#SaveTheAnkles

I think it's the depth that matters. The grain will always fail before glue. Mortise and tenon digs deeper so there is more grain to resist failure as well as moment of rotation. The dominos are rather shallow. If the dominos extended deeper into the wood, it might be stronger.

I'm just happy you're OK. Both joints are clearly strong enough for their intended purpose.

In my experience the wood ALWAYS fails before the glue in the short term, but some glues get brittle and fail over time (you see this in old furniture, especially chairs.) The "over time" part matters with doors because their joints are basically under constant pressure from the moment they're hung.

The mortise & tenon went in deeper thus had more viber to carry the weight

Very interesting test. I will go with the mortice & tenon because I don't have a way to justify the funds for a domino, but will admit I have lust in my heart for Festool. As I am approaching retirement and will have more time than money, I will be happy sticking with the old school way to make this joint. I have only made one door (exterior basement) and it is still swinging. Tite Bond III if anyone is wondering.

It looks like with the traditional mortise and tenon, your sides around the mortise are thicker. If you made the mortise and tenon with traditional proportions like thirds, you have a third of the thickness on each side of the tenon. By doubling the dominoes, you only have a quarter or less on each side of the dominoes.

Awesome video!! Also, the tip about mixing a little extra epoxy to check its setup is something I never thought about. Stashing that one away in the ol’ tool belt. Also, also, yay hypotheses 😂 Glad I found your channel, man!

@ENCurtis I just stumbled upon this video you have done. Very interesting video here. I am late to this party, April 2024, but after watching this video and reading almost all of the posts from the viewers, I have a few bits of woodworking that a retired tree killer can impart. @ 2:58 you are showing your stile and rail sample pieces after being machined. They appear to have been made from Tulip Poplar. Poplar is considered a hardwood, is very srable, lower costs than oak, and it has excellent machining properties. It is an excellent lumber to use if you plan on applying a paint finish. The reason that there is a need for fastening devices, is the adheasive used to hold two pieces of wood together, no matter the type and or the brand of adhesive that is used, CAN NOT SUCCESSFULLY BOND THE WOOD GRAIN TOGETHER WHEN THEY ARE AT OPPOSING DIRECTIONS. If the grain was oriented in the same direction any glue would be sufficient, all by itself. The exception to this would be if you were trying to glue end grain to end grain, OR AS IN YOUR SAMPLES END GRAIN TO VERTICAL GRAIN. Since this would be totally impractical, a millennial of time ago some wood butcher invented a practical way to join two piece's of wood without any glues. Ever since then any one else doing the same thing always tried to improve on that idea. Some failed and some did make improvements. Fast forward thousands of years and there are hundreds of ways to SKIN THE PROVERBIAL CAT. Many ways today require glues. If you are trying to mimic the joints in a typical stile and rail interior door, your lumber should be aproxamently 1 3/4" thick by 5" wide. No matter what type of fastening you plan on using, YOU MUST ALSO CONSIDER THE MACHINING REQUIREMENTS FOR ANY WOOD OR GLASS PANEL THAT WILL BE INCORPORATED INTO THE DOOR. These machining requirements may and will dictate the size and location of fastening devices like tenons, dominos or dowels. Tenon and domino thickness or dowel diameter should be aproxamently 1/3 the thickness of your stiles and rails. Tenon length and mortise depth should be aproxamently 75% of the stile and rail width. Tenon width should be aproxamently 75% of the stile and rail width. Tenon should have rounded edges. Mortise should have rounded corners to prevent possible splitting along the square corners. This type of joint can be fully assembled with either glue, or by using 1/4 diameter wood dowels/pins thru the mortise and tenons. If your preferred method is to use dominos, I have no knowledge of what sizes are available. But one of your viewers noted that they were designed for alignment only. On your sample 6 dominos removed too much material and caused the stile to fracture on the outside shoulder. A row of three dominos would have left a larger shoulder thickness and a much stronger stile. Can you get and machine for a domino that is aproxamently 7 to 8 inches long? This type of a joint must be fully assembled with glue. Door companies have been using dowels for a very, very, very long time. They have been using typical 1/2" to 5/8" diameter by 7 to 8 inch long dowels, fully assembled using glue. Great video with lots of information to ponder! Keep up the good work.

Nice tip on the making extra and the reason why. Awesome

Be interesting to see using the DF700 (BIG DOMINO MACHINE) with 140mm (5.512in.) long. That would get you closer to "same - same" testing (depth of tenon to depth of domino) Also could try to clip off the tenon and mortise of both of the "straight grain" pieces, add the big domino in place and try to break your ankle again...:) Probably best not to try this anymore and I think for most of us, either one of these is going to be plenty strong as no one with any sense will construct a cantilevered wood joint without adding a brace, cable, chain, etc., etc. for the obvious reasons. We (the subscribers) do learn an awful lot from you with the simple and explicit knowledge you pass our way... many thanks to you for all you do!

Erik! Was on the edge of my seat the whole time! I’d like to see the BTS video of that! Great video!

OK, that was fun! I am fairly certain the choice of two rows of dominos weakened the mortise side of that joint. The distance from the edge to the domino was thinner than the distance from the edge to the mortise in the other case. That part of the wood is what failed. I also agree that the depth of the mortise gave it an advantage, but that's probably not significant in this failure. IMO!

I think the wood around the mortise was thicker than around the domino, thus giving it the advantage. Obviously both are strong enough to do the job.

Maybe the shallow depth of the Domino gives you a double-whammy. What failed looks like the vertical piece. Pushing down on the horizontal piece make a lever with the fulcrum at the shoulder and the dominoes on the other end. For a given length you push down on, a shorter domino gives the lever more mechanical advantage. I think what may be giving the double-whammy is that the shorter tenons distribute the greater force over a smaller area, which would be more tensile stress on fibers . But I dont have your tenon dimension, and it's possible that your double rows give as much if not more area. The round edges would also tend to concentrate the force. The female sides "blowing out" are consistent with the dominos being driven down like a splitting wedge. Big picture, though: if that's what you had to do to break the joint, nobody's coming through your client's locked door without a key or a ram.

You were right the first time in the theory vs hypothesis contention. hypothesis: set forth as an explanation for the occurrence of some specified group of phenomena, either asserted merely as a provisional conjecture to guide investigation (working hypothesis ) or accepted as highly probable in the light of established facts. Theory: def. #2--a proposed explanation whose status is still conjectural and subject to experimentation, in contrast to well-established propositions that are regarded as reporting matters of actual fact. Great test..Both joints are strong enough to keep a door intact, unless a 7.0 earthquake hits, then you grab the nearest mortise and tenon door for safety. Dominoes are probably faster and, as other have pointed out, size matters, and they take less skill.

Fun video. Maybe a little closer to the ground next time!😀. Honestly, I've seen a bunch of these and I think the answer is: they're both plenty strong. Keep the content coming; we love it!

If we weren’t dealing with a natural product the outcome could have gone either way. Being someone who has trimmed trees for many years what’s evident to us on the outside is not always the reality of what’s happening inside. However I totally enjoyed your ninja like testing to prove or disprove your theory. Hell this is just good clean fun. Thanks

An interesting and practically test. (1) I think your point about the grain structure of the board that broke apart is sound. In another test, the pieces of wood being tested should be cut from boards with the same wood grain orientations, if possible. (2) If you calculated the total glue surface of each joint, you might find that the glue surface on the single, large tenon exceeded the glue surface of the smaller, multiple floating tenons in this cases. I'm not sure about that, but it would be relevant to the test to determine this. One way to address this is to calculate the glue surface of the entire set of smaller tenons and then cut a single large tenon so that it has the same total glue surface. Testing two joints with the same glue surface area would be a more direct test of the soundness of each type of joint. (3) Work to ensure that the tightness of fit of the large tenon is the same as that of the floating tenons. (4) Equalize the length of each type of tenon to see if this affects the relative strength of each type of joint. The simple fact that the single tenon was longer gives it added resistance to cantilevered force. I don't know what the results of a test using these added controls would be, but it would certainly be interesting. Thanks for an interesting and thoughtful video.

Fascinating!! Thanks for this!!

Cool test, thanks for sharing. I think with the mortise and tenon the tenon was engaging more of the wood across the grain, the domino joint was only engaging an inch of wood grain? That would make a big difference in strength.

Love the video and I think your intuitions are very incisive. Ever read Understanding Wood by R. Bruce Hoadley? An old carpenter gave me his copy and it is wonderful.

Length of the tenon. Japanese makers do mortises so deep that you can see the light shining through the bottom for the added strength of an additional few millimeters. By hand :)

From the perspective of someone comming from physics, i clearly see an advantage in the length of the traditional mortise and tenon. If you draw the forces for both systems, it's clear that for the longer mortise and tenon, there is less pulling force on the grain that got ripped apart in the domino joint. So if this is the weak point of that joint then it makes total sense that the mortise and tenon was able to hold more weight simply due the the higher leverage it had and the smaller forces this puts on the grain that failed. It's simply pulling less on that grain.

Great video Erik, really informative. One question though: Why did you choose epoxy rather than wood glue?

Hello, TL;DR; It is the tenon length that gives the strength. OK, have done the same test HOWEVER, I did use two 14x140mm dominos using the Domi-zilla (DF700) and the traditional tenon was 70mm deep in the wood. I also used longer lengths to exert more force on the joint. Glued it all up with epoxy and stressed it. They both _eventally_ broke at about the same point. I also modelled this in cad then ran a mechanical simulation with the same results +/- margin of error. Ta, ./M

Fun to watch. I wouldn't read too much into it though because of the grain differences between the two. Ideally, you'd start with 16 quarter stock and make 8 quarter that then from same tree for each. Also, you'd do it like 10 times for each. No one has time or money to want to test that thoroughly. Also, even if you found evidence one way or the other, unlikely to change how some would do their work. Still fun and enjoyed it.

The length of the tenon is what made the difference here. If the Domino 700 was used with longer dominoes I believe it would have held up just as well.

Super interesting. Thanks jack dorsey

Apples and oranges. You can pin a traditional M&T joint for incredible strength without using glue whereas not so much with dominoes.

I liked the test; the outcome was as I would expect. My question is about use of resin epoxy. What are the factors you use to decide to use it on other projects. I can see the open time would be an advantage.

What a fun experiment this was! What I wonder now is to what extent the thickness of the remaining beam fibers led to the faster breaking of the dominoes? The beam is only as strong as its weakest part, I'd say. Suppose the tenon had been made not in the middle, but on one third of the beam thickness, would it have been just as strong? However, I'm afraid I'll have to try that myself...🤕

You just saved folks $1,800 big ones!!! M&T’s can save you money! Great video!

I believe, for purposes of making joints such as a door needs (able to withstand constant shock and live loads), the D500 is not recommended but the D700 is. D 500 is more fore case work and perhaps trim work, boxes, cabinets, perhaps desks but not tables. Chairs? What do you guys say?

I think you clearly demonstrated that the surface area of wood involved in both joints was not the determining factor for failure. It was the surrounding wood that failed, not the joint. I would say that for the boards being joined, the domino joint resulted in less thickness in the surrounding wood compared to the tenon joint. Maybe by as much as half. It would also be interesting to see how things go if the other side of the joint is vertical, so the tenon/dominos point down. Also, if you do this again, maybe have the horizontal member just 4 or 5 inches off the ground. 🙂 Fun video though.

great vid as always would love to see mortise and tenon done with no glue just dowels or a through tenon with wedge

Another solid video, thanks for sharing! Are you and your shop mates going to do any collaborations in the future?

Similar to other comments, the depth matters w.r.t. leverage, and the MT is significantly deeper than the dominos. Also, the mortise shoulders are thicker (and therefore stronger) than the shoulders around the two columns of dominos. The domino version failure is clearly in the upper part of the shoulders. Maybe a better comparison would be with deeper dominos and similar width shoulders.

you had a 6 inch tenon and 2 inch domino. But since I do real tenons and don't have a domino machine I am pleased the real tenon did so well. Thank you for the video!

Glad we could help out with this experiment!

I think the real issue is the amount of glue surface area, as well as depth of the domino mortices and corresponding tenons. I happen to be a Treeologist, by the way.

Once again a great video, thank you! Plus love the mug from Chris Pye.

Haha, I’ve used the line “it’s ok, I used to be a gymnast” way too many times myself!

The length of the tenon is the most critical difference in the two in this particular experiment, not domino vs traditional tenon. The traditional joint did better because having the longer tenon, it had more cross grain bond area.

Ahhh Yes! Sweet victory!

also, can make one extra wide custom sized domino, for a total floating tenon, and still able to take advantage of domino efficiency. and i agree that the lengths should of been the same for the two.

Thank for the video I needed that to help me understand what's stronger. By the way Philly in the building!! I never really bump into somebody out here like me that's into woodworking lol. Love you're style of work.

Next hypothetical theoretical hypothesis: Is a rounded traditional tenon stronger/weaker than a squared tenon?

I recently made a set of chairs with traditional mortise and tenon, and then right after made a set with dominos, and while the chairs are different designs they had similar amounts of joints. The dominos were sooo much faster I’m selling my square chisel mortise machine, and won’t look back at all. If a chair is put under undue stress maybe it will blow out, but leaning back won’t be the cause, it would take falling off a balcony or moving truck

Ive no clue what Im talking about but the thinner edge profile of the dominoes might be concentrating the force into a smaller area (fewer fibres). A bit like narrow chisel/wide chisel. Ofc depth, thickness from motice to shoulder edge, grain, defects etc are all possible factors. PS I was however sitting here thinking that M&T looks looser.😂

Cool experiment. If you do more like that in the future, you could screw a 2x4 to the oak posts above your head like a pull up bar. Might save an ankle.

Like the video! One thing I noticed before you glued up is that the tenon was longer than the dominos. Would the domino joint be stronger if you used longer dominos? Would you even be able to use longer dominos or is that a limitation of that system?

Fun Video. The REAL question: is an ASSEMBLY ( multiple rails and (2) stiles) sufficiently rigid with either connection? I am leaning toward a definite MAYBE, regardless of grain direction. A person could really go down a rabbit hole with this one 🤣🤣

thanks for the tips

If you had asked me before the test I would have said the mortise and tenon would be stronger. It just looks more solid and beefier to me.

I think it was just a difference in leverage... dominoes only had 1 inch on insertion to counteract the lever arm while the tenon had more than two inches. Imagine the fulcrum at the deepest part of the joint, and you levering against the grain strengh nearest to where you were applying pressure.

would the tenon be stronger if you doweled "through" it? so once in the mortise you'd then dowel through the face of the board through the tenon and out the back of the board? would give it a lot of "shear" strength when given lateral force would it not?

How long did it take to complete each joint including layout. I’m old school and have a Delta mortiser and tenon jig. Presumably once set up would cut all four joints without layout. Cost 20 years ago for both….maybe $400? I know my 3 hp Jet table saw cost less than a Domino.cheers

Well, I guess that's why old time woodworkers used mortise and tenon joints instead of Dominos!

Exactly how strong does a joint have to be? Which joint was easier to make? Quicker? Asking for a friend.....

I make a fair few interior and exterior doors, mostly with the Domino. Where that sort of strength is required (which is very seldomly) I use 100mm long 14mm wide Domino’s…..using the short 60mm ones gives little penetration and fibre support. Very good video otherwise. PS: I’ve never had a door or wooden gate fail with Dominos…..never.

I am looking at the failure from an Engineering perspective. The bending moment creates tension at the top of the joint and compression at the bottom of the joint. The dominoes and the tenon resist shear. The tenon has a larger shear area and is stronger in shear. The failure was not a shear failure. If you had used only the top two dominoes, the failure would probably have been the same. The additional 4 dominoes did not significantly increase the strength of the joint for configuration of this test (bending moment the direction tested). It appears that the noises you heard were the beginning of failure parallel to the wood grain and not of the glue joint. This certainly appears true with the ultimate failure of the dominoes test. I suspect that the tenon did a better job of load sharing on the wood after the first cracks were heard because the tenon has a significant bending strength in itself. The dominoes do not have this inherent strength, Ironically, if you had used just the lower two dominoes, the joint might have been stronger. This is because: 1. There was no shear failure. 2: There would have been no interruption of the grain at the top of the joint (where failure began)

I am embarrassed to say how much I enjoyed this video

I’ve never used epoxy for glue before…hmmm. Also a thought about glueing with epoxy… in a mortise & tenon joint… could the joint be even stronger if you purposely “dovetailed” the mortise just a little. (Have it tight at the shoulder, but open up the bottom just a little). My thoughts are that since epoxy can “fill gaps” that this would almost create a “dovetailed mortise and tenon” lol. Just rambling, but anyone got any feedback on this?!

Sorry to complain, but I have dyslexia. So, I try to freeze the frame to read your IVCs. However, you leave your comments on the screen for such short periods that sometimes it takes me multiple tries just to catch it... diminishing the enjoyment I get from your content. Other than that, you are one of the best I've ever watched.

Is it possible that the grain gave way because the dominoes don't go as deep as the m&t? As in the m&t has support further along so the wood grain. An spread the pressure

I will always take Mortis a tenon over dominos anyday. But then I work with hand tools exclusively.

I had a feeling the dominoes would fail because they’re so short compared to the tenon.

I hypthesize that square tenons should be even stronger because they offer a larger surface area in all, and more surface area and material perpendicular to the force exerted.

I don't know if you are familiar with Project Farm, he tests all kinds of tools. I would have given it to him to see what the pound failure would have been. Me, since I am an old fart, more than twice your age, I would have had the support board under the beam/joint to hold it up, I would have laid it on its side, so only 1 1/2 inches off the ground. Much safer....

SURFACE AREA...The breakage occurred at the exact depth of the floating tenons...that is not naught. You sighted that the shoulder separated on BOTH...SO, that only leaves the flat-grain-to-flat-grain surface area left for support and the large mortise had, I'd say, at least TWICE the flat-grain-to-flat-grain surface area of the dominoes...AND ALSO most of that at considerably greater depth. I think that even if the grain patterns were reversed, you'd get exactly the same result. AND, I'd bet that a bridal joint would hold even stronger than the mortise and tenon did because even MORE surface area.

I wonder what the result would be in white oak/walnut/maple instead of the poplar you used.

Hi, so I'm late to the party on this video. I'm halfway through it. So my thoughts are, the traditional mortise and tenon will be far stronger. In fact a traditional full length mortise and tenon with wedges even stronger so much more glue again... the domino's are a glorified dowel. I have the machines too. The domino's are way to easy to snap. I think to give the domino or loose tenon a chance you need the xl machine and home made domino's from the timber you are using. So my guess is the domino's will tear apart. The other true test jig would be. Simulate a locked door and someone trying to kick it in. Would the tenon or domino hold better in that scenario 🤔 Might need to visit someone with a hydronic press to simulate that pressure 😅

pro tip: festool is desperately trying to shadowban this video

Great video brother

Not for nothing, but festool themselves say that dominoes add No strength to a joint, they are they are designed for alignment, and the glue is what adds all the strength to joint. It was cool to see it proven though.

Fun experiment! Love your age call out. At 42, I really hear ya. You know what's next though, scientific method says to repeat this a few times ;)

This is not a fair test. I don't know what the gluing surface area of the mortise and tenon join is compared to the domino join - let's just assume that they are roughly equal in this case - but If you compare the length of the tenon at 4:10 with that of the protruding domino at 5:05, the domino's exposed length is not even half that of the tenon. If the dominos went twice as deep, twice the force would need to be exerted on the wood member that broke in order for the member to break. Despite this, this is a very instructive demonstration although I would like to see for once a join strength comparison where no glue is used and where all parameters of the two joins compared (apart from the very join geometry itself) are kept equal.

The Mortise just goes deeper into the mating board. Longer hard wood dowels might actually be stronger.

You should leave those big Oak beams just oak grain. Get rid of the white paint that's on them. That's what I'd do

"I'm 35!" Frickin' kid.😄 I would cut the mortise and tenon out of the straight grained boards, install dominos, and try again. Also, you could build a little platform to stand on that hangs from the board, thus protecting your delicate ankles.

Is there a sudden rash of antique furniture breaking that we need stronger joints suddenly?

What about testing the joint you discussed previously where you combined a mortise and tenon with dominoes. I’m really curious if that would make the joint stronger or weaker.

America must be wonderful, to be able to use a fine piece of timber to experiment on. In Australia we have no timber industry that wants to deal in cabinet timbers, its all pulp chip wood, common pine and fast growing gum only useful for fence posts. If you are lucky enough to have a exotic timber merchant within 200 miles the price is just astronomical. So you can get a small selection of nice woods, but you would never just use it to experiment on. I would haply kill someone to get some of that Unobtanium, (the massive Oak beams and posts you have in your factory.)

Beam go right - left Column go up n down One more ting NO such thing as cement sidewalks; Portland cement is a powder that binds fine, coarse aggregates with the aid of water. It's called a 'concrete' sidewalk. U R welcome Cheers,

I think too much wood was severed during the installation of all those dominoes. You effectively turned the end of the vertical board into "particle board" with all those chips. The failure is throughout the domino's area... just like a particle board failure looks. Joint strength isn't only about "glue surface area".

No join is stronger than the weakest part! You can use the strongest glue in the world, and even use steel tenons, but if the wood is thinner on one sample than the other, it will fail sooner (assuming the wood is comparable grain-wise).

Better test would to have used wood in sillier grain pattern as the mortise and tennon

Maybe the use of two rows of domino's caused some weakness in the piece? Maybe if you had a single larger (fatter) row of domino's instead of a double row.

Make the tenon the same depth as the domino. If you are using a lever to test, then failure relies on a fulcrum and load. Both these are dependent on distance.

I would propose that the green wood is heart wood and that is usually harder and thus more brittle and thats why it broke.

A lot of fun. Thank you.

Ah dead trees, our favorite material :D

What type of wood was that. Just curious

That was fun and very interesting think both would hold up if the grain direction was straight on both ,glad you didn’t injure yourself.

Can you test with the XL and 14x75mm Dominos?

No matter what you do, a joint will never be stronger than the base material. Hogging out big holes does not help. Dominos, dowels, box joints, dovetail, ... none of them fuse together more fibers of 2 pieces of wood like a simple miter joint glue-up.

The longer tenon and consequently lever forces are in favor of this joint.

I see you're using that square that you said you never use! :)

You got a lot of nerves, or maybe not…maybe you had too much of the stuff in the cup “liquid nerves”! 😂 But your test showed that the amount dominoes put too much pressure on the grain of the fibers along with how many dominoes. Great example, glad you didnt hurt yourself!😊