JavaScript App Uses Advanced Math To Make PCBs Easier To Etch

We all remember the litany from various math classes we’ve taken, where frustration at a failure to understand a difficult concept bubbles over into the classic, “When am I ever going to need to know this in real life?” But as we all know, even the most esoteric mathematical concepts have applications in the real world, and failure to master them can come back to haunt you.

Take Voronoi diagrams, for example. While we don’t recall being exposed to these in any math class, it turns out that they can be quite useful in a seemingly unrelated area: converting PCB designs into easy-to-etch tessellated patterns. Voronoi diagrams are in effect a plane divided into different regions, or “cells”, each centered on a “seed” object. Each cell is the set of points that are closer to a particular seed than they are to any other seed. For PCBs the seeds can be represented by the traces; dividing the plane up into cells around those traces results in a tessellated pattern that’s easily etched.

To make this useful to PCB creators, [Craig Iannello] came up with a JavaScript application that takes an image of a PCB, tessellates the traces, and spits out G-code suitable for a laser engraver. A blank PCB covered with a layer of spray paint, the tessellated pattern is engraved into the paint, and the board is etched and drilled in the usual fashion. [Craig]’s program makes allowances for adding specific features to the board, like odd-shaped pads or traces that need specific routing.

This isn’t the first time we’ve seen Voronoi diagrams employed for PCB design, but the method looks so easy that we’d love to give it a try. It even looks as though it might work for CNC milling of boards too.

SVG To Gerber, Without The Pain

We’ve all marveled at the high quality PCB artwork used within the #BadgeLife and other communities to produce eye-catching designs, but those of you who have dipped your toes in the PCB artwork water will know that it’s hardly an easy process. [Jaseg] may have an answer though with gerbolyze, his software for processing SVG files into Gerber layers or KiCAD footprints.

His impetus for building it came from disappointing experience with other scripts that simply tried to rasterise any SVG they were given, or didn’t fully support the complete SVG spec. It’s designed for minimal preprocessing, allowing for as streamlined a process as possible. It includes a bitmap vectoriser to handle everything that can be thrown at it, and the GitHub repository has full instructions including examples of the output for different settings.

This is the latest in a long progression of enhancements to the PCB art process, but it’s not by any means the first time we’ve ventured down this path. In particular [Brian Benchoff] did a lot of work on the production of multi-colour PCBs.

These Wire Strippers Are Made From PCBs

The rise in cheap PCB fabrication has made old-school prototyping methods such as wire wrapping somewhat passé, but it still has its place. And if you’re going to wire wrap, you’re going to want a quick and easy way to strip that fine Kynar-insulated wire. So why not use PCB material to make this handy wire-wrapping wire stripper?

The tool that [danielrp] built is pretty simple – just a pair of razor blades held together so as to form a narrow slot to cut insulation while leaving the conductor untouched. The body of the tool is formed of two PCBs, between which the blades are sandwiched. [danielrp] designed the outline of the PCBs in DraftSight, then exported a DXF into EAGLE to make the Gerbers. The fabricated boards needed a little post-processing, including tapping the holes on one side to accept the screws that hold the tool together. We were surprised that FR4 took the threads at all, but it seems to work for this low-torque application. The disposable snap-type blades were sandwiched between the PCBs and the gap between them adjusted for nick-free stripping. The video below shows the design and build process.

We always appreciate homemade tools, and the fact that you can get a stack of PCBs for almost nothing makes us wonder what else we could use them for. We recently saw them used in a unique word clock, and even turned into a folding circuit sculpture.

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Homemade Test Jig Is Cheaper Than Outsourcing

In the past, [Sjaak] has had his testing and programming jigs made for him in Shenzhen, but realized they weren’t that great of a value. They weren’t terribly expensive in the grand scheme of things, but they didn’t include any wiring, so he was still spending his own time and money. His quest to develop his own in-house jigs not only netted him a considerable cost savings in the end, but also produced a nicely detailed post on his site for anyone else who may be heading down the same path. That’s a win-win in our book.

The idea behind a jig is pretty simple: essentially it’s just a mount that holds the PCB, and a set of pins which contact the appropriate points on the board. The jig can then provide power, programming, status LEDs for testing, etc. Basically anything that you can’t or don’t want to include on the final board, but will help in testing or programming them.

To start, [Sjaak] begins with a blank PCB in Eagle and imports his target board. With the two lined up, he can then mark where he wants the pins to go on the jig, and add labels to the silkscreen to make things a little easier during diagnostics. The target board is then removed, the file converted to Gerber, and it’s sent off for manufacturing. With a few more tweaks, the file is then exported to DXF and laser cut out of acrylic. When the PCBs come back, it’s just a matter of sandwiching it all together with some standoffs and adding the pins.

[Sjaak] mentions that he was inspired by an old post on how SparkFun was internally handling their test jigs, though we think with a dash of automation he could make things even easier for himself.

The Gerber Behind Gerber Files

When we create a printed circuit board, the chances are these days that we’ll export it through our CAD package’s CAM tool, and send the resulting files to an inexpensive PCB fabrication house. A marvel of the modern age, bringing together computerised manufacturing, the Internet, and globalised trade to do something that would have been impossible only a few years ago without significant expenditure.

Those files we send off to China or wherever our boards are produced are called Gerber files. It’s a word that has become part of the currency of our art, “I’ll send them the Gerbers” trips off the tongue without our considering the word’s origin.

This morning we’re indebted to [drudrudru] for sending us a link to an EDN article that lifts the lid on who Gerber files are named for. [H. Joseph Gerber] was a prolific inventor whose work laid the ground for the CNC machines that provide us as hackers and makers with so many of the tools we take for granted. Just think: without his work we might not have our CNC routers, 3D printers, vinyl cutters and much more, and as for PCBs, we’d still be fiddling about with crêpe paper tape and acetate.

An Austrian Holocaust survivor who escaped to the USA in 1940, [Gerber] began his business with an elastic variable scale for performing numerical conversions that he patented while still an engineering student. The story goes that he used the elastic cord from his pyjamas to create the prototype. This was followed by an ever-more-sophisticated range of drafting, plotting, and digitizing tools, which led naturally into the then-emerging CNC field. It is probably safe to say that in the succeeding decades there has not been an area of manufacturing that has not been touched by his work.

So take a look at the article, read [Gerber]’s company history page, his Wikipedia page, raise a toast to the memory of a great engineer, and never, ever, spell “Gerber file” with a lower-case G.

Solder Stencils With A 3D Printer

If you are soldering with paste, a stencil makes life a lot easier. Sure, you can apply paste by hand with a syringe, but a modern PCB might have hundreds or even thousands of pads. Like a lot of us, [Robert Kirberich] doesn’t like paying to have stencils made and he wondered if he could use his 3D printer to make stencils. He found the answer was yes.

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Circuit Plotting With An HP Plotter

Over the last few years we’ve seen a few commercial products that aim to put an entire PCB fab line on a desktop. As audacious as that sounds, there were a few booths showing off just that at CES last week, with one getting a $50k check from some blog. [Connor] and [Feiran] decided to do the hacker version of a PCB printer: an old HP plotter converted to modern hardware with a web interface with a conductive ink pen.

The plotter in question is a 1983 HP HIPLOT DMP-29 that was, like all old HP gear, a masterpiece of science and engineering. These electronics were discarded (preserved may be a better word) and replaced with modern hardware. The old servo motors ran at about 1.5A each, and a standard H-Bridge chip and beefy lab power supply these motors were the only part of the original plotter that were reused. For accurate positioning, a few 10-turn pots were duct taped to the motor shafts and fed into the ATMega1284p used for controlling the whole thing.

One of the more interesting aspects of the build is the web interface. This is a small JavaScript app that is capable of drawing lines on the X and Y axes and sends the resulting coordinates from a server to the printer. It’s very cool, but not as cool as the [Connor] and [Feiran]’s end goal: using existing Gerber files to draw some traces. They’re successfully parsing Gerber files, throwing out all the superfluous commands (drills, etc), and plotting them in conductive ink.

The final iteration of hardware wasn’t exactly what [Connor] and [Feiran] had in mind, but that’s mostly an issue with the terrible conductivity of the conductive ink. They’ve tried to fix this by running the pen over each line five times, but that introduces some backlash. This is the final project for an electrical engineering class, so we’re going to say that’s alright.

Video below.

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