[MUSIC] [Music] all right, folks? Eric Wooldridge here With the additive Guru Channel. And today I want to take a quick little moment to talk about some of the science of FDM production and some of the common terminology, specifically, we’re going to talk about the shells associated with 3d printing, so shells can also be associated with the internal wall thickness. If we look at this little test cube that I have it has the design of it is has a certain design of wall thickness. However, what goes on the inside could be totally different from what we see on the outside and what goes on the inside has a significant difference in the overall performance and shell’s control a lot of that one of the things to keep in mind in terms of object, performance and object strength is that it’s all about the extreme skins, For example, when we’re bending something we’re pulling on something. It often has a lot of failure associated with the structure right in these zones, not so much the middle zones this is can be seen in a lot of our building construction stuff. For example, we don’t build a lot of beams just out of solids when we can build them out of shaped steel like this. So for example, we don’t do a solid steel block to make a beam. We make a beam, looks like an i-beam or W beam where the concentration of material is on the extreme points and there’s not a lot of useful or there’s not a lot of actual wasted material. Put in here, so Shell’s matter to our production. Symone, zoom in real quickly! We’re going to just do a test run to. I’m using cure for the example and a good old fashioned test. Keep and I actually have this cube set to one shell. Now what it is is if you look closely and it building up, you can see right here that there’s one wall and there’s another wall moving in closer, so there is a wall here, and there’s a wall here and notice the rest of it is infill in between okay now. Watch what happens when I go into my settings and I can change this by going into in Kira to my little edit button right here, and I can choose the custom option down at the bottom, and then I can choose to expand or contract. All of these different features. The one I’m longest change is the shell. Now there’s a lot of options here. We can actually just set it to 3 and notice the has a little pop up, but notice when I do this, we have a have a change in wall thickness. It other kinds of things 3 is the quickest example to show this, so I hit 3 It slice slices and we’re back in preview mode and look, you see that there is one two three, four five walls from one side to the other. So now this entire wall is one solid wall, not an edge and some infill in between watch. What happens when I change it it to now we have five steel. We may say well. It doesn’t make any sense. How’d you get that? Well, it’s because of the fact that this things actually filling in from one side or the other, and sometimes there’s not enough space to turn around and actually do a infill, so it just adds another wall. I switch it back to one, and so it’s providing a wall again here and here, and that’s one thing you have to understand. In terms of shelves. They work from wherever there’s an open space, so for example, on the outside. It is going well right here. It’s going one shell in and this was open the design, so there’s one shell we change it to two shells, and then it has to add in one shell, the other shell one shell, the other shell and again there’s not enough space for an infielder, even matter, so it’s actually adding in a third shell there. Let me give you a different part, so you can see a little bit more. Clearly there we go now. I’ve brought in a solid cube in terms of design and so the SDL itself Looks like the outside solid as you can kind of see there. We run the slice with two shells or two wall counts. You never switch the preview and you see what happens. All of this is infill. Here’s your two walls. So that’s interesting. Let’s change it to six, and now we see that it has six shells. So what am I doing And by increasing the shells? I’m basically increasing, and it’s which is ten. I’m increasing the internal wall thickness of the design, basically, the distance between solid wall structure and when infill starts to kick in, they may say. Well, why don’t we just do it as a solid well, that sort of wastes material in terms of object performance again going back to that example of an i-beam, they’re shaped this way because we don’t really get a lot of benefit out of this zone or this zone. In terms of a beam’s performance, it’s more about the extreme perimeters of an object in terms of performance than it is in the middle now in terms of compression. If you’re just pushing down on something, yeah, the more material you have the better it is, but a lot of times our parts aren’t just, you know, surely in compression, so I say all that to make you aware of how you can go in and actually modify your settings within your individual slicer and get an optimized strength, you may turn around and produce a lot of shells here. Typically, we range from 4 to 6 shells, depending on our situation if it starts failing beyond that, then we need to do a redesign in terms, our overall shape and the infill pattern can be addressed. And, you know, we have another video for that, but for right now you want to play around with these shells to optimize your internal strength Now, just so, you know? How wide is it from here to here? Well, that depends on the number of shells and also the size of your nozzle. So this is your. Fdm system nozzle and it’s got an opening, which most of them do average at point zero four. Then your shell. Wall thickness is four shells times point four. It’s a very bad point. Four point four equals one point six, So my wall thickness would be roughly the nozzle size times the number of shells now. This is not an exact because there’s a little bit of squish factor sometimes that occurs, but this gets you pretty close to the ball the ballpark. Now you may also notice that there is the bottom, and you know, bottom top thickness, and that is also essentially the number of shells that puts on the bottom of the part and eventually the top of the part. We can see that real quickly. I’ll preview back down and it. It’s hard to actually tell, but it’s actually increasing the number of times that it goes from one layer to the next, so we can change that real quickly. Again you’ll notice There are factors of 0.4 because that’s the size of the nozzle for this particular printer, But I may actually step mine up to 1.6 Actually, I’m sorry, it’s not the nozzle. It’s the layer height, so we’re at points to 1.5 that kind of thing, and we generally like the equivalent of you know what we would consider for shells, even though it’s not exactly the same, so the top and bottom thickness note would be set to one point six. Maybe two point four just depends on what you’re after and that way you have a top and wall up here at the top of the cube at the bottom of the cube, a thickness wall of two point four again, this will change this won’t change, but your layer height would affect that, so they’re just using an over right here, all right, so even points out that. Hey, you’re essentially getting 12 top layers out of that because it may be set to point one five or point two, and you got to be aware of that kind of thing, but at the end of the day. What really matters in terms of your settings because a lot of software’s are different or a lot of slicing software so different is how many wall shells. And how thick is your top layer? How thick is your bottom layer or your of your structure? You can also think of it like this. If we were to cut the block open, what’s still sitting on the printbed? Here’s our side walls. Here’s our bottoms and here’s the top. How thick is this? How thick is this? And how thick is this? In our scenario, ours would be the four times point four, which is one point six and here at the top. It’s going to be two point four, and at the bottom, it’s going to be two point four. The rest of it would be in jail, so that is one of the ways that you can go in and make changes to your different software again. We’re using Curie on this to demonstrate it, but there is a lot of science and performance that’s going to be based on how thick that is how thick that is and how thick that is now. Keep in mind! The more solid. The these walls are the longer it’s going to take to print, so that may be a trade off for you based on your performance, and if you’re making an object that is, you know, just aesthetic and pleasing. Maybe it’s a vase or something. Then you don’t need to set it to a four wall count. You might get by with just two or three, and that way you have at least enough strength to handle it being knocked over something, but nothing really really pressing. Also if you set it to one, then you might get more of a transparency effect, which is often desired in certain applications. So that’s the kind of thing you have to play with anyway. That’s the concept of shell counts or wall thicknesses and what we recommend is go get a cube of some type calibration cube. That’s providing some of the files or just don’t think your verse wherever and play around with these features. Again you go in. Kyra, you go down a custom and expand the shell wall, and I’d like you to play with changing the wall. Count and checking out the preview, so just essentially do it. I’ve done so that you can get a feel for it. Hit the slice, switch to preview mode so that you can see it and experiment with that. All right, so that’s it for that one. We’ll see you next time.