Nobody is Amazed Enough

I’m no kind of engineer or industrial design guy. I do make a lot of physical things, but it’s mostly artworks, and old fashioned artworks at that—stone and wood carving. Nothing much has changed in those media in 150 years, and even then it was just power tools to speed up the same things they already did.

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A sample from Autodesk’s site. The virtual parts all move, shafts turn, the spring compresses, etc.

It’s perverse to live in the 21st technological Renaissance, and limit yourself to materials and techniques that have been around since the end of the Bronze Age. With this in mind, I recently borrowed a Makerbot Replicator 3D printer, downloaded a program called Fusion360 and set about joining the 21st Century. (I’m lucky to have friends who can lend a guy a printer!)

Holy $%^#!, but this stuff has come a long way. Forget the printer—Fusion360 is a potential career killer. Don’t even start playing with it unless you’re prepared to get obsessed. It’s magic, really. It takes a little time to get the basics, but it’s a nice shallow learning curve and you can start building simple designs the first day.  

And the things you can build! My puny first effort is that Raspberry Pi Computer case below. I designed it (badly), printed it, redesigned it (better), and printed it again.  I tried a few versions and finally came up with a nice one that stacks, has a lid for the top, and accepts custom lids for sensors and cameras and such. The idea is that they are modular, so I can house a compute cluster in a stack of these, or combine them with similar housings for sensors and cameras  that can be used indoors or out. The Pi fits in it, the plugs line up with the holes and the units and lid snap with a satisfying click.  The final version has snap-in plugs to seal unused holes and vents in the bottom of each unit so you can suck air through a stack of them. 

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Day one with Fusion 360.

It’s CAD, so obviously you can build up complex shapes and manipulate them in space, but that’s just the beginning.

First of all, CAD is not “like a drawing program, but better.”  The individual components that you sketch out are built up of parameterized objects. (I apologize in advance to CAD people if I abuse their terms, but what do you expect? I’m a noob.) For example, in CAD, a circle isn’t a string of black pixels. Pixels are just a picture of a circle. What you get is more of a Platonic circle, an abstraction that you can manipulate in countless ways. If you put one on the plane and then drag it perpendicularly, you have a cylinder. If you drag in a circle, you have a donut, or if you drag it in a circle while you move the circle’s center at the same time,  you get a helical spring. The resulting form won’t be just pixels either. They’re abstractions like the original circle. For instance, you can apply threads a cylinder to make a screw, or similarly thread the inside of a circular hole.

Everything you manipulate is like this. You can draw a rectangle, then pull it up to make a solid. Then you can draw a smaller rectangle on the top, and push it down to turn the solid into a box. And naturally, you can turn these things anyway you want, or see them from many sides at once as you work.  If you have forms that meet on a line (straight, curvy, or even compound curly, you can soften the joint with fillets or round the corners if it’s outside corners.

This is the simple stuff—CAD isn’t just sculpting out of virtual solids. You can also work with “developable forms” i.e, shapes you can cut out of flat sheets and then fold (think sheet-metal ductwork.)

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Day two, a few versions later, minus the plugs and variant cases. More room inside for air flow and accommodating attached shields, etc. ,plus overhangs so water will run off.

You aren’t limited to building up from simple geometric primitives. You can build up complex surfaces with compound curves and smoothly join them, automatically fairing all the joints to get the kind of shapes you’d find on an automobile body, propeller, turbine blade, or even completely irregular forms.

As I said, designing forms is just the beginning. Real machines have many parts, and accordingly you can link the gears, shafts and housings you design and animate the whole to see if things are actually lining up and interacting the way you imagine, with gear driving gear, turning shafts, etc.

The bicycle frame in the picture above is like that.  It’s one of Autodesk’s samples (I wish I were that advanced.) It’s a beautiful thing merely as a drawing but it’s more than that–it’s a mathematical model that you can animate to see if it behaves as you imagined, or run finite-element-analysis on to see where it will break under real forces. Not to mention the fact that you can squirt the parts out to a 3d printer or CNC machines to create physical prototypes.

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This is a beautiful rendering, but what you can’t see is that every internal part, bolts, nuts, pistons, crankshaft, etc. is fully specified in the same detail and perfection.  You can  browse through the many lovely renderings here. It’s the work of Patel Vaibhav. Its all in the link.

 

Finite element analysis is what takes it from being just a CAD tool to being a platform for engineering. That kind of analysis lets you test a design mathematically to be sure that you are neither building in weak spots nor throwing unneeded material at the problem.

The full capabilities would fill a book, but it’s worth mentioning one major thing that sets Fusion360 apart from the numerous other CAD packages: it’s entirely cloud-based.  You use your own computers horsepower to do the display and number-crunching tasks, but storage is all in the cloud. This matters enormously to anyone working with a team for a host of reasons. For one thing it doesn’t matter whether the people you’re working with are at the next desk or on the other side of the world. It’s all the same. The other thing is that the hassles that cluster around file storage, versioning, merging work, backing up, etc., are the bane of every digital medium as soon as the team size exceeds one.  And it’s not just hassle—if you do it yourself, you court disaster when fire or flood wipes out your unbacked up server (yes, I know you have never neglected to backup. Only other people are that stupid.)

This is a commercial product. It costs either $360/year or $1500/year depending on the version you want. But that’s for commercial use. For students and artists they’ve been known to cut a deal for 0$/year.

A Few Days Later

I posted the above at the beginning of the week. Here’s something I drew up yesterday. It’s just a meaningless doo-dad to try things out, but it’s accurate enough to animate, if that’s what it’s called. Hopefully this morning I’ll be able to get the gears turning, put some retaining rings on the shafts, etc.

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