Flashing jig


#1

I’m trying to imagine what you might think a “flashing jig” is if you’re not into electronics… No, it’s not the worst strip tease ever, it’s a frame you put a circuit board on that connects an external programmer device to points on the board so that you can write code (or “flash the firmware”) to the CPU. Previously I’d have a circuit board fabricated with holes in the (hopefully) correct locations and 3D print a frame to hold the board in the right place. If I make a mistake or decide to change the design, the turnaround is hours for the 3D printer, or many days for the PCB fab. With the Glowforge I went from start to finish in about five hours, and a lot of that was learning how Inkscape works.

I did a few iterations on cardboard first to get everything sized just right, then a couple of little drill guides to get the right size for the pogo pins, the spring-loaded contacts that press against the circuit board. It took about five minutes to draw them up, even less to cut them out, and it gave me a totally perfect fit. I didn’t have to do any careful measurement, look up manufacturing tolerances, or dig out data sheets. I’m totally giddy about how the Glowforge enables prototyping with fast iterations. My first cut of the base layer in acrylic had a glitch on it, so I fixed that and had a new one in just a couple of minutes. The hole alignment wasn’t perfect so I made some tweaks and ran off another one. To thoroughly belabor the point: If I had to spin a new PCB for that, I’d be waiting over a week for it or I’d have to spend a bundle on one-day turnaround.

And man, that acrylic sure does look cool. :slight_smile:


#2

Tested on the first one, 0.8 was too tight and 0.9 was too loose so I added a decimal point and went again. 0.88 was the winner. The pins are 1.00 mm, so that puts the kerf at 0.12mm, or around 5 mil if I’m doing my math right.


#3

No static issues with acrylic?

Nice work, and agree how quick and easy it is to prototype. 40+ yr EE hobbyist here…


#4

Oh, that’s a great point! It hadn’t crossed my mind, but now I’m having flashbacks to the high school physics demo where you rub the acrylic wand with wool to charge it. Yikes. I’ve never had a problem with ESD here since it’s relatively humid, but maybe I’ll do it over in wood. (Since it’ll take almost no time at all!)


#5

Understanding level is nill, but it looks like a cool solution to a tiny problem! :smile:


#6

You could run some copper or other metallic tape around the edges, and connect to ground - I’m sure there’s a ground on there somewhere?


#7

Ooh. I gotta start in on this. I have been using way too many ingenious workarounds.


#8

This is perfect for Practical cuts


Practical cuts
#9

Oh, I forgot about Practical Cuts! I’ll post the wood version over there. Thanks! :slight_smile:


#10

I use the Glowforge all the time for little jigs like this! It’s sooooo much quicker and easier than sending a board out for fab for a one-off tool. Yours looks awesome!


#11

Pictures or it never happened! :slight_smile:


#12

We’d need a few NDAs first :slight_smile:


#13

Funny, when I built this I was wondering about how much the GF bootstrapped itself. :slight_smile: Do you also have a bin full of purple PCBs?


#14

A few :slight_smile: