Very cheap molded enclosures?

[Joerg]

Hello Ken,

Can you get away with 0.015" thick?

Not really. If someone grabs the thing and happens to be a football
player or professional wrestler this kind of front panel might go
"ka-crunch".

Regards, Joerg

 

[Joerg]

Hello Spehro,

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.

Yes, that is a serious concern. I am hoping that one of my client's
contract mfgs might become interested where I know what level of quality
they deliver. And where they know that my stuff won't create an end test
nightmare for them.

When I was a kid you could get jobs soldering products like this.
Nowadays regulations have put a crimp into that and most kids don't know
how to solder. Even quite a few engineers don't :-(

Regards, Joerg

 

[Ken Smith]

Not really. If someone grabs the thing and happens to be a football
player or professional wrestler this kind of front panel might go
"ka-crunch".

How about plastic that has enough color that you can't see through it?
The LEDs could be mounted on the PCB behind it. A very dark green solder
mask with a ruby red clear plastic in front of it is hard to see. Red LED
light would go through the red plastic OK I think.

 

[Joerg]

Hello Ken,

How about plastic that has enough color that you can't see through it?
The LEDs could be mounted on the PCB behind it. A very dark green solder
mask with a ruby red clear plastic in front of it is hard to see. Red LED
light would go through the red plastic OK I think.

That would work but even clear plastic would. Seeing the innards
wouldn't be a big deal. An added advantage is that people would be able
to see when a battery left in there for a long time began to look
'funky' and leak. The problem is that such see-through or translucent
colored enclosures are not very widespread and thus usually pricey.

Regards, Joerg

 

[Rich Grise]

Hello NT,


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

Use a piece of lexan for the lid, with SMT LEDs and "tact" switches,
and screen-print silvered traces on it. You might want to conformal
coat it, as well.

And I'm almost sure I've seen project boxes, like at RS, that accept
a recessed lid.

Good Luck!
Rich

 

[Rich Grise]

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.


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


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.

I temped once at a place that made some huge instrument (like, 18" tall in
a 19" rack panel) and they had a big PCB with about 100 ordinary LEDs, and
in front of that a solid piece of clear plastic, screen-printed black but
with a clear spot for each LED.

The parallax made it hard to tell which was which, so I got a couple of
soda straws and cut them up to make a little sleeve for each LED.

I have a Xilinx board that a client sent me, which has 8x SMT green LEDs
and little, teeny, tiny SMT resistors, and actually looks quite classy.

Cheers!
Rich

 

[Rich Grise]

Hello Ken,

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


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.


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.

Heh! I just mentioned doing this about two posts up-thread, but I used
soda straws. The price is certainly right! ;-) (just have your crew
grab a few at lunch every day. ;-p )

Cheers!
RIch

 

[JeffM]

::Use a piece of lexan for the lid
:: Rich Grise

...they had a big PCB with about 100 ordinary LEDs,
and in front of that a solid piece of clear plastic,
screen-printed black but with a clear spot for each LED.

...parallax...soda straws...a little sleeve for each LED.
Rich Grise

I can't wait to hear where this falls short.
It is brilliant in its simplicity.

 

[Rich Grise]

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

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.

If you use aluminum or FR-4 for a recessed front panel, they can be
punched for pennies, please forgive the alliteration.

And with SMT stuff, you might not even need it punched, except maybe
the plated-through holes. I don't know if typical vias are drilled
or punched.

Cheers!
Rich

 

[Zak]

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.

What about a few large holes, or an ugly molded hole, and a stick-on
with an opaque print on the back side?


Thomas

 

[Joerg]

Hello Rich,

Use a piece of lexan for the lid, with SMT LEDs and "tact" switches,
and screen-print silvered traces on it. You might want to conformal
coat it, as well.

And I'm almost sure I've seen project boxes, like at RS, that accept
a recessed lid.

Yes, and I have one somewhere. But I paid over $7 for it so even in
quantities it'll be $4 or more. And it doesn't give you a battery holder.

Regards, Joerg

 

[Tim Wescott]

If you use aluminum or FR-4 for a recessed front panel, they can be
punched for pennies, please forgive the alliteration.

And with SMT stuff, you might not even need it punched, except maybe
the plated-through holes. I don't know if typical vias are drilled
or punched.

Cheers!
Rich

This is the third or fourth post of Rich's that used "punch" for
"drill". It took that long to seep through my poor slow brain:

If you start with an enclosure with the right materials and design, and
plan on putting a stick-on top panel then you can have the holes punched
in one operation with a custom die. A set of dies with round holes
should be relatively cheap. If you punch toward the inside of the box
the holes can even be a bit ratty as long as they're clean on top (or at
least ugly but concave) where you need to stick on the label. You could
even have a few oblong holes (like for the ribbon cable from the panel)
at a bit higher cost for the die.

I'd inquire at your local tool-and-die maker, or perhaps several. Some
_will_ turn you away; you need the capable one with an open mind who
wants to listen and do business. If you can't find anyone local then
try rec.crafts.metalworking -- some of those guys run shops. If that
doesn't work then email me: I know a shop that used to be really into
that sort of innovation until the owner died. They may still be but its
one of my dad's contacts so its been a while since I've heard from them.

You may even be able to do a proof run in the states then ship the dies
overseas for the production work.

Another thought is an enclosure that takes end panels -- as Rich said
having a bunch of aluminum front and rear panels stomped out on an NC
machine should be pretty cheap.

 

[Charlie Edmondson]

Hello Tim,


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.



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



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.


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.



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.



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

Jeorg,
Are the standard Hammond boxes out of your price range? I have a sample
(somewhere) of a box about 4x3x1 with a battery compartment and a clear
end panel. No need to drill except for switches or i/o...

Charlie

 

[Joerg]

Hello Zak,

What about a few large holes, or an ugly molded hole, and a stick-on
with an opaque print on the back side?

I have seen that on some cheap remotes and it became ugly after short
use. The overlay became bumpy and after a while it began to tear.

Regards, Joerg

 

[Rich Grise]

Hello Zak,

I have seen that on some cheap remotes and it became ugly after short
use. The overlay became bumpy and after a while it began to tear.

I concur here - if it's subject to handling by ordinary people, it should
be built like a tank.

But, of course, I'm still attached to my idea of a lexan panel and SMT
LEDs on a board that's recessed a little - wait, never mind, that's a
board _and_ a panel that have to be mounted.... :-/

Thanks,
Rich

 

[Joerg]

Hello Charlie,

Are the standard Hammond boxes out of your price range? I have a sample
(somewhere) of a box about 4x3x1 with a battery compartment and a clear
end panel. No need to drill except for switches or i/o...

They are out of price range.

Regards, Joerg

 

[Joerg]

Hello Tim, Hello Rich,

At least for the US and Europe my experience is that pennies really
meant dimes. And then it gets too expensive.



Vias are drilled and if PCB shops would do other materials they'd be
able to get it done for a reasonable price. But usually they only drill
materials such as FR4 and Teflon.

If you start with an enclosure with the right materials and design, and
plan on putting a stick-on top panel then you can have the holes punched
in one operation with a custom die. ...

It is an option. But in the past I found that the quote didn't get any
better for punching. Drilling is usually an easy operation but they all
wanted around 10c or more per hole. Have to still shop Asia though.

I'd inquire at your local tool-and-die maker, or perhaps several. Some
_will_ turn you away; you need the capable one with an open mind who
wants to listen and do business. If you can't find anyone local then
try rec.crafts.metalworking -- some of those guys run shops. If that
doesn't work then email me: I know a shop that used to be really into
that sort of innovation until the owner died. They may still be but its
one of my dad's contacts so its been a while since I've heard from them.

Thanks, maybe I'll do that. Or maybe I should buy a CNC drill and do it
all in my garage. Somebody would just have to sit there and load and
unload the front shells. I have seen one in action and the drilling
sequence was blazingly fast. If it had a conveyor belt instead of hand
loading it could have done several hundred front shells in a hour.

You may even be able to do a proof run in the states then ship the dies
overseas for the production work.

Another thought is an enclosure that takes end panels -- as Rich said
having a bunch of aluminum front and rear panels stomped out on an NC
machine should be pretty cheap.

Aluminum would be nice. But ideally the whole enlosure should be
production efficient. Snap in the circuit board and battery tongues,
then snap together the two enclosure halves, done.

Regards, Joerg

 

[Joerg]

Hello Jeff,

I can't wait to hear where this falls short.
It is brilliant in its simplicity.

Yes, it is. Coming up with simple and cheap tricks to solve a problem is
what makes engineers great. I used drip irrigation hose for this job
before. But come to think of it, that stuff cost about $4 for 100ft at
the hardware store. I bet Rich's straw solution costs less per 100ft.
Dang, I have wasted money...

This reminds me of the old Drake shortwave receivers. Some had hardly
more parts in them than grampa's tube radio but the performance was
tremendously better.

Regards, Joerg

 

[Joerg]

Hello Rich,

I concur here - if it's subject to handling by ordinary people, it should
be built like a tank.

Yes, else you get too many returns or 'warranty' claims. It's not just
people. Then there is the new puppy dog that has the unquenchable urge
to sink its teeth into anything that resembles a toy.

But, of course, I'm still attached to my idea of a lexan panel and SMT
LEDs on a board that's recessed a little - wait, never mind, that's a
board _and_ a panel that have to be mounted.... :-/

That would be ok if board and Lexan panel would snap into place without
screws and the back of the box had a battery compartment with a sliding
lid. When I looked at the standard program of the major box
manufacturers I could not find anything like that. Just the usual (and
expensive) project boxes.

Units like the one I am thinking about don't need to be repairable. So
the snap-in action may well be irreversible.

Regards, Joerg

 

[Spehro Pefhany]

Hello Jeff,


Yes, it is. Coming up with simple and cheap tricks to solve a problem is
what makes engineers great. I used drip irrigation hose for this job
before. But come to think of it, that stuff cost about $4 for 100ft at
the hardware store. I bet Rich's straw solution costs less per 100ft.
Dang, I have wasted money...

Wait till someone asks you what the flammability rating is on those
straws...


Best regards,
Spehro Pefhany