" or "roughness" of the wood, which is difficult to characterize. But, clamping pressure becomes more important when the wood is less smooth. To the extent that the glue is filling any gaps, clamping pressure matters more. Another reason clamping matters is that the project can warp or shift while the glue is drying. This can ruin a project. Clamping can prevent movement (if that is a goal and it is done right, of course). Clamping can also force the parts to shift, so extra clamps and/or cauls are needed to prevent any movement.
Wow, heck of a video on wood glue. You answered a huge number of questions I’ve asked myself, clamp time, fit, etc.. Great video, thank you. Looking forward to your next vid, you a great job at explaining what you’re doing, why, and the editing is very good. Thank you, a woodworker from Missouri.
Fantastic. Limited variables to 1 at a time. Love the thought out testing methonds. Just fantastic
This was great!
Thanks bud! I hope you get a much needed break for the holidays!
I like this video very much because as an engineer, this is exactly the type of experiments I'm interested in to understand why we do things the way we do them and challenge tribal knowledge or rules of thumb. I'm writing my very first (and hopefully longest) youtube comment here because I'd like to make a few suggestions that may make your future experiments/videos even more valuable.
1. Include information about the spread of your samples
Instead of bar charts, I suggest using "box plots" as they are a common way to display information about the average and the spread of the samples together. With few samples like here, you may also just overlay the individual samples over your bar chart, but I'd still prefer some of the statistics that a box plot has to offer.
Why this is important: you concluded that 4hr clamping is sufficient for you, because in average the joint is just strong enough, without considering how consistently this is the case. But would you still make the same conclusion if half of your samples are very weak and half of them are very strong, resulting in a just strong enough average?
2. Validate your assumptions
The underlying assumption you make here is that with 24hr of clamping, the joint is as strong as it gets and it is still weaker than just wood due to being stiffer. It would be interesting to see experiments with more than 24hr clamping time to validate (or invalidate) that the strength does not increase further.
Why this is important: assuming after 48hr of clamping you can double the strength compared to 24hr clamping, would you still just clamp for 24hr if you have a project where strength matters more than clamping time?
3. Separate potential causes to make fair comparisons
Your experiment with hand clamping and letting the piece dry clearly shows that there are at least two major causes for joint strength. One of them being the clamping time and the other being the total drying time. I think these can and need to be separated in that you test the strength after the same amount of total drying time for all the samples. If you can keep all the variables except for one fixed, you can show which has how much impact.
Why this is important: what if the clamping time has almost no impact (as long as there was some) but it's really only the total drying time that matters? I.e. would you still do 4hr clamping if after 1hr of clamping and 24hr total drying time you get the same strength as with 24hr clamping/drying time (Your hand-clamping experiment potentially indicates that this could actually be the case)?
When repeating such an experiment I suggest to first find the clamping time that results in maximum strength and take that as a reference. Then, try different clamping times but keep the total drying time the same as the one that reaches maximum strength before testing the samples. And in the analysis, also show the spread of the different samples ;)
This is super helpful. The 'when to take clamps off' question is something most woodworkers encounter.
Came over from Scott Walsh. Love your channel brother! You've definitely earned my sub. I know that these kinds of videos are very difficult to make and you need to take time to be with your family. No one on their deathbed is going to say, "I wish I had made one more YT video." Keep up the good work.
Thanks bud! Appreciate the kind words. And agreed- I definitely prioritize family time. Which is why my publish schedule is vary spaced out.
OH MAN. This is the deep dive I've been waiting for. Thank you for this!
One of the best wood working videos I’ve ever seen. Great job. Very helpful.
Dude thanks so much! Thank you for watching
Excellent video! I shared it with my woodworking buddies. Great information! Thanks for doing all the footwork for this data. I know all the behind-the-scenes stuff is often forgotten when we watch these videos. For us, it's ten minutes. For you, it's a huge investment of time. Thank you, sir!!
I wonder if greater clamping pressure causes more glue to squeeze out, but then if that clamping pressure is released before the glue dries/cures enough to hold the joint tightly together, then there joint has an effective glue deficit. Less pressure means more space between fibers, which means more glue is needed.
I agree, soon as I saw he had transducers on the clamps to measure clamping pressure I was eager to see variant in clamping pressures tested.
Great testing video. That took a pile of time to pull off. I appreciate the 'woodworking science'. We need more clips like these on the net. Keep up the GREAT WORK, my friend.
This was an interesting video! I liked how you did 5 samples per test.
I watched this after seeing the joint testing video you did with Scott Walsh, and you've definitely earned my subscription! I only own a few clamps and I'm definitely one of those who leaves them on overnight if not a full 24 hours so knowing this will help ease my anxiety about taking them off sooner. Thanks, and I look forward to seeing more of your testing videos!
I never leave my stuff in clamps for more than an hour or two, unless I am just going to bed and happen to leave them in clamps overnight. I also don't use excessive glue. like most people. Removing the clamps after an an hour doesn't make for a weaker joint, as long as you let the glue cure before you stress the joint. 30 mins may be a bit short, but you were also using titebond 3. Original has a quicker set time
Absolutely love this kind of content, I've thought of several tests over the years but never put the time into doing them. I definitely subscribed
I love your perfect explanation of a well executed scientific process.
From observating your experiment, I am smarter now than I was before.
Short, concise, expert advice.
Thank you. This will be my procedure going forward.
Most of my glue-ups are segmented rings for wood turning. This is useful information to me, especially allowing the joints to cure for 24 hours. This will speed up my assembly process while still producing a strong, safe bond.
I've seen a couple of your stress tests and I have one compliment on your test setup. A lot of videos that I see people doing similar tests they use a luggage scale and try to capture the readout with a camera to find the frame with the highest reading. Your setup is much better because of the peak-hold feature of your scale. LCD displays, especially on inexpensive luggage scales have a fairly slow refresh rate so the actual peak reading may never show on the LCD. The peak hold of your scale will actually capture the peak reading even if it happens between LCD refreshes. Thank you for the quality of your test setup.
Very very informative! You answered nagging questions that I’ve had for decades! No more overnight clamping for me!
Man that was a well
Conducted test. All controls were controlled and the test rig was an excellent setup! Kudos!
Thanks! Since your name is Kyle, you might like the “hidden dangers of diy” video 🤣
Love your scientific approach to woodworking issues. Very professional and informative. Keep up the good work.
Yes! You make valuable, quality video, Suman. Doesn't matter if they don't come out often. Good stuff is worth waiting for, and it can only come as you are able, not as others wish.
Very helpful to quantify the time effects of clamping glue-ups. Adequate clamping pressure, released at 4 hours but NOT disturbed for 24, and on to the next tasks. It would make sense to have left them all for 24 hours as directed, to see if it matters when the clamps were removed. I suspect it wouldn't matter so long as the glue lines were intact.
You are so right that the quality of the edge match is most important. And that means you don't need a clamp every 3 inches either. I glued a 3 piece panel of cheap wood with jointed edges for a painted sign that rotted away after 15 years in the rain, snow & ice. But it never came apart.
Thank you so much!
I think what happend in the last test is that when you released the clamps - the structure of glue was weakened by the released wood and when the glue hardened it was already damaged by this clamp-release movement.
What I find funny about this is that it tracks with my experience and practices. I always assumed cure time was the major factor, and clamping is mostly to ensure the most surface area for the glue is being contacted before it sets up enough to hold that pressure itself (how sprung joints work). I typically take my clamps off after 3-4 hrs as I only have a few, and unless the wood is particularly "featured" I really don't want to leave them overnight in those clamps.
By clamping you push excess glue from joint. When you remove clamps after 30 minutes you release pressure on wood so a little tiny gap can occur on joint, but there is no glue to fill that gap.
So it doesn't matter that you leave it for 24 hours, joint is already weak.
When you making joints using just hands or weak pressure, you don't push so much glue out from joint, you don't store tension in wood, so wood don't try to break that joint and glue can do the job. There is probably a little more glue in such joint but it doesn't matter.
10 minutes were very enjoyable and time flew by. Thank you, it was a useful video. Be safe dear friend
Thanks!
Hi Suman
Very cool that Scott collaborated with you.
You are our scientist!
Thank you
Ed😊
Haha thanks. We are friends in real life.
This was enlightening. Congratulations on your method, the editing, the data collection and everything. Awesome work
great video suman!
🙌
I just LOVE theses kind of test base video where we get to conffont our habits to rigorous testing method and growing from that new knowledge
I love Titebond III.
However, I have believed - from my woodworking experience [I used to be a luthier] and am now a woodcraftsman - that it is weak unless it is left undisturbed for 24hrs. After then, it is an excellent bonding agent, and as you have shown, only 4hrs is necessary for reliable strength.
But good to have your scientific experiments to draw from, really appreciate it.
Great work, thanks.
I am pleased that I came across this video. It answered some of my questions about the strength of glue joints. I would like to see the exact same test on a series of boards with one difference. Instead of clamping for a time period and immediately testing the strength, I would like to see the boards set aside for a week, (and possibly other intervals of time) before testing the joint. It is my understanding that curing time is a crucial component in joint strength.I would be surprised if you found the differences to be the same after a week. I have restored furniture for years and have found that clamping for at least an hour works well enough for me to use the glued up pieces in further construction, yet it takes a long time for the wood joint to really cure properly. I wouldn't want to stress any joint that I had glued for a long time. The glue contains water or possibly another medium which does alter the moisture level of the wood. I have never seen any tests that determine the moisture content in the wood before and after a joint fails. You have definitely answered some of these questions. I am greedy for more.
Great video!!!! I am in the middle of a glue up and got curious. It’s awesome to see someone cover a topic in such detail. Thanks for the info!
Edit* I probably shoulda finished the video before commenting haha. In any case, I'd be interested to see the differences anyways!
Amazing video! What I'd be interested to see is this same test, except instead of trying to break the joint immediately after the clamps are removed, let the glue fully cure
To avoid confusion here's an example. Clamp the wood for 5 minutes, remove clamps, and let glue cure for 24 hours. Come back and test the joint.
Agreed. It would add more value for sure. Just didn’t have the time or capacity to double up production schedule for this video.
@WoodcraftBySuman I edit my comment if you didn't see. I should be more patient and watch the full video before commenting haha.
In any case, I completely understand. I have some limited content creating history and I know first hand the limiting factors of being small and just not having enough time to do everything you'd like to do! Still, amazing video. Youve just gained another sub for what it's worth 😊
@@PureNrGG haha thanks!
I'm not a wood worker but this info will be very helpful in the future. Thanks for the video!
Saved me a pile of testing , thank you. I am also sharing because I think someone who takes the time to do testing is a valuable asset to any wood workers out there.
Appreciate you! 🙌
Such excellent work! This is the kind of research the world needs!
Great test and convincing presentation. Thanks from a Germany engineer and amateur woodworker.
To me the most interesting element of these tests is the no clamp test. I've seen some great videos discussing clamp pressure.
Over time I've reduced my clamp pressure. I now clamp to achieve squeeze out and typically unclamp after 20 to 25 minutes and put the piece aside over night.
Agree, when releasing the clamps wood have a tendency to "swell" if I can put it that way. and well half dried glue the stretches and creates air pockets or pulls away from the micro bonds its made with the wood.
I've been making panels out of pallet wood. Planed faces, some bowing, heated but not too warm shop, Titebond 3. I have have a limited amount of clamps etc, so I can only do 1-2 panels at a time.
I leave them in clamps for about 90min. After that they are pretty solid, but I can still easily scrape the squeezeout off. Next day they are good and ready to go in the planer. I have done about 30 boards like this and so far no problems.
Excellent video! Well presented and thoroughly thought through.
Excellent tests! For decades I have suspected that clamping is mostly insurance of the tightest possible joint for a given glue up and this seems to confirm :)
Interesting! I can only guess that on that last one, when you removed the clamps, the connection was partly separated. The one you just "hand-clamped" was left to rest over night without any stress. Keep up the good work!
Great presentation!!! I agree that most woodworkers will opt for an overnight clamping. It is my understanding that your test method is to clamp for X amount of time and stress test shortly after unclamping. As the Titebond label states, “Clamp for a minimum of 30 minutes” and “Do not stress joint for 24 hours.” If possible, can you please do another test with the same clamp times but with a stress test after a total clamp and cure time of 24 hours.
Great video, thanks so much for taking the time -- very useful and interesting, but with a "real life" competing for your time, impressive you were able to do such thorough and careful testing, and then the video editing.
It would be nice to see the range of the results on the graph as well.
Nice well paced presentation with excellent test based info on glue/clamping strength relationships. First time on your channel, wil be back to learn more. Thanks for sharing.
The hand-clamped joints left more glue in the joint, which pulled the wood together as it shrank while drying. The clamping process squeezed most of the glue out and glue was wiped away. As that tiny amount of glue shrank, it was replaced by air, which is weak as you can get. Thanks for this excellent testing !!! 😊
Should have mentioned the spring-back / rebound of wood after removing clamp. With no force applied this rebound would suck in air, since all the glue had been squished away. Having excess glue would pull the wood together as it shrank, and because of extra glue, no air gaps.
I used wood glue couple times without clamp. I noticed glue has a tendency to pull itself together in thickness dimension and push the joint apart which leave the joint without fully glued after dry.
such a great video Suman... i definitely learned a bit. your approach and execution of these tests is nothing short of amazing.
I usually leave the clamps on for 4-6 hours. Also, I stress to my viewers not to use an excessive amount of glue or too much clamping pressure.
Love it! At some point, I have to test glue quantity and clamping pressure. There are some questions, especially on glue starving a joint that needs to be seriously considered. I think the 175-250psi recommendation by titebond is wayyyy too high.
I love the scientific approach you've brought to your channel. There are so many possibilities for things to test in the shop, I always look forward to what you'll test next!
Great testing. Another factor I have found (50 years since I was an apprentice) that you mention is glue line thickness. We used to do panels with no clamps - rubbed joint. It would interesting to compare - several panels clamped together and several with a rubbed joint. For those unfamiliar, take the 2 pieces with good glue joints, glue the edges and press the joints together to ensure glue spread and also squeeze out any excess glue (with experience you should be able to apply just the right amount of glue for a .003 to .006 thick glue line) then stand the “panel “ on edge allow to dry. For wide panels lean 2 sticks against the wall to support the panel at a nearly vertical angle.
I love these kinds of videos. I need to make a setup for testing like this. I've had some glue joints that I couldn't get apart after 10 minutes and the only reason I can think of that is because it was summer in Colorado and it was very dry. I realize the wood wasn't aligned properly and took a hammer to it and that sucker would not move. it always feels like I have 5-10 minutes, when there's low humidity, before there's no undoing the joint without breaking the wood.
the hand-held joint was the coolest finding of this. I had seen some youtube video where the person would just hold two pieces together and that was it, no clamps. It seemed crazy, but now it doesn't seem so crazy. I had assumed the person had done it before and knew it'd be fine, but this shows it's fine with lightly used things.
Temperature is a huge factor. Also the jig was designed to really force these joints to snap in a hurry. I made it that way because I wasn’t sure if my scales would max out before joint faliure. And keep in mind, the test pieces are pretty small compared to most glueups with mich larger surface area involved.
Subscribed after seeing the Scott Walsh video "This Simple Joint is Stronger Than a Dovetail!" Thanks for the content!
I saw somewhere on TH-cam this tip: rub two small pieces of coarse grit sandpaper together, say 80 or 100 grit. Sprinkle just enough of this grit in a couple of areas where the clamping force is greatest. The idea is to compress the grit into the wood so that there is no gap created by the grit.
thanks. really well done. releasing clamps after 30mins releases pressure and weakens the glue. Personally I: put a few clamps on & leave them on overnight.
That’s a great video on glue ups, I’m curious about the warnings of over tightening your clamps and having too much glue squeeze out.
Great info, you saved a lot of extra glue time, and clamps. I always wondered about using tape on glued miter joints, now I see some proof thanks to you.