Wanted info on fabrication of a case/enclosure for an commercial electronics project

[Reza Naima]

Well, after about a year of R&D, a friend and myself have built a
small device we want to sell to the various niche markets. Now that
we have the hardware done, we need to deal with fabrication of a case
for the device such that it looks good and will make the product more
marketeable. This is where I need help. First off some specifics
about the unit :

- Powered by 1 or 2 AAA batteries so it needs to have a battery
compartment
- Needs to be as light as possible
- Will be exposed to the elements; needs to be water resistant
- Needs to have an LCD display exposed (if the case is
transparent, this is a no-brainer)
- Will have a mini-b USB connector
- it needs to attach to external sensors. For example, it needs to
get speed and cadence information from a bicycle. So either we make
our own sensors and connector, or we have the device compatible with
existing bike computer harneses. This would require metal contact
points to be exposed outside of the case.
- it needs to have 4/5 buttons on the device.

I really havn't a clue where to begin. We have working prototypes
that are fairly large, and we can reduce the size and change the shape
as necessary before PCB production/assembly. However, I'm not sure
what our options are regarding materials, methods, costs, etc.
Ideally, I want to optimize on the following factors (in order)...


1) Cost (we're doing this out of pocket)
2) Aestetics
3) Durrability

Any help would be greatly appreciated.
Thanks!
Reza

 

[Paul Rudolph]

Well, after about a year of R&D, a friend and myself have built a
small device we want to sell to the various niche markets. Now that
we have the hardware done, we need to deal with fabrication of a case
for the device such that it looks good and will make the product more
marketeable. This is where I need help. First off some specifics
about the unit :

- Powered by 1 or 2 AAA batteries so it needs to have a battery
compartment
- Needs to be as light as possible
- Will be exposed to the elements; needs to be water resistant
- Needs to have an LCD display exposed (if the case is
transparent, this is a no-brainer)
- Will have a mini-b USB connector
- it needs to attach to external sensors. For example, it needs to
get speed and cadence information from a bicycle. So either we make
our own sensors and connector, or we have the device compatible with
existing bike computer harneses. This would require metal contact
points to be exposed outside of the case.
- it needs to have 4/5 buttons on the device.

I really havn't a clue where to begin. We have working prototypes
that are fairly large, and we can reduce the size and change the shape
as necessary before PCB production/assembly. However, I'm not sure
what our options are regarding materials, methods, costs, etc.
Ideally, I want to optimize on the following factors (in order)...


1) Cost (we're doing this out of pocket)
2) Aestetics
3) Durrability

Any help would be greatly appreciated.
Thanks!
Reza

You don't have the money to pay someone to do the work. I'd focus on getting
the money to have the product development done right.

 

[matt meerian]

Well, after about a year of R&D, a friend and myself have built a
small device we want to sell to the various niche markets. Now that
we have the hardware done, we need to deal with fabrication of a case
for the device such that it looks good and will make the product more
marketeable. This is where I need help. First off some specifics
about the unit :

- Powered by 1 or 2 AAA batteries so it needs to have a battery
compartment
- Needs to be as light as possible
- Will be exposed to the elements; needs to be water resistant
- Needs to have an LCD display exposed (if the case is
transparent, this is a no-brainer)
- Will have a mini-b USB connector
- it needs to attach to external sensors. For example, it needs to
get speed and cadence information from a bicycle. So either we make
our own sensors and connector, or we have the device compatible with
existing bike computer harneses. This would require metal contact
points to be exposed outside of the case.
- it needs to have 4/5 buttons on the device.

I really havn't a clue where to begin. We have working prototypes
that are fairly large, and we can reduce the size and change the shape
as necessary before PCB production/assembly. However, I'm not sure
what our options are regarding materials, methods, costs, etc.
Ideally, I want to optimize on the following factors (in order)...


1) Cost (we're doing this out of pocket)
2) Aestetics
3) Durrability

Any help would be greatly appreciated.
Thanks!
Reza

Hi Reza,
There was very low budget project I worked on earlier this year that
incorporated two AAA batteries and a USB connector. The enclosure was
semi transparent blue and the right size to have two PCB mounted AAA
battery holders inside. (I think it was a Serpac C-4 or C-6 series) The
only downside to using the enclosure was a single screw had to be
removed to change the batteries. One thing that helped was placing the
PCB near where the two halves of the enclosure separated. A hand
nibbler tool and hole punch was used to make the cutouts for the PCB
mounted connectors and push buttons. This might be something you could
do with a "small version" prototype.
Shameless self promotion: There was a small article I did on a cadence
counter for bicycles a few years back. It didn't have an LCD display,
but the data could be uploaded to the desktop computer. See the online
edition of Circuit Cellar at:
http://www.chipcenter.com/circuitcellar/january01/c0101mm1.htm
Good luck with your project.

 

[Rob Campbell]

Well, after about a year of R&D, a friend and myself have built a
small device we want to sell to the various niche markets. Now that
we have the hardware done, we need to deal with fabrication of a case
for the device such that it looks good and will make the product more
marketeable. This is where I need help. First off some specifics
about the unit :

<snip>

Please tell me that you've done market research - i.e., identified and
gained the interest of if not letters of intent from likely customers -
before doing all this work. If not, you should now, before investing any
more time and money. misc.entrepreneurs.moderated and
misc.business.marketing.moderated are good resources.

Also, the impression I get from your post is that packaging is an
afterthought. It shouldn't be, especially for a consumer device and/or one
that will see rugged use, such as on a bicycle. Even if it's going to sit on
a shelf and look good, your laundry list of packaging details isn't trivial.
The R may be done, but the D isn't.

Sorry for being presumptuous. You may have already done the research and
thought all these things through.

Rob Campbell

 

[Ken Taylor]

<snip>

Please tell me that you've done market research - i.e., identified and
gained the interest of if not letters of intent from likely customers -
before doing all this work. If not, you should now, before investing any
more time and money. misc.entrepreneurs.moderated and
misc.business.marketing.moderated are good resources.

Also, the impression I get from your post is that packaging is an
afterthought. It shouldn't be, especially for a consumer device and/or one
that will see rugged use, such as on a bicycle. Even if it's going to sit on
a shelf and look good, your laundry list of packaging details isn't trivial.
The R may be done, but the D isn't.

Sorry for being presumptuous. You may have already done the research and
thought all these things through.

Rob Campbell

Ditto Rob's comments. Assuming the best case, look for an off-the-shelf
package that will do your job, as fabricating from scratch will be long,
involved and costly. Minimum tailoring should be the goal. There's bound to
be case or plastics suppliers in your area who can supply you a standard
weatherproof product without too much drama.

Ken

 

[Reza Naima]

We've talked to a lot of people and there seems to be sufficient
interest. We're looking at selling this via word-of-mouth and
magazine advertisement initially, and if it takes off there, then to
ramp up production and pursue retail outlets. The largetst
complication with regards to existing cases is that it somehow needs
to mount on a bicycle handle. Ideally, it would need to integrate
with existing harnesses to reduce cost.

One thought I had was to carve out a rough design in some soft
material, make a mold of it myself, and use some resins to make a
small number of cases. This seems like it's the most labour and time
intensive, but the cheapest option and I dont see why it couldn't
work.

So far, we've worked primarily on the electronics. But the form
factor can be any shape now. So I suppose we are now doing that
aspect of the research.

Also, as this product will be sold for $300-$400, I just see people as
being more interested in the product if it looks more "polished" and
"professional". This is why I am opposed to the modification of
existing cases idea, as it will not look as "professional". But it is
worth investigating, so I'll start checking out some suppliers.

Finally, I called up a tooling shop to see what the cost of the mold
would be. based on what I described to him, his best guess is around
$3k for the mold, and possibly $2k if he can use a unit dye (though
that would limit where I can use the mold).

Also, does anyone know if it's supposed to be spelled mold or mould.
I've seen it both ways.

thanks again,
reza

 

[Marc H.Popek]

Reza,
Slightly Off topic... I recently return from a Trade Show IN Philadelphia.
On South Street Party district, I happenstanced into a no cover bar with a
Rap group. Now most radio Rap is vile and I don't normally listen to it.
What I heard that night was wonderful. On tune went something like this, "
Opinions... everyone's got em.... Opinions... aint facts..."

and then went onto the story line.....


There lots of ideas on exactly how a business should run, and given the aide
range of solution and outcomes,, " Opinions... everyone's got em....
Opinions... aint facts..."

Happy selling, sell sell sell that's the focus.


There are many companies that have plastic work boxes. Good one in east
coast USA ..name escapes me at present.. sola? They had an upscale version
of the radio shack boxes. some with battery compartments and others, you may
have to buy a shell ,and have it "worked" and then use it as your
housing.... till if ever you tool a plastic mold and customize things.

 

[Bill Shymanski]

I may have missed it, but has anyone else in the thread mentioned FCC
requirements for radio/TV interference? ( Assuming that you're
targetting sales in the United States.) I thought any digital product
(barring something with a clock frequency lower than some very low
number that I don't recall) had to be tested for RF interference before
it could be sold in any volume.

Perhaps you've already looked into this but if not, a little research
now might save some trouble later on.


Bill

 

[Khim Bittle]

I may have missed it, but has anyone else in the thread mentioned FCC
requirements for radio/TV interference? ( Assuming that you're
targetting sales in the United States.) I thought any digital product
(barring something with a clock frequency lower than some very low
number that I don't recall) had to be tested for RF interference before
it could be sold in any volume.

There is a exception if the unit is battery powered , an unintentional
radiator ( like this unit ) and is only to be used in moving vehicles
.... BUT if you take the unit off your vehicle and plug it into your
computer for download whamo you now have to be tested.

( note FCC testing and fixing problems gets expensive fast and it is
much wiser to carefully package up front )

You must have the unit tested BEFORE it is marketed ! yup hard to
believe , the FCC handed out fines at the CES show of $10-20K for
marketing of untested units.

KB

 

[Carlos Antunes]

You must have the unit tested BEFORE it is marketed ! yup hard to
believe , the FCC handed out fines at the CES show of $10-20K for
marketing of untested units.

Does anyone have an idea of how much it costs to test a product for
compliance?

Thanks!

Carlos Antunes

 

[Marc H.Popek]

the testing is relatively inexpensive for fcc filing of simple license free
(part 15) items, figure 1-3k for the event and the report and filing.

However, this assumes that your products already MEETs the FCC requirement.
The testing is only a test and cannot CRWEATE compliance. Compliance comes
from managing the frequency plan, harmonics, etc.. first to insure
compliance... then you go to the test range and Verify the you compliance
and the third party supplies the drat and report. Nice and cozy process.

Marco

 

[Reza Naima]

Great advice! It's been on the back of my mind to have some testing
done, but I assumed that it wouldn't be an issue 'till we went fully
retail with the product. The product already has sheilding on the
potential problem points (the GPS unit & antenna amplifier). However
The unit will be plugged into a PC to download data. Does anyone know
what type of testing is required, how to do it, and how much it costs?
If it is radiating, can we supply a metal box to put the device in
when plugging it into a PC? And what about metalic paints? Can I get
the inside of the case sprayed with such paints to add shielding?
What's the easiest way to test the unit myself before submitting it to
the FCC for their testing?

Also, on the case front, there are some pictures of a laser cut
acrylic case that looks great on this website :

http://www.positron.org/projects/juicebox/

I now need to make calls to find out pricing information.

Thanks everyone for the input so far!

Reza

 

[Khim Bittle]

Great advice! It's been on the back of my mind to have some testing
done, but I assumed that it wouldn't be an issue 'till we went fully
retail with the product. The product already has sheilding on the
potential problem points (the GPS unit & antenna amplifier). However
The unit will be plugged into a PC to download data. Does anyone know
what type of testing is required, how to do it, and how much it costs?

$800 - $1600

If it is radiating, can we supply a metal box to put the device in
when plugging it into a PC? And what about metalic paints? Can I get
the inside of the case sprayed with such paints to add shielding?

Yes , I have worked with case suppliers who charged $150 setup and a
couple of $ per piece to spray. Conductive paints have several issues
including cracking if the plastic case can flex , and flaking of the
paint over time leaving little conductive particles floating around
inside the electronics.

What's the easiest way to test the unit myself before submitting it to
the FCC for their testing?

At a minimum you need a good spectrum analyzer and the appropriate
antenna(s) / lna / cabling ( costing $15-30 thousand $ ) and the
appropriate knowledge and test space. Antenna must be able to be
moved and rotated. The correct answer here .... it's time to find a
local test lab , give em a big hug , tell then you will bring them
some business and make them your buddy and you will probably be able
to do some quick checks at a decent price.

KB

( obtw ... if you are designing a nifty little gps logging box for
your bicycle I hope you have reviewed the little garmin bicycle unit
and others in the pipeline , I only say this because I suspect they
will sell on the market for less than you can buy your parts for ,
well good luck )

 

[Ralph Mason]

We've talked to a lot of people and there seems to be sufficient
interest. We're looking at selling this via word-of-mouth and
magazine advertisement initially, and if it takes off there, then to
ramp up production and pursue retail outlets. The largetst
complication with regards to existing cases is that it somehow needs
to mount on a bicycle handle. Ideally, it would need to integrate
with existing harnesses to reduce cost.

One thought I had was to carve out a rough design in some soft
material, make a mold of it myself, and use some resins to make a
small number of cases. This seems like it's the most labour and time
intensive, but the cheapest option and I dont see why it couldn't
work.

So far, we've worked primarily on the electronics. But the form
factor can be any shape now. So I suppose we are now doing that
aspect of the research.

Also, as this product will be sold for $300-$400, I just see people as
being more interested in the product if it looks more "polished" and
"professional". This is why I am opposed to the modification of
existing cases idea, as it will not look as "professional". But it is
worth investigating, so I'll start checking out some suppliers.

Finally, I called up a tooling shop to see what the cost of the mold
would be. based on what I described to him, his best guess is around
$3k for the mold, and possibly $2k if he can use a unit dye (though
that would limit where I can use the mold).

Also, does anyone know if it's supposed to be spelled mold or mould.
I've seen it both ways.

Well if the product sells for that much, perhaps in the beginning you could
just buy an off the shelf bicycle computer, remove it's innards and use that
case. You should be able to find a suitable donor for $20.

Ralph

 

[Meindert Sprang]

For those that are interested.. I did some research and it seems as if
I only need a DoC (Documentation(?) of Compliance). As this is

Declaration of Conformity

Now, out of curiosity -- does anyone know of similar excemptions for
CE testing?

Same procedure, but there are, as far as I know, now exemptions. But the
standards and limits against which the device is tested, are roughly the
same for FCC part 15 class B and the corresponding IEC standards used for CE
marking. These are IEC 61000-6-3 (compatibility) and EN/IEC 61000-6-1
(emission). The IEC standards are a bit 'tighter than those for FCC, so if
you measure for IEC, you're automatically ok for FCC.

Meindert

 

[RP Henry]

Now, our device has a GPS unit in it which might also clasify it as a
Receiver, but the GPS will never be used inside home (it can't
anyhow..), so I'm guessing (hoping) that I dont need full catagory b
testing.

Why not? I have seen GPS work in my house (wood frame, cement tile roof)
and in the top floor of a standard So Cal office building (steel frame,
wood/tar roof).

 

[Howard Goldstein]

: Now, our device has a GPS unit in it which might also clasify it as a
: Receiver, but the GPS will never be used inside home (it can't
: anyhow..), so I'm guessing (hoping) that I dont need full catagory b
: testing.

You could be shocked at what passes category B testing. I sure was,
most recently with a clone 386 on ISA board with ISM radio, GPS, and
DC switcher, all in a plastic case with zero shielding and near contempt
paid towards lead dressing and other normal levels of good hygiene.