

Ask HN: How does one prototype a physical product? - rgr

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).<p>Where do I start? Any pointers will be greatly appreciated.
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tstegart
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.

~~~
tstegart
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.

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ph0rque
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).

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

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ph0rque
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).

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dreamingaway
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.

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npk
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

~~~
pbrown
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.

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brk
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.

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mhb
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.

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bprater
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.

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

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qaexl
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-...](http://www.fourhourworkweek.com/blog/2007/11/26/a-beginners-
guide-how-to-rent-your-ideas-to-fortune-500-companies-plus-video/)

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.

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saundby
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.

~~~
stosd
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

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knieveltech
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.

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cmos
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...](http://www.sparkfun.com/commerce/static.php?name=custom_enclosure_design)

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.

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

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NonEUCitizen
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>

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

