Staples

Ladies and gentlemen, we got him. Another machine made almost exclusively out of sheet metal. Staples are really in the best category of objects because you understand them immediately. But if you leave them on your desk, you'll keep noticing important details for weeks. But there's one thing that bothered me, and that's that you can't actually see what happens when you use it. So we're making a big one with a transparent front so we can look at it with a high-speed camera. Let'start with the thing that got me to make this video in the first place, which is my love for sheet metal mechanisms. Look at this little slider, for example, that keeps the stapler closed and allows it to open up for refills. And then look under here. Normally, you can't make sharp square corners on a bend. It's always rounded over. But we need a sharp corner for this slider to function. So what did they do? They made a little relief, cut it short and only bent it square and not back up again. This way, they created what I would call an artificial square corner. It's brilliant, and you can imagine doing it on a larger scale if you need that for some reason. The slider is stamped, folded over It's probably even folded And the catch is spiky But what's that? It moved itself back under the catch. That's because there is a second catch. These types of mechanisms really always remind me of how a function of an object is usually just a shape. So by being a bit clever, you can make something simple Do things It just blows my mind. It's just a few pieces of metal with a very specific shape. This old Swingline 747 was recommended to me by stapler enthusiasts, the greatest Keith, as a basis for the bigger version. And instead of a slider, it uses the axle that the spring wraps around as a click mechanism to keep it closed. And this new 747 just uses two bent tabs that fall into these little holes. Then another beautiful design on this one. You'd think that this is a rivet that's flared out to keep it from falling out. But no, it's a straight shaft and it can move a little bit. And it's held in place in the middle by the spring rod. And this rod is kept in place by the carriage. So if we move the carriage all the way back, we can bend the rod enough to remove it from its slot, which allows us to remove the main axle. And then the whole thing comes apart. It's held together really quite elegantly, I think. Time for the anvil, the thing that bends the staples. The staples are bent inwards for a permanent connection. Or if you rotate the anvil around, they are bent outwards for a temporary connection. Because you can pull them out sideways as the staples more of a squiggly line than a closed loop. And now we actually want to see the bending action happen, of course. So let's make a big stapler. If you want to see the full bolt process from log to stapler, you can do so on my other channel, No Home. One of the trickiest part for me is of course the anvil, because I can't make it out of wood. That's where the sponsor of this video comes in JLC CNC. I designed the anvil not just to be bigger, but the slots are also open to the front, so you can hopefully see the bend happening. Then I uploaded it to their portal, got a quote, and a couple days later it came in the mail, all the way from China. As fast as a three to five days, they say. I forgot to press record when opening it, so here's the reverse footage of me repacking it. Look at it! So nice! They do all kinds of materials, but I just went with a random steel, because it doesn't need to be extremely strong or lightweight or anything It just needs to be steel. If you need anything in a CNC machine, JLC CNC can do it. Simple, complex, one-offs They have three 5-axis CNC machines. Three axis machines are X, Y and Z, as you can imagine, and five axis machines generally add two rotation axes of the part to be able to come from different directions. Yet a $70 coupon by using the link below. Thanks JLC CNC for sponsoring this video. Then we obviously need to make some staples! Let's take a look. They need some kind of way to share off of the strip one by one. I always thought a staple strip was just a piece of sheet metal that was almost cut through, but if we look at it under the microscope, we can see that they are actually glued together. On these staples, we can actually bend the strip that gives the used a flexible glue. These strips are glued together as long wires before being cut and then bent. Otherwise, you'd never be able to get them cut at exactly the same length as this. Not to mention the hassle of dealing with individual pieces of wire. No thank you. Order of operations is everything with stuff We can also see that the staple wire is wider in one direction than the other. That's to make sure it bends inwards or outwards and not forwards or backwards. And the tips are cut with a cutter that has a stupidly low bevel angle, even lower than my wire cutters I think, and in the case of staples, that's actually helpful, because they become sharp just by cutting them. In my big design, I left the staples attached with a little tap of metal instead of fussing about with glue. I first did a test with increasing the size of this little tap and 0. 3mm seemed to work, partly because by bending the metal, the corner needs to stretch, becomes smaller on the outside and already tears the tap halfway through. I thought that was a really neat detail. With an enormous laser, we cut a piece of sheet metal into strips that were connected with these tabs and then they were bent into an actual staple shape. This was just at my local metal workshop. Great guys. Alright, let's load it. Set up the Kronos 4K12 high-speed camera. Thanks Chrono Technologies for sending it to me. And then the first test at 1000fps. Blah-bam! There are parts that do work. It pushes the staple. The staples release from the strip. There's enough power to bend the staple. It even has enough power to destroy itself, I see. One thing I did wrong in my design of this apple is that I made these slots way too small. As you can see in the real one, the imaginary circles would overlap by quite a margin. That way the staple has to bend less sharply, which costs less energy. And you have more wiggle room to hit it in the right spot. For the one I made, I have to hit it exactly right, otherwise it doesn't work. And as you can see, it hits somewhere else. My staples are also way too flimsy. They go into the wood a little bit, sometimes. The reason it bends too quickly is partly because I made them too long. I wanted to staple big pieces of wood together and needed space to fold them over. But what I didn'think of is that when you double the length of a col And again! Clop bam! Clop bam! Now in close-up at 11,000 frames per second for good measure. One interesting thing you can see is that my big staples really bend quite nicely along the curve of the anvil, while a regular staple seems much more flat. Although not always. If you look closely at a paper under the staple, you can see that it must have moved the tips of the legs in, while the staple bent from the top corner. And the paper is not strong enough to hold it in place, so it has a little bit. But if you take multiple layers of paper, then it suddenly is strong enough to hold the legs of the staple in position. And then you can see that the staple follows the curve of the anvil. I told you, details were weeks! One thing that you can see quite nicely is how the driver pushes the staple off of the strip. In the Boss Stitch, the 747 Retro, and the big one, the driver is simply a bent piece of steel. On the old 747, you can also see that they just push on the legs with these pokey bits on the side. They ignore the crown as much as possible. On the new one, however, they just have a little bit of a divot in the middle. What's more interesting, however, is that it's not fixed in place. You can see that the top makes a rotating motion. You can actually see it really well on the big one, because I put the pivot point a little bit too high up. I had quite a bit of problems with that. Unless, of course, you just don't attach it to the pivot point and make it follow a straight channel instead. Another thing they did in this newer one is that they gave the bottom stapler holder a spring too, to make sure that it never truly binds up. Then, one of my most favorite parts of the machine, the spring that pushes or pulls the staples forward to reload them after you used one. There are two widely used methods to push the staples forward, a compression spring and a tension spring. I think the tension spring is much more elegant. Look at it. It opens itself. No need to fiddle around holding it in position in order to get new staples in. Now, the problem with the spring is that it takes up space. And you can see that in the Bosch stitch, which uses a compression spring, where only about half the magazine is usable because the spring cannot compress to zero. In a tension spring, the same thing happens, but just in reverse. So it couldn't easily pull something all the way forward. Not to mention that it would be in the way to load the staples. The way to fix both of these issues is to fold it over and connect it to the top. So it only ever has to string to half its size. And because it's connected to the top, you move the spring out of the way and even pull the carriage in the other direction. I love it. One important detail is, of course, to make sure that the carriage is properly held down. Something I forgot to do with my big stapler. The spring pulls or pushes on the carriage, which only has two noteworthy things. The first is that the spring is mounted on the back so that it can push past the folding point of the spring. The second is that it only pushes against the legs of the staples and not against the top of the crown. You can see it very clearly in the Bosch stitch. As a staple moves down, the crown loses contact immediately. Well, the legs almost act So if you press on the crown, you get all kinds of funky stuff happening. Another feature that most staplers have is that you can open them all the way in order to tack something to a pole or something Tacking is a term for stapling when you don't bend the ends over. If you do this a lot, you might be tempted to start swinging it around And they are not made for that. However, this one is. And it's really nothing special. It's just a bit beefier and heavier on the end. Very handy if you're building with these large sheets of vapor barrier stuff, for example. But some things can't handle a hammer blow. And you'll see that by pushing, it often bends the staple instead of going in. Introducing the tacker. This uses a spring-loaded mechanism to shoot the staple into the wood at a very high speed. The reason that a tacker can shoot staples into harder materials is firstly that they generally use thicker staplers. But even if you could use the same staples, a tacker would be able to penetrate slightly harder materials because of two reasons. Inertia and strain rate. For a staple to buckle, the middle needs to accelerate sideways. And the faster you need that to happen, the more force you're going to need. So at really, really high speeds, staples and nails resist bending just because they don't want to accelerate sideways. Strain rate is a bit more fun, even though I believe that it plays a lesser role. Materials behave differently depending on the speed at which you try to move them. Ooblak is the most famous example, of course. But low-carbon steel that staples are made from also becomes slightly stiffer at higher speeds. However, so does wood. But we would need to keep in mind what our failure modes are. The staple fails when it bends and it will never fracture. So a stiffer, slightly more brittle staple is fine, because it will never become brittle enough to snap in this scenario. The wood, on the other hand, is different. First of all, we want it to fail. And right under the staple, we are breaking the wood. We don't want to waste energy by bending it. So you can imagine that stiffer wood helps with penetration. Today's homework is to find a sheet metal mechanism and explain some interesting detail about it. You can do that in the Discord Homework channel. I will link it in the W. And I'll Oh, and don't worry if you see this video I would still love to hear about it.