Space: the final frontier!
…at least that is how I am beginning to feel as design software and its features evolve. In this post, I want to talk about the basics – specifically the basics of component design.
The age-old question will arise at times: do I begin the design at 0,0,0 or do I design the component in its assembly position? Does it matter? Well, yes and no. With most CAD software packages, you have the ability to constrain or mate the feature to the component it is mating to. So technically, almost every component can be designed at 0,0,0 and then just assembled when you are done, as long as you have a mating condition to work with. This method is typically referred to as Bottom Up design. You see this most often in design of off-the-shelf items you would basically plug and play as needed, e.g. Fasteners, Tubing, Brackets, etc.
The alternative to this type of design is when you have a group of components that don’t necessarily mate together but need to come into the correct assembly position every time they are inserted. This method is typically referred to as Top Down design. In the Automotive realm of design, all of the body panels are designed using a top down method. Generally you will hear the term “designed in body position,” which indicates it is a top down design.
The key to working on a top down design is that every component is designed using a common axis system, aka common 0,0,0 location. The major systems in a vehicle that are used in other vehicles as well will be developed using a common axis system that won’t be the vehicle axis system. For example, an engine would maybe have an axis system built at the rear face of the block and the centerline of the crank. […]