Making Casings for Prototype Electronic Devices?

kiddailey asks: "I'm working on a project for self-enrichment that involves creating a working prototype of an electronic device. I've made a model of the basic shape of the device out of Sculpey ^(tm) and want to use it as a mold to make the actual plastic housing that I can then insert the electronics into. Has anyone done something like this before? Is there any way to achieve this without a significant R&D buget?"

Depends how small it is

[Yarn]

I generally use wood, light, strong, cheap, but labour intensive to shape. And flammable :)

You are asking about material science

[forkspoon]

You are discussing the job of people who practice materials science. Materials scientists study a lot of chemistry and some physics and also learn a lot about shaping solids. Other areas of interest are molecular structures of certain materials and manipulating various structures tiny scales either chemically or mechanically to produce the indented material or structure.

Try finding a machinist or a materials science firm that does designs for and implements commercial plastic or metal housings for consumer products. These firms are few and far between, and most material scientists work directly for companies that mass produce products, but you should be able to find someone to help you. The best bet for you would be to come up with a detailed design for the housing and hire a firm to produce prototypes for you according to the design. The shaping of plastic and metals is not something you can really do in your home, unless you are a materials scientist or you have a great deal of knowledge and experience with such things.

Thanks,

Travis
[e-mail]

3d printing?

[Bazzargh]

You could send your design as a cad file to Toybuilders [toybuilders.com] and they'll 3d print you one.

However as you've already made your model you'll want it scanned. There are companies that will do this for you [necoinc.com] too - though they dont quote prices like Toybuilders do, so I guess it'll be expensive.

I noticed from Neco's page that a Rapid Prototyping and Manufacturing [sme.org] exhibition is taking place in Cincinatti on Tuesday (29th April) until May 2. If you get the list of exhibitors [sme.org] I am sure someone will be able to help.

Cheers,
Baz

Re:sculpey/fimo clay

[Usquebaugh]

RTFQ he's already using sculpey, he wants something better.

Moldmaking..

[RapaNui]

You could always use that as a 'plug' (male model) from which to make a female mold (out of glassfibre or plaster).
You can then make a thin shell casing from the female mold, in glassfibre or carbon (looks _very_ cool).

Hydrocal is a hard plaster/cement type compound that works _really_ well for short run molds, or for one-off parts, generic plaster works well. If the shape is complex, eg. has undercuts, then you'll need to make the mold from silicone. Check out Special Effect Supply [fxsupply.com], they seem to stock a lot of the stuff.

Once you have the mold, you can then lay up a part using polyester (Yuck!) or epoxy resin and glass, carbon or kevlar fabric. Glass fabrics are now also available in colors (I've seen red, silver and blue) if you don't want to paint the final part. Another option is to cast the part using a polyurethane resin, (try ProCast [mfcomposites.com]
)
You will probably have to make a multi-part mold in order to define a wall thickness, though.

Maybe check out FibreGlast [fibreglast.com] for some ideas.

There are _much_ more elegant ways to do this (eg. CNC machining), but molded glass or polyurethane is probably about the easiest / cheapest method of prototyping this sort of thing. With a bit of effort, you can get _really_ professional looking results.

Re:Moldmaking..

[RapaNui]

My 'Yuck' was mainly due to the fact that it's physically nasty to work with - ie. the fume factor, (and the 'goo factor), and sometimes it's curing is somewhat unpredictable (mainly due to going off while you're working with it).
Epoxy does have somewhat better mechanical properties (if your application demands it), and you can generally tailor the cure to your needs (most epoxies have different hardeners for different tasks). Also you can get epoxies with _very_ low viscosity (almost like water) for tricky jobs.
Epoxy _is_, however, even nastier than polyester chemically (physiologically), and is _way_ more expensive.

Re:carbon fibre....

[Zurk]

note that carbon fibre parts are *expensive* and dangerous to work with even though they look nice. always wear a organic respirator and gloves to prevent carbon fibres entering your skin (which they do pretty easily) and the resin from overwhelming you with fumes.
molds can typically be made for 400 bucks and the part for another 500-600 bucks. fibreglast.com gives all the info including technical brochures anyway.

Depends on how crazy

[CharlieG]

It depends on how crazy you want to get. If it's going to metal, try going down to your local machine shop and asking them, OR post a question on Rec.crafts.metalworking

Even if it needs to be cast, that can be done (esp if you want it done in Al) - you could look up "Backyard Foundry"

Of course, now we're talking about a REAL geek hobby - Metalworking! Hot metal, dangerious tools, and it takes a brain

Limited production runs?

[orn]

How about the same question but with limited production runs? How could you build say 20 to 100 plastic or metal (whatever is cheap) small electronic cases?

The small time inventor is back.

Rudy

Re:Limited production runs?

[CharlieG]

CNC Machining - Perfect - we used to have it done all the time

Charlie

Re:Limited production runs?

[NoMoreNicksLeft]

Well, sheet metal is easy, it's stamped. For about $500 for a decent compressor, and another $200 for a 40 ton hydrraulic press (this is how much pressure, not how much it weighs) you'd have the basic machinery. Small dies would be rather cheap, maybe as little as 5-10 hours work, and $100 raw materials. A die, by the way, fits in the press, and acts like a cookie cutter. It can cut, bend, and stretch metal, even into shapes that you wouldn't think possible.

I've been wanting to do this for awhile, but even the simplest die still requires a decent machine shop. Harbor Freight Tools does have a cheapy mill (metal cutting/shaping tool) for about $300....

Plastic pieces require an injection molding maachine. The molds are carved out of aluminum generally, and would be cheap to make. They're chemically treated (anodized), and I've found a local firm that will do it cheaply (about $20 per). Generally, even used injection mold machines are too expensive for the hobbyist ($5000+) but I've heard of people building their own.

If you'rer serious, but strapped for cash, a dremel and some vises can do alot for simple things. It is only sheet metal, after all, and if you're careful, you can bend it precisely and attractively. Never been able to make them look as slick or mass produced, though.

Check out Lindsay's books

[bluGill]

Check out Lindsay books [lindsaybks.com]. Make sure you get a dead tree catalog, not all their books are online. They have books on how to do a lot of cool things that you can apply. Glass, sheet metal, poured metal, pottery, Plastic (injection or vacuum) molding. All on a dot it yourself from scraps. Most of their books are from the early 1900's, so they are obsolete compared to modern mythods, but still useful. Note that you would have to be crazy to do some of what they will tell you how to do. It would still be fun to do it though.

Yahoo has a group of Hobbicast [yahoo.com] If you are interested in metal casting (my personal interest). I'm sure there are other groups for those interested in other materials.

Have fun!

QuickParts.com

[diegoq]

QuickParts [quickparts.com] will make a part for you out of various materials. You send them a 3D file (STL) and they send you the part. Pretty cool, really.

They have an online automatic quote generator for most rapid prototyping. It's a bit pricey, a small half-dollar size part I had quoted was around $150 (+/- $50 depening upon materials, size, complexity, etc..).

Re:QuickParts.com

[kiddailey]

I didn't want to disclose the details of my design to a 3rd party, but it looks like QuickParts may be exactly what I need. Thanks!!

Re:Vacuumforming Plastic: Star Wars armor techniqu

[kiddailey]

The reason that existing project containers would not suffice is because my project is an exercise in shape design as it applies to usability.

Basically, I'm trying to create a working prototype so I can test how usable it really is -- and a lot of that usability depends on the form factor of the device.