Very cheap molded enclosures?

[Joerg]

Hello Newsgroup,

Again I came upon the usual hardcore enclosure challenge: Initial
quantities will be low, 10k to 20k/year, but the whole device would be
doomed if production cost would be greater than $7-8. Sales just
wouldn't happen.

Question: Is there a company that offers "shuttle runs" for enclosures?
Just as they are offered for chips where you 'ride along' on a corner of
someone else's wafer? Or a company that would do the whole production
based on one of their standard enclosures?

I checked with the usual plastic enclosure makers and it just won't fly.
At that qty a regular run-of-the-mills enclosure of 1.5" by 3" would
cost well over $5. While the raw case would drop to around $2 (still too
high) they charge an arm and a leg for drilling and I need at least a
dozen holes for LED and stuff. Heck, often they even charge extra for a
battery holder so I wonder whether they anticipate that the usual design
will be a perpetuum mobile that doesn't need any power.

I my case I need a cheap 'snap together' enclosure that can accomodate
2-3 AA cells or AAA cells, has a dozen LED holes and maybe a small power
switch. The circuit board would then be adapted to whatever it needs to
be for that enclosure.

Regards, Joerg

 

[Ken Smith]

high) they charge an arm and a leg for drilling and I need at least a
dozen holes for LED and stuff.

Are you sure you really need that many holes? This may be the place to
get clever to save the design. Multicolor LEDs and combining controls may
help.

I've had letting a machine shop do it come out cheaper than having a
molding company do it. If you can start with something they can grip very
easily, a machine shop can make holes very quickly. My prices are way
above yours but its worth asking.

If you had a box with a big square opening, could you make a PCB with
holes in it to fit? If your electronics is simple enough, it could be on
the hidden side.

 

[Joerg]

Hello Ken,

Are you sure you really need that many holes? This may be the place to
get clever to save the design. Multicolor LEDs and combining controls may
help.

The box would have to display the presence of about a dozen events and
this can't really be combined. Several events can happen in parallel.
There needs to be a brief notion next to each LED which could be done
with a self-adhesive (peel and stick) overlay next to the row of LEDs.
Ideally in a large font of at least 20 point.

A linear array of LED would make viewing from a distance tricky and
would require the label font to be very small. These arrays also cost
quite a bit.

I've had letting a machine shop do it come out cheaper than having a
molding company do it. If you can start with something they can grip very
easily, a machine shop can make holes very quickly. My prices are way
above yours but its worth asking.

So far it is around 15c/hole and that's too much. But the real problem
is the box itself. With a battery holding facility of a somewhat decent
quality that alone becomes quite expensive.

If you had a box with a big square opening, could you make a PCB with
holes in it to fit? If your electronics is simple enough, it could be on
the hidden side.

I could make the PCB anything it needs to be and the electronics are
quite simple. Space isn't an issue.

Regards, Joerg

 

[[email protected]]

Hello Ken,

The box would have to display the presence of about a dozen events and
this can't really be combined. Several events can happen in parallel.
There needs to be a brief notion next to each LED which could be done
with a self-adhesive (peel and stick) overlay next to the row of LEDs.
Ideally in a large font of at least 20 point.

A linear array of LED would make viewing from a distance tricky and
would require the label font to be very small. These arrays also cost
quite a bit.




So far it is around 15c/hole and that's too much. But the real problem
is the box itself. With a battery holding facility of a somewhat decent
quality that alone becomes quite expensive.


I could make the PCB anything it needs to be and the electronics are
quite simple. Space isn't an issue.

Regards, Joerg

I've never tried this, but will pull it outta my ass cos you look
fairly stuck. What if you use the pcb as one of the 6 box sides:
discard the original lid and use a suitably sized drilled pcb, with all
controls and LEDs mounted in holes in it. All the tronics would need to
be sm on the other side. Unlikely, but who knows, with no more info on
your product.


NT

 

[Joerg]

Hello NT,

I've never tried this, but will pull it outta my ass cos you look
fairly stuck. What if you use the pcb as one of the 6 box sides:
discard the original lid and use a suitably sized drilled pcb, with all
controls and LEDs mounted in holes in it. All the tronics would need to
be sm on the other side. Unlikely, but who knows, with no more info on
your product.

It is a pretty simple product. Can't tell much about it but basically it
catches roughly a dozen events which need to be signaled via a row of
LEDs. The PCB will have to be double sided for cost reasons and one side
is mostly ground (because of a uC). Not all of that side can be ground
so it would look a little utilitarian if it would show.

I thought about having another PCB produced that just contains the holes
because it seems that machine drilling enclosure parts costs a lot more
per hole than the same hole on a PCB. However, then you need a box into
which that PCB can be mounted without exposing the rough FR4 edges.

Another method is to try to find a product from a very different market
but with an enclosure that would work and then approach that
manufacturer. I will try this since I found one with such an enclosure
but in the past I have seen little success with such business
propositions. Large companies often just don't have a mechanism in place
to handle such deals. It would be really easy revenue for them.

Regards, Joerg

 

[Ken Smith]

A linear array of LED would make viewing from a distance tricky and
would require the label font to be very small. These arrays also cost
quite a bit.

How about a semi-clear window with a row of normal LEDs behind it? This
may cost less than a row of holes. Perhaps the box could be made out of
something clear.

So far it is around 15c/hole and that's too much. But the real problem
is the box itself. With a battery holding facility of a somewhat decent
quality that alone becomes quite expensive.

How about a, solder down 9V holder or the like and requiring that the box
be opened to change the battery?

I could make the PCB anything it needs to be and the electronics are
quite simple. Space isn't an issue.

How about really bright LEDs and no holes in the PCB for them? Since you
want largish spacing, the spreading of the light may not be a bad thing.

 

[Ken Smith]

is mostly ground (because of a uC). Not all of that side can be ground
so it would look a little utilitarian if it would show.

Make your sticky label cover all the sins?

 

[Spehro Pefhany]

I have seen little success with such business
propositions. Large companies often just don't have a mechanism in place
to handle such deals. It would be really easy revenue for them.

I know from my experience being approached that it doesn't seem so
attractive to take the fruits of tens of thousands of dollars in
tooling and sell them on the street. What if they helped a competitor
get going? It's a *welcome* barrier to entry once the money is sunk.

Are the quantity requirements firm (min 10k-15k), or this something
that you have to build and see if the market comes?


Best regards,
Spehro Pefhany

 

[[email protected]]

Hello NT,


It is a pretty simple product. Can't tell much about it but basically it
catches roughly a dozen events which need to be signaled via a row of
LEDs. The PCB will have to be double sided for cost reasons and one side
is mostly ground (because of a uC). Not all of that side can be ground
so it would look a little utilitarian if it would show.

spray it, or make it all coppered and etchmasked with only fine spacing
between ground and other tracks, or cover it with yout front label. Or
be daring and incorporate geometric designs in the ground plane to make
the other tracks not stand out.

I thought about having another PCB produced that just contains the holes
because it seems that machine drilling enclosure parts costs a lot more
per hole than the same hole on a PCB. However, then you need a box into
which that PCB can be mounted without exposing the rough FR4 edges.

most diy project boxes are like that. No idea whether that kind of
finish suits your app tho.

Another method is to try to find a product from a very different market
but with an enclosure that would work and then approach that
manufacturer. I will try this since I found one with such an enclosure
but in the past I have seen little success with such business
propositions. Large companies often just don't have a mechanism in place
to handle such deals. It would be really easy revenue for them.

Regards, Joerg

I reckon Kens idea is the smartest, no holes and ultrabrights. You
could use the copper ground plane on the outer side to make optical
holes if you want, or patterns etc - or even possibly a lit up letter,
words or symbol.


NT

 

[Tim Wescott]

Hello Newsgroup,

Again I came upon the usual hardcore enclosure challenge: Initial
quantities will be low, 10k to 20k/year, but the whole device would be
doomed if production cost would be greater than $7-8. Sales just
wouldn't happen.

I like your posts, Joerg. "Low quantities" = "10k/year". I've never
worked on anything with production higher than 100ea per year.

Question: Is there a company that offers "shuttle runs" for enclosures?
Just as they are offered for chips where you 'ride along' on a corner of
someone else's wafer?

The difference is that if you want the enclosure to be really cheap per
piece you need to have the holes, and all other features, molded in.
Drilling them after the fact will simply cost more.

Or a company that would do the whole production
based on one of their standard enclosures?

I liked the suggestion to buy standard enclosures but have your own
machine shop do the drilling. This may not save you anything after all,
but it shouldn't be discounted.

If you place your LEDs in one or two rows you may be able to get away
with one or two slots, which may be less than a bunch of holes. This
may save some $$ if you have the work done at a stateside machine shop.

I checked with the usual plastic enclosure makers and it just won't fly.
At that qty a regular run-of-the-mills enclosure of 1.5" by 3" would
cost well over $5. While the raw case would drop to around $2 (still too
high) they charge an arm and a leg for drilling and I need at least a
dozen holes for LED and stuff. Heck, often they even charge extra for a
battery holder so I wonder whether they anticipate that the usual design
will be a perpetuum mobile that doesn't need any power.

Most of those enclosures go into products that are well under 10k/year
-- and I think you've found out why.

I see a lot of stuff that I would estimate to be in the 1k/year (EPROM
programmers, cheap frequency counters for ham radio, etc.) done in
bent-up sheet metal. This doesn't accommodate your battery, but it
seems to be a sweet spot (and rugged, too).

I my case I need a cheap 'snap together' enclosure that can accomodate
2-3 AA cells or AAA cells, has a dozen LED holes and maybe a small power
switch. The circuit board would then be adapted to whatever it needs to
be for that enclosure.

Regards, Joerg

Have you investigated going straight to Taiwan? How about having a
custom enclosure made (possibly in Taiwan)? It seems that for 10k/year
you can afford to have some tooling made. I see stuff in what appears
to be ready-made plastic cases that don't come from any of the usual
suspects that I see in catalogs; I suspect there's a thriving industry
for this over there if you can figure out how to tap into it.

If you go to the far east you don't even really need drawings. If you
have a case all drilled and ready to go you can send it out as your
"drawing" -- but you'll get an exact copy which may upset your local
case manufacturer.

Years ago one of the suppliers in the street rod industry, who was known
for sending parts of old Fords to Taiwan to be duplicated cheaply, came
out with a cowl vent hinge for '32 Fords. Interestingly enough, instead
of being a copy of a genuine Ford article -- two stamped steel pieces
that were spot welded together -- it was a few thick sheet piece that
was were bent on a jig, then wire welded with pieces of pipe for pivots
-- just like the ones my Dad's company had been making for years.

We took one of ours to them at a show, along with a real one. They
confessed that they'd taken a rusty old one out of a clapped-out street
rod and sent it off; it never occurred to them that they were making a
repo of a repo.

We all had a good laugh (and they changed to a more genuine design).

 

[Joerg]

Hello Spehro,

I know from my experience being approached that it doesn't seem so
attractive to take the fruits of tens of thousands of dollars in
tooling and sell them on the street. What if they helped a competitor
get going? It's a *welcome* barrier to entry once the money is sunk.

Doesn't have to be that way. We could enter into a contract making it
very clear that it's going into a totally different market. Actually,
we'd be more than willing to let them take over production for the whole
thing once the sales volume matures. That should be a win-win situation,
allowing them to crank a windfall out of their current mold design plus
pocketing some margin for producing the units.

Are the quantity requirements firm (min 10k-15k), or this something
that you have to build and see if the market comes?

It's the usual, build and see. Initially it would be best to just buy
the enclosure parts from them sans screen print. Then, when it does take
off, move mass production to that company if they'd be interested.

Regards, Joerg

 

[Joerg]

Hello Ken,

How about a semi-clear window with a row of normal LEDs behind it? This
may cost less than a row of holes. Perhaps the box could be made out of
something clear.

I thought about clear boxes but those aren't very cheap.

How about a, solder down 9V holder or the like and requiring that the box
be opened to change the battery?

No 9V blocks, they are a pain. Ripped off snap contacts and all that, it
would create too many 'warranty' returns. Having to open the box
wouldn't be an issue though. I think people have gotten used to that
since this is what you have to do to change the batteries on many
outdoor remote temperature sensors. My non-EE wife has no problems doing
that.

How about really bright LEDs and no holes in the PCB for them? Since you
want largish spacing, the spreading of the light may not be a bad thing.

Super brights blow the budget and would slurp up batteries too fast.
Spread would be a problem but that could be mitigated by sliding tubing
pieces over them. Drip irrigation tube snippets or the like.

Regards, Joerg

 

[Joerg]

Hello Tim,

I like your posts, Joerg. "Low quantities" = "10k/year". I've never
worked on anything with production higher than 100ea per year.

Mostly I also work on lower volume stuff. But I actually enjoy those
cut-throat price-driven high volume designs. 10k is low, a molded
solution usually requires several times that.

The difference is that if you want the enclosure to be really cheap per
piece you need to have the holes, and all other features, molded in.
Drilling them after the fact will simply cost more.

On molded parts we always had everything molded in. No machine shop work
whatsoever. But these were things that ran in larger quantities, often
disposables.

I liked the suggestion to buy standard enclosures but have your own
machine shop do the drilling. This may not save you anything after all,
but it shouldn't be discounted.

I don't discount that but the prices I saw in the US are way too high.
Have to shop around some more.

If you place your LEDs in one or two rows you may be able to get away
with one or two slots, which may be less than a bunch of holes. This
may save some $$ if you have the work done at a stateside machine shop.

Slots often cost a lot more than drilled holes. The other downside is
that if you use the regular round through-hole LEDs for cost reasons the
gaps would allow dirt to lodge there. While the circuit can be made
dirt-tolerant it would look icky after a while. Especially when people
use the device while eating one of those Carl's Jr burgers.

Most of those enclosures go into products that are well under 10k/year
-- and I think you've found out why.

Yes, and that's why I don't understand the darth of enclosures that
already have holes in them. I mean, other than motes and repeaters there
aren't many designs that don't need signaling or user interaction.

Have you investigated going straight to Taiwan? How about having a
custom enclosure made (possibly in Taiwan)? It seems that for 10k/year
you can afford to have some tooling made. I see stuff in what appears
to be ready-made plastic cases that don't come from any of the usual
suspects that I see in catalogs; I suspect there's a thriving industry
for this over there if you can figure out how to tap into it.

If you go to the far east you don't even really need drawings. If you
have a case all drilled and ready to go you can send it out as your
"drawing" -- but you'll get an exact copy which may upset your local
case manufacturer.

I don't have much in terms of good leads over there. But I am working on
it. China might be another option. The ideal situation would be a
company that can take care of the enclosure and then produce the whole
unit as well.

Years ago one of the suppliers in the street rod industry, who was known
for sending parts of old Fords to Taiwan to be duplicated cheaply, came
out with a cowl vent hinge for '32 Fords. Interestingly enough, instead
of being a copy of a genuine Ford article -- two stamped steel pieces
that were spot welded together -- it was a few thick sheet piece that
was were bent on a jig, then wire welded with pieces of pipe for pivots
-- just like the ones my Dad's company had been making for years.

Cool, IIRC that is also done with airplane parts for the really old
freighters and prop passenger planes. There are a lot of DC3 still in
regular service and somewhere they must get their parts from. Those
airlines don't look like they could buy genuine spare parts all the time.

Regards, Joerg

 

[Roger Hamlett]

On molded parts we always had everything molded in. No machine shop work

whatsoever. But these were things that ran in larger quantities, often
disposables.

In the UK at least, there is an intermediate 'form' of injection moulding
available. With this, the dies are made of much lower quality material,
with a life expectancy of only about 2K+ pieces. They are made using a
fairly simple CNC process, and the tooling costs are perhaps 1/100th that
of a normal injection moulding process. For orders smaller than this,
there are companies dong CNC folding processes, where the main box is
formed from sheets of ABS, CNC milled, then folded and cut glued. They
also have systems to add rails and supports. These processes cover
quantities from about 2 off, up to perhaps 4K off, with proper injection
moulding, combined with bonding for things like clear inserts, becoming
the more economic process for larger numbers. I suspect you will find that
similar setups exist in the States, but finding the company is the
problem..

Best Wishes

 

[Joerg]

Hello NT,

I reckon Kens idea is the smartest, no holes and ultrabrights. You
could use the copper ground plane on the outer side to make optical
holes if you want, or patterns etc - or even possibly a lit up letter,
words or symbol.

Ultrabrights are expensive and use too much battery juice. "See-through"
FR4 would be really cool but unfortunately it's pretty milky.

Regards, Joerg

 

[Frank Bemelman]

I my case I need a cheap 'snap together' enclosure that can accomodate
2-3 AA cells or AAA cells, has a dozen LED holes and maybe a small power
switch. The circuit board would then be adapted to whatever it needs to
be for that enclosure.

I've seen these LAN cable testers, with a row of leds. Something like
this:
http://www.action-electronics.com/ptlktest.htm

Or perhaps this:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=997064&sku=T456-5007

Or search for 5840131551 on Ebay.

Get one of each and see which fits best. Then find a seller on
www.alibaba.com
and buy 10.000 for a buck a piece.

 

[Joerg]

Hello Frank,

Or perhaps this:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=997064&sku=T456-5007

This one looks nice, except that it has that dreaded 9V battery.

Get one of each and see which fits best. Then find a seller on
www.alibaba.com
and buy 10.000 for a buck a piece.

Well, you can't get the whole unit there for that price ;-)

But I am browsing around already to look at some big contract
manufacturers. Preferably one that has a contact office in the US.

Regards, Joerg

 

[Joerg]

Hello Roger,

In the UK at least, there is an intermediate 'form' of injection moulding
available. With this, the dies are made of much lower quality material,
with a life expectancy of only about 2K+ pieces. They are made using a
fairly simple CNC process, and the tooling costs are perhaps 1/100th that
of a normal injection moulding process. ...

We have those in the US as well. However, whenever we looked into that
in the past the cost savings weren't nearly that large and we ended up
taking the plunge into the cold water, going diectly to classical
injection molding. But when a client or project is VC financed they may
not let you take that plunge.

... For orders smaller than this,
there are companies dong CNC folding processes, where the main box is
formed from sheets of ABS, CNC milled, then folded and cut glued. ...

That is rather expensive in the US. I don't see any way to keep
enclosure costs under $4 that way. Well, maybe in Asia.

Regards, Joerg

 

[Ken Smith]

Ultrabrights are expensive and use too much battery juice. "See-through"
FR4 would be really cool but unfortunately it's pretty milky.

Can you get away with 0.015" thick?

 

[Spehro Pefhany]

Hello Frank,


This one looks nice, except that it has that dreaded 9V battery.


Well, you can't get the whole unit there for that price ;-)

But I am browsing around already to look at some big contract
manufacturers. Preferably one that has a contact office in the US.

A real problem with small offshore quantities at low prices is that
the suppliers you really want to deal with really don't want your
business, and they ones who really do want your business are the ones
you really do not want to deal with. Really.



Best regards,
Spehro Pefhany