Very cheap molded enclosures?

Hello Spehro,

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

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.

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

I can't wait to hear where this falls short. 8-) It is brilliant in its simplicity.

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.

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

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

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

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

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

Hello Ken,

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

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

Another unsure idea: one punched square hole, with all your (square) LEDs huddled up together in the middle of the panel, and legends written using pointer lines to enable 2 columns of text to point to your LED cluster. Or you could even divide your panel like a pie chart, with white and light grey segments, to make LED ID visually clearer.

A block of 9 square LEDs with eg a power one as the middle one. 2 such clusters if need be.

Less likely, but might work wth a few cases, guillotine the edge of the front panel off, and that missing edge strip is where your line of sqaure LEDs sits.

NT

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

Best regards, Spehro Pefhany

A thought slightly off track from boxes: are you using the cheaper brown phenolic paper pcbs? Theyre.... cheaper.

Not really on topic here... I've always vaguely wondered about going to extremes with pcb cost, and using a piece of thick card with copper foil stuck on it. Varnish the card, etch the foil, and mount in the case by applying glue to the PCB and pressing pcb into place. The case provides mechanical rigidity. However thats not a serious suggestion for your project, any more than would be using a tortilla, just a muse-ment. I'd just like to see someone some day do some work on cheap PCB materials and come up with something far less costly than FR4 or phenolic thats good enough for mass production.

NT

Hello Rich,

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

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

Thomas

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.

Regards, Joerg

Hello Charlie,

They are out of price range.

Regards, 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.

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.

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.

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