How do we design a box (enclosure) for an electronic product

[Ray]

Hello all,
I want to design a power supply enclosure which would look
professional. The front panel will be from plastic, the rest will
be metalic. I don't know where to start really, is there some
software that will enable me to make the design on a file so that
I can send it off to a company that would manufacture it ?
Tia.

 

[Rich Webb]

On Sat, 4 Oct 2003 00:43:07 +0000 (UTC), "Ray" <ray2003@btinternet.com>
wrote:

Hello all,
I want to design a power supply enclosure which would look
professional. The front panel will be from plastic, the rest will
be metalic. I don't know where to start really, is there some
software that will enable me to make the design on a file so that
I can send it off to a company that would manufacture it ?

Unless you can recover the non-recurring engineering costs of designing
a custom enclosure, find an off-the-shelf one that works.

You can often get custom front panels made fairly cheaply (basically
holes in sheet goods), painted or anodized, and with silk screened
markings. Check with Elma Electronic UK.

If you want to design your own, you'll either need to provide complete
manufacturing drawings or add the cost of the production of the drawings
(and the inevitable revisions) to the NRE.

--
Rich Webb Norfolk, VA

 

[Ray]

You can often get custom front panels made fairly cheaply (basically
holes in sheet goods), painted or anodized, and with silk screened
markings. Check with Elma Electronic UK.

If you want to design your own, you'll either need to provide complete
manufacturing drawings or add the cost of the production of the drawings
(and the inevitable revisions) to the NRE.

How do I create a drawing, we never learnt how to do this in EE.
Is there some software we use to design boxes. I heard of
autocad, is this the tool, if so, do I need to get special customisation
for box/panel production ? Is there a free evaluation version ?
Tia

 

[Mark Fergerson]

Ray wrote:

Hello all,
I want to design a power supply enclosure which would look
professional. The front panel will be from plastic, the rest will
be metalic. I don't know where to start really, is there some
software that will enable me to make the design on a file so that
I can send it off to a company that would manufacture it ?

This is for a one-off or a production design?

If the former, look at as many commercial units as you
can and decide what you like best, then copy it as well as
possible (assuming you can open it up and see how the
airflow, connection, and similar problems are handled). FTM
you may like the guts of one and the outside of another.

Have you ever done any sheet metal work? It's not all
that hard, and a useful skill. The tools can get expensive
though.

BTW, a plastic faceplate is a bad idea for a SMPS as they
can radiate lots of EM noise. A plastic _cover_ on a metal
plate works if it stays cool enough.

If the latter, you must work for a very small company.
EEs are rarely tasked with enclosure design. ;&gt

Mark L. Fergerson

 

[JeffM]

we never learnt how to do this in EE.
Shame on your instructors.

CAD packages are expensive and the learning curve is outrageous
(especially AutoCAD). There are other vector-based alternatives:
http://www.engineering-group.com/ENGINEERSMALL/cad.htm

If, however, all you need is a line drawing that is easily printed/replicated,
a bitmapped paint package is an easy option.
MSPAINT is already on your Windoze box.

 

[Ray]

Shame on your instructors.

CAD packages are expensive and the learning curve is outrageous
(especially AutoCAD). There are other vector-based alternatives:
http://www.engineering-group.com/ENGINEERSMALL/cad.htm

If, however, all you need is a line drawing that is easily printed/replicated,
a bitmapped paint package is an easy option.
MSPAINT is already on your Windoze box.

hi, thanks for the link which I will look up. Regarding your suggestion to use
mspaint how will I know if production companies accept bitmap files. Also,
bitmaps are 2 dimensional, some features of my plastic from panel will have
3D designs, for example the panels will need to have a raised frame. How
will I know how to draw the things that I want in a 2 dimensional sheet, surely
there are some convensions ( which mspaint will not be able to enforce ).
A library of designs will also be useful. What do the professionals use ?

 

[Peter Bennett]

On Sat, 4 Oct 2003 22:50:18 +0000 (UTC), "Ray"
<ray2003@btinternet.com> wrote:

Shame on your instructors.

CAD packages are expensive and the learning curve is outrageous
(especially AutoCAD). There are other vector-based alternatives:
http://www.engineering-group.com/ENGINEERSMALL/cad.htm

If, however, all you need is a line drawing that is easily printed/replicated,
a bitmapped paint package is an easy option.
MSPAINT is already on your Windoze box.

hi, thanks for the link which I will look up. Regarding your suggestion to use
mspaint how will I know if production companies accept bitmap files. Also,
bitmaps are 2 dimensional, some features of my plastic from panel will have
3D designs, for example the panels will need to have a raised frame. How
will I know how to draw the things that I want in a 2 dimensional sheet, surely
there are some convensions ( which mspaint will not be able to enforce ).
A library of designs will also be useful. What do the professionals use ?

If this is a one-off or small production job, I'd strongly recommend
using a ready-made box, available from Farnell and other electronic
distributors (I normally use Hammond boxes, because the distributor I
normally work with carries them - don't know what makes you'll have in
the UK). If you use a ready-made box, then you just have to design
the front and rear panels.

AutoCad is a very common mechanical drafting package - but it is
EXPENSIVE. There are cheaper mechanical drafting packages available
(search for Intellicad - an AutoCad clone) - many offer
ACad-compatible output, which may be desirable if you are sending the
job to an outside company that wants machine-readable drawings.

There are certainly drawing conventions in mechanical drafting, but I
wouldn't expect ACad or other programs to enforce them.

I have recently started using Front Panel Express
(http://www.frontpanelexpress) - they supply the design program, and
deliver panels in a few days. That URL will get the US office in
Seattle WA - the parent company is in Germany.


--
Peter Bennett, VE7CEI
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[Ray]

This is for a one-off or a production design?

If the former, look at as many commercial units as you
can and decide what you like best, then copy it as well as
possible (assuming you can open it up and see how the
airflow, connection, and similar problems are handled). FTM
you may like the guts of one and the outside of another.

Have you ever done any sheet metal work? It's not all
that hard, and a useful skill. The tools can get expensive
though.

no as yet...

BTW, a plastic faceplate is a bad idea for a SMPS as they
can radiate lots of EM noise. A plastic _cover_ on a metal
plate works if it stays cool enough.

I'm am talking about a low voltage/low current one.

If the latter, you must work for a very small company.
EEs are rarely tasked with enclosure design. ;&gt

So who then is tasked with enclosure design ?
Is that something I need a degree for as well ?

 

[JeffM]

|strongly recommend using a ready-made box...
|I normally use Hammond boxes...
|Peter Bennett

Well said; Stay away from custom anything if possible.
Take this advice with you throughout your life.

a plastic faceplate is a bad idea for a SMPS
...radiate lots of EM noise.
A plastic _cover_ on a metal plate works if it stays cool enough
Mark L. Fergerson

This is the easy way to minimize the custom stuff;
plastic is much easier/cheaper to fab than metal.
In addition, would you like this enclosure to trap a fire inside it
should something go terribly wrong? 6 metal sides are mandatory for this.
If you are going to be doing designing/engineering,
you will have to start considering worst-case scenerios.

, you must work for a very small company.
EEs are rarely tasked with enclosure design. ;&gt
Mark L. Fergerson

Don't mind Mark. He's just spoiled. ;-)
Some engineers/techs actually enjoy branching out.


~how will I know if production companies accept bitmap files ?

Ask them--and remember they're working for you.
A piece of paper is all a good fabriction man needs.
(Doing it on the computer just makes it easy for you to make 92 copies.)
If they want to get paid, they'll accommodate your needs.
You can always find someone else to take your money.


~How will I know how to draw the things that I want in a 2 dimensional sheet,
~surely there are some convensions [sic]
~Ray

Yes there are. A visit to google.com could be educational.
(search terms) Drafting OR "Mechanical drawing" Basics OR Beginning

To get you started, the simplest standard drawing looks something like this:
--------------
| TOP |
| VIEW |
| |
--------------

-------------- --------------
| FRONT | | SIDE |
| VIEW | | VIEW |
| | | |
-------------- --------------
Drawing Title
Engineer's name
Draftsman's name
revision # date

 

[Fred Abse]

On Sun, 05 Oct 2003 00:08:41 -0700, JeffM wrote:

plastic is much
easier/cheaper to fab than metal

Disagree. Most plastics don't fold worth a damn, and can be difficult to
join with "normal" workshop methods.

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

 

[Fred Abse]

On Sat, 04 Oct 2003 13:44:59 -0700, JeffM wrote:

CAD packages are expensive and the learning curve is outrageous
(especially AutoCAD). There are other vector-based alternatives:
http://www.engineering-group.com/ENGINEERSMALL/cad.htm

If, however, all you need is a line drawing that is easily
printed/replicated, a bitmapped paint package is an easy option. MSPAINT
is already on your Windoze box.

What's wrong with good old-fashioned drawing instruments and paper for a
quick simple box?

IMO, nobody should go near a CAD package until they've learnt the
fundamentals of engineering drawing.

QCAD (free for Windoze and just about every flavor of Unix) is a good
starting point, if a little basic. Learnt in a couple hours to a
reasonable level of fluency.

CAD - "Can't anybody draw?"

--
Then there's duct tape ...
(Garrison Keillor)
nofr@sbhevre.pbzchyvax.pb.hx

 

[Ray]

Yes there are. A visit to google.com could be educational.
(search terms) Drafting OR "Mechanical drawing" Basics OR Beginning

What uni degrees teach you this ? are there reccomended books ?

 

[Mark Fergerson]

JeffM wrote:

|strongly recommend using a ready-made box...
|I normally use Hammond boxes...
|Peter Bennett

Well said; Stay away from custom anything if possible.
Take this advice with you throughout your life.

Agree, on the condition that the "standard part" is built
appropriately for the application.

a plastic faceplate is a bad idea for a SMPS
...radiate lots of EM noise.
A plastic _cover_ on a metal plate works if it stays cool enough
Mark L. Fergerson


This is the easy way to minimize the custom stuff;
plastic is much easier/cheaper to fab than metal.

Cheaper ain't always better, though.

In addition, would you like this enclosure to trap a fire inside it
should something go terribly wrong? 6 metal sides are mandatory for this.

Good point, and better than mine re: radiated EM.

If you are going to be doing designing/engineering,
you will have to start considering worst-case scenerios.

And never stop.

, you must work for a very small company.
EEs are rarely tasked with enclosure design. ;&gt
Mark L. Fergerson


Don't mind Mark. He's just spoiled. ;-)

Moi? I just wanted to point out that most companies
allocate tasks according to resumes er skills.

Some engineers/techs actually enjoy branching out.

Hey, that's why I asked the OP if he'd ever bent metal.
Aside from the skills acquisition, it's extremely satisfying
to build something unique that not only works, but does so
better than anything you could have bought ready-made.

Getting the pro look merely requires inspiration,
practice, and the "right" tools.

~how will I know if production companies accept bitmap files ?

If they want to get paid, they'll accommodate your needs.

Or at least tell you what they can and can't do. OTOH
smaller companies claim they can't afford the software
(anti-"bells & whistles" mentality) and larger ones won't do
small runs or one-offs.

~How will I know how to draw the things that I want in a 2 dimensional sheet,
~surely there are some convensions [sic]
~Ray

Yes there are. A visit to google.com could be educational.
(search terms) Drafting OR "Mechanical drawing" Basics OR Beginning

<rant begins>

The World Is Going To Hell In A Handbasket.

By the time I'd graduated High School (1970), I'd had two
years each of Mechanical Drawing, Metal Shop, and Radio Shop
(among other things). What the HELL are they teaching these
days??? I know, shop classes are "hazardous"; I blackened,
cut, and burnt my fingers in those classes, but the benefits
far outweighed the harm. I guess we make better consumers if
we aren't allowed to learn how to build our own stuff.

<rant ends>

One can always haunt used-book stores for decent texts on
Mech Drawing (and other stuff they used to teach)...

Mark L. Fergerson

 

[JeffM]

I didn't get my sheepskin until I completed 2 of these courses
(and that was in the pencil & paper days).

It wouldn't seem to be that hard to find.
A check with a junior college which has any technical courses or an
extension course thru your local government's/school's continuing
education program
should do it.
A high school drafting teacher could point you in a direction.
If Devry or ITT Tech is nearby, ask them.

 

[Bob Masta]

On Sat, 4 Oct 2003 00:43:07 +0000 (UTC), "Ray"
<ray2003@btinternet.com> wrote:

Hello all,
I want to design a power supply enclosure which would look
professional. The front panel will be from plastic, the rest will
be metalic. I don't know where to start really, is there some
software that will enable me to make the design on a file so that
I can send it off to a company that would manufacture it ?
Tia.

To echo what others have said, look for a pre-made
box where all you need to do is punch/drill the front
and rear panels.

You may also be upset, as I was in my early days,
to discover that for many projects the enclosure and
controls can end up costing far more than the
electronics inside. This is a fact of life that I just
had to get used to, but it sure grated on me!

Of course, it's no problem if you are building
expensive systems and can easily absorb
enclosure costs, but it always seems that there
a lots of good ideas for smaller products that die on the
vine once you figure in these little details of
rea life.





Bob Masta
dqatechATdaqartaDOTcom

D A Q A R T A
Data AcQuisition And Real-Time Analysis
www.daqarta.com

 

[Ray]

To echo what others have said, look for a pre-made
box where all you need to do is punch/drill the front
and rear panels.

You may also be upset, as I was in my early days,
to discover that for many projects the enclosure and
controls can end up costing far more than the
electronics inside. This is a fact of life that I just
had to get used to, but it sure grated on me!

Of course, it's no problem if you are building
expensive systems and can easily absorb
enclosure costs, but it always seems that there
a lots of good ideas for smaller products that die on the
vine once you figure in these little details of
rea life.

I was more interested in the process involved. Telling me to buy
a ready made box is I suppose not a bad idea, but it doesn't
teach me anything new. Assume I can absorb the cost and all the
rest of it, what tools do I need for the design, what experience
do I need for the design, what knowledge do I need for the
design, what materials are available, if plastic - what sort of
materials, what sort of colors, transparant/non transparent,
patterns and textures. Certain plastics are softer than others.
How do the design packages/software change when I choose
different materials.

Sorry to be so boaring (probably), but I have absolutely no
knowledge on the subject and I need a sort of overview of
the process.

 

[Peter Bennett]

On Mon, 6 Oct 2003 16:55:45 +0000 (UTC), "Ray"
<ray2003@btinternet.com> wrote:

I was more interested in the process involved. Telling me to buy
a ready made box is I suppose not a bad idea, but it doesn't
teach me anything new. Assume I can absorb the cost and all the
rest of it, what tools do I need for the design,

If you have no mechanical design or drafting experience, go to a
library and look for books on the topic. You can do entirely adequate
drawings with pencil and paper - and it might be best to start that
way, rather than trying to learn a CAD program at the same time.

what experience do I need for the design,
what knowledge do I need for the
design, what materials are available, if plastic - what sort of
materials, what sort of colors, transparant/non transparent,
patterns and textures. Certain plastics are softer than others.
How do the design packages/software change when I choose
different materials.

I suppose I started (several centuries ago) using commercial cabinets,
and seeing what materials they used, and how they were put together
(as well as observing how instruments I used or worked on were
packaged).

You might have a look around http://www.hammondmfg.com/ and other
enclosure manufacturers' sites to see what products are available, and
what materials are used. Hammond has mechanical drawings of some of
their products on-line, so you can see what a drawing should look
like.

--
Peter Bennett, VE7CEI
new newsgroup users info : http://vancouver-webpages.com/nnq
GPS and NMEA info: http://vancouver-webpages.com/peter
Vancouver Power Squadron: http://vancouver.powersquadron.ca

 

[SammyD]

You can download an extended eval copy of IntelliCAD from www.cadopia.com .

Peter Bennett <peterbb@interchange.ubc.ca> wrote in message news:<u6qunvkcslrhtqad13jj0ol5fb3t18r6kh@news.supernews.com>...

On Sat, 4 Oct 2003 22:50:18 +0000 (UTC), "Ray"
ray2003@btinternet.com> wrote:

Shame on your instructors.

CAD packages are expensive and the learning curve is outrageous
(especially AutoCAD). There are other vector-based alternatives:
http://www.engineering-group.com/ENGINEERSMALL/cad.htm

If, however, all you need is a line drawing that is easily printed/replicated,
a bitmapped paint package is an easy option.
MSPAINT is already on your Windoze box.

hi, thanks for the link which I will look up. Regarding your suggestion to use
mspaint how will I know if production companies accept bitmap files. Also,
bitmaps are 2 dimensional, some features of my plastic from panel will have
3D designs, for example the panels will need to have a raised frame. How
will I know how to draw the things that I want in a 2 dimensional sheet, surely
there are some convensions ( which mspaint will not be able to enforce ).
A library of designs will also be useful. What do the professionals use ?


If this is a one-off or small production job, I'd strongly recommend
using a ready-made box, available from Farnell and other electronic
distributors (I normally use Hammond boxes, because the distributor I
normally work with carries them - don't know what makes you'll have in
the UK). If you use a ready-made box, then you just have to design
the front and rear panels.

AutoCad is a very common mechanical drafting package - but it is
EXPENSIVE. There are cheaper mechanical drafting packages available
(search for Intellicad - an AutoCad clone) - many offer
ACad-compatible output, which may be desirable if you are sending the
job to an outside company that wants machine-readable drawings.

There are certainly drawing conventions in mechanical drafting, but I
wouldn't expect ACad or other programs to enforce them.

I have recently started using Front Panel Express
(http://www.frontpanelexpress) - they supply the design program, and
deliver panels in a few days. That URL will get the US office in
Seattle WA - the parent company is in Germany.

 

[Mark Fergerson]

Ray wrote:

I was more interested in the process involved. Telling me to buy
a ready made box is I suppose not a bad idea, but it doesn't
teach me anything new. Assume I can absorb the cost and all the
rest of it, what tools do I need for the design, what experience
do I need for the design, what knowledge do I need for the
design, what materials are available, if plastic - what sort of
materials, what sort of colors, transparant/non transparent,
patterns and textures. Certain plastics are softer than others.
How do the design packages/software change when I choose
different materials.

So, you want to learn all the stuff a company knows about
enclosure design, to get "the pro look"? I concur, some
(paper) drafting texts and/or CAD practice ought to do you a
lot of good for the final design stage. But before that, you
also need to consider some other things like:

Heat management (will the case temp damage any cosmetic
plastics, do you provide ventilation, active or passive, how
much, do you need to add a fan, how do you wire it in, will
you need a bigger fuse, [which gets recursive because you
have to modify the power supply], is heatsinking components
to the case OK, are insulators needed, what kind and so on)

Mechanical issues (how to mount the circuitry bits to the
box, is it OK if screwheads show, how to stabilize/isolate
anything vibrating inside, is it gonna sit on anything else
so will it need antislip feet, if so how large and how
"nonslippery", will anything sit on it so how strong does it
need to be, is servicing an issue so how difficult should it
be to get to replaceable parts like fuses)

"Real estate" competition on the floor/desktop it'll
occupy (is a particular shape dictated by styling or is it
dictated by components)

and so on.

That's the main reason prebuilt boxes are so often
recommended for DIYers; a lot of that work is done for you.
Granted they're sorta generic, but you can dress them up any
way you want.

That's just some of the engineering details. As for
plastic/metal, the Big Boys often start with styling;
Marketing cobbles up a shape, texture, and color scheme,
then Engineering has to contort the hardware to fit. For a
DIY, it's largely a matter of taste once you get the other
issues settled (or you can do it like the Big Boys do if you
don't mind the recursive headaches). Selecting materials to
satisfy your esthetics then depends on your confidence in
your abilities to work a given material. I don't know why
you ask about this re: software; in the Corporate CAD world,
a solid is a solid in most packages and AFAIK nobody cares
until the actual toolmaker has to specify drills, punches,
dies, and so on because as you mention, some are softer,
brittler, etc. and need special (read expensive) handling.
As this info comes back to Accounting, they may sign on to
changes which Marketing has to approve, and so on. Besides,
if you're gonna do this yourself, why learn something you
won't need (like expensive software)?

So look at some commercial "pro look" stuff and think
about the manufacturer's priorities; was form more important
than function, the other way around, or did they strike a
balance? What would you do differently, and why? Is what
you'd do feasible and/or cost effective?

Sorry to be so boaring (probably), but I have absolutely no
knowledge on the subject and I need a sort of overview of
the process.

Many of us have held jobs in all the fields involved
(and/or overheard skull sessions in other departments), so
that's how we got our overview. Nothing teaches like
experience, but you can try plowing through texts on all
these subjects and learning at home.

OTOH depending on your age, lots of companies hold open
house days where students can tour various departments to
see how the Big Boys do things. Hell, sometimes they even
let adults in...

Oh, and as Bob Masta says, the package may end up costing
more than the contents. OTOH if all you're investing is your
time, and you reap all that knowledge, it may be worth it.
Accounting departments like OJT, too. ;&gt

Mark L. Fergerson

 

[ddwyer]

Sorry to be so boaring (probably), but I have absolutely no
knowledge on the subject and I need a sort of overview of
the process.


Your questions demonstrate that the process is working.

Tooling for unique plastic case is only OK for 100k+
Entrepreneurs adapt surprising alternative cases check buying a mass
produced high volume finished product removing the innards and placing
your circuit inside like a cuckoo
--
ddwyer