Design
Let's go back to some definitions: “. . . design is more concerned with the basic layout of a product with its core functionality and user experience in mind” and “Design for Manufacture and Assembly (DFMA) is the combination of two methodologies; Design for Manufacture, which means the design for ease of manufacture of the parts that will form a product, and Design for Assembly, which means the design of the product for ease of assembly deriving creative ideas at the same time.”
Note “deriving creative ideas at the same time” as I think this is important to keep in mind. Try to avoid tunnel vision where you are totally focused on one small part of the design process and so lose track of how that part needs to interact with all the other parts of the item being designed. It can be easy to fall into that trap, and you emerge from your thoughts with the perfect design for Part A, and find that it no longer fits with parts B, C and F. In his “Two-stroke Tuner's Handbook” Gordon Jennings begins the chapter on expansion chambers (the exhaust) recounting an anecdote about Walter Kaaden, the man behind the successful MZ GP bikes. He says:
“Kaaden remarked, only in jest, “You'll know when you have the design right, because the chamber will then be impossible to fit on the motorcycle without having it drag the ground, burn the rider's leg, or force the relocation of one or more major components”. Of course, all present had a fine laugh, but the joke contained a large and bitter kernel of truth.”
I think there are clearly at least three major elements to the design process. You need to:
It might be good to add a fourth element, “always keep your time and money budget in mind”!
Tools To Help The Design Process
After defining what you want to make and blocking out your time/energy/money budget to see if there are enough of those items to justify starting the project, you'll probably start the design process by coming up with some initial “what if?” design concepts.
If the project is small, like a wheel spacer, it may pretty well define itself so you've informally done this step already. After all, there are only a few design elements that you can tweak on the spacer. You know it needs a specific length to fit the space, it needs an internal diameter to fit the axle, and it needs enough surface area on the end faces to match the swing arm on one side and the wheel on the other. The external dimensions may vary depending on the stiffness/strength/hardness of the material you intend to use. On the other hand, the external dimensions may be tightly constrained by the items the spacer is keeping, and so they will drive the choice of the material to be used.
Let's presume you want to design a chassis for a particular engine, perhaps a Kawasaki Ninja 400 (since I've got one of those as a project). In that case, you need to know the shape of the engine and related components, accurate locations for mounting points, and the volume the engine occupies that will prevent you from locating other components in the same space.
How do you get all that information?
Ideally, you'd have all components on hand and a set of detailed computer-aided design (CAD) three dimensional (3D) models of each individual part. But most projects are designed in a less than ideal world . . . What if you have neither the parts nor drawings/models?
The Internet can help you get started. You will need to sharpen your web search skills, but there is often a LOT of information that can be found that will help you.
The first thing to do is try to find detailed photos and drawings from the manufacturer's public relations packets when they introduced the model. Some of those may be at the manufacturer's website, and others may appear in various articles that have been published on the Internet. I was able to find a nice set of front and side view photos of the N400 engine comparing it to the outlines of the N300 engine it was replacing. Unfortunately, Kawasaki neglected to put a ruled-scale in the photos to allow them to be accurately scaled to use in a CAD model. But if you can find good photos of an entire vehicle you can often pick something like a wheel rim or brake rotor that is a known size, and then use that to scale that photo, and then import the engine photo and scale it to match. Again, the PR packages often have very nice side/end/top view photos in them. If you can't find them from the manufacturer, then look to good photos from articles. If you can't find them there, then do image searches and see if someone has posted a nice photo of their bike that you can use.
Another good source are the OEM owner's/parts/shop manuals. Since the manufacturers have CAD models of their bikes, they often create 2D drawings from them to illustrate their manuals. You may have to piece several partial images together to get a full side view, but that is usually not a big problem. Most every modern motorcycle seems to have an online parts fiche available. Those may be largely isometric views but sometimes you can find a nice side view. Owner and shop manuals may be posted on the Internet, or you might need to purchase a copy from someone.
Another place to look for images are online sales sites like eBay. The photos may not be studio quality but if you look at enough of them you probably will get lucky and find something useful. Also look for auctions of major components, like engine cases, side covers, cylinder heads etc as you can get a good idea about those individual parts to help you understand how they all fit together.
If all else fails, take some photos of your own if you see a vehicle of interest. You don't have to get close to it and deal with the “what are you doing with my bike?” questions as you are better off using a long telephoto lens from a distance to flatten the image. If you are able to put a ruled scale (inch or metric, whatever you like to use) in the photo it will be a help in scaling the final image to a given size.
Note that for this initial design stage a good graphics program can be used as you don't need accurate CAD models when you are doodling and trying to come up with something (or hopefully several somethings) that might work for the project. I find the free paint.net (an outgrowth of the old Microsoft “Paint” program) to be very useful and powerful (but if you like it please drop a token of your appreciation to the developers). If you have Adobe Photoshop/Illustrator, CorelDraw, etc you should be good to go. Even MS Paint, included with the various MS operating systems can do a lot of useful work, but you'll find that having a program that lets you put images on different layers, set the opacity of the layers and then overlay them is very helpful.
to be continued . . .
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