Card-edge module: Notch in PCB? Housing? - Page 1
Forum section: electronics / projects

author: TinkeringSteve
author_rank: Frequent Contributor
timestamp: March 16, 2014, 04:07:26 pm
content: Hey!I want to make an expansion module for an old 1980's keyboard I have, such an old-school module with one PCB, which terminates as a card-edge on one end, and some flat rectangular case around it (roughly 6 x 2 x 6...8 cm³)Note: I'm a total beginner with PCB design. Using DipTrace for a while now.Three problems:1)The card edge needs two notches in the PCB, each about 1mm wide and a few mm high, as the slot requires it for enforcing correct orientation.For now, this is just for myself, so I guess I could saw them in by hand.When this thing is working, though, I'm going to ask in musicians' forums whether anyone else may be interested, and then I may have to make more.Can a cheap PCB maker (2-layer) do this notch stuff for me?2)Also, the module slot is somewhat wider than the card edge slot. So I could make the PCB a bit wider above the card edge part, to have more space. But will this be a problem, to get those corners off the PCB which will make the card-edge less wide than the rest of the PCB?3)Do you have any idea how I could get plastic housings for such a module? There will probably not be standard ones which happily fit my needs.The only idea I came up with so far is to ask around, like, here, who has a 3D printer & would be willing to make it for me, assuming his program can import a 3D model I can export from my surface based 3d modeller... ugh... (or I may rather try DesignSpark mechanical some day, heh)

author: I_may_be_drunk_right_now
author_rank: Contributor
timestamp: March 17, 2014, 01:10:59 am
content: My friend, what keyboard? I assume you mean a musical keyboard since you speak about modules?Slots are usually best negotiated beforehand when dealing with hobby-level PCBs. The suppliers may not be expecting this, it's not common.But it's something that's done all the time in the industrial world. You will need to ask BEFORE you start what size of mill the PCB supplier works with. A common size is 63 mils or 1.5mm but like drills, mills come in many sizes.ASK YOUR SUPPLIER FIRST. There might be an extra charge too!Also make sure that you specify clearly exactly what you want ON YOUR GERBER (or whatever output format) since the person actually setting up the work is not the person you emailed. If you add information to your drawing, make sure it's consistent!!! Don't forget the inside of the slot has a radius, it is not square.If you can't find a supplier that does slots, simply drill a few non-plated holes as a guide so you can use a hacksaw later, it's not a big deal.2) I don't really understand what you mean.3) Forget 3D printers unless you have infinite time on your hands, just keep googling the usual hobby case suppliers.

author: TinkeringSteve
author_rank: Frequent Contributor
timestamp: March 17, 2014, 09:52:27 am
content: Quote from: I_may_be_drunk_right_now on March 17, 2014, 01:10:59 amquick reply for now:I mean, the "cave" in the device around the card edge slot is quite a bit wider than the slot plastic, it's not very tight around it.So my PCB could be somewhat wider than the slot length - save for the part of the PCB which needs to actually fit into the slot.This would result in a non-rectangular PCB. Which is a problem I guess - better avoid?(I would just prefer more routing area in wideness of the PCB if possible, as opposed to height, i.e. the PCB more sticking out of the host device is not nice)

author: TinkeringSteve
author_rank: Frequent Contributor
timestamp: March 25, 2014, 07:36:20 pm
content: Well, "the usual hobby case suppliers", I only know a few online sellers with hobby cases here, and I've never found anything that would fit.Also, to be honest, much too much time was wasted on that search already, it seems to be kind of futile since it's not so likely that a general purpose case will fit for this application. It has to fit "exactly"."Forget 3D printers unless you have infinite time on your hands"Why do you say that?I wasn't planning on getting one myself, but perhaps find someone who has one in operation already and some routine putting 3D model files through it.I have no idea what it would cost with simple setups, though. (material etc)I know a company with a huge multi-material printer, and doing something there would be prohibitively expensive.