Motorsport Composite Fundamentals: Flanging & Filleting

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Flanging & Filleting

05.34

00:00	Flanges, as you might have gathered by the name, describe the sections of the mould around the perimeter of the mould surface.
00:06	These are often, but not always, perpendicular to the pull direction.
00:10	They serve multiple purposes, like stiffening the mould, providing an area to lever against during release, and in the case of multi-piece moulds, like we discussed in the previous module, they provide an area where we can make locating and fixing features for the mould sections.
00:26	Not all pattern making projects require us to make flanges, as in some cases they're naturally part of the pattern.
00:33	However, in many cases, we'll need to construct them on our pattern so they're included when we make the mould.
00:39	Luckily, our CRX fenders we're now so familiar with will provide a great example.
00:44	So, we'll look at making some flanges using plastic flute board, aka sign board, which is probably the most accessible option.
00:52	The flute board we're using is five millimeters thick, meaning we can bend it if needed, but it's relatively stiff and strong to hold its structure.
01:01	Our resins also won't bond to it, which is helpful, even though we'll be applying release agents to the surface soon.
01:07	First, we'll set up the fenders on a bench in the orientation that will allow us access to all the faces of the part that will lay up the first part of the mould against.
01:16	Then, using scissors or a blade, we cut the board to the profiles we need for the main flange that will run along the mould split line.
01:24	Again, that's along the transition from the outer face of the fender to the mounting flange.
01:28	From here, we can use a hot glue gun to stick the board to the edge of the fender.
01:33	We'll also cut some small pieces of board to hold the underside of the flange off the table while everything dries, and to support the flange when it comes time to lay up the mould.
01:42	Following this, we'll basically just carry on around the edge of the part, flanging behind the indicator mounting area and around the back edge of the fender.
01:51	We could also flange around the lip of the arch, but it's not necessary.
01:55	So, we'll just lay up the mould over this edge of the part and then trim it back after it's cured.
02:00	Again, this will all make sense as we progress through the rest of the work, which you'll see in the next section of the course.
02:06	Side note here, depending on the intricacy of the part that we're working on and how good our hot glue gun is, this flanging process can be quite frustrating.
02:15	So, again, don't beat yourself up if it's not going as smooth as it looks in this video.
02:20	This is a fairly freestyle approach, with lots of trimming, test fits, trial and error.
02:25	There are of course alternatives to this flute board flanging process, like using tooling or model board, MDF, or really any suitable flat board or sheet material.
02:34	If we're using something porous like MDF, the surface will need to be sealed before any release agents or resins are applied to it.
02:41	These thicker boards offer the benefit of more rigidity, however, they aren't quite so easy to cut and bend if we've got an intricate pattern.
02:48	So, it's really just a matter of using whatever works best for our particular project.
02:53	It's also worth mentioning that when working with CAD, we can often include the flanges in our design and have them CNC machined or 3D printed onto our pattern or even our mold.
03:04	Without going on too much of a tangent, we'll look at some of these alternatives and worked examples as we add them to the course.
03:10	With our flanges in place, we can add our locating features.
03:13	These are simply the small rubber pads designed for the use on the bottom of furniture feet to protect the floor and prevent them from sliding.
03:21	They're circular pads around 10 millimeters in diameter and 3 millimeters tall, with adhesive on one side so we can stick them to the surface of the flange around 25 millimeters or an inch or so from the edge of the part, spaced at around 200 millimeters or so, although more or less is fine to suit the part.
03:39	The final step is filling unwanted details, as there are often features of the pattern we don't want in the final part, or fill any details as well as any holes or cavities that resin could run into and cure, potentially causing release issues.
03:53	It's also typical to round or fillet sharp internal corners where we might get flashing, release issues, or simply just want to create a nice curved edge on the part.
04:03	For this, we'll use modeling clay aka plasticine, although filleting wax works great here as well.
04:08	We can fill behind the bolt holes for mounting the fender to the car and the indicator housing to the fender, as well as any gaps between the flute board flanges and the part.
04:18	Using filleting tools can help manipulate the plasticine into place and create smooth surfaces, but our fingers and thumbs also work well.
04:25	Flash tape is another option here, depending on the detail we're trying to fill.
04:29	That covers the work required in terms of preparing the pattern for our CRX fenders.
04:34	We'll continue with this example, applying release agents, gel coats, and constructing the mold in the next section of the course.
04:41	So, for now, let's summarize the key points to remember.
04:43	Flanges are the area of the mold around the perimeter of the part that serve various purposes.
04:49	We often need to make these in our pattern making stage, so they're included as we construct the mold.
04:54	A commonly used and accessible approach is using plastic flute board, cutting it to shape, and hot gluing it around the edges of our pattern.
05:02	It's a fairly freestyle process, but the intention is to make a sturdy flange that will hold up to the mold making process.
05:09	Locating features can then be included on the flanges at this point.
05:13	A cheap and practical example is stick-on non -slip furniture feet.
05:17	We can then use modeling clay, plasticine, filleting wax, or flash tape to fill and blank off any details we don't want to include in the mold, and fill any holes resin could flow into, as well as fillet any internal corners.