What's the Best Wood Joint || Insanely Strong Joinery!

Dovetail: you are testing it at its weakest 45d angle whereas it is designed to resist pulling pressure at 90d (when you pull the drawer open). But the simple miter joint is angled to best resist your test. So part of the result is the angle of force applied by the way you set up the test. I know you are just having fun, but you might consider setting up the same test but with pulling pressure and pushing apart pressure, not just weight at a 45d angle from above.

Great video, I was missing the mitter with dowels though. The mitter was definitely not on the top of my list, but now it is, so I wonder how steonger would dowels make it.

👩‍🎓🔩👌❤

Going to start using Miter Joints for everything >:)

What about a miter joint with pocket holes outside instead of splines?

Now I want to make a stool using a Miter joint with Splines

I bet the strongest joint would be finger joint has the most surface area

Some rude comments regarding the glue...joint making. I would say, try the dovetail again, same scenario...but both boards cut to the same dimension. I would bet you get a better result. However...you are breaking these joints at an angle...so I get the mitre style joint being able to spread pressure better. I liked this video regardless of any flaws...because it does make you think about the joint for the job. Something a few carpenters tend to forget...or at least forget to ask the client when designing furniture that has to take weight into consideration. 🤔

What about 1/2 lap, mortise and tenon, rabbet, and biscuit joints? Would love to see another test including these joints.

I can explain the difference in between the butt joint and the miter joint strength. 45 degree cut of the miter joint results in an increase of the contact area by a 1.414 proportion. This would not account for all the increase. Looking at how the glue joint is loaded, there is much more shear across the butt joint as it is loaded up at a 45 degree angle in your setup. The miter joint is loaded straight up and down through the joint. The glue only has to resist enough to counter the moment in joint which is the downward load times the perpendicular distance to the joint from the downward line of action of the placed load. This is why the miter joint can be loaded so much more in your setup.

Thank you for your video. I have gotten interested in making wooden boxes, and I just learned about the miter and spline joint from your video. This joint looks very nice and strong. It also looks a lot easier to make than a box joint for someone with fewer tools.

Everything that is said about gluing end grain is wrong. How wood glue works is completely misunderstood here. It is hardly surprising that the miter cut is strong. It is because the glue soaks into the pores of the end grain that it works so well. The glue soaks into the pores, adheres to itself, and hooks into the two pieces. If the glue cannot soak into the wood, it won't bond the wood. Wood glue does not create a chemical bond. It relies on drying into hundreds if microscopic "fibers" of dried glue that span the gap.

Consider gluing two pieces of glass together with wood glue. Two smooth pieces of smooth glass will not hold. Now consider two glass pieces with hundreds of microscopic holes in them. The glue soaks into the holes and where they line up on each piece, the glue spans that gap. If the inside of the holes are pocketed and rough and the bottoms are dumbbell shaped, that piece of dried glue is hooked into the wood.

The failure of a butt joint, end grain against the face, is not because the end grain side is weak. It is because the face side is weak. The end grain fibers don't break, the face grain fibers peel away from the rest of the board or the glue, which is simply resting on the surface of the wood, simply peals away. If the glue can't soak in, it won't hole. Might just as well try gluing two pieces of glass together.

I am going to intellectually abuse the reader by repeating what he said. What he says is, "We know that gluing end grain to anything just isn't a strong joint." That statement stands as proven wrong. He proved this with the miter joint that that came is at #6, the third strongest joint. We shall never make that statement again, shall we?

He goes on to say, "Because end grain is full of all these little pores so as you apply glue to that end grain, well the glue likes to migrate away from your joint into those pores so you end up with less glue holding that joint together." None of this is correct. Do not ever speak these words again. It is clearly a failed hypothesis. I will put money down on the fact that gluing two end grains together will be stronger than gluing any two equivalently sized face grained pieces.

you didn’t do a box finger joint - I think they would be pretty strong, but a well made dovetail would beat them all as would a good dowel joint - those were both shabby examples in your test.

This is a super interesting video to show up in my feed... I'm planning to make a wooden canoe just using angles and joints... Is there a specific joint you'd recommend for my odd project? Essentially I'm planning to make the mid body of the canoe using a series of 135 degree angles, if that might change any recommendations. So far, I was figuring connecting all the planks using a series of box joints, but it seems from this I should do miters with splines instead. How far apart between splines would be recommended for connections between the sides of the lengths of the planks?

I would expect miter joint with dominos and splines may would be the strongest

Would be nice to see screws and nails thrown in as a reference of strength compared to the wood joints.

Should've had 4 or 5 sets of each joint to get an average breaking point. Doing this would factor out any anomalies from wood grain, glue coverage, or human error.

Thanks!

What about doing some of those joints plus wood screws whose heads are concealed by dowls?

Joints should be selected based upon the type and direction of force they will withstand.

I think the strength of the simple miter joint comes from how you clamp them together. I notive you added two pieces of wood to allow an extra clamp direction to push the miter surfaces together, rather than just the right angle clamp. This should be critical to the result. Hope to see another test without that clamp.

Somthing to be said about flat surface glue area

A wedge shaped spline through a miter joint 😮

Miter joint plus dowl!

I'm a beginner and I was deciding what kind of joint I wanted to start practicing and this was helpful. For me and my equipment, it's the box joint. Now I'm going to watch your video on box joint and get ready to make my first box. It will be a Box Joint box. Maybe I make a smaller Box Joint Joint Box after that. With box hinges so it will be a box hinged, Box Joint Joint Box.

Great Tests!!! Thank You!!! Pocket Hole Push vs Pull test would have reversed the Pocket Hole Test for sure. Using 5 dowels instead of 3 and would have made the dowel joint much stronger. Ordinary deck screws (predrilled with a very thin bit) are incredibly strong. The problem with screws is that they can work loose on a flexing or vibrating joint. 5 dowels on the miter joint may have been the strongest?

I would speculate that the dove tail joints acted as wedges in opening up the other side.

This was a cool video, I really think that for the next one, you need to make at least 3 of each to have a bit of a sample size to eliminate oddities.

Someone should do the miter with splines test, but cut the kerfs at alternating angles. This test in particular, it would be using some mechanical strength.

You're hilarious.
I'm going to make something soon with wood....as soon as I finish my kitchen. Took out the sink hole today, whoo hoo!
They call me Wonder Woman

You should try to do router dove tail joint, then dowels on the dove tails, then after it's all dry add pocket holes. 😂😂😂

isn't it possible that the butt joint would snap at even like 30, if given more time? like a day? I think durability will vary even more

Surface area of the glue up and the orientation of the wood grain are definitely considerations for strength when it comes to joinery, but if you look back at the box joint and dovetail breaking it wasn’t the joinery that failed but rather the glue. There is only so much pressure that the wood glue is rated to hold, and where your box joint and dovetail surfaces are not marred or torn out it is because of the glue failure not the joinery. Those are some fine examples of joinery. The miter joint and the mitered spline joint are likely the strongest joinery in your test because of the significant increase in surface area on a 45 degree miter joint and also distribution of forces is significantly altered on a miter joint.

Excellent

Wow. That dovetail wasn't built for strength. The lobes should be even. ... The kicker for me is that aesthetically it looked off-balance too. 1:sqrroot2 proportions would look better.

shouldve used titebond 3. titebond 2 is for mongoloids. Also, for the 9000th time since release, dominos are overpriced pieces of shit

It's a real interesting test with some surprising results. But most people use plywood for drawers so you should test that to with just miters and pocket holes.

When you are breaking a join, you are applying leverage forces. The fulcrum of the lever is the inside edge of the join. Max pressure of the lever is at 90 deg and most of your joins are 90 deg joins. The only counter force is the area of friction (glue) of the join, itself. Finger joins have more surface area contact between the two pieces so they are stronger. But miter joints are 45 deg joins, not 90 deg. Since max force of our lever pressure is at 90 deg, the inside edge of the 45 deg join essentially avoids the max stress of the weight being applied (some of the pressure is actually applied to pushing the two pieces together). I would still think that a finger or dovetail would work better in something like a drawer front because the stress applied there is pulling, not a 90 deg lever trying to fold the join in on itself. Thanks for a great video!

Great info, eye opening for sure!!!

I had this indica joint that was actually really strong.

mechanical engineer: my take is that the way dovetails are hand cut left a stress concentration at the inner edge of the tail (see failure pic for where it split). this is where the saw stops when hand cutting the tails. routing the dovetail would likely do a little better job (similar to box joint). altho box joint would still be better since it is shearing the glue only and not exerting a force that is splitting the tails

Box joint with a dowel right through end.

Thanks for your excellent research!
Sincerely, from a solid state physicist and engineer.

At the risk of exposing my knowledge this is my guess from strongest to weakest

1. Dove tail
2. Pocket hole outside
3. Box joint
4. Dowel pins
5. Miter splines
6. Domino
7. Pocket hole inside
8. Lamello
9. Miter joint
10. Butt joint

Thanks

How about a miter joint with dowel pins. 🧐

Be careful judging the strength of joints based only on this one test. Forces applied at various spots and in various directions may expose the weak joints and really show off the traditionally considered strong joints. This was one case only, could try hanging weights for example and get totally different results. There are shear forces (across a joint), tensile strength (pulling), compression strength (loaded like a column) and a combination of them.

Would have enjoyed this a lot more without all the creepy suggestive jokes.