Practical 3D Printing: CAD

Back to course

Watch This Course

$199 USD $99.50 USD

-OR-

Or 8 easy payments of only $12.44 USD Instant access. Easy checkout. No fees. Learn more

Enroll Now
8 easy payments of only $12.44 USD

Course Access for Life

60 day money back guarantee

CAD

06.55

00:00	This section of the course will be all about transferring the theoretical knowledge that we've learnt about SLA 3D printing into practical skills.
00:08	It's important to note that 3D modelling isn't the focus of this course.
00:12	If any of what we cover in this module isn't clear to you, I'd strongly suggest checking out the HPA 3D Modelling and CAD for Motorsport course where you can learn these skills.
00:23	For this example we'll be using a real car part to help illustrate how these skills are applied and further worked examples will be added to this course over time so we can dive deeper into different materials, applications and considerations.
00:37	The specific part for this example is a set of velocity stacks for our Honda K20 engines individual throttle bodies in our CRX endurance race car.
00:47	These will essentially be functional prototypes used on the engine to serve as validation for a few different ideas.
00:55	Most importantly, the length of the velocity stacks has an impact on the powerband of the engine so by printing up different length prototypes, fitting them and measuring the results on the dyno, we'll be able to make informed decisions on what length is going to work best for our application.
01:11	The stacks have also been designed with some features to mount a fuel rail for a secondary set of injectors to be mounted towards the end of the bell mouth.
01:20	This way the primary injectors closer to the ports can provide good drivability and transient response through the lower rev range while the idea behind the secondary set of injectors is to increase the mixing of the intake air and fuel at high RPM in the interest of power.
01:37	We've been testing velocity stacks 3D printed using a high temperature resin on a street car with success.
01:43	So, this will also be a test for the material to see if it's capable of withstanding the heat from a more demanding application of dyno testing and potentially in race use.
01:54	Velocity stacks for motorsport applications are typically made from spun or machined aluminium or in some cases from carbon fibre.
02:02	We do have some tight packaging constraints for this project.
02:05	In most cases a K20 with ITBs and a Honda EF generation chassis will have the intake protruding from the bonnet or hood.
02:14	However, the aim in this case is to keep the entire package under the factory bonnet line.
02:19	To help here we're using a specific intake manifold from Genve that curves downwards.
02:25	We also have some curved velocity stacks that are cast aluminium to help further here although they're not designed for this application so need some extra work to make them fit.
02:36	While these conventional manufacturing processes work well and produce parts fit for purpose, they don't allow for any experimentation which is why we're turning to rapid prototyping in the form of SLA 3D printing.
02:48	Additionally the design flexibility provided by additive manufacturing has allowed us to create a curved velocity stack with features for mounting the secondary injectors without adding any extra complexity to the manufacturing process.
03:02	We don't have to worry about a sock style air filter fitting over the velocity stacks as the future design of a carbon fibre air box will involve a panel filter and ducting from the front bumper.
03:14	All that's really critical in this case is to keep clear of the inside of the bonnet.
03:18	The 3D modelling process for these parts was done in Autodesk Fusion.
03:23	This process involved working off a 3D scan of the engine bay and the underside of the bonnet.
03:28	We also have a solid model of the intake manifold and the throttle bodies that was created using the manufacturer's drawings from their websites as the canvas, essentially tracing out the parts and reverse engineering them.
03:41	With all of these references in place, it was fairly straightforward to model the base flange of the stack.
03:46	Then use the surface loft and revolve tools to create the curved and tapered body.
03:51	By modifying the dimensions here, we're able to create different variations for the velocity stacks.
03:57	The flexibility of surface modelling is well suited to additive manufacturing.
04:02	We just have to thicken the surfaces to create a solid body that we can actually print.
04:07	An EV14 compact injector model that was downloaded from GrabCAD, which is a popular CAD model sharing website, was used as a reference to build the injector bosses from a series of extrude features.
04:19	Some inspiration was taken from the Group 2 BMW CSL race car which has the injector protruding through the wall of the velocity stack, keeping it out of the airflow.
04:30	This is opposed to placing the injectors and the fuel rail straight in the middle of the bell mouth, blocking the airflow.
04:37	After this we used another reference model of the fuel rail to make some mounts, supporting it in the desired location.
04:43	The configuration function in Fusion was used to set up the aspects as the dimensions from the sketch of the arc that controls the length of the velocity stack.
04:53	We'll be using three different configurations of 50, 80 and 110mm long velocity stacks, giving us a good range for our dyno tests.
05:03	The radius of the arc was also adjusted in each configuration to ensure that the part fits inside our packaging constraints.
05:10	For this example, these constraints were an important driver behind the design.
05:15	In terms of DFM considerations, our design doesn't contain any features that should prove difficult for SLA 3D printing.
05:22	There's no excessively fine details other than the threads for the fuel rail mount which we can chase with a tap.
05:29	The part will be printed solid rather than hollow in the interest of thermal mass so there's no need for escape or relief holes.
05:36	The only concern is the witness marks from the supports on the surface as these will be somewhat unavoidable and we want the flange sealing surface as well as the o-ring surface for the injectors to be nice and smooth.
05:49	But we can fix these with some finishing processes after printing.
05:53	Once we're happy with the design, we can use the 3D print function from under the utilities tab to send each body to our print utility or in other words our slicer.
06:03	Which for this example will be ChittuBox Basic.
06:05	But we'll come back to this in the following modules.
06:09	The key takeaways from this module are that with a good solid setup of our design file, with individual components, appropriate joints and references, the modelling process is fairly straightforward.
06:20	Surface modelling tools are often used for modelling SLA 3D printed parts as they offer a lot of flexibility just like the manufacturing process.
06:29	However, surface models do of course need to be converted to solid bodies before printing.
06:34	The most important things to keep in mind during the modelling process is the function of the parts and the constraints as well as the DFM considerations to ensure that we end up with a part that can be manufactured effectively and efficiently and also justifies the manufacturing method of choice.