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Motorsport Fabrication Fundamentals: Design and Planning

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Design and Planning


00:00 - Like any skill, motorsport fabrication requires a sound knowledge of the fundamentals but there's also a range of practical skills that you're going to need to understand and master.
00:10 In this set of modules, we'll be taking you through a selection of these practical skills, as well as offering you some tips and techniques that will speed up your projects and ensure better results.
00:22 Regardless what task you're intending to take on, planning is essential and as the old saying goes, failing to plan is planning to fail and this applies firmly to any fabrication project.
00:35 This is an essential step before we ever pick up the angle grinder or break out the welder and will ensure we have a solid plan we can follow as well as making sure we use the correct materials and techniques.
00:47 Turning our ideas into real world parts will start with us drawing out these ideas and adding dimensions to them before we can start actually making them.
00:56 These days it's most likely to see parts being designed in 3D modelling software such as Solidworks or Fusion360 and if you have the skills to do so, then this is absolutely a powerful way of designing and visualising your parts as well as validating parts fitment.
01:13 If 3D modelling isn't your specialty though, the trusty pencil and paper is still a perfectly viable way of designing your parts.
01:21 It's tempting to skip this step and jump ahead into cutting some material but the time spent here will always pay dividends in the long run, ensuring that your part fits just right as well as avoiding wasting time and money remaking the component due to an easily avoidable oversight.
01:39 There's no shortage of options when it comes to initial sketches of your design and no doubt there's plenty of parts of record holding race cars that started life as an impromptu scribble on the back of napkin at a restaurant.
01:52 When inspiration strikes, we want to be ready to take advantage of it.
01:56 More typical options for developing our drawings include plain A4 paper however graph paper offers us some distinct advantages.
02:05 Graph paper uses a continuous square grid that you can either buy in A4 or in A3 pad and this provides a clear reference for scale as well as giving us the easy ability to draw perpendicular lines by using the squares of the graph paper as a guide.
02:21 From here, we can begin using a sharp pencil and eraser to develop our drawing as this allows for easy changes to the drawing if required.
02:30 A 300 mm ruler will help for the longer lines and a 150 mm ruler will cover the rest.
02:36 If your part consists of circular shapes then a compass is also a helpful addition, or you can also use circle templates for smaller holes like bolt holes and internal pockets.
02:49 In this module, we'll go through the process of designing and drawing up a role centre adjuster for our Toyota 86 race car.
02:56 This locates into the bottom of the hub or upright and locates the outer spherical bearing onto the lower control arm.
03:03 By fitting spacers of different thicknesses between the lower control arm and the hub, the roll centre location can be adjusted.
03:11 This part fits nicely on a sheet of A4 graph paper but if it didn't, we can step up to A3 or chose to halve the measurements and draw this in half scale on A4 paper.
03:22 It is however important to clearly note if your drawing is scaled to avoid any potential mix ups if you're relying on a machinist to make your parts after you've drawn them.
03:33 There are a few critical measurement dimensions on this part and we'll also be making a few changes to the existing part in order to make it stronger.
03:42 The key dimensions here include the overall length, the diameter of the part that locates through the spherical bearing and the diameter where the part locates in the hub.
03:52 The existing part uses a taper in the hub which replicates the taper on the stock lower ball joint.
03:59 In our case though, this limits the diameter of the part and hence its ultimate strength.
04:04 We aren't restricted to retaining this taper so by having our machinist open this out to a parallel hole in the hub, we have more flexibility with the diameter of this part.
04:14 In this case, we've opted to make this diameter 18 mm which is 2 mm larger than the widest diameter of the existing taper and this will provide a significant increased in strength.
04:25 Using our digital caliper is a good way of understanding these dimensions and what changes we can make to the design.
04:32 Since we're no longer locating the part in a taper, we need a method of locating the part against the hub and this can be achieved by adding a wide, flat surface into the design that will locate against the underside of the hub.
04:46 This further spreads the load and again will improve the strength.
04:50 As we learned in the design fundamentals section of the course, sharp edges will introduce stress raises so a generous radius is necessary on both sides of this flat section.
05:02 By machining flats onto this surface, it will also allow us to hold the part with the crescent, preventing it from spinning and slipping during installation and removal.
05:12 This is difficult to add to our drawing if we're viewing the part from just one direction like we have so far.
05:18 For this reason, it's common with more complicated parts to provide multiple views or projections.
05:23 This can then allow us to detail the flaps that we want to add in a plan view of the part as you can see here.
05:30 We also need to use a nut on both ends of the roll centre adjuster.
05:34 One to locate it into the hub and the other to attach it to the lower control arm.
05:39 By understanding the diameter of the material we're working with, we can then decide on an appropriate thread for these nuts.
05:46 In each case, we want to ensure that the outside diameter of the nut is going to be substantially larger than the outside diameter of our material to ensure the nut can positively locate it.
05:56 To achieve this, we've chosen M16 x 2 nyloc nuts for both ends.
06:01 Using the depth probe of the caliper, we can confirm the thickness of the hub which is important to define the height of this part for the roll centre adjuster.
06:10 For example, if we made this part too long then the nut would bottom before contacting the hub, meaning that the roll centre adjuster would not be positively located and tight.
06:20 With a solid understanding of the diameters and lengths required, we can add these into our drawing.
06:26 Once we have our measurements, it's best to start with an overall dimension that leaves plenty of room for the minor dimensions inside of it.
06:33 Once we have our part drawn up, we can then confidently machine the part if we have the tools required or provide these drawings to our local machine shop.
06:41 By supplying the dimension drawings, the machinist will have all of the information needed and your part will be guaranteed to fit right the first time.
06:50 For these parts to be machined and the materials required for the complete roll centre adjuster, the cost is going to be a fraction of the price of an aftermarket item, whilst producing a quality motorsport component that fits exactly how we want it to.
07:04 By keeping these drawings filed away, we can repeat the process easily should we need another part in the future.

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