Drilling PCBs with cameras and math

PCB

After making your first PCB, you’re immediately faced with your next challenge – drilling the holes. It’s a doable task with a small drill press, but a lot of makers already have a small CNC mill or router, but how to make that work the first time? [Alessio] has you covered with a technique that uses a CNC-mounted webcam and some linear algebra for perfect through-holes the first time and every time.

A few months ago we saw [Alessio]‘s work with transform matrices and PCB drills. The reasoning behind this technique is if a PCB isn’t exactly aligned to a CNC mill’s axes, or if the scaling for a toner transfer board is a bit off, automating the drilling process will only end in pain, with holes going through traces and a whole host of other nasty things. The application of linear algebra gets around this problem – taking a measurement off of two or three known locations, it’s easy to program a CNC machine to drill exactly where it’s supposed to.

[Alessio]‘s new project takes the same mathematical techniques and applies them to a very sleek application that uses a drill-mounted webcam. After taping his homebrew PCB down to the mill, [Alessio] simply marks off a few known points, imports the drill file, and lets a computer calculate where to drill the holes. The results are remarkable – with a soldermask and silkscreen equipment, these handmade boards can be just as good as professionally manufactured boards,

There are Windows and OS X binaries for [Alessio]‘s tool available on his page, with a video demo available below.

[Read more...]

Custom boards at home without etching

PCB

PC board houses are getting more accessable and less expensive all the time. Some of us are even getting very, very good at making our own circuit boards at home. There are times, though, when a project or prototype requires an extremely cheap custom board right now, something etching a custom board won’t allow. [KopfKopfKopfAffe] has a unique solution to this problem, able to create custom boards in under an hour without any nasty chemicals.

Instead of starting his build with copper-clad board, [KopfAffe] used every rapid prototyper’s friend, simple one-sided perf board. The shape of the board was milled out on a CNC machine, and both the top silk screen and bottom layer were marked off using the toner transfer method. After that, a custom circuit is just a matter of placing components and putting solder bridges between all the marked pads.

[KopfAffe] is only using this technique for single-sided boards, but we don’t see any reason why it couldn’t be employed for simple double-sided boards. This would still have the problem of making vias between the layers, but that’s still a problem with proper, home-etched double sided boards.

Script lets you import Eagle boards for use in FreeCAD

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[Christian Aurich] wanted to use his Eagle CAD circuit board design in a proper CAD program in order to design enclosures. There are already a few options along these lines, but they didn’t quite fit his needs so he developed a script to import Eagle boards into FreeCAD. The script is packaged as a python macro for FreeCAD.

In describing the shortcomings of what’s already out there [Christian] does mention the use of EagleUp to model boards in Google SketchUp. But he feels the way the data is produced by SketchUp makes these models work well with 3D printing, but says they’re not easy to use with mechanical design CAD software. He also feels that the photo-realistic renderings are useless when developing enclosures.

It’s worth mentioning that this approach is only possible because CadSoft’s migration to XML makes it dead simple to get at the data.

Finding the cheapest board house

PCB

The prices for custom made circuit boards has never been cheaper, but surprisingly we’ve never seen a comparison of prices between the major board houses. [Brad] took the time to dig in to the price of 10 boards manufactured by Seeed Studios, OHS Park, and BatchPCB. He made some pretty graphs and also answered the question of where you can get your circuits made cheaply.

[Brad] got the prices for boards up to 20 cm x 20 cm from Seeed Studio’s Fusion PCB service, OSH Park, and BatchPCB. These results were graphed with Octave and showed some rather surprising results.

For boards over 20 cm2, the cheapest option is Seeed Studios. In fact, the price difference between Seeed and the other board houses for the maximum sized board is impressive; a 400 cm2 board from Seeed costs $150, while the same board from OSH Park is close to $1000.

Of course most boards are much smaller, so the bottom line is  for boards less than 20 cm2, your best bet is to go with OHS Park. If you don’t care when your boards arrive, or you need more than 10 or so, Seeed is the way to go. As far as the quality of the boards go, OSH Park is up there at the top as well.

Laser cut PCBs

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Despite what you may have heard, those 40 Watt laser cutters actually can cut out traces on your next PCB.

Since he got his laser cutter a year and a half ago, [Rich] over at Nothing Labs has been trying to cut PCBs with it. Others have tried, usually by masking off a piece of copper followed by chemical etching. [Rich] wanted a one-step process, though, and his laser cutter really isn’t up to the task of cutting metal.

All that changed when he heard of another maker cutting  .001″ thick stainless steel on a similar laser cutter. Stainless steel isn’t solderable, but mild steel is. After finding a very thin piece of mild steel, [Rich] taped it down to a sheet of acrylic, designed a simple 555 blinky LED circuit, and tried out a new technique.

It turns out it is possible to cut very thin steel into circuit traces, and with enough flux to turn them into a functional circuit. As a bonus the resulting circuit looks really cool and a board can be made in mere minutes.

It’s not the thing for very fine work – the minimum trace width [Rich] can get is about 1/16″, but it is a very fast way to prototype a few circuits.

[Read more...]

Birth of an Arduino

Hey look, an Arduino without its clothes on. This one’s just started its journey to becoming the ubiquitous prototyping tool. The image is from [Bunnie's] recent tour of the fab house where Arduino boards are made.

As it says on every true Arduino board, they’re made in Italy. [Bunnie's] trip to the factory happened in Scarmagno, on the outskirts of Torino. The process starts with large sheets of FR4 copper clad material, usually about 1 by 1.5 meters in size. The first task is to send the sheets through a CNC drill. With all of the holes done it’s time for some etch resist; the image above is just after the resist has been applied. A robotic system takes over from here, running the panels through the chemicals which first etch away the copper, then remove the resist and plate the remaining traces. From there it’s off to another machine for solder mask and silk screen.

There are videos of each step available. But our favorite piece is the image at the end that shows a pallet with stacks of completed PCB panels which are headed off to be populated with components.

[via Reddit]

Glass PCB LED clock

This clock looks fantastic because of the glass PCB used for the build. This banner image allows you to see all the traces and components, but when it is lifted off of the desk surface the LEDs which make up the 7-segment digits appear to be floating.

The concept isn’t new, but it’s a much larger format than we’ve seen before. When we first looked at [CNLohr's] glass PCB fabrication he was using microscope slides. This uses a much larger pane of glass but it seems the fabrication still uses copper foil glued to the glass, then toner transfer etched like normal.

Here he’s testing out some 74LV164 chips as constant current drivers. One of the commenters on the Reddit thread is skeptical about using the chip in this way and so are we. But as the video after the break shows, it seems to work (at least for now). [CNLohr] also mentions that the AVR soldered on the display is burnt out which doesn’t help his case. Still, we love the look and can’t wait to see where he goes from here!

[Read more...]

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