The Evolution Of A DIY Circuit Board Plotter

August 31, 2016 by Gerrit Coetzee 23 Comments

In this three part video series we watch [Dirk Herrendoerfer] go from scraps to a nice 3D printed assembly as he iterates through the design of a pen plotter for making circuit boards.

[dana] mentioned [Dirk]’s work in the comments of this post which describes a different process. Many permanent markers stick to copper well enough to last through the chemical etching process. While hand drawing definitely produces some cool, organic-looking boards, for sharp lines and SMDs it gets a bit harder; to the point where it becomes advisable to just let a robot do it.

Of course, [Dirk] was aware of this fact of life. He just didn’t have a robot on hand. He did have some electronic detritus, fishing line, an Arduino, scrap wood, brass tubes, and determination. The first version‘s frame consisted of wooden blocks set on their ends with holes drilled to accept brass rods. The carriage was protoboard and hot glue. Slightly larger brass tubing served as bushings and guide. As primitive as it was the plotter performed admirably, albeit slowly.

The second version was a mechanical improvement over the first, but largely the same. The software got a nice improvement. It worked better and had some speed to it.

The latest version has some fancy software upgrades; such as acceleration. The frame has gone from random bits of shop trash to a nicely refined 3D printed assembly. Even the steppers have been changed to the popular 28BYJ-48 series. All the files, software and hardware, are available on GitHub. The three videos are viewable after the break. It’s a great example of what a good hacker can put together for practically no money.

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Impressive Junkyard CNC Made From Fancy Garbage

August 30, 2016 by Gerrit Coetzee 29 Comments

We’ll just come out and say it, [reboots] has friends with nice garbage. Sure, some of us have friends who are desperately trying to, “gift,” us a CRT monitor, hope dropping like a rock into their stomach when they realize they can’t escape the recycling fee. [reboots] has friends who buy other people’s poorly thought out CNC projects and then gift him with the parts.

After dismantling the contraption he found himself with nice US and Japanese made linear motion components. However, he needed a CNC controller to drive it all. So he helped another friend clean out their garage and came away with a FlashCut CNC controller.

Now that he had a controller and the motion components whirring nicely, he really needed a frame to put it all in. We like to imagine that he was at a friend’s barbeque having a beer. In one corner of the yard was an entire Boeing 747. A mouldering scanning electron microscope with a tattered and faded blue tarp barely covering its delicate instrumentation sat in another corner. Countless tech treasures were scattered about in various states. It was then that he spotted a rusting gamma ray spectrometer in the corner that just happened to have the perfect, rigid, gantry frame for his CNC machine.

Of course, his friend obliged and gladly gave up the spectrometer. Now it was time to put all together. The gantry was set on a scavenged institutional door. The linear motion frames were bolted in place. Quite a few components had to be made, naturally, of scrap materials.

Most people will start by using a handheld router for the spindle. The benefits are obvious: they’re inexpensive, easy to procure, and generally come with mounts. But, there are some definite downsides, one of the most glaring of which is the lack of true speed control.

Even routers that allow you to adjust the speed (a fairly common feature on new models) generally don’t actually regulate that speed. So, you end up with a handful of speed settings which aren’t even predictable under load. Furthermore, they usually rely on high RPMs to do their work. For those reasons, handheld woodworking routers aren’t the best choice for a mill that you intend to cut metal with.

[reboots] noticed this problem while building this machine and came up with an inexpensive way to build a speed-controlled spindle. His design uses a brushless DC motor, controlled through a hobby ESC (electronic speed control), which uses a belt to drive the spindle. The spindle itself is mounted using skateboard bearings, and ends in an E11 collet (suitable for light machining in aluminum).

With the ESC providing control of the brushless motor, he’s able to directly control the spindle speed via software. This means that spindle speeds can be changed with G-code, allowing for optimized feeds and speeds for different operations. The belt-drive increases torque while separating the motor from the spindle, which should keep things cool, and reduce rotating mass on the spindle itself. Now all [reboots] needs to do is add a DIY tool changer!

How Accurate Is Microstepping Really?

August 29, 2016 by Moritz Walter 160 Comments

Stepper motors divide a full rotation into hundreds of discrete steps, which makes them ideal to precisely control movements, be it in cars, robots, 3D printers or CNC machines. Most stepper motors you’ll encounter in DIY projects, 3D printers, and small CNC machines are bi-polar, 2-phase hybrid stepper motors, either with 200 or — in the high-res variant — with 400 steps per revolution. This results in a step angle of 1.8 °, respectively 0.9 °.

Can you increase the resolution of this stepper motor?

In a way, steps are the pixels of motion, and oftentimes, the given, physical resolution isn’t enough. Hard-switching a stepper motor’s coils in full-step mode (wave-drive) causes the motor to jump from one step position to the next, resulting in overshoot, torque ripple, and vibrations. Also, we want to increase the resolution of a stepper motor for more accurate positioning. Modern stepper motor drivers feature microstepping, a driving technique that squeezes arbitrary numbers of microsteps into every single full-step of a stepper motor, which noticeably reduces vibrations and (supposedly) increases the stepper motor’s resolution and accuracy.

On the one hand, microsteps are really steps that a stepper motor can physically execute, even under load. On the other hand, they usually don’t add to the stepper motor’s positioning accuracy. Microstepping is bound to cause confusion. This article is dedicated to clearing that up a bit and — since it’s a very driver dependent matter — I’ll also compare the microstepping capabilities of the commonly used A4988, DRV8825 and TB6560AHQ motor drivers.

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Much More Than A Desktop Mill: The DIY VMC Build

August 27, 2016 by Cameron Coward 21 Comments

A VMC (vertical machining center) is essentially a CNC vertical milling machine on steroids. Many CNC mills are just manual milling machines that have been converted to CNC control. They work nicely, but have a number of drawbacks when it comes to real world CNC milling: manual tool changes, lack of chip collection, lack of coolant containment, and backlash issues (which a manual machinist normally compensates for).

These problems are solved with a VMC, which will usually have an automatic tool changer, and an enclosure to contain coolant and wash chips down into a collection pan. They are, however, very expensive, very big, and very heavy. Building one from scratch is a massive undertaking, but one which [Chris DePrisco] was brave enough to take on.

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Hands-On The Shaper Origin: A Tool That Changes How We Build

August 25, 2016 by Gerrit Coetzee 199 Comments

I bet the hand saw really changed some things. One day you’re hacking away at a log with an ax. It’s sweaty, awful work, and the results are never what you’d expect. The next day the clever new apprentice down at the blacksmith’s shop is demoing his beta of his new Saw invention and looking for testers, investors, and a girlfriend. From that day onward the work is never the same again. It’s not an incremental change, it’s a change. Pure and simple.

This is one of those moments. The world of tools is seeing a new change, and I think this is the first of many tools that will change the way we build.

Like most things that are a big change, the components to build them have been around for a while. In fact, most of the time, the actual object in question has existed in some form or another for years. Like a crack in a dam, eventually someone comes up with the variation on the idea that is just right. That actually does what everything else has been promising to do. It’s not new, but it’s the difference between crude and gasoline.

My poetic rasping aside, the Shaper Origin is the future of making things. It’s tempting to boil it down and say that it’s a CNC machine, or a router. It’s just, more than that. It makes us more. Suddenly complex cuts on any flat surface are easy. Really easy. There’s no endless hours with the bandsaw and sander. There’s no need for a 25,000 dollar gantry router to take up half a garage. No need for layout tools. No need to stress about alignment. There’s not even a real need to jump between the tool and a computer. It can be both the design tool and the production tool. It’s like a magic pencil that summons whatever it draws. But even I had to see it to believe it.

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Add Robotic Farming To Your Backyard With Farmbot Genesis

August 19, 2016 by Gerrit Coetzee 29 Comments

Growing your own food is a fun hobby and generally as rewarding as people say it is. However, it does have its quirks and it definitely equires quite the time input. That’s why it was so satisfying to watch Farmbot push a weed underground. Take that!

Farmbot is a project that has been going on for a few years now, it was a semifinalist in the Hackaday Prize 2014, and that development time shows in the project documented on their website. The robot can plant, water, analyze, and weed a garden filled with arbitrarily chosen plant life. It’s low power and low maintenance. On top of that, every single bit is documented on their website. It’s really well done and thorough. They are gearing up to sell kits, but if you want it now; just do it yourself.

The bot itself is exactly what you’d expect if you were to pick out the cheapest most accessible way to build a robot: aluminum extrusions, plate metal, and 3D printer parts make up the frame. The brain is a Raspberry Pi hooked to its regular companion, an Arduino. On top of all this is a fairly comprehensive software stack.

The user can lay out the garden graphically. They can get as macro or micro as they’d like about the routines the robot uses. The robot will happily come to life in intervals and manage a garden. They hope that by selling kits they’ll interest a whole slew of hackers who can contribute back to the problem of small scale robotic farming.

Star Track: A Lesson In Positional Astronomy With Lasers

August 10, 2016 by Gerrit Coetzee 32 Comments

[gocivici] threatened us with a tutorial on positional astronomy when we started reading his tutorial on a Arduino Powered Star Pointer and he delivered. We’d pick him to help us take the One Ring to Mordor; we’d never get lost and his threat-delivery-rate makes him less likely to pull a Boromir.

As we mentioned he starts off with a really succinct and well written tutorial on celestial coordinates that antiquity would have killed to have. If we were writing a bit of code to do our own positional astronomy system, this is the tab we’d have open. Incidentally, that’s exactly what he encourages those who have followed the tutorial to do.

The star pointer itself is a high powered green laser pointer (battery powered), 3D printed parts, and an amalgam of fourteen dollars of Chinese tech cruft. The project uses two Arduino clones to process serial commands and manage two 28byj-48 stepper motors. The 2nd Arduino clone was purely to supplement the digital pins of the first; we paused a bit at that, but then we realized that import arduinos have gotten so cheap they probably are more affordable than an I2C breakout board or stepper driver these days. The body was designed with a mixture of Tinkercad and something we’d not heard of, OpenJsCAD.

Once it’s all assembled and tested the only thing left to do is go outside with your contraption. After making sure that you’ve followed all the local regulations for not pointing lasers at airplanes, point the laser at the north star. After that you can plug in any star coordinate and the laser will swing towards it and track its location in the sky. Pretty cool.

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