Thread by @gravislizard

i think a lot about how injection molding is so absolutely crucial to the design of simple things

among old-electronics enthusiasts, it's common to see something unusual and not buy / take it because the power connector is some weird funky *shape*. not voltage, shape. because it turns out that suspending pins in a particular shape is incredibly hard

if you have a device that takes power like this, you're fucked unless you can find these specific connectors, because you simply can't make them at home.

(those ones aren't that uncommon but plenty are)

it's weird because it isn't a thing you can "whittle." no amount of diligence and personal dedication will make this possible. you need an injection molding press and a machine shop. they don't have to be good, but you need them

you can't halfass it, you can't find some other way to do it that's "close enough", you can't bodge it even temporarily, you can't get free-hanging socket pins (they'll short together.) you just *cannot* have a plug-and-socket connection without injection molding.

you couldn't even machine a plug and socket because the details are so fine. it's weird to think about, but even the most wretched chinese toy covered in casting flash still has bosses and standoffs that you can't replicate through manual means, you just *can't*

a plastic standoff, joined to a complicated curved 1/16" plastic skin but *molded as one piece*, will hold up to years of use. you can't solve that with glue or screws, and this will always limit the capabillities of anyone without a quarter million dollars in reserve

DIY hobby stuff is cool but has absolutely hit a wall as far as chassis, which means that the OSSC, one of the most impressive "indie" electronics accomplishments, has multiple sophisticated PCBs but no chassis, because PCBs are far easier to make than a chassis

I got my MCE2VGA last night and it comes with a 3d printed case, and while I appreciate that they provided that, it still exposes big chunks of the circuitry. An injection molded case could have perfectly conformed, exposing only tiny holes for controls and jacks

And that's as far as things are likely to go. Injection molding is incredibly precise, even "cheap garbage" is, and will never be practical for small runs. It sucks!

I wonder how the occasional kickstarter or cottage-industry project with an injection molded chassis gets them done. Honestly I can't picture what the production process looks like.

i'm sure there are companies that do small-ish runs, but will they take your PCB design and do all the solidworks design for you? if not, how do you find a process engineer when you're just some guy who built an FPGA gadget?

anyway
this applies to so much. not just electronics. there are so many things you can't really make out of the commodity "whittleable" materials like sheet goods or wood, usually because they need highly precise and very rigid positioning of embedded metal components

conversely, i think a lot about how PC mount connectors like DC power jacks come from the factory on their last legs, only moments away from cracking a solder joint, and how there's no alternative because plastic can't take the stress

by which I mean, there's no way to mount a DC power jack or usb port in a chassis rigidly unless you cast it in (no!) or use a flanged connector with a fastening nut (usually impractical to impossible)

mind you we're talking miniaturization at this point which is a highly constrained circumstance. but yeah my core thesis is that you can't whittle a SanDisk mp3 player

you can try as hard as you want but there's only one way to make an mp3 player that fits in your pocket and it's
- single board
- probably a single chip
- all surface mount components including buttons and jacks
- injection molded chassis

the answer by the way is "there's a bunch of options" read the replies