Practical 3D Printing: CAD

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CAD

09.48

00:00	This section of the course will be all about transferring the theoretical knowledge that we have learnt around FDM 3D printing into practical skills.
00:07	We'll use this same process for the main four types of 3D printing that we'll be discussing in this course, using a worked example of a real car part to help illustrate how the skills are applied.
00:20	Further worked examples will be added to this course over time so we can dive deeper into different materials, applications and considerations.
00:28	While FDM can absolutely produce end-use, motorsport-ready parts, the worked example we'll be using in this section will be a prototype, more specifically a brake caliper bracket for mounting an aftermarket caliper to a suspension upright.
00:42	This brake caliper bracket was designed as a worked example as part of the HPA 3D scanning course.
00:49	I'd recommend checking it out if you're interested in exactly how we got to this point, and of course learning more about 3D scanning.
00:56	This process involved, first of all, scanning the upright and the caliper, and then setting up the assembly in CAD with a model of a hub and a brake disc.
01:05	The caliper was positioned over the disc in the ideal location, and then the bracket was designed to mount the caliper in that position.
01:12	The brake disc hat was also chosen from an off-the-shelf offering so the package would fit inside the specific wheels that will be used on this car.
01:21	By 3D printing the bracket, we can double check that we've got the position of the caliper correct relative to the disc, and that we're not going to run into any other clearance issues.
01:30	This will also give us a chance to see the design in its real form as it can be hard to get a full understanding from the digital model on our computer screen.
01:40	The final caliper bracket part will be machined from aluminium, which won't be cheap.
01:45	But this prototype will be, and it'll give us the peace of mind before moving forward, allowing us to catch any issues and save us some time and money in the future.
01:54	While we're at it, we'll also print a prototype of the disc hat to confirm the dimensions are correct and the assembly will fit inside our wheels before we make that purchase.
02:03	In this module our focus will be on the CAD work and the DFM considerations required to make our current design and prepare it for 3D printing.
02:12	3D printing is of course possible without 3D modelling skills, but the reality is, if you want to make the most out of it, being proficient in CAD is important.
02:22	So, if you're not already experienced with CAD, then I'd recommend checking out the HPA 3D Modelling & CAD for Motorsport course.
02:28	This will get you set up to design parts like this that you'll be able to bring to life with 3D printing.
02:34	With that said, we won't be focusing on the details of CAD modelling right now and we'll gloss over a lot of the basics.
02:40	We will, however, be sharing the CAD models for these parts moving forward in case you want to try printing them on your own setup to compare your results.
02:48	With that out of the way, let's jump into our CAD software.
02:51	We're using Autodesk Fusion in this course as it's a powerful and accessible option that's become very popular at a hobbyist level all the way through to top-tier professionals in our industry.
03:02	Starting with our assembly of the upright and brake components, we'll create a copy of the bracket so we can modify it without changing the original design.
03:11	This is easily done by right-clicking the body in the browser and selecting the Move Copy tool, then checking the Create Copy box in the bottom of the pop-up window before clicking OK.
03:21	This part was designed with DFM considerations for machining in mind and it's a relatively straightforward part to machine.
03:29	But now that we're 3D printing it using FDM, we have a new set of DFM considerations.
03:35	Again, things are fairly simple.
03:37	We have no unsupported walls, hanging bridges, or fine details.
03:41	The holes in the part are plenty big enough to be printed accurately and we don't want to actually make them too big for now.
03:48	Otherwise, it'll be harder to spot any misalignment in the parts.
03:51	So, we're going to have to make some adjustments to the holes in the upright that we might need to adjust, which is the main reason for printing this prototype.
03:57	By printing the part in the correct orientation, we should be able to get a very accurate model, but we'll discuss this more in the coming slicing module.
04:06	The only features of concern are the threaded holes for mounting the part to the upright.
04:11	Trying to print threads of this size with our FDM printer is possible, but it's not ideal.
04:16	And if we drill and tap the threads, they likely won't be strong enough to support the weight of the caliper.
04:21	So, we'll remove the threads from the holes and add hex nut pockets to the bracket so it can be mounted to the upright with hardware.
04:30	Thinking ahead, this will also clamp the part, adding strength between the printed layers.
04:35	With this, we can use M12 hardware and be confident that it will support the weight of the caliper.
04:41	These holes are modeled using the threaded hole tool.
04:45	And if we print them as is, they'll only be about 10.5mm in diameter, clearly not large enough for an M12 bolt.
04:53	Let's sketch on the top face and make new circles, concentric with those we've just projected, but 12.5mm in diameter, so we have enough clearance for our M12 bolts, while still being small enough that we can tell if the holes in our bracket match that of the upright.
05:09	Next, we'll use the circumscribed polygon tool to sketch hexagons centered on the projected holes.
05:16	By taking a physical measurement of one of the M12 nuts that we've printed, we can see that they measure about 19mm across the flats.
05:24	We'll make our hexagon 19.5mm in this dimension to easily fit the nut, but still prevent it from rotating.
05:32	After finishing the sketch, we can use the extrude tool to cut the 12.5mm holes through the entire part, and then again to cut the hexagons down 10mm, which matches the depth of the nut, but leaves plenty of material to clamp through as well.
05:47	That's all that's required for the bracket, so let's look at sending it to our slicing software, and there's a few options here.
05:53	One option is to hide all the components and the bodies other than our modified bracket, and then select the export from under the file tab, and choose the mesh file format like STL.
06:04	Some slices like Bamboo Studio, which we'll be using from this example, can also work with step files.
06:10	Alternatively, we can right click the body and select save as mesh, or select export 3D print from the mesh toolbar, or make 3D print from the utility toolbar.
06:22	All of these options will open the same pop-up window, where we can change the preparation type between entering the Fusion CAM or manufacturing workspace, export a mesh file, or change the method we'll use of sending our design directly to our print utility, in other words, the slicer program.
06:40	For this example, we'll be using Bamboo Studio, so we just need to find this application, and then choose the mesh format we want, STL binary is a nice simple option that's perfect for this part.
06:53	The units we designed the part in also need to be selected, which was millimetres in our case, as does the mesh refinement, which we'll leave as the high setting, and then click ok.
07:04	This will open the application and drop the file onto the build platform, but we'll leave that there for now and come back to this stage in a coming module.
07:12	Moving on to the brake disc hat, this isn't a part that we've designed, just an off the shelf product, from a brake parts supplier that should work well for this application.
07:22	We just want to prove it will work before spending the money.
07:25	It's been modelled based on drawings and specifications from the suppliers website, and also features threaded holes, so we'll make the same nut pockets to clamp the part together, and fix it to the disc with M8 hardware.
07:39	The actual part uses 5 16ths hardware, but this is very close to M8, and we have metric hardware on hand in our workshop.
07:46	The disc is an external component in our assembly, so we'll start by opening it, and then creating a copy of the hat, so we're not modifying the original.
07:55	Let's hide everything we don't need, like the original hat, disc and hardware.
08:00	From here we'll sketch on the front of the hat, and then project one of the holes, again sketching a slightly larger circle, concentric with this, at 8.5mm, giving some clearance for our hardware.
08:12	Then with a hexagon, with a dimension of 13mm across, we'll make a hole in the middle of the flat to hold the M8 nut and stop it from rotating.
08:20	We'll extrude the circle through the entire part to clearance the holes, and then the hexagon 7mm down so the nut is sub-flush with the mounting face, and won't interfere if we try to fit a wheel to the assembly when checking for clearance.
08:34	Then it's just a matter of using the circular pattern tool to copy these features to the other holes.
08:39	From here it's just like before, we can export a mesh or step file, send our file directly to our slicing software, or even do the slicing in Fusion's manufacturing workspace.
08:50	Assuming this fit up with the prototypes goes well, we'll purchase the disc hat and then double check again with this and our 3D printed brake caliper bracket.
08:59	We'll carry on with the other FDM practical skills in the following modules, and progress to printing these parts and testing them out.
09:06	So, let's recap this module before moving on.
09:09	CAD or 3D modelling isn't imperative to using 3D printing, but it does allow us to use this technology to its fullest, to its full potential.
09:17	It's during this stage that keeping our DFM considerations in mind is critical.
09:22	Often parts that were designed with another manufacturing method in mind, but will be 3D printed as prototypes, need to be revised for a new set of DFM considerations.
09:33	Once we're happy with the model, it's just a matter of exporting the file in the appropriate format for the slicing software that we intend to use, and some software will even allow us to transfer the files directly.