3D Modeling & CAD for Motorsport: Step 2-A : Modelling - Flange Sketch
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Step 2-A : Modelling - Flange Sketch
10.05
| 00:00 | - Now it's time for the core phase of our CAD work, the design and modelling process. |
| 00:04 | Because we already have our scans and canvas set up, we can use them as a reference to model around. |
| 00:11 | As we previously mentioned, the type of material we're using and the manufacturing process will dictate how we model the design. |
| 00:17 | And we need to keep the limitations of machining billet aluminium in a CNC mill in mind. |
| 00:23 | We'll discuss a few of these as we continue with the design process. |
| 00:27 | Like most models, we'll start with a sketch and this will be on the top plane where our canvas is located and the mounting surface for the valve cover in regards to our 3D scans. |
| 00:37 | The 2D sketch will define the profile of the flange of the valve cover by tracing the profile of the cylinder head flange shown in the canvas. |
| 00:45 | But the sketch might also be useful as a reference for other features we build off the flange. |
| 00:51 | But this will make more sense soon. |
| 00:53 | We'll start by placing the main holes for fixing the valve cover to the head using the circle tool. |
| 00:59 | The middle fixing hole is on the origin as we use this to define the location of the other holes as well as other features. |
| 01:07 | It's possible to drag the centre of each hole into alignment with the canvas holes and then use the fix constraint to prevent them from moving and define their position. |
| 01:17 | However this method isn't ideal as there's no chance of getting nice round dimensions that we can use for our technical drawing which can help us check the final part for accuracy. |
| 01:28 | It's best to use dimensions to define the position of the circles so we can make small adjustments easily and check that they match the measurements that we took from the cylinder head. |
| 01:37 | We can still use constrants where it makes sense though to keep the sketch tidy and be able to make efficient changes without having to modify unnecessary amounts of dimensions. |
| 01:48 | For example, using a horizontal constraint between each of the 4 pairs of horizontally opposed holes. |
| 01:55 | Also if we select all the circles by holding shift and clicking each circle and then apply the equal constraint, they all have the same diameter captured under one constraint, keeping things tidy and avoiding reference issues. |
| 02:08 | We want to lock down the position of the circles using our known physical measurements and finding the other dimensions with some trial and error to see what lines up with the canvas. |
| 02:18 | When the profile changes to black, this shows the position and size is fully defined. |
| 02:24 | While we are making adjustments, it's worth making continuous checks if the circles still line up with the canvas. |
| 02:30 | This process is fairly typical for aligning a 2D sketch with a canvas but gives us a good parametric brace that we can adjust if needed. |
| 02:39 | The method of sketching the spark plug holes is a little bit more logical, placing larger circles all in vertical alignment with the origin and the centre hole. |
| 02:48 | Setting their spacing with dimensions and constraints until fully defined. |
| 02:52 | From here, we can move onto tracing the flange profile which seems to be a fairly regular shape but actually has some logical geometric patterns that will make sense as we move through the process. |
| 03:05 | We can first place larger circles over each of the fixing holes and the spark plug holes so we have 2 and sometimes 3 concentric circles at each point which essentially just means they share the same centrepoint. |
| 03:19 | Then we can set the radius to match the edge of the flange. |
| 03:23 | Next up, more circles, this time we'll add pairs of circles horizontally in line with the spark plug holes and tangent to some of the circles we just created inside the flange profile. |
| 03:34 | Using our tangent constraints for this of course as well as some vertical constraints. |
| 03:39 | Again, more concentric circles to match the edge of the flange followed by more constraints to fully define the sketch. |
| 03:47 | That should just about do it for circles for now so let's move onto the line tool and sketch some of the straighter parts of the flange profile. |
| 03:55 | We can draw lines tangent to the circles we've already sketched to match the front, back, side, inner and outer edges of the flange and use constraints and dimensions to define them. |
| 04:05 | We'll come back to round the corners with the fillet tool to match the flange on the canvas soon. |
| 04:10 | At this point, everything in our sketch can be fully defined and the next steps will be following the curved edges of the flange between our circles and straight lines to complete the profile. |
| 04:22 | From here we can use the fillet tool or tangent arc tool to add the remaining curve profile between the open sections and the webbing between the spark plug holes. |
| 04:33 | Moving on, we need to use the trim tool to remove sections of the sketch that we don't need which will also make it easier to use the fillet tool and round the corners along the side of the flange. |
| 04:44 | During this process we'll likely remove some constraints and our sketch will no longer be fully defined and turn from black to blue. |
| 04:51 | We just need to be aware of this and re add the constraints to fix it. |
| 04:56 | In some cases, it can also be helpful to change features to construction lines if they don't form part of the profile but we want to keep them to avoid losing constraints like the middle hole at the back edge for example. |
| 05:09 | I recommend working around the sketch, trimming sections with a methodical approach to keep track of what changes remove constraints so we can fix them straight away. |
| 05:19 | When areas go undefined we can click and drag them and based on how they move, this will tell us what we need to do to constrain them. |
| 05:27 | With all the unwanted parts of the sketch removed, we can use the fillet tool to round the remaining sharp corners and match the profile of the flange on the canvas. |
| 05:36 | In some cases, where the corner is too sharp, it might not be possible to use the fillet tool. |
| 05:41 | In this case, we can use the 3 point arc tool and tangent constraints at the intersectons to the other curves and then an equal constraint. |
| 05:50 | Then just use the trim tool again to remove the unwanted sections. |
| 05:54 | It's important that every internal corner is rounded since the part will be machined on a mill and therefore the minimum internal radius will determine the minimum tool size. |
| 06:05 | But we'll come back to this in a later module. |
| 06:07 | With that, the main profile of our flange is complete, but although the sketch will be primarily used to create the flange of the valve cover, we can also use it to create most of the rest of the primary structure of the valve cover. |
| 06:21 | This just takes a bit of forward thinking and it may seem vague if you're following along and don't yet have a view of the finished product but basically we just need to thicken the flange in a few areas to add structure for the sides of the valve cover. |
| 06:35 | One of the key areas is down the driver's side where there will be two breather ports for AN fittings. |
| 06:41 | One between the first and second side mounting holes and the other just behind the third. |
| 06:46 | This is just a matter of using the line tool to fill in the areas we want using co linear constraints where necessary and again using the arc tool to round the transition into the flange with equal and tangent constraints to help define the sketch and kept things tidy. |
| 07:03 | The new inside line for the rear breather can be extended back towards the rear flange which is another area that we need to add more material. |
| 07:11 | There are a few reasons for this, one being that the back wall of the valve cover will need to be on an angle to clear the scuttle panel easier during installation and therefore the back internal edges of the flange need to be moved a bit further in to retain the thickness through the wall. |
| 07:28 | In the factory configuration there is a bracket on the rear of the intake cam which acts as a distributor mount. |
| 07:35 | This is no longer needed so we'll remove that and integrate the cap into the valve cover to tidy things up a bit and minimise the chance of an oil leak at the back corner. |
| 07:45 | This can be done with the line tool and then the fillet tool to round the corners. |
| 07:49 | To avoid making the internal walls of the valve cover over complicated by following the profiles of the flange, we can straighten things up a bit, again using the line tool. |
| 07:59 | This also means the walls can step in, leaving room on the outside to access the mounting hardware and allow for thickness in the walls. |
| 08:07 | This is probably a bit confusing at this point but it'll become clear soon after we start to generate the 3D body of the valve cover. |
| 08:15 | Since we are moving into the inside enclosure of the valve cover, we need to be careful we aren't causing any clearance issues, specifically making sure we leave clearance to the cam caps and valve train. |
| 08:28 | We just need to be aware of this and check the model against the 3D scan of the cylinder head as we start to generate 3D bodies. |
| 08:35 | In the back of the valve cover, we'll make some relief cut outs around the cams for some extra clearance as we don't want any interference here. |
| 08:44 | Using the canvas and physical measurements to determine where the edges of the camshaft are, we can sketch this geometry with the line tool and back to back tangent arcs to form an S shape curved step. |
| 08:57 | Using a point on the mid point of each line, allows us to line them up with the camshaft and set the width for clearance. |
| 09:04 | The final part to finish off this major first sketch is at the front of the valve cover. |
| 09:09 | We currently have a coolant radiator bypass hardline mounted to the front of the valve cover which we'd like to retain for simplicity as it's a good practical solution. |
| 09:19 | So let's add provisions for this into our sketch. |
| 09:22 | Starting with a horizontal construction line with a mid point to help set the spacing with a circle at each end for the holes and a larger concentric circle for the outer flange. |
| 09:34 | After removing unwanted sections with the trim tool, this can be tied into the existing flange with the fillet tool. |
| 09:41 | This wraps up our first sketch which using our canvas for reference, has positioned our mounting holes and spark plug holes, defined the flange profile and added provisions for a range of other features and considerations. |
| 09:54 | Although this was a major process it'll provide a basis for the rest of our model and really increase our efficiency from here on. |
