3D Modeling & CAD for Motorsport: Step 2-C : Modelling - Details and Extra Features
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Step 2-C : Modelling - Details and Extra Features
16.06
| 00:00 | - With the bulk of the valve cover roughed out, it's time to add all the necessary features to make it function as well as some finishing touches. |
| 00:08 | One of the last things we worked on was the valley for the ignition coils and now we'll add to this with the fixtures and provisions to mount the coils. |
| 00:16 | We'll start with the bosses to fix the coils in place, using a sketch on the mounting face of the coil tabs that projects the coil mounting holes along with some other larger concentric circles. |
| 00:29 | Then, using the extrude tool to make bosses down to the surface of the valley of the valve cover. |
| 00:35 | After hiding the coils temporarily and making our previous sketch visible again, the next step is to use the hole tool. |
| 00:42 | Let's select the centre point of each mounting boss and change the extents preference to two, selecting the top face of the valley as our target again. |
| 00:52 | Then create a simple tapped hole for the hardware with a flat bottom. |
| 00:57 | On the bottom face of the top section of the coil, there's a small tab that's currently interfering with the top valley surface. |
| 01:05 | This can be used as an extra security to lock the coil in place and prevent it from rotating. |
| 01:11 | We'll just add a small pocket for clearance around these, starting again with a sketch on the top surface of the valley. |
| 01:17 | We can project the bottom face of the tab on each coil and then use the offset tool to offset this profile. |
| 01:25 | And then include some fillets to round the sharp corners for machining. |
| 01:29 | Then cut this into the top surface just up until the corresponding face of the coil tab. |
| 01:35 | Although this does reduce the thickness of the top bore slightly in these spots, some geometry we'll add in a moment to support the coil stalk bosses will mitigate this, on that note clearly we're missing the actual holes for our coils to protrude through the valve cover so let's add them next. |
| 01:51 | This is relatively easy as we've previously created the profiles so we can jump straight into the extrude tool in this case. |
| 02:00 | Making our first sketch visible again and selecting the spark plug holes then cutting these through the entire valve cover. |
| 02:07 | We actually need to change these spark plug holes to a counter bore style with a sloped step, to house the upper section of the coil stalk and create a seal. |
| 02:17 | Luckily we have an engine with a similar feature in our workshop that I was able to measure so let's start creating this geometry with another sketch on the top surface of the coil valley. |
| 02:28 | Firstly projecting each spark plug hole and then adding another larger concentric circle that will form a counter bore. |
| 02:35 | Next we'll open the extrude tool and cut this down into the valve cover. |
| 02:39 | To turn the flat step of the counter bore we've created into a sloped surface, we'll use the chamfer tool and select the inner edge of each hole, making an equal distant chamfer the same width as the step. |
| 02:53 | After finishing our chamfer we'll make our coils visible again and use the section analysis tool through the right plane to check what we've just done as we can't see this from outside the part. |
| 03:05 | Now we can clearly see how the coil stalk fits in the hole and this flange that shows interference is actually a flexible rubber seal that will deform as the coil slides down the bore so this looks perfect. |
| 03:18 | We can also see though that the top section where the coil stalk boss meets the bottom of the valley could do with some more reinforcement. |
| 03:26 | We'll then sketch on the bottom surface of the valley inside our valve cover and project the edge that runs around the intersection of the bosses and the sketch surface. |
| 03:35 | We can then use the offset tool to copy these profiles but spaced out, finish this sketch then extrude this new profile up to the bosses joining them to the valve cover body of course. |
| 03:49 | To match the counter bore inside the bosses, we'll finish them with an equal distant chamfer on the edge. |
| 03:55 | Moving on, let's create the threaded holes for the breathers, starting with another sketch on the outer faces of the breather provisions to provide some centre points for the hole. |
| 04:06 | We'll project the sketch plane faces in the top of the flange and draw a horizontal line, co linear with the top of the flange. |
| 04:13 | Then use construction lines from the corner to corner to find the centre points, placing a circle here. |
| 04:21 | This will be used as the centre points for our hole tool. |
| 04:24 | The holes will use -10 ORB to -10 AN adaptors so we can fit our existing breather lines to the catch can. |
| 04:33 | The extent for this hole tool can be set as the inner side wall of the valve cover. |
| 04:37 | The closest thread to what we need in the Fusion 360 library will be under the ANSI unified screw threads. |
| 04:46 | From here we can select 0.875 inches as the size and 7/8-14UNF as the thread. |
| 04:53 | This isn't technically the correct thread so we won't bother modelling it and we'll remember to use a note designating the thread on our technical drawing. |
| 05:02 | To finish these holes we'll use a small chamfer around the leading edge which we use as the ceiling surface for the o ring of the ORB fitting. |
| 05:11 | The outside of the valve cover is finished at this stage with regard to the features so let's use the fillet tool to round the remaining sharp edges before moving back inside. |
| 05:23 | Something worth noting here with parts like this with a lot of intricate curves and details, is it can get quite difficult to get the results we want with the fillet tool and it can be even more difficult to determine why. |
| 05:36 | In some cases, there can be an underlying reason for it, in other cases it's just the program being buggy so we might need to adjust things to work around these issues. |
| 05:47 | Inside the fillet tool it's possible to use multiple selection sets with different radii, holding command on a Mac or shift on a Microsoft, will help select multiple entities and these could be faces where the fillet will be applied to all the edges around the face, or individual edges. |
| 06:06 | Clicking the plus button on the fillet tool allows us to create multiple selection sets all with different radii. |
| 06:12 | On the top of the part around the coil mounts and locating tab recesses, we'll use a chamfer for a slightly different look and a lead into the holes. |
| 06:22 | Next we'll move back to the breather ports to finish them up. |
| 06:25 | What we need is a baffle plate that stops the oil being sprayed off the rotating camshaft and straight out the breather port. |
| 06:33 | Instead, we want to minimise the amount of oil that actually leaves the breather ports while still allowing it to vent the crank case pressure. |
| 06:41 | In factory valve covers, these are often riveted in and in some aftermarket options, they use steel wool or the plates will be held in place with fasteners. |
| 06:52 | We really want to avoid this if possible as a loose screw in the valve train can be catastrophic. |
| 06:58 | Instead, we'll aim for a design where the baffle plate is held in place by the valve cover itself being fixed to the cylinder head and since we don't have much space inside the sides of the valve cover to the camshaft caps, we'll try to integrate this into the wall. |
| 07:14 | The other thing to consider here is that there will be an o ring groove also running along this face where it contacts the flange so we need to leave enough space for this, meaning we need to keep the pocket for the breather as low profile as possible. |
| 07:28 | To make a cavity for this all to fit in, let's sketch on the bottom face of the valve cover that mounts to the cylinder head and start by projecting the entire flange and also the threaded breather ports. |
| 07:40 | We'l sketch a shape inline with each breather port with the line tangent arc and centre to centre slot tools that basically forms half of a rounded rectangle as a recess for the gas flow with a vertical slot to hold the baffle plate. |
| 07:56 | Another short vertical slot inside the main one will be for a tab on the baffle plate to hold it in place. |
| 08:03 | At this point we can make our flange canvas visible again and check out slots which show the position of our baffle plates overlap with the flange, meaning they will be held in place. |
| 08:14 | Back to our extrude tool, we want to make an extruded cut of both of these profiles excluding the end sections of the long slots, high enough up the wall so it just passes the breather port. |
| 08:26 | The reason we want to exclude these sections is because they are very thin so require a very small machine tool size. |
| 08:34 | And we don't want them to be tool long as this will cause issues with the small tooling having to plunge too deep. |
| 08:41 | Instead we'll make another extrude cutting these sections a short depth into the part. |
| 08:47 | Following this, another extrude just of the short slot profiles. |
| 08:51 | In this case, if we set the extent to 2 object and select the bottom face of the pocket and then use an offset to cut the slot a bit futher into the part. |
| 09:02 | While we're at it, let's create the breather plates themself, starting with a sketch on the outside of the recess we just made. |
| 09:09 | The first thing we'll do is set our line type to construction and project the edges of the breather pockets onto the sketch, including the tangent edges. |
| 09:18 | For the curved side faces, we need to use the intersect sketch tool. |
| 09:24 | Changing the line type back off construction mode, we can use the line tool to sketch a profile of the plate just inside the projected edges. |
| 09:33 | Being sure to dimension the small offsets between our sketch profile and the projected lines from the top face and the side walls so we can be sure the plate will slide into the pocket without any issues. |
| 09:46 | Using the fillet tool, we'll radius all the external corners. |
| 09:50 | Clearly, we don't want to cover our breather ports completely so we need to add some slots to this to let our breather vent the crank case pressure. |
| 09:59 | Two vertical slots in the middle of the plate and one horizontal slot up along the lower edge should be sufficient. |
| 10:06 | If we find we require more or less baffling or venting, we can increase or decrease the size of these slots easily as they'll just be cheap sheet metal parts. |
| 10:16 | Naturally we need to copy this sketch on the other breather port using as many constraints as needed to fully define the part and avoid doubling up on unecessary dimensions. |
| 10:27 | Next we'll jump over to our sheet metal toolbar and select the flange tool. |
| 10:31 | Selecting the profiles we've just sketched, obviously excluding the slotted holes with the orientation preference to create the body in the correct direction inside the slot. |
| 10:42 | We can check our sheet metal rules to make sure these are the correct thickness. |
| 10:47 | Moving on, we'll make our o ring grooves. |
| 10:49 | One around the main outer flange profile and one around each of the spark plug holes and also the centre mounting hole. |
| 10:57 | We're going to use a 3mm diameter high temperature o ring for this and we can look at charts for static seals to give us the dimensions for the groove. |
| 11:07 | To model this, we'll use the sweep tool, perfect for cutting the groove profile around what will be an irregular path which is the two sketches we're going to require. |
| 11:18 | Starting with the path, we'll sketch on the flange profile and it'll be helpful to view our canvas again for this process as well as showing our first sketch of the flange. |
| 11:28 | We'll use the project tool to include the inner sketch profile from the first sketch that follows the inner edge of the flange all the way around and also the inner circles for the spark plug holes and the centre mounting hole. |
| 11:42 | Then offset the profiles outside the projected curves. |
| 11:46 | A few modifications are required to the profile, easily made with the line and arc tools to ensure the groove stays inside the flange and avoids any features in the valve cover like the breather cut outs. |
| 11:59 | It's worth making the circular o rings a standard size that we can easily order from a supplier in the diameter and material that we want. |
| 12:08 | Next we need to sketch the sweep profile on the right plane which intersects all of the sweep paths, one of the requirements for a sweep. |
| 12:16 | We can also use the intersect tool to find the point of intersection. |
| 12:21 | For each profile we'll sketch a small centre point rectangle on the intersection point and create our cross section using the dimensions of the o ring groove chart. |
| 12:31 | Then it's just a matter of using the sweep tool to cut each groove into the flange then double check our groove doesn't interfere with the breathers and stays inside the flange. |
| 12:41 | The final step before finishing the valve cover by rounding all the internal edges is to add some webbing as a relatively lightweight method of reinforcing the main shell of the valve cover. |
| 12:53 | Sketching on the bottom inside face of the ignition coil valley, we'll project the vertical faces and use the line tool to sketch the webbing centrelines in line with the spark plug holes. |
| 13:06 | This will form one series of webbing and the other will be from 3 vertical lines down the middle of the valve cover. |
| 13:12 | We can then use the web tool and select the horizontal lines, setting the thickness and direction to symmetric so the lines are the centrelines of the webbing. |
| 13:22 | The extent type will be 2 next and we may need to flip the direction so the webbing extends into the top section of the valve cover. |
| 13:31 | Then a similar process for the 3 vertical lines for the sketch, making a thinner web and having the webbing extend a set distance downwards towards the flange of the valve cover. |
| 13:42 | Finally we're ready to finish off the inside with the fillet tool. |
| 13:46 | This is a bit of a process to say the least, selecting all the edges we want to apply the fillet to or surfaces where all the connecting edges are to be rounded to speed up the process. |
| 13:57 | With complicated geometry like this, the tool will sometimes struggle to generate the fillet, so it's just a matter of finding work arounds like slightly different radii or splitting the process up across multiple fillet features. |
| 14:11 | The radius of the internal corners will be critical to the tooling used in the machining process so if we have a good idea of this, we can add it now but it may need to be reviewed after working with our machinist. |
| 14:24 | At this stage, let's turn on our engine bay and valve cover scans and have a good check to make sure there's no chance of unwanted interference, the holes all line up nicely and of course we're happy with how it looks. |
| 14:37 | With everything looking good, that completes what has been a very lengthy process of modelling the valve cover, which started with laying out some references in the form of canvases and 3D scans to help us model a valve cover. |
| 14:50 | First we created a sketch for the flange profile which included some other features, then we built the main structure of the valve cover, rounding the main edges for a clean look and also creating clearance for the scuttle panel. |
| 15:04 | From here, we hollowed out the inside and created the bosses for the ignition coils to reach the spark plugs. |
| 15:11 | While adding features to secure the ignition coils. |
| 15:15 | We also added breather ports with baffle plates and o ring grooves. |
| 15:19 | Finishing up with some webbing to reinforce the main structure and rounding all the hard edges to reduce potential stress concentrations and simply finish the part in terms of aesthetics. |
| 15:31 | Moving on, we'll use some of our analysis tools and communicate with the manufacturer to better understand our design and identify any areas for improvement. |
| 15:41 | Then it's onto prototyping, post processes and manufacturing. |
