Ask HN: How does one prototype a physical product? | Hacker News Reader

Ask HN: How does one prototype a physical product?

36 pointsrgr24 comments

I have an idea for a product I want to prototype. It's a physical object, sort of like a plastic toy. It doesn't have a microprocessor or any electronics for that matter. Unfortunately, my background is in software, and I don't know zilch about industrial or mechanical engineering, especially when it comes to plastic manufacturing (unless you consider playing with legos as a kid relevant experience).

Where do I start? Any pointers will be greatly appreciated.

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Clay, paper mache, foam, legos, wire, sheet metal, balsa, glass, wood. You can carve a mold and inject molten plastic (styrofoam beads) at home (preferably well ventilated). You can also melt soft metals and use sand molds.

Thats simple prototyping. To get an exact replica, in the same materials you want to use for final production, there are shops that will make plastic or metal molds from CAD files, or can carve with lathes, etc.

Edit, I should add wax. Its actually an incredible material for prototyping. It carves especially well, and you can add pieces if they fall off accidentally, or you decide to change the design. If you don't like it, melt it down and form a new block. Lastly, when you're ready to make a mold, you can encase it in sand or another substance, and then melt the wax away to leave your shape.

Like someone mentioned below, resin works as well. its a great way to do additive design, adding material over time to get the thickness or curvature over time.

Make a CAD model of it, then send that file to get it prototyped. I've used http://www.redeyeondemand.com and http://www.quickparts.com before; didn't have any extreme experiences with either of them (either good or bad).

A paper model is a good first step because the materials are cheap and easy to work with. Modeling clay, etc are good second steps.

For a first timer CAD modeling is a lot of investment, but it's definitely where you want to be. You can buy a desktop 3D printer now for $5k (http://www.desktopfactory.com/our_product/).

How hard would you say CAD is to pick up for someone with no experience?

It isn't that hard although the pro packages can be very intimidating. It's more a matter of time commitment than conceptual difficulty. Sketchup is pretty easy, I'd start there.

To tell you the truth, I learned CAD while designing cases for the electronic products in my previous startup, and it took literally weeks; not more than a month. To get started, I went through several steps of the SolidWorks tutorial, then started over on things I wanted to make. The easiest package for me was SolidWorks, although the latest versions of AutoCAD are just as easy. While SketchUp is easy, it's awkward to to CAD-y things like draw a line and simultaneously specify its length (at least, that was the case when I tried it a year ago).

In less than a week you should be able to make useful stuff. These are the kinds of programs, though, that it is easy to forget much of what you learn after you don't use them for a while.

Rhino has an evaluation version which is limited to 25 saves. They have very good tutorials, extensive documentation and an amazingly helpful support team and user group.

Can you recommend any sources for learning CAD modeling?

Hi. I work for a company that does a huge amount of prototypes for all types of companies and industries. I would recommend using Google's sketchup over all the other options. It's free and gives you much better results than other software packages, even the ones you pay for. Doing something in rhino looks nice on the computer but is a huge pain when you go to actually create it because it doesn't have basic mechanical structure to it.

Check out www.protocafe.com They do a great job with everything i send them. Cheap and professional.

How complicated is it? Can you make it yourself? It's probably best if you do. If you have something you want to make in quantitiy, you'll want to hire someone who is experienced with tooling up a factory efficiently. What you're doing is not really engineering, but more like "drafting".

If you live in the bay area: http://techshop.ws/

If it's relatively simple, you can find a CAM house that will build the part for you, but then it becomes expensive. This place has an FDM house (wikipedia for details): http://www.emachineshop.com

You can find cheap drafters on craigslist who can make a solid model of your part that you would ship to the machine shop.

good luck

I second http://www.emachineshop.com The software is fairly easy to use. You can get your prototype built in pretty much any material you can imagine, and the price is pretty good too.

My only problem was the cost to ship custom cut boat glass to Alaska. Ouch.

I've done this a few times. Mostly for industrial design projects like product bezels and cases and such.

I usually "carve" something out of wood and paint to get an idea of physical appearances, fit, etc. From that I'll usually make a fiberglass model (so that I can test fit something that is close to the actual dimensions/thickness of the actual item). Then I Google for a local freelance CNC shop in my area and commission a formal CAD drawing and prototype milled out of a plastic.

From there you can generally figure if your design is right for injection molding, vacuum forming, etc. Find the right CAD guy and they can often help guide you somewhat with the design as well.

Happy to help if you need more info.

For 3D modeling, I like Rhino (http://www.rhino3d.com) ($800). The support the company provides on their usenet group is unbelievably good and there is a huge community of extraordinarily helpful users.

Shapeways for rapid prototyping (http://www.shapeways.com). Many people who use Shapeways use Blender which is a free 3D modeler.

Great question.

There is very little magic to the prototyping phase. Google 'rapid prototype' (maybe add 'plastic' to it) and find a shop that has a price that is in your budget. (The price usually has to do with size of the blank they will work on for you.)

Spend a bit of time looking at the different methods of creating a prototype from plastic. Some use a type of "printer", others carve it from a chunk of plastic. Find out the pros-and-cons of the different methods. (Cost vs accuracy vs material.)

Find out what software format they import from and build your prototype in software that can export in that format. Email them the data, your credit card number, and in a few days, you should have your prototype!

Enjoy this phase -- the tricky/expensive part is going from the prototype phase to production.

How about a RepRap, the Replicating Rapid Prototyper? http://www.reprap.org

My girlfriend got a degree in Industrial Design, and that is the kind of things they do all the time. Sometimes the degree program is called "Product Design". With Auburn University, it is part of the College of Design. They generally have a studio class, design products and make prototypes out of them. This includes poster displays. There is also a big shop, like a collegiate version of Industrial Arts or shop class at high school.

You may be able to find such a program at a local university and ask a college student to make it for you. Whether or not you are planning to patent it, you will want to have them assign all rights to you, making this a work-for-hire, and be careful about the co-invetor stuff. Alternatively, you can get in with a local high school and borrow the shop class. Back in high school, I remember those old custodial staff messing around in shop class for their personal project (while the teacher spent time playing Quake with my friends and I).

Lastly, I highly recommend checking out Stephen Key's articles, such as this interview: http://www.fourhourworkweek.com/blog/2007/11/26/a-beginners-...

It includes a video where Key shows how he prototyped one of the ideas he had. There are other information in there too about licensing strategies.

You might try a sculpting class at your local community college. It'll get you some basic skills, resources to use, and be inexpensive. Talk to the teacher at some point in class about what you'd like to do. If more of your ideas run this way you'll have a good start.

My prototypes usually start out on engineering paper, get a few quick 3D CAD drawings, then get made up in polymer clay as a form for a mold for shell casting. The 3D step is new, and hasn't eliminated the clay stage, where I still catch problems and see new opportunities that the computer doesn't bring out for me.

So I'll make a solid item out of polymer clay, then press that into more clay to make a negative mold. Then I make a shell casting by putting mold release on the negative form, pouring in some liquid acrylic, and wobbling the mold in my hand to let the acrylic build up a shell over the whole surface. There are other ways I use, too, but this is a favorite quick and dirty method.

There are books on plastic casting that teach the basics, but there's nothing like hands on in a class with an instructor, even if all you're doing in the class is learning the basic sculpting skills and tools.

If you are programmer you will appreciate the process if you see it as geometry. Design is a bit a religious thing. he he.

1. Shape determines fabrication & material: Flat objects (including faceted, folded) can be best prototyped using paper/boards/sheets. Simply curved objects (cones, cylinders) aka single curvature surfacing & developables can be also done using paper. Complex forms aka double curvature requires either complex fab such as rapid prototyping, molding, pressing etc or rationalization (eg take a sphere cut it in layers, cut out flat sheets, glue, sand ie downgrade to previous option).

2. Drawing: You can use either a mesh 3d editor: sketchup, blender, or NURBS / subdivision surfacing: rhino, solidworks, maya (download demo where available). This is only for the intuitive part of making the form. Even though simpler I would suggest avoiding 2d apps as they tend to be tough ie misleading for physical objects (fine for plans and pcbs)

3. Fun: code it! You need OpenGL + you favorite language. Generate a polyhedral model, flatten it send to printer, assemble. Or just write out an STL file (super simple text format) and send it to a 3d printer (by far the easiest method for noobs). If you want cheep use z-corp powder puff machines (ceramic-ish), if you want an actually functional prototype use SLS (plastic)

4. Find a product designer or architect (the building kind) and work together =)

hope that helps

It doesn't make sense to bother with jobbing out initial fabrication of a prototype unless you've got VERY deep pockets and absolutely plan on going into production. Unless both of these are true I suggest modeling the part from balsa or foam and then cast your prototype in resin or low temperature metal.

I noticed the other day that www.sparkfun.com does custom 3D design and prototype, though this probably isn't the cheapest option as you'll be paying them to make the design: http://www.sparkfun.com/commerce/static.php?name=custom_encl...

There are lots of premade 'enclosures' that you could hack apart to get what you want as well: http://www.boxenclosures.com/category/category.html

However, I would recommend something like the online services mentioned here that send you prototypes. Don't be intimidated.. just go through the tutorials and you'll be surprised at how easy it is.

Use blue foam and get some razor blades and sandpaper. That should do it for the first few iterations.

from visiting techshop, i found out that google SketchUp (plus a plugin) can be used as the CAD tool for their Dimension SST. SketchUp tutorials: http://sketchup.google.com/training/videos.html

sculpy, wood, foam, sandpaper, exacto knives, chisels, saws.

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