Practical 3D Printing: CAD

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CAD

08.24

00:00	This section of the course will be all about taking our new theoretical SLS 3D printing knowledge and transferring it into practical skills.
00:08	In saying that, our approach to this form of 3D printing throughout the course has been on the assumption that any SLS 3D printed parts we're responsible for will be printed by a third party manufacturer.
00:20	So, we'll be continuing with that approach throughout the practical skills section.
00:25	This will provide a more realistic perspective and skills as it's unlikely anyone taking this course will have hands on access to an SLS printer.
00:33	We'll be using a worked example of a real car part to help illustrate how these skills are applied.
00:39	And further worked examples will be added to the course over time so we can dive deeper into different materials, applications and considerations.
00:48	The part we're going to use for this example is an intake manifold adapter for Gen-B individual throttle bodies onto a Toyota Beams 3SGE engine.
00:58	This is powering a Toyota AE86 race car and is currently set up with stock ITBs from a Toyota 4AGE blacktop engine.
01:07	A 2 litre 3SGE in a race car naturally has different airflow requirements to the factory 1.6 litre 4AGE.
01:15	So, we're hoping to see some small but worthwhile gains from slightly larger throttles.
01:20	In the largely unrewarding realm of NA tuning in any case.
01:25	For this setup, the 3SGE has a short base intake manifold with a rubber isolator that our new adapter will mount to.
01:33	This is hugely beneficial to our project because it achieves a few things.
01:37	First, it'll reduce conductive heat transfer to the 3D printed adapter, dampen vibrations that lead to fatigue failures and also provide a sealing surface.
01:47	Another benefit is that the injectors and fuel rail mount directly to the cylinder head which means we don't need to account for them in our design.
01:56	The current setup runs on what's referred to as alpha N, meaning that the engine tuning or calibration is primarily based on the throttle position sensor or TPS with some compensation reference from the MAP sensor.
02:10	Again, the TPS is attached to the throttles so all we need to worry about is adapting the ITBs to the base manifold and incorporating the MAP sensor.
02:19	If you're not familiar with all these Toyota and tuning technicalities, don't worry as it's not the focus of this module.
02:26	We're using this as an example purely because this process of adapting parts from another application to our specific use is common in motorsport and the one off custom nature is well suited to additive manufacturing.
02:40	We'll be 3D printing the part from glass filled nylon 12 which is a common material used for intake manifolds in modern OEM vehicles.
02:48	While it's possible to 3D print nylon using cheaper FDM printing, SLS will produce a better surface finish and mechanical properties which is critical to a functional part like this.
03:00	Also since the part will be too large for most consumer grade FDM machines that we're likely to own, it'll require use of an industrial manufacturing service, negating most of the cost advantage of FDM over SLS.
03:14	The beauty of SLS 3D printing is that it doesn't require support structures so we'll have more flexibility in our design to create internal passages for the likes of balance tubes that can also be used to provide a MAP sensor reference.
03:29	It's important that we play to these advantages to justify the use of SLS 3D printing over other manufacturing processes like FDM, investment casting or machining while also keeping in mind the DFM considerations.
03:43	This will be a relatively expensive exercise so we really want to get it right the first time.
03:48	With all of that in mind, let's quickly look at how we created the model.
03:52	As always, 3D modelling isn't the focus so if any of what we cover here 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.
04:04	This part was designed using 3D scans of the engine bay with the base manifold attached, as well as a solid model of the Gen-V throttle bodies created from taking physical measurements of the parts.
04:16	Setting these up in our workspace in the desired position means we had a clear reference that we could work off and essentially just join the dots to model our adapter.
04:25	A key feature is the holes in the flange for mounting the throttle bodies.
04:29	These will feature threaded inserts which, looking ahead for a moment, is a service offered by Prototech who will be printing this part for us.
04:38	The inserts used are those found in the McMaster Car catalogue.
04:42	For those who aren't familiar with McMaster Car, they're an industrial supply company with almost any piece of hardware you'd need for any job.
04:50	They've become very popular in the CAD space as they offer 3D models and technical drawings that we can use in our projects and many CAD programs even have McMaster Car plugins.
05:02	A quick search through their catalogue and we've found the brass heat set threaded inserts for plastic parts.
05:08	We'll use the M5 by 0.8 inserts that are 11.1mm long.
05:13	What's important is sizing our holes in the part appropriately for the specified 0.277 inch hole diameter and the minimum depth of 11.9mm as well as a good amount of wall thickness around the holes.
05:29	The vacuum rail for our MAP sensor is another interesting feature and this is where we've played into the strengths of SLS.
05:36	There's a small port on the side of each runner that collects into a thin vacuum rail with a barb on one end for a length of rubber hose to connect to the MAP sensor.
05:45	The routing of the rail curves around to allow access to certain hardware, that means we can remove the entire intake manifold from the cylinder head without having to separate it into individual pieces.
05:57	This vacuum rail would be something almost impossible to produce as a single piece in any way other than SLS 3D printing, thanks to the fact that we don't need to use support structures and this brings us to our all important DFM considerations.
06:12	While we want to keep the size of the ports on the runner walls as small as possible, their diameter along with the internal diameter of the vacuum rail was kept to a minimum of 5mm.
06:24	This is necessary to allow the excess unfused powder to be removed from the part after printing which will be aided by some compressed air.
06:32	It should be noted that there's a section at the barbed end with a smaller internal diameter but because it's short enough, this shouldn't cause any issues.
06:41	Other than that, there are no features of this design that raise any concern with regards to the manufacturing process.
06:48	There are also no excessively fine details that wouldn't be achievable or small gaps or enclosures that might trap unfused powder.
06:56	The bolt holes are 9mm in diameter which should provide plenty of tolerance for the M8 hardware without causing a sloppy fit up that could lead to misalignment in the internal surfaces of the runners and upset airflow.
07:10	On finishing the design, we printed a prototype using our FDM printer.
07:14	This was a relatively cheap way to provide peace of mind that the part will fit as intended without any oversights before paying for it to be SLS printed.
07:24	Now, we're happy with the design, we can export a step or mesh file that we'll provide to our 3D printing service provider in the following modules to bring our design to life.
07:35	Before wrapping up, we need to produce a basic technical drawing for the threaded inserts.
07:40	This just needs to contain a simple view of the part, giving a clear indication of the holes that should receive the threaded inserts.
07:48	We'll also note the specific McMaster car part number and which surface we want the inserts to be flush with.
07:55	With that, let's recap this module.
07:57	With a good solid setup of our design file, the modelling process is fairly straightforward.
08:02	As always the most important things to keep in mind during the modelling process is the function of the part and the constraints as well as DFM considerations to ensure we end up with a part that can be manufactured effectively and efficiently and also justifies the manufacturing method of choice.