 Greetings humans. Good morning. Good afternoon now. Happy DEF CON. It's Saturday. You guys made it through the night and thanks for showing up here. So what up? So my name is machinist. I am here to give a quick little presentation on mechanical engineering for noobs. I've done industrial customers over the last few years, and I found there's sort of a common theme between where all the limitations of these people's knowledge is as far as turning up an imaginary object into a real tangible object we can hold in our hands. So I just want to kind of give you a little bit of insight over I don't know a quick little crash course in how to take a vague idea, put some dimensions, put it in the 3D world, and output it somehow. So a little bit about myself. I'm from Southern California. I help run a hacker space out there where we pretty much focus on the industrial arts. I have a machine shop background. I went to trade school rather than engineering schools. I learned how to crank handles and sweep the floors rather than, you know, calculus and top-end kind of stuff. So all of my background comes from like practical applications of being able to take a measurement, put it into solid works, and get it out of your 3D printer. So trying to focus on here. Like I've been saying, we're working on trying to put some sort of framework about how to deal with taking a real quick simple little widget like I have up here on the table or anything like this. The one on the right is actually a project that got me started at DEF CON five years ago for the Breverage Cooling Contraption Contest. It was one part of a giant pressure tube for phase change dry eyes. It's really crazy there's video about that. But that's just one of the kinds of problems that we're trying to solve with very basic mechanical engineering concepts. But there are a few different considerations that we need to take into account like how big do these things need to be and in what range can we have these parts, you know, bigger or smaller? That's a very nuanced subject that hopefully I can enlighten you guys about a little bit just for practical applications. You know, like I'll save you the trouble of having to go to school and get a mechanical engineering degree will last as much as I can in your head here in the next half an hour. So when we're first trying to solve this problem, a good question to ask yourself is how many of these parts am I going to make? Am I only going to make one, a hundred, a hundred thousand? Because those choices dramatically affect how you're going to approach the problem. If you're only going to make one, maybe I need a CNC machine to just custom mill, you know, one little piece. Maybe a guy can do it by hand in his garage. Who knows? If you need ten million of them, maybe you need to start considering something like an injection mold machine. So that way you have a very high cost of startup for equipment and tooling and research and development. But once you get everything up and running, your injection mold machine plunks out parts every, you know, ten seconds at a tenth of a cent a piece, you know, rather than if you manufacture something one-off in a machine shop, you you're costing several hundreds of dollars just for the setup time just to get the machine ready to make that one single part. So scalability is an important concept when you're trying to figure out, like, can I get this product out into the real world? And that's another thing that 3D printers are wonderful for. I highly recommend you guys tinker around with those a little bit just because it totally changes the game about producing a single trinket. It just trivializes the amount of effort it takes to get to your first prototype or, you know, maybe the 3D printed part is good enough for it in results. So just some food for thought. So what are we going to do to make these measurements? How accurately do we need to measure these things? So you'll have to forgive me for my shitty webcam software. I couldn't figure out here in the last five minutes, but my favorite tool is just a set of little shitty digital calipers from Harbor Freight. You pretty much get what you pay for when it comes to these kinds of tools, but I use this every single day. It's my workhorse. So, you know, these are like $15 from Harbor Freight, but they're not highly accurate. They're not that high quality. You can easily get some of these that are, I don't know, $150, $300, you know, heirloom quality from your grandfather who, you know, had it in his oak box, you know, imported from Switzerland back in the 70s. So calipers are pretty much my workhorse, my go-to, but they're not good for a precise measurement. They're only good enough for reference, and I'll show you what that means here in just a minute. I've got another set of tools here, some micrometers. So, these things are essentially measuring the same things as my calipers, just to a more accurate degree here. I'll stop moving around so I can focus. So, I have a little rotating thimble here. Let's see if we can see that. Here we go. So, this is taking measurements in thousands of an inch. My little thimble is trying to keep track of it, but you always need to be able to read the analog versions. Like, these calipers here are digital, but I definitely prefer the mechanical dial calipers just because they always work. You don't have to worry about the batteries. Another thing to consider about these tools is they're fragile. They're trying to measure very precise bits. So, like, if you take this on a cutting tool on these sharp blades here and just grind it around putting all sorts of pressure, you're going to ruin the very delicate. There's some very delicate faces right in here that need to stay flat and precise and precision ground. So, it just requires a little bit of understanding of the tool, how to take some measurements. There's an outer diameter measure here. There's an inner diameter measurement here, and there's also a depth measurement on that backside. Just a couple of faces that you can use. Even right here, there's a depth measurement you can use between these two faces. So, like I said, I highly recommend you get a pair of these, learn how to use them because it does take a little bit of skill because you can actually force these calipers to take a bad measurement. So, let's just take a quick little measurement here along this part. 371. Now, I can deform this. 365. So, just something to consider, right? I can actually deform this a measurable amount by putting too much pressure on my thumb. So, like I said, it takes a little bit of practice to get used to learn how to measure, but we can also take a couple of quick measurements. So, we got this hole back here. Hey, 372. That's about the same size as that thickness. But, 370, 372. That's a weird number. I'm a big fan of grids or dividing by fractional amounts. You see that a lot in manufacturing, where things are 8ths of an inch, 3 eighths of an inch. So, 370 is really close to 375, which is 3 eighths of an inch. So, you can pretty much assume that this was meant to be designed at 375, but it was manufactured a little bit small. So, just something to consider, right? Like, what was the actual intent of this part? What is the function of this little part? What's it supposed to do and how accurate doesn't need to be made in relation to that? So, we'll go over a couple of those concepts here as we go through the talk. So, decimal places of accuracy. That's a pretty big one that always blows my mind when it comes to engineers. They're like, okay, you know, something that's 40 inches long needs to be accurate to like 1 tenth of a nats hair, you know, overall temperatures and conditions. It's just impossible to consider making something so large with such a small percentage of error. You know, margin of error is what we're always trying to work with with mechanical engineering. You can never make precise perfect parts. And anybody spend some time over the Lockpick Village recently today or in Defconn's past, because what we're trying to do in the Lockpick Village is use some mechanical engineering concepts to exploit manufacturing tolerances. The locks can't be made perfectly. The little pins aren't the same size. They're not all drilled in the same line. So, by using the small little variances, the tiny little bits of slop in the system, you can bypass the system or make tools to, you know, do new creative things with the system. So, that's what I'm trying to get across is like, you know, there's lots of little tiny details and that's where the devil is, right? Like 90% of the work is in the last 10% of the details when it comes to mechanical engineering. So, I took some rough measurements off this part. We took a look at it, but we need to be able to intellectualize this somehow. I like to get it down on paper. Whenever someone comes to my shop looking for some help trying to manufacture a little widget like this, I always try and tell them, you know, even if you don't have any engineering skill, I'll just try and draw it on like a cocktail napkin. So, that way we can, you know, start going through the process of what this shape looks like and what we're supposed to end up with. So, we'll do just that. I'll just pull up some Microsoft Paint before we go to the Hardcore Solidworks. So, we got my little widget here and I'll just make a quick little representation of it. Awesome. So, let's see how close that is. So, one thing to consider about this part here is like, what the hell is it even for? Why am I even bothering to go through this talk? This is actually a part that I was approached with at work a few weeks ago. My boss just handed me that little widget and says, here, I need a hundred more of these and I need a hundred of the mirror, the opposite side. So, he just threw this little part at me, no other instructions than that, not even a blueprint. So, figure it out, Bozo. Like, that's your job, right? So, okay, I had to go through the process like, what was the original design attempt? What was this thing even supposed to be? It looks just like a little pro magnum drawing up on a cave somewhere. So, I have the part assembled here and this is actually a bearing block. There's two little bearings that are supposed to fit on this dowel pin, which goes nicely into these edges here. So, this is just meant to support some roller bearings to support some weight as they roll across and I guess they were disposable, they wear out over time, so they needed a few copies of these. With that in mind, the dowel pin here gives us a little bit of food for thought. Dowel pins are usually found in commodity sizes, fractional sizes, eighth of an inch, quarter of an inch. In this case, it's 3 eighths of an inch, 0.375 exactly. This is actually a reference you can use too. So, let's see what this tells me. 375, perfect. So, this is the initial design intent of the part. Everything needs to fit around this dowel pin and everything gets built around that. Yes, sir. Can you hold it till the end? Okay. So, design intent, I want to grill this concept in you guys. Like, what's the most important factor about our design? And where else can we fudge everything? Where else can we move things around or build things around? Because the most important factor is the size of this hole in the middle that holds this dowel pin. If I make this hole too small, the dowel pin doesn't go in at all. It's a very precise size. If I make this hole even a little bit too big, the dowel pin rolls around and flops around and doesn't hold a bearing trough anymore to wear itself out. So, the dowel pin is the most precise shape on this part and we'll build everything around that. So, let's do some more chicken scratches here. This dowel pin part right there. We measured it at 0.37. We want to talk about tolerancing, right? Like, how sloppy can this dimension be? How much is too much? How little is too little? In this case, to get a very good fit on this part, I can only be a little bit bigger, but no smaller. So, in this case, I need to call out this dimension a little bit more accurately. Like, 0.375 doesn't tell me enough. I need to know how much wiggle room I have. So, if I cannot go any smaller, I need to call out that tolerance as being minus zero. I cannot go any lower than that decimal amount. If I can go a little bit bigger, I can call that out right here plus 0.001. So, one thousandths of an inch. This part can be no smaller and only a tiny little bit bigger than that shaft to make everything work as intended. And we can start building everything else around that. Like, you know, the dimension from up here to down here isn't so important anymore. It's nice to have close, but it doesn't need to be as precise. So, when we have this part, we're trying to figure out like what that size is. I think I remember it being like 1.2 inches. Now, notice there's a difference in the decimal places as well. And we'll get into that here some more reasoning why I'm being so specific about these sizes. 1.2 gives me a little bit more wiggle room. If I was going to call out that tolerance over here, I'll write it down here so it's a little bit more legible. 1.2, if that dimension isn't so critical, if it can be a little bit offset from how I've measured it here, we can say plus or minus 0.01. So, that gives me 10,000ths of an inch, 100th of an inch to work with. I can be a little bit smaller or a little bit bigger. It just means that the guy making these parts doesn't have to be so careful when it comes to that one dimension, but that middle hole is really, really critical. We also need to be able to take a few different views of this because this is only looking at one projection. It doesn't give me all the important details that are necessary to build this part. And I'm kind of tired of looking at paint. Let's look at this in something a little more sophisticated. So, like I was saying earlier, I've been doing a lot of SOLIDWORKS engineering the last few years, specifically towards computer-aided manufacturing. So, in other words, I had to take little widgets like this all day long from a digital version to a physical version using big manufacturing machines and SOLIDWORKS to help me along. So, this is essentially the same thing. SOLIDWORKS is a pretty powerful tool. It's also not very cheap unless you're a student, but it's pretty much the hot ticket out there on the market. Highly recommended you use it. It's just really cool, very powerful, but I've also got some neat tricks up my sleeve later for you guys to see. Very inexpensive as in free software that's just about as powerful. So, this is all sketch-based. We just have to do the same thing here. I'm just making like a quick generalization of what that shape should look like. And these little tractor lines here, sort of, they're giving me suggestions of how I want to place my next point. I'm not going to get into the details about the nitty-gritty of the software because that's not why we're really here, but at least this way you'll get to see some reasoning, some method to this madness. So, I didn't start at the center hole. I'm designing the rest of the body around. There's a zillion different ways you can make parts. There's lots of wrong ways, there's a few right ways, and every approach has its pros and cons. And one neat thing about SOLIDWORKS is it's incremental. As you start building these parts, you say, oh, I need to change something. So, you can step back, make a little tweak, and rebuild your part from there. That's why design intent is important because if you start at the wrong place, try and make a change backwards a little bit. Sometimes it blows up your model and doesn't work. And maybe we can see an example of that here in a minute. So, I just took a quick little generalization of this part, and we'll add some more dimensions to it. So, this edge from here to here, let's just call that 1.2 inches from the top to the bottom, but we have to get kind of creative here. We need to give it some sort of orientation. I can't just call a dimension to this apex. I have to call a dimension to a hidden center line here. Okay, 1.2, call these edges tangent. I'm just adding some relations, you know, making this sketch a little bit more defined. So, this way, all I can really do is change a few of these features, but we're getting pretty close to what this design should look like. So, what I want to know is what the distance is from here to where that curve is. Not a terribly important detail, but just to get this design looking right. And we can eyeball this dimension. Helps if my calipers are on. There we go. So, about 450. Let's just call that good enough, right? It's close. Let's call 500. That sounds like a better round number. Ah, that looks all right. Who cares? We can set that later. All right. So, let's take this 2D sketch and turn it into something three dimensions. We measured the width of the part is 375 thousandths of an inch. We got this 2D shape, and now we need to turn it into a 3D object that we can manipulate in different ways. We'll just extrude the shape out by .375. Gives me a quick little sample. And that's what our part looks like. Now, I've been blabbering on and on and on about the design intent, the importance of that hole in the middle. Let's call that out right now. Solidworks is really neat because it's all sketch-based. You just add little sketches together, subtract little sketches from one another, but my general modeling philosophy is keep it simple stupid. It just makes it way easier when you have very simple little designs that you tweak incrementally rather than trying to like incorporate all the geometry into one single sketch. Just keep that in mind as you go down the road for this kind of stuff. So, the middle hole is 375, and I'm just going to place a new sketch arbitrarily on this top plane up here. You can see my little origin is just showing me the horizontal and vertical orientation, and I want to put a hole that's concentric with this outer radius right here. So, I can wake up this outer radius and it shows me where the center of the radius is. Real cool predictive modeling. So, it sometimes is kind of a pain, but it does help a lot to have the software sort of guess what you're looking for. It tries to keep you out of trouble, but the saying is SolidWorks doesn't make you a better engineer. It just helps you engineer bad designs faster. So, we'll add some dimensions. We said that hole is 375. See, it calls out to 380. Why is that? I only have two significant digits set up on SolidWorks. Hate to bore you guys to death with going through little features here, but just something to think about, right? And how deep was that hole? Instead of making an extruded boss, we're going to extrude cut, and I measured that earlier at 320 deep. It doesn't go all the way, so you can see it doesn't quite penetrate that bottom. Okay, so we're starting to get there, but my part was a little more nuanced. So, yeah, there's a nice little outer radius on this part. It's only a cosmetic thing, but hey, that's what gets you from 80% to 100%. Just a quick little visual sparkle, a visual cue that all the edges match up and line up is really cool. So, let's put that fillet into SolidWorks. One, two, four, there you go. And this is cool. It's just one simple tool. Select tangency and that edge. Our fillet's on there. We also had some holes down here on the bottom. So, these are two tapped holes. They're threaded holes meant to take a bolt, a certain size bolt. And there's very critical considerations once you start talking about threads and holes and bolts. Anybody own the machinery's handbook at home? So, all of you go out and buy that from Amazon because I use that like my Bible. It has all the information you'd ever need to determine like fit and fitment, how big these dowel pins come, and just mechanical engineers gold mine from hundreds of years of collective resources and knowledge. It just it'll help you get in and get out of many pinches. So, I got these two threaded holes and this could be very painful for an engineer to have to like spec out. Like SolidWorks just really makes the whole process easier. So, whole process. Waka waka. I haven't had enough liquor today. Where's my Scotch? So, this is an 832 hole and I'll just do the same thing here. All I need to do is give SolidWorks a sketch relation and it will put in all the detailed information for me. So, all types it is on a threaded hole but it has a near side counter sink on it. So, this is just kind of floating around here in space. Add some relations here. So, I have a new sketch that's open. I'm going to convert this edge to use some reference geometry. Same thing in here. So, now we have some references where I can place a hole along the centerline of this part. And you notice these dotted lines that's referring to construction lines. They're only for reference in the design. Somewhere along. So, I can either dimension to a center or dimension across a span just using a little bit of cleverness in technique here. Let's make those holes 750 thousandths of an inch apart, three-eighths of an inch apart. I don't have a second hole on here yet because, hey, keep it simple stupid. I can just make a quick little mirror. So, I'll make a mid plane in between these two edges that I can now make a reference mirror around. So, we have our 832 hole and make a mirror across our new plane right there. Bam. So, there's our part ready to go. So, what do we do at this point? Right? We need to make a couple of choices. This is something that we can send out to the C and C machine. That usually requires a very skilled artisan to run the machine. They're non-trivial to use just because it takes years and years to learn how to handle the big robots and different kinds of alloys. Like I said, non-trivial venture to get these things to machine, especially if you're trying to do it yourself. 3D printing has been a great tool that's revolutionized the way I've made things in the last few months, few years. Now that we have the physical shape here, it's a piece of cake to export this to something that a 3D printer would understand. This is a native SOLIDWORKS file, so it's not really friendly with like exporting to like open source software. This is very closed, very contained, but all we need to do is save the file type as an STL. That's the 3D printer's favorite file type preference. And one weird thing about STL files, if you're not aware of this, is that it saves the files without any curves on them. Everything is broken up in a straight line, so just consider that in your InDesign. Since this dowel pin I have up here for this part is perfectly round, but I'm going to end up with a part with straight serrated edges, like is that going to be okay? Probably from a 3D printed part because the plastic isn't going to be, it's going to have some give, it'll flex, you know, I can force a pin in there if there's a little bit of a size difference where aluminum is going to be a little more difficult to force a too big pin in a too small hole. So just something to think about, you know, now that we've got this part, you know, saved out in a 3D printer friendly fashion, let's go ahead and fire up some 3D printer software to look at some considerations of how we would manipulate the object at this point, because it's almost there, right? We don't quite have it lined up, we don't have it in our hands. This is the 3D printer software I use for my Stratasys 3D printer. My HackerSpace back home has a really fancy industrial 3D printer that we're very lucky to be able to use and make really cool stuff with, but I've been able to get my hands on a MakerBot in recent months. Anybody in the audience have MakerBot? Awesome. How do you like your 3D printer? Yes. Awesome. So yeah, 3D printers are great tools, but you just have to have a need to use them. Like, not everybody likes downloading fake dog poop off of Thingiverse, right? Like, take a custom design and output it through your 3D printer totally changes the device from being like a novelty trinket to something you can actually use and, you know, problem solve with. So keep that in mind. So let's import this part in. We got our STL file on our desktop, and we can see it in our virtual world just sort of oriented there, no big deal. Now, there's a few different holes and a few different orientations that we need to take some considerations on. The 3D printer, the way that it layers the print, you know, slice by slice, you get these really weird grain patterns and structural differences in the grain pattern. It's kind of like wood. It's strong along the grain, but very weak across the grain. So every 10,000ths of an inch, every little slice that this part goes up is going to, it's going to be strong along the slice, but weak across the slice. So with this bearing, when you put this pin in there, if there's any sort of like shear force, that might be something you'd want to consider in the design of this part. Conversely, we also do have a minimum size limitation for how big we can make the smallest feature on a 3D printed part, and usually it's about 40,000ths of an inch. For reference, 40,000ths of an inch is about the size of your fingernail or about one millimeter if you prefer metric units. So some of these details like those holes on the side with the little threads, they're going to be more accurate. They're going to need more accuracy than the 3D printer can produce. So that's, that would be one limiting factor why we could not produce this part exclusively using a 3D printer. Now there are ways around that. You could use some threaded inserts or just tap a hole in there, but that goes into a slightly deeper subject than we'll probably be getting into here. So once I've oriented this part, you know, if I want to have the support material, you know, fill in this hole, or if I want the hole to be, you know, open to the air and nothing be filled in there at all. Or, you know, maybe we do decide that we can print with those threads on the bottom. And if we slice across the big hole, then it doesn't matter. So just something to think about. From this point, it's really easy. It's just pretty much point and go. You tell the printer, you know, how thick I want my layers to be, how how dense I want my part to be. You can print them full solid or hollow if you want them faster and cheaper or as a prototype. So then automagically the software, you know, figures out, you know, what the perimeter of each one of these slices are. It puts all the toolpath of all of those slices together and exports it to your 3D printer. And hopefully later today we can get out the MakerBot. We'll probably set up in here and tinker around with it a little bit if you guys are curious. So if I had the printer here, we could take this out and export it. But that's kind of the general idea. And I did realize I got a little distracted from my slideshow. But don't worry, I hate death by PowerPoint. So I only got like five slides for you guys. So a couple other concepts, right? Like we talked about how many zeros. Here's some information, sort of like what I was chicken scratching up on the up on the screen there. Another interesting thing I learned is I'm always looking for reference dimensions, right? Like in the shop I have something called 1, 2, 3 blocks. They're very precise blocks that are round exactly, you know, one inch and two inches and three inches. And I can always check my calipers to say, oh, yeah, that's exactly one inch. That's they're true. They're measuring accurately. But a really neat gauge of measurement is a big glider. My buddy John Gandy turned me on to this. It measures about 990 across the edges, like less than about 1% shy of an inch. So very, very accurate gauge of an inch if you ever need that in the near future. Kind of a neat hack. So this is an example of a 3D printed part using some threaded holes like I was talking about. Now, referring back to the machinery's handbook with all the information about thread pitch and the distance between each thread and the size between the minor diameter and the major diameter of the holes, you can pretty much forget a lot of that when you're using SOLIDWORKS because it takes a lot of that painful detail out of the process. But in this instance, we were able to use a creative solution to these holes. Typically, if you would make holes in a piece of aluminum, you'd have to do a spot drill just to get like a starter hole. You'd have to get a very specific size drill for whatever size thread you want. And then you have to thread the tap in very, very carefully to form the shapes of those grooves on the way down. But with plastic, it's not nearly as tough as aluminum so you can use a little bit more wiggle room. The hole doesn't have to be precise. It's okay if there's no straight edges. And metal cutting tools really like to remove plastic material from a hole. So what we just ended up doing here is we skipped the first three steps of producing these tap of these threaded holes inside of a part and just directly modeled the precise hole into the 3D printed part. And all you needed to do was run a tap down there and it was done. So very, very trivial way to bypass what would have normally been a very difficult project on either a milling machine or, you know, even if you had like some drill motors who were trying to do this with it, just using a 3D printer to bypass a lot of these typical engineering problems, you know, it allows you to do smart work than hard work. I guess that's the point I'm trying to get across here. So talking again about tolerance and slop and measurements and accuracy, if you ever need to send a print out to a manufacturing house or engineer or whatever, they're always going to ask you, you know, how many zeros do you want in the design? And that will directly correlate to how many zeros you want in the dollar price. So a pretty reasonable amount is about 5,000 some an inch plus or minus, you know, that might as well be a mile for any manufacturing process. That's a little more than the thickness of a sheet of paper. So just to give you an idea of like how big or how little that would affect your end result. There's our machinery's handbook again. I can't stress enough what an important reference that is for dealing with even the simplest engineering problems or processes. It has lots of really good information in it, like the thermal expansion rate of materials. So if you have dissimilar materials bolted together that go through thermal changes. So, you know, that's something you might want to consider is how much they're going to grow, how much they're going to stretch and expand, and you know, what kinds of forces that adds to all the fasteners over a distance. So, you know, very open ended, top heavy subject to try and get into. But hopefully we showed you guys a couple of interesting concepts here to sort of get you down the road, just to give you an idea of how this is done in the real world. I still got a little bit of time here, I believe. Do want to do a little bit of Q&A here, but I did want to show you guys a neat little treat that I discovered in the past few months. So, like I said, I was doing SolidWorks Engineering for a few years. SolidWorks is like $4,000 for the base package. It sucks to try and go out there and buy as, you know, just a user trying to discover this for the first time. So, recently there's been a great online alternative called Onshape, which was developed by the original SolidWorks team. Actually, John Hirsch is spearheaded the Onshape project and he was one of the original members of the MIT Blackjack team. So, the guy got rich, screw in Vegas, you know, went out and made SolidWorks and now he's doing something Onshape. It's free, basically SolidWorks. So, once I find my Onshape. So, it's free to sign up. They're still in beta right now, but it's 90% of the functionality you need in SolidWorks with, you know, 10% of the features. Like this will accomplish 95% of the things I've done inside of SolidWorks. So, I've already drawn this part, but I'll draw it again just so you guys can see the same process is the same. Once you know Onshape, you know SolidWorks. So, it's just a really neat way to like ramp up very easy 3D modeling tools and even the hot keys are the same when you go to SolidWorks. So, it's really, really cool. Very, very close accurate representation. So, we'll just go ahead and make a new document. It wants me to delete something. Hold on. Those always go perfectly. I'm just glad SolidWorks didn't crash. Like that was amazing, dude. So, this is essentially the same workspace that we have here, but this is all getting rendered on the cloud. One problem with SolidWorks is that it usually requires a Death Star workstation with a, you know, needs very specific licensing requirements and I mean, this dinosaur is 20 pounds. I don't know why I'm still carrying this thing around, but I guess it's better than the way they used to do CAD on, you know, big Vax PDP system. So, I guess I don't have to whine anymore now that you can do CAD on a tablet on a thin device. I've done it on Chrome OS before. So, it just works. And what's really neat is you're always on the latest version when you're running, you know, the cloud based CAD where SolidWorks is a non-trivial install. As a SolidWorks support engineer, I spent the first three months out of every year helping people unscrew their software installs. So, I'm sure none of you guys know what that's like. So, same process here. You know, we have a couple of little planes that we can work with. We'll just draw a new sketch plane on this front plane. Go view normal too, so we look directly down on top of it. And we'll just start drawing some lines. So, that's starting to look like something. So, the hot key for line is L, we'll go figure, right? And I'm just kind of roughing out this model. All these lines are blue because I haven't locked them down. They're still free floating. So, like, I can grab these points, you know, draw and drag them around. It's trying to align vertically with that edge right there. That's what I want it to do. Same thing, you know, with the diameters here of, you know, these arcs or the end points of the arcs. So, just kind of cool to know that you can drag and drop this stuff around. Let's see. We want to try and make these edges tangent right there. There's at least two curves. Oh, I just deleted everything. Huh, let's do that again. So, maybe we'll start with a circle. There you go. That's looking better. And then I'll draw the rest of the design around it. Maybe that's the easier way. See, now it already knows that the line is tangent. So, sometimes you beat your head up against a wall trying to solve a problem one way. If you just take a few steps back and try a different approach, usually you can get this software to agree with you. Just like every other piece of software I'm sure you guys specialize with. So, now we have that edge tangent. We'll do the same thing on the other side. There we go. You notice how it changed my relations to finally find a tangency once I drag the cursor around to a more tangent area. So, it's something to think about. So, now I can draw the rest of this design. Okay, that looks right. So, we still have some sketches here. And the only way I can make a 3D solid object is if I have one path around the outer edge. Right now, solid works or on-shape wouldn't know how to deal with this because it doesn't know if I want to make a solid body out of that circle or out of that of the rest of the part or out of both of them. So, it usually helps to trim these tools to trim these things a little bit. See where is my dimensions, sketch features. There you go. Sorry, I've only used the software like three times. So, I can just trim that inner edge. And now we have something we can turn into an extrusion. And this should look similar from what we were just dealing with. 0.375. Put a new sketch on this top face. There's my concentric point. Again, I'm getting really good at this. I must be running low on liquor. Done with this one. So, this is a little bit weird. The buttons are changed around it. Like I said, it's pretty much the same concept, even the same shapes that you select for the various tools. But this instance, I want to remove that hole, go 320 deep. It's pretty close. Oh yeah, I forgot to fill it on the outside. Same tool here, right? One, two, five. So, that's an eighth of an inch. And this already guessed, hey, I want to fill it around the tangency of that edge. So, there we go. Hide these sketch planes. And let's see how close that is to SOLIDWORKS. Side-by-side comparison of the right-hand side. $4,000 plus commodity software. The left-hand side. Free online CAD that came out just a few months ago. Please use it because it's freaking wonderful. Blow your mind. So, I think that about wraps up what I had for you guys. I have time for some questions or comments or interesting anecdotes if anybody has them. Am I familiar with SketchUp as a question? Yes, I am familiar with SketchUp and I've used it once, smashed my face in the keyboard for about 15 minutes and got nothing to happen. So, I gave up. Why use SketchUp when you have this online for free? Interesting. So, the gentleman was mentioning that when he's been using his 3D printer, making the parts completely solid dramatically affects the thermal expansion rate. When they cool off, if you have a solid model, they shrink or grow more than if you had the model maybe 60% full, is that right? So, yeah, I've experienced very similar things myself using the MakerBot style 3D printers. You do have to accommodate for a little bit of that flex and warp and shrinkage. Yes, especially so. Thanks for coming out guys.