87VIDEO Dowel Joint Testing

In this video I want to have a little fun. I'm going to do something here I've never done before

I don't know how this is going to turn out, but if you remember we did a dowel joint demonstration in a previous video

And these are the pieces of wood here that we joined. And as you recall they're connected with two 3 8 inch, 2 inch long fluted dowels like this

And it's glued in place. So I just wanted to see how strong this was in some numerical way

And that's the setup I've got here. I've got a scale which goes up to 440 pounds of pull

And it's anchored over here. There's a strap clamp that I'm going to tighten up

And the other end of the arrangement hooks on here. So I really don't know what's going to happen. I hope something's going to break

I hope I can pull it far enough to break. And then we can see what's going on here on the scale while we do that

I'm curious to see just where this is going to fail. And I really don't know where that's going to be

I should say before we get going, I have never seen a dowel joint fail

So in normal practice it's not like it's iffy or just barely strong enough

It's a great strong joint and very versatile. But everything does have its limits

So let's just explore the limits here. As I said the scale goes up to 440 pounds

But of course there's a lot more force than that that's being applied to the joint here because of the leverage involved

I'm not sure how many times that figure would multiply through this piece here

But well let's just crank it up and see what's going to happen

In case you're wondering about this thing, I've got another camera here so we can get the footage directly from the scale as we start pulling

But let's fire that camera up and see what breaks first. So this blue thing here is called a strap clamp. I actually use clamps like this quite a bit for woodworking

They're very useful. But let's just see what happens here. So I'm cranking this up now. We're getting some bending

Now we've got 80 pounds of force applied. So far 100. Oh! Where did it break

Now isn't that interesting? Ah, look at that. Let's take it out here and take a closer look

So it basically just pulled straight out. It pulled straight out. It tore some of the wood. Let's see if I can get it completely apart

Wow, it's still quite solid. There we go. Well it started to break that one

It basically pulled out this dowel, broke the wood that just happened to be incidentally glued between the dowels, and then sheared that one off as well

So it broke at about 120 pounds of pull, worked through the leverage of this length of wood

So as I said, I don't know how much force was on here, but that was way more than would ever be applied to this sort of a joint

And especially that kind of bending as well. The bending really added a lot of stress to it

But as you can see, a good strong joint and nice and reliable

Never broke a dowel joint in real life in my experience, but now we know at least what this one could do