Say I have a prototype gizmo that needs a case, with provision for low-precision (+-10-20 mil) location of a small lens and a motor.
Say also that it ought to be some medium-swoopy injection moulded plastic thing, to show to prospective partners.
Say further that I'm not a mechanical CAD guy at all.
What are the best/cheapest/fastest/lowest-agita methods for getting this done?
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 hobbs at electrooptical dot net http://electrooptical.net
Traditionally you only get to pick (at most) two of the first three, so adding a fourth condition probably still limits you to two of the first three.
IMHO the prototype should not be injection molded - it should be CNC milled (or at least that's one option.) Injection molds cost serious money, which is fine when you spit out a million units and can divide the mold cost by a million. CNC milling can do a moderately decent job of medium-swoopy, and be followed up by some finishing to take the milling marks out for appearances sake. There are various plastics that mill nicely. You wouldn't want to use it for any serious production volume, but in 1,2,12 it's much more cost effective.
The other practical option is to go find something in the marketplace that has a case you can adapt.
In either option, you point out clearly and throughly and in the fine print as well that the case is a prototype case and the final production item may differ due to volume of production considerations.
-- Cats, coffee, chocolate...vices to live by
s
Stereolithograhy with hand rework... Holds to .0004" or so.
Steve
Somebody will have to do some CAD on this and they may already have a prototype source that they're comfortable with.
However, it's probably worth looking at
Of course, a 'net search on "rapid prototype" will turn up a bazillion alternatives.
-- Rich Webb Norfolk, VA
-- http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4GFRC_en&q=3-D+printer JF
I'd make a case or two out of wood, cover it with vinyl or leather and include some fancy hardware, hinges, corners, latches and the like all available on line. If I were not a mechanical cad guy, I'd use "pencil cad," that is, simple rough sketches on paper to design it, then saw it out or have it done by a cabinet guy. No need to make a federal case out of it for demo purposes.
Some have suggested CNC and that is an option but will cost you more and take longer than a wood box. You can graduate to CNC or even injection molding, vacuum forming or other techniques when the production volume dictates. Don't put the cart before the horse.
I like the suggestion of doing it in wood. Hinges don't go well with "modern" swoopiness, but a band of electrical tape around two halves of a clamshell can be an amazingly durable* and discrete way of simulating snap-together halves. If you need it to be _really_ swoopy and you can envision the shape, fiberglass over foam may work.
Or swing through your local Wall-Mart for something that looks about right, gut it, and put your swoopy thing in its case.
-- www.wescottdesign.com
Ha! Congratulations! That's the first time I've seen agita used in a post! :>
I'd backstep a minute, first. Are these prospective partners "tech savvy" or just "wallets with legs"? I.e., can you show them an ugly prototype *uncased* but functional. Then, a touchy-feely "potential package" and expect them to put the two together in their minds?
In this case, you can make the touchy-feely item out of a variety of easily molded/sculpted material (whittle a bar of soap/balsa!). This allows you to separate the two aspects cleanly.
I've used this approach in the past and watched "industrial engineers" essentially copy my original mockup -- but make it "sleek and sexy". I.e., let the folks who know all the human factors issues put the finishing touches on the package and then, later, fit your "guts" into it.
I'm meeting with a plastics maker next month and I'll be taking the same approach -- show up with some 3D renderings (CAD) and a block of balsa shaped, sanded and painted so we have something to "explore" together.
Good Luck.
We've machined pretty nice looking prototype things from solid polycarb or solid aluminum. That's reasonable if the gadgets are small.
John
something like SLA or cnc milled plastic would be the the obvious solution, but you'll need a cad guy to "computerize" the design.
or you could download the app from
-Lasse
Look for rapid-prototyping places in your neighborhood, preferably small ones. Then ask them whether they can provide CAD services or whether they know someone in the neighborhood who can on a consulting/contract basis. It is really important that the CAD guy is local. That way the two of you can sit down and discuss things like "I want this here to be mounted over yonder ..."
Molding is way too expensive at this stage, needs to be machined unless you must demonstrate a few thousand units. If it has to impress some suits a machine version can look very similar to a molded product.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
It either milling or 3D printing. The problem with 3D printed prototypes is that they need ome work afterwards and the tolerances are not very good.
-- Failure does not prove something is impossible, failure simply indicates you are not using the right tools... nico@nctdevpuntnl (punt=.) --------------------------------------------------------------
Pretty easy to use software for non-CAD guys like us. So intuitive you can whip up a simple box in 10 minutes. Instant quote inside the program, and choice of materials and processes.
Dave.
-- ================================================ Check out my Electronics Engineering Video Blog & Podcast: http://www.eevblog.com
A few states here in the US have a company called Tap Plastics that carries a reasonable range of plastics in sheet, rod and square form, and glues, and epoxies. They also will make simple boxes, forms, etc from stock. 2D drawings is their style; usually isometrics is not required. Maybe there are sheet plastic sales "offices" that will do this. At minimum have them cut panels of thickness and sizes needed, buy the glue / solvent and DIY.
Possible alternate: look at the various electronic plastic boxes made by Bud, Hammond, etc and do not ignore potting boxes. Modify if need.
s t
ade
Pac-Tec has some pretty nice boxes too. Link:
It's early, and I've not had my coffee yet -- but....
Another approach would be to go buy one of those Tickle Me Elmo dolls at Toys-R-Us, gut it (literally), and cram the gizmo inside. After the shock & awe phase wears off, this approach might actually serve to force your audience to focus on the gizmo, rather than it's packaging. Sort of like a little bit of reverse psychology.
- mpm
Hi, Phil:-
Most realistic would be to design the parts so that they 'can' be injection molded (there are rules that need to be followed to make sure the parts will be manufacturable etc esp. wrt draft angles, features related to the parting line, and wall thicknesses) and then send the 3D solid models out to a prototype shop. It can be made with SLA or other additive methods, or it can be made with subtractive methods (eg. CNC machining).
Swoopy parts are hard to do, and extra hard to do well. You might want to play with modelling clay etc. to get the shape. Sometimes it's easier to define the surfaces in something like Rhino and then import them into a 3D CAD program. The 3D models can be used to generate tool paths for machining or directly to output Rapid Prototype models (which generally require painting etc. to look decent).
I use Solidworks to make 3D models. Solidedge is also popular. It takes a couple of years of effort to learn all this stuff if you're starting from scratch, so you might want to look for someone local who can help and who you can meet with in person. I know a fair bit about plastic part design and a fair bit about mold design-- if you have simple questions fire away. I've also used a few different RPT service bureaus to make various plastic and machined Al part prototypes (some of them come in at 1/5 the price of our usual low volume precision machine shops, but with 'relaxed' specifications and extra design restrictions).
Best regards, Spehro Pefhany
s
Carving the official molds form hardened steel is expensive, but I've read low-run (50 pcs) plastic injection molds can be made of epoxy-- that's an intermediate possibility for protos. Aluminum, too: somewhat longer-lasting (1-5k pcs?), but a step more money too.
-- Cheers, James Arthur
Well, maybe in Asia, or if cost is not too important :-)
You can economize on the molds but for a few demo prototypes like Phil wants I would try to get away without any molds. Just have the actual enclosure parts themselves machined, not the molds. Since most of us are not MEs or tool and die makers the best avenue would be to have it put on CAD by someone who knows AutoCAD and then ask a rapid prototyping shop how much money it'll take to make five of those.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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e sRhino ($1k,
Lots to learn though--both to use the programs, and how to design injectable parts. Non-trivial.
-- Cheers, James Arthur
But probably not SolidWorks. I bet they make sure none of their stuff ever lands at discount stores :-)
I bought DesignCAD-3D there. All of ten bucks for a mildly aged version. As you said, tons to learn, not much time for that, it's total overkill for me. But I mainly bought it to be able to read in and annotate AutoCad drawings and that works quite nicely.
Yesterday I got a 3D drawing from a client, to look at it from a reliabitity and EMC point of view. Really cool, you can virtually spin it around, look inside, etc.
-- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM.
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