Parametric Mesh Editing and Reverse Engineering for Fusion 360

JASON LICHTMAN: Hello, and welcome to today's AU class. My name is Jason Lichtman, and I'm going to be teaching you about Meshing Around-- How the New Fusion 360 Parametric Mesh Workspace Sets the Bar for Mesh Editing and Reverse Engineering.

Why talk about mesh files at all? Well, if you can tell from this Facebook forum post, we have a lot of people out there that have so many questions about mesh files. They download a mesh file from the internet, from Thingiverse, GrabCAD, or anywhere else, and they wonder, how can I edit that file? And they're frustrated by the fact that you can't edit it easily. In fact, some of the answers you're going to see from those forum posts are that you should just go and design that from scratch, just go and model it from the beginning, waste all of that effort. But thankfully Fusion 360 is going to change that. Our goal is to be able to make it way easier for you to reverse-engineer and edit mesh files like the one you see on the screen from that forum post.

So our goal is going to be to make that way simpler, be able to take away everything like that forum post and be able to make it easier. As of July 6, 2021, Autodesk Fusion 360 overhauled the mesh workspace. And as a result, you have new tools at your disposal to make everything significantly easier.

Today we have a packed agenda. I'm going to tell you a little bit about myself, the speaker. Then we're going to jump into a pretty broad topic about what mesh files are, what they really represent, and how they represent them, as well as B-Rep bodies. I will explain, of course, what that means. We're going to talk a little bit about the differences between mesh bodies and those B-Rep bodies. And we're going to explain why working with mesh files can be so difficult. Then we're going to jump right into the actual features of Fusion 360 when it comes to meshes, everything from how to import mesh files, tips for working with mesh bodies that contain color or texture, we're going to talk about repairing problematic mesh files, we're going to tell you a little bit about face groups, what they are and how to use them.

And then we're going to get into editing meshes, both parametrically and through what's called direct editing, or non-parametrically. We're going to show you three methods to work with those mesh files. The first is going to be how to convert mesh bodies to solid bodies without a 50,000-polygon limit. We're going to talk about how to convert mesh bodies to editable B-Rep solids. And we're going to talk about how to combine engineered features with existing mesh bodies and do so seamlessly.

So let's start with About your Speaker. My name is Jason Lichtman. I'm a Senior Technical Specialist for Design and Manufacturing here at Autodesk. And I focus on Fusion 360 in particular. I come from a background in mechanical engineering, both in my undergraduate as well as in my master's degree. And I spent well over 10 years in industry design and consumer products.

I have some specialties, which include designing for moldability-- so think of injection molding, carbon fiber molding, roto molding, and a whole lot of other molding processes. I also have a specialty in 3D printing, 3D scanning, and reverse engineering, which should come handy for today's topic.

So next part of this is we're going to talk a little bit about those mesh bodies and answer all of those questions that I talked about before. But it all starts with some basic definitions. So first, what is a mesh body? You can see two different types of mesh bodies on the screen at the moment. The one in the left is made of triangles and the one on the right is made of quads or squares. But they are both polygon meshes. They are faceted based on these little polygons. Either of those polygons are triangles, like you see on the left, or they're squares like you see on the right. But either way they are polygonal.

And really what it comes down to is that these are 3D models. And the way that you define them is based on connecting points together in these polygons. Whether they're triangles or squares doesn't really matter. The point here is simply that these polygons define the 3D object. There are a lot of different file types for mesh bodies. But the most common are STL, OBJ, 3MF, and even FBX files.

The files are you're more likely to be working with on a regular basis are what are called B-Reps, or Boundary Representational bodies. They can be surfaces and they can be solids. But either way, these are 3D models that are defined by the boundaries themselves.

There are lots of different file types for B-Rep bodies. But some typical ones are IGES files, STEP files, SAT files, parasolid files, which are known for their X_T or X_B file format, but they're really just parasolid files, IPT files, which are native Inventor files, CATPARTs, which are native CATIA files, SLDPRTs, which come from SolidWorks, F3D or F3Z, which come from Fusion 360, or PRT files that come from a variety of different places.

The key here is that these are 3D models that are defined by the boundaries. So to really understand the difference between them, we have to start by thinking of different ways to represent an image.

We're going to start really basic here with 2D image in particular. On the left and on the right, you can see two Autodesk logos, recently updated logos, I must add. The one in the left is a vector file and the one on the right is actually a raster file. The vector is a way to define that 2D image. The raster is also another way to define that 2D image.

On first glance, they seem like they're identical to each other. But when you start to look at the details, you're going to start to see that, zoomed in, the A on the right is slightly more blurry than the one on the left. And if you Zoom in even further, you're going to see that there's a lot of blurriness on the right.

In fact, the one on the right is comprised of pixels. You can see that now on the screen. The one on the left, the vector image, is actually defined by mathematical formulas.

So just like we talked earlier about how the mesh files are defined by the polygons and the B-Rep files are defined by the boundaries, these images are defined by mathematical formulas or by pixels. And there's a big difference between the two. There are different softwares out there that specialize in these types of images. And this example I'm going to give you happens to be using Adobe products, but there are a lot of other softwares out there that do similar.

On the left, you have Adobe Illustrator, which is a vector editing software for vector images. And the one on the right is Adobe Photoshop, which is meant for raster or bitmap image editing. When we start to look at that logo again, on first glance, they still look identical. But again, when you start to zoom in within the programs, you're going to see that, on the left, with the vector program, it treats the A as an object. That's a mathematical formula for that A. And it's all just one formula, so it's one object.

And the one on the right is that raster or bitmap image. And again it's based on pixels. What I want to point out, though, is that between these two different programs, the tool sets that you see just highlighting in orange right now, those are different between the programs. On the left, in the vector editing program, the tools that I have at my disposal are things like pathfinding, things like Boolean combines, of combining two different vectors together. Whether you want to keep the outside or keep the inside or keep only what's in between, the point is simply we're really manipulating the entire object together.

On the right, however, we're manipulating pixels. So what you're going to see here are things like brushes and the ability to erase pixels or blur pixels and things like that very much at the pixel level. So let's talk a little bit about compatibility between those two different file types still at the 2D image level. If you want to take a vector image and you want to bring it into a raster or bitmap image editing program like Photoshop, you certainly can do that. So you could take that vector, bring it into Photoshop, but you are going to find that you have limited use of that vector object because of the way that the image editing program is intending to edit the objects.

The same is also true in reverse. If you want to bring in a raster image and bring it into the vector editing program like Adobe Illustrator, you can certainly do that. You will, however, find again that you have limited use of that raster image, again because the way that Illustrator is editing things is not really meant for rasters.

So the next thing that people try to do is to try to convert from one to the other. And that's a pretty reasonable expectation. If you want to start with your Adobe Illustrator vector and you want to turn it into a raster, we call that rasterizing. And you can certainly rasterize that letter A. And it's going to look really good. Right now I'm actually exaggerating. You can kind of see there's a little bit of a blur on the right. But in reality, this would come in nice and clean at high fidelity or high quality.

The same is not exactly true in reverse though. If you start with that raster image and you try to convert it into a vector-- we call that vectorizing an image-- you're going to find that, while it looks proper on first glance, when you start to look at the details, you're going to find that it's really low fidelity. If you look at those corners you see in red-- and I'll focus on one of them in particular-- you're going to see that that conversion from the raster image into the vector image tends to include imperfections. It's making some assumptions. And we all know what happens when you make assumptions.

So the reality is that going from the vector to the raster is a nice one-way street. Going the other direction is severely problematic. Now let's see how that relates to a 3D model. First, we have to talk about ways you can represent a 3D model. There are a lot of different ways you can represent them. The mesh files you see in the bottom right-hand corner, that's just one way to represent 3D models.

You can also represent them using wireframe, using point clouds, using subdivisional surfaces. And in the center, you see the boundary representational surfaces and solids that we already talked about. You'll see that it's front and center and larger than the rest because it is far more common these days in the engineering programs that you're probably using, whether it's CATIA, NX, Creo, SolidWorks, Inventor, or Fusion 360 and more, they all typically use boundary representation to define the 3D models that you work with.

And that means-- let's actually go and see what that means-- that if you want to take the explanation I gave you earlier about the 2D image and think of it in the 3D world, I want you to think of the boundary representational objects as 3D vectors. And I want you to think of the mesh files represented by those polygons to be like the 3D version of the raster or the bitmap. And I want you to think of each of the triangles or the quads as a 3D pixel.

And so once you start thinking of things this way, it'll start to make sense why, when you bring a mesh file into an engineering program that's typically using boundary representation, you have limitations in what you could actually do to edit that file. And it makes a lot of sense in that way.

So let's talk about the conversion. If you wanted to convert from the boundary representation of a 3D object into the raster or into the mesh file type, you can do so at high fidelity. It will come in really nice every time. If, however, you want to go from the mesh body into the boundary representation, unfortunately that's where you're going to get the low fidelity and you're going to have problems, just like when I showed you earlier, with the 2D image from the raster into the vector.

In many softwares, I'll also want to point out that this is not even possible. So lots of softwares will not let you convert from mesh to solid or mesh to B-Rep. And in many softwares it'll let you do the conversion, but it's severely limited in the number of these 3D pixels or the polygons that you're allowed to convert. And once you do the conversion, it can often be very hardware-intensive for you to actually work with those files.

So now that you have a basic foundation of why mesh files are hard to work with because now you understand how they're defined and how the softwares actually interpret them, now we're going to jump right into the software itself.

And I'm going to show you the different mesh features and workflows. We're going to start with importing mesh files. We'll talk about those tips for working with the mesh bodies that contain color and texture. We'll go into repairing the problematic mesh files. We'll talk about face groups. We'll go into editing the meshes parametrically and non-parametrically. And then we'll get into the three types of conversion-- converting the mesh bodies to a solid body without the 50,000-polygon limit, converting the mesh body into the editable B-Rep solid, and lastly, combining engineered features with existing mesh bodies seamlessly.

So let's start with our live demo. Here we are in Fusion 360. And I have a file that we're going to see quite a bit today. I'm actually going to use this gearbox cover for all of our demonstration.

But we're going to start with importing a mesh. So let's start with a new file. And you're going to see here, at the top, a Mesh tab. That tab is going to be where you're going to find the vast majority of the features you're going to want to use for mesh editing and reverse engineering.

So once I'm in this Mesh tab, I can say Insert Mesh and I can find the mesh from my computer. And here I have a folder full of mesh files for us to play with. And I want to point out that there are a lot of different file types for meshes. And again, there are pros and cons of each of those file types.

So if I start here, for example, with this gearbox cover, and we're going to bring in, let's say, this one here is perfectly fine, with no color. You're going to see that, at the moment, it's not asking me for any units. And the reason is because the file that I brought in is a 3MF file. And 3MF files automatically contain unit information. So it doesn't have to ask you what units this was created in.

But if you do import an STL file or an OBJ file, it will ask you for the units. And choose correctly, because it will make sure that the file comes in at the right size.

I will also point out that the fact that it asks you here at all when you bring an STL or OBJ file, is important. If you do the opposite, of instead of importing using this insert mesh, if you were to go to the Data panel and you were to upload a mesh file from your computer, you will find that it's not going to ask you for the units, regardless of file type you bring in. And it will assume centimeters as the units.

Now, in my experience, we most often use millimeters or inches. So centimeters tends to be wrong most of the time. So rather than import my mesh files through the Open dialog or the Upload dialog, I do personally recommend that you bring it in using the Insert Mesh functionality that I showed you a moment ago.

Once you bring it in, it will look something like the mesh you see on the screen. And it looks pretty good. I can see all of the different facets. And now I'm pretty good to go. If I want to bring in multiple meshes, I'll also point out that you can select multiple of these files at the same time. And if you hit Open, it'll bring in all of those different meshes all at the same time. And because this happens to be the same file, you're going to notice that they're all kind of on top of each other. But you get the idea that you can bring in your meshes. Whether it's one or multiple doesn't matter. It's perfectly fine.

Now, if you do bring in a mesh file that happens to contain color-- let's go and do that together-- you're going to find that you might not actually see the color. So let's go and bring in the displacement map here. And when I look at this particular file and rotate it around, I don't see any color. So here are some tips and tricks for you.

The first is to go to your Display settings at the bottom of your screen. You can go to Mesh Display. And you'll see here a checkbox for Face Groups. I toggle this on and off very often. But I do want to point out that when this Face Groups is checked, any color that's in your model by default, that's already built into your model, will not be displayed.

So if you want to see that, uncheck this Face Groups button. And now you're going to see the model with color. If you do not still see color, it could mean that the model itself doesn't contain color. Or it could mean that there is an option in your settings you're going to want to modify.

I'll show you that setting in just a second. But first, let's verify that our model has color. I can go to the mesh body here on the left, right-click and go to Properties. And under this little mesh tab, you're going to see plenty of useful information about your mesh body, how many facets there are, how many face groups come in with your model already-- and we'll talk a little bit more about face groups shortly-- how many shells are in your model, which is essentially like bodies within the body. It's a little confusing, but you can have multiple shells in your mesh. And lastly here we can see Texture and Color. This particular model has texture but no color. I know that it is also confusing because it looks like it's colored. But the reality is that texture and color are essentially the same thing, just slightly nerdy different definitions.

But this model definitely says that there is texture and there's no color. But texture can be color. So this is actually color. Looks great.

So if your model says that there's texture or color but you still are not seeing the color, go to the top-right corner and click on your initials or your picture. Go to your Preferences. And I recommend going to the preferences for your material. So if I go to the material here, make sure that this checkbox here is not checked. Apply a different appearance can override the color in your mesh file. So make sure to uncheck that button and hit OK. And once you do, you should in fact see color in your model. So that's great.

So let's say you bring in a mesh and it actually has some problems. Let's go and bring in another mesh and we'll take a look at that scenario. So I go to my mesh tab, insert my mesh, and this one I already know is going to have some import errors. It looks good on first glance, but I can kind of see it actually has some missing areas here.

If I don't want to have to visually inspect it but I want to make sure I know if it's good or not, I could go back to that Mesh Properties. And you're going to see here, under Mesh, a bunch of useful information, the same info I saw before. But I can also go to Mesh Analysis. And this is going to tell me if the mesh is closed, if it's oriented, and if it has positive volume. If you're going to 3D print something, you want that mesh to be closed and you very much want it to have a positive volume. This mesh, with its errors, does not have either. It's not closed and it does not have a positive volume.

I can also see, even without going into the Mesh Properties, that I have a yellow warning here telling me that that mesh is not closed, not oriented, and does not have a positive volume.

If I want to fix this, I can go under Prepare. And you're going to see here an option for Repair. I can also get to that same menu simply by clicking on the yellow warning that you see right here. Once you bring up the Repair dialog, you're going to see options such as Close Holes, Stitch and Remove, Wrap and also Rebuild. These are four different methods to repair your mesh.

If you want to take this even further, you can turn on, in your preferences, this option that says Analyze Defects. And this will give you even more options to be able to see what the problems are and how to fix it. To do that, go to your icon in the top-right corner with your picture or your initials, and go to Preferences. Go to Preview in the bottom left-hand corner. I'll go and do that here.

And what you're going to want here is for the mesh workspace. Let's go and find that. Actually hold on a moment. We'll hide a bunch of stuff here. If we go to the mesh-- here it is, Mesh Repair Analysis. Make sure this is checked. And you'll also have the ability to use that Advanced Repair tool. I already have that on, as you saw earlier.

So let's go back into the Repair tool. And you'll see that I have, again, those four different methods to do the repair. If you highlight over or hover over this with your mouse, you'll see that it will describe, in some detail, what the difference is between these different methods. And it will also tell you how fast or slow it will take to actually do the repair. This is actually a relative thing. So this is just comparing the, let's say, close-holes approach versus the rebuild approach.

If you do choose the rebuild approach, you will see that there are actually different options even within the rebuild. There's Fast, Preserve Sharp Edges, Accurate, and Blocky. Altogether, you'll find that you have seven different options for repairing your mesh.

If you'd like to see what is actually going to do to do the repair, you can hit the Preview button. But before I do, let's go and take a look at our defects. I'll go and analyze, and now it's going to tell me in detail what the problems are with my mesh. If I hit the Preview button, not only is it going to preview what the repair itself is going to look like, it'll also preview what the analysis is going to show once it's done its repair as well. So this is a fantastic tool to be able to quickly and easily repair your mesh so you can continue to work on it. And in my opinion, it's better to do this repair early so that you have a clean, good mesh to work with for the remainder of your design.

So we now have a clean, repaired mesh. What are we going to do to edit it? Well, before we edit it, we're going to talk a little bit about face groups. So let's go ahead and close out these messages that we just looked at. And let's go and start with this one right here. And I don't see any face groups at the moment, but I know that they are there. Remember, earlier, I told you that you have to turn off the face groups to be able to see color in your model. But if you want to see face groups, you better turn on that face group's selection to be able to see them.

So we're going to go back to Display Settings, Mesh Display. And I'll check the box this time for face groups. And now I'm seeing a model with a pastel kaleidoscope of colors. Each of these face groups is a group of faces, individual triangles or quads that are grouped together. You can group these together manually, and you can also do it automatically using Fusion 360 Generate Face Groups command.

I've actually already used it. So here you could see the results. And again, remember that these are groups of faces that are grouped together. So this area right here-- and I'll zoom in here-- is actually an arc. This one here is also an arc. This one here is also an arc.

This purple one up top is actually a flat face. It figured out automatically that all of these triangles represent something that is flat. And if I zoom out a little bit and reselect the top, again, here, this is recognizing this as flat.

So how do I actually create these face groups? Well, let's go back one step in our timeline. This is what the mesh looked like when it was first imported. And it had one face group to prove it. Again, we'll go back in here to our Properties. We'll go to our mesh options here in mesh properties. And you'll see Face Group count, 1. Perfect.

Now let's go to the Mesh tab. And under Prepare, you're going to see two different tools for face groups. We have Generate Face Groups and Combine Face Groups. The Combine Face Groups assumes that you already have face groups you want to combine.

So let's start with Generate Face Groups that we can create some that we can choose to combine later. I'll choose the body itself, and then a type. We have two options here, fast and accurate. Fast is exactly what it sounds. It's going to be fast. Accurate is going to be much more accurate, typically slower, but not necessarily. Keep in mind that these are actually two different methods. They're not really just options within one method.

So the fast option is using an angle threshold to figure out what should be grouped together. And the accurate method is using a boundary tolerance. Remember earlier that the way that we define things can be based on a variety of different information.

So this one is using the boundaries, very much like the B-Rep use boundaries as well. You can change the boundary tolerance to speed up the calculations if you would like, or make it really detailed if you want it to be more accurate. You can also hit the Preview button to be able to preview the results.

I'm going to go and hit the OK button and let it do its calculations. In about 10 or 15 seconds, we're going to see the results and hopefully see the same pastel kaleidoscope that we saw earlier of all of those different face groups.

Now keep in mind that if you would like to change the settings, you can always go back and change the settings and have it recalculate. And if it turns out that you're not so happy with the results but you're close to happy, you can also combine different face groups that it calculated for you together to become a single face group. And that could be really handy as well, especially in areas that are highly detailed and maybe the automatic face group creation wasn't able to capture that geometry perfectly. But the point here is simply that by generating the face groups, we're able to be able to select each of these features, so to speak, or groups, individually.

Perfect. And so now I'm seeing everything the way I like it. And let's pretend for a moment that I did want to group something together. I would go to Prepare, Combine Face Groups. And I could select any two of these groups together. Hit OK. And now it becomes one face group.

You want to change what you're doing or change that selection, you could go back and edit your feature and now select the third group. Hit OK. And again, it combined that together. It actually did a great job in the first place. So I don't really want to combine these together. I'll just go and hit that Delete button. And it's gone from my timeline. But the point here is simply face groups are a great way to be able to select individual features. Why is this important? Well, the next part of our class today is going to give you that answer. It's all about editing meshes.

When you go to that mesh tab at the very top, you're going to see Modify here in the dropdown. And under Modify, I have a variety of different ways that I could edit meshes. I can re-mesh a mesh, which is like re-topologize, like make new triangles in different places for the same object. I could also reduce the mesh, which is very similar. I could do things like shell the mesh, or hollow it, or combine meshes together, and a whole lot more.

The key here is that everything that you're seeing on the screen at the moment is parametric. And by that I mean that there's a recipe at the very bottom of my screen in what we call the timeline that's going to capture what I'm doing, when I'm doing. And I can always go back and edit it. Just like with solid modeling and just like with surface modeling and sheet metal modeling, now you could do all of the same with mesh modeling as well.

But I do want to point out that when you're using a command like, let's say, the Remesh or the Shell command, everything here is going to be based on either bodies-- and you could see that in this dropdown or menu right here-- or it's going to be based on bodies or face groups. So you could see here I can mesh the entire body. Or instead I can select an individual face group and remesh the face group. And that's why generating that face group is so important and so helpful. Because again, everything that I'm going to do here is going to be based on the face groups.

If, for example, I want to go and change the size-- so let's say I did not follow the instructions of this course, and instead of saying insert mesh, I uploaded my mesh and it came in the wrong size, I can come in here and use the Scale Mesh functionality here, select an origin to scale by, and maybe scale this by 2x. So now it's twice as big. But if it turns out I didn't really want it to be twice as big, I wanted it to be 2.54 times as big because I'm scaling from one set of units to another, I can go back, because this is parametric, and edit this feature and change this from 2 to 2.54. And now I have this updated.

I can also do the same with our other commands as well. So if it turns out that what you're trying to do is to split this mesh into multiple pieces, I could use, for example-- let's pick a different plane here. We'll go and pick this one here. I can go and do a plane cut and fill this in and hit OK.

And now I have my updated mesh. But if it turns out I really wanted to change that plane, I could go back and edit this feature and move the plane and hit OK. And again, it will update my model. If I want to go back and change my scale factor, and in fact I didn't really mean 2.54, I meant 254, you could do that too. You're going to need to zoom out quite a bit. But the point here is simply that this is fully parametric like the other areas in Fusion 360.

Now, this comes with a cost. And that cost is that everything that I'm doing here is at the object level, either the body object or the face group object. What I'm not doing is making changes at the individual triangle level. And many of you out there are probably used to editing meshes at that polygon level or that triangle level.

Now, fear not. Autodesk did not take any functionality away from that original mesh workspace. The new mesh workspace is actually new and improved. It's built upon the original, but it's even better. If you would like to edit that mesh using the individual triangles, you're going to want to direct edit the mesh. And by direct edit, all I mean by that is that you're going to be editing the mesh not parametrically as opposed to parametrically.

There are two ways you could do this. You could go to Modify and say Direct Edit. What it will do is it will take the body at this point in time in your timeline and create a direct editable version of that body. If you wanted to keep your parametric history on but still make changes to the mesh, you can kind of do that, but you are going to want to make the direct edits rather to the original mesh body. So for that, I would go to the timeline, find the very beginning of the timeline where I inserted the mesh, and edit the feature.

At that point, I'm going to see the mesh before any of those parametric edits happened. But while I'm in this mode and directly editing the mesh, you're going to notice that I am going to be able to select individual triangles. And that's incredibly important here on what you're trying to do. So I can select individual triangles like I am right here, and under Modify, make changes to this, whether I want to remesh that area or I want to erase and fill that area and a whole lot more. The point here is simply that the direct editing environment is going to allow you to be able to make your edits, although not parametrically, at the triangle level.

So you have two options. You can edit your mesh parametric at the body or the face group level, or you can edit your mesh non-parametrically at the triangle level. And again, to access this, under Modify, you're going to Direct Edit, that will create a direct editing environment within the timeline at that point in time, or you could go back into your original mesh and say you want to edit that feature, which again is going to bring you into that direct editing environment. So there are plenty of ways for you to go and be able to edit your mesh.

Let's talk about a slightly different subject. Let's talk a little bit about how to go and convert meshes into solids. Because while editing a mesh is incredibly helpful, there are plenty of times where you're going to want to convert that mesh into a solid to be able to work on it. And that is certainly possible in Fusion 360.

So let's say you want to convert this mesh into a solid to be able to work on it. Well, we have a mesh on the screen. Let's go and do our conversion. We're going to go back in time just slightly. So this is the starting point. And I want to convert this into a solid. I can go to my mesh tab here and use the Convert Mesh button. And you're going to see some options here. The first one is faceted. The faceted option is going to do a one-to-one conversion from a mesh body to a solid body. And every single phase or facet or triangle will be present in the final result.

When I go and I hit OK, it's going to go and do that conversion. The body converted from a mesh body into a solid body. The name still says mesh body, because that's what it was called before. But this is very much a solid body.

And now I could go and make changes to this however much I'd like. So I can cut holes in this, I can do a whole lot. In fact, if I wanted to clean this up slightly, I could also select individual triangles on flat faces and hit the Delete key to simplify them. This will work very well on flat faces like the face I selected a moment ago and the one that I'm selecting right now, but this will not work on arcs and circles and cylinders and things like that. So keep that in mind.

This, however, will make your model significantly simpler so that it's easier to work with and so that your system doesn't bog down while working with them. But at this point, if I wanted to go and create a sketch and maybe make this hole bigger, I could go and draw a hole, just like this, and make my extrude cut through my model.

And now I have a nice clean cut through my model. If I don't like that hole or I don't like the size or the position of that hole, remember this is still parametric. So I can come back here and change the size or change the position however I'd like. And when I'm ready, of course, and I hit the Finish Sketch button, it's going to update whatever it is that I did. Not necessarily saying I did a great move there, but you get the idea here.

Now, in years past, you could have already done this in Fusion 360. But this was limited to 50,000 polygons or 50,000 triangles. Many people thought it was limited to 10,000 because you would get a warning. Anything over 10,000, you'd get a warning. But anything over 50,000 would fail immediately. Anything between 10,000 and 50,000 would work, but of course bog down your system.

Nowadays you no longer have a 50,000-polygon limit or a 10,000 polygon warning. Instead you can convert a mesh however detailed you'd like. Now, I will admit for the purpose of this demonstration, that this particular mesh body, if we go back in time slightly, was pretty low on

The facet count. It was just under 10,000. But keep in mind, again, that this will work regardless of how many triangles you have. But keep in mind that, if we're talking about many hundreds of thousands or millions, this could have a severe impact on your performance. So you might need or want a higher-end computer for you to be able to use this. But just keep in mind that the software itself will not limit you to 50,000 triangles.

Now, there is another method for you to do the conversion that I think is fantastic. So let's actually go and show you that. Let's go back into our model here. This is the model that already had the face groups generated, if you recall. And you could see them on the screen.

If you go back to the mesh, convert mesh, you're going to see that there is a second option here called Prismatic. And the prismatic method requires you to have face groups generated already. So what this is going to do is it's going to read those face groups and use it to help define what this model should actually be. So if it sees a face group for what's supposed to be a flat surface, it recognizes it as a flat face. If it sees a face group that's a cylindrical face, it recognizes it as a cylinder. And so the idea here is for Fusion 360 to give you a cleaner and much more editable model than simply doing the faceted approach you saw earlier.

So I'm going to go and hit the OK button. And in just a couple of seconds, wow, I now have a solid body that is very much editable. We'll go back to our Bodies folder here and just confirm.

Again, despite the name, this is still a solid body indicated by this white cylinder icon. But now I have a solid body that not only could I create sketches and extrude through, now I can actually direct edit as well. So if it turns out that I would like to make this diameter smaller, I can select that diameter and simply make it a millimeter smaller. I want to add a fillet to this particular edge, I could go and add 2 millimeter fillet no problem. This is a solid body that is as clean as you're possibly going to get, and therefore the easiest for you to use and easiest for you to work with.

And that's incredibly important. Because converting a mesh into a solid, we don't want it to be frustrating. And once you do the conversion, we want you to be able to work with this seamlessly so you don't have to go and rebuild a model from scratch like the people on the Facebook forum might tell you.

So this is a great method to convert your meshes into solids so you could then go and work with them. And keep in mind, you're not just limited to moving faces and adding fillets. You can do a whole lot more. So just another example here, I'll go and select, let's say, this hole region. And I could simply hit the Delete key, and it actually fills it in automatically. It's absolutely incredible what you could do with models like this once they're converted.

So with that, we have one other method that I would like to show you. And this method is kind of opposite.

So let's go and open up a slightly different model. Same part, different file. We're going to go into this one right here. And this is going to show you what happens when you want to add engineered features to the mesh without converting it.

So we're starting with the same place we started earlier. I have a mesh file, and it has roughly 10,000 polygons. And let's pretend for a second that this is much more complex than 10,000. What if this is 100,000 or what if this is a million?

Remember I said earlier that the conversion from the mesh to the B-Rep can have some serious performance hits on your machine. And we're trying to make this so that it's as seamless as possible. And as a result, there are times where you might not want to convert from a mesh to a solid to be able to put on those features.