Homemade EDM Machine Moves From Prototype To Production

Of all the methods of making big pieces of metal into smaller pieces of metal, perhaps none is more interesting than electrical discharge machining. EDM is also notoriously fussy, what with having to control an arc discharge while precisely positioning the tool relative to the workpiece. Still, some home gamers give it a whirl, and we love to share their successes, like this work-in-progress EDM machine. (Video, embedded below.)

We’ve linked [Andy]’s first videos below the break, and we’d expect there will be a few more before all is said and done. But really, for being fairly early in the project, [Andy] has made a lot of progress. EDM is basically using an electric arc to remove material from a workpiece, but as anyone who has unintentionally performed EDM on, say, a screwdriver by shorting it across the terminals in a live outlet box, the process needs to be controlled to be useful.

Part 1 shows the start of the build using an old tap burning machine, a 60-volt power supply, and a simple pulse generator. This was enough to experiment with the basics of both the mechanical control of electrode positioning, and the electrical aspects of getting a sustained, useful discharge. Part 2 continues with refinements that led very quickly to the first useful parts, machined quickly and cleanly from thin stock using a custom tool. We’ll admit to being impressed — many EDM builds either never get to the point of making simple holes, or stop when progressing beyond that initial success proves daunting. Of course, when [Andy] drops the fact that he made the buttons for the control panel on his homemade injection molding machine, one gets the feeling that anything is possible.

We’re looking forward to more on this build. We’ve seen a few EDM builds before, but none with this much potential.

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A $50 CNC

In theory, there’s isn’t much to building a CNC machine. Hook a bit to a motor and move the motor around with some lead screws and stepper motors. Easy. But, of course, the devil is in the details. [DAZ] made a nice-looking and inexpensive rig that probably isn’t the most precise CNC in the world, but it looks like it does a good enough job and he claims he spent about $50 on it. The video below shows some of the work it has done, and it doesn’t look bad.

This isn’t a rainy afternoon project. You’ll need to cut some wood and 3D print many parts. The drives use M8 threaded rod. Electronics is just an Arduino running standard software.

The steppers looked pretty light duty, and we wondered if it would have been worthwhile to trade them out for beefier ones instead of modifying the ones used for bipolar operation. Still, the results did look good for $50. The 775 spindle is another place you could probably spend a little more and get something better. Non-printed linear rails, and a better screw? The point is that you’ve got a basis to build from.

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Stepper Motor Analyzer Reveals All

In theory, you really don’t need much to work with electronics. A scope ought to do everything. However, for special purposes, it is handy to have meters, logic analyzers, and other special-purpose instruments. If you work on motion systems like 3D printers and CNC machines, you ought to have a way to look at stepper motors. You don’t? [Zapta] has a great Simple Stepper Motor Analyzer and [Teaching Tech] has a great video (see below) that shows some of the great things it can do.

What can it do? It analyzes the motor in place and can visualize what’s happening during stepping, microstepping, and other operating modes. Connecting the instrument is easy since you just use a four-pin pass-through connector.

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Hacking An Air Assist For The Ortur Laser

Getting great results from a laser cutter takes a bit of effort to make sure all of the settings are just right. But even then, if the air between the material and the laser source is full of smoke and debris it will interfere with the laser beam and throw off the results. The solution is to add air assist which continuously clears that area.

Earlier this year I bought an Ortur laser engraver/cutter and have been hacking on it to improve the stock capabilities. last month I talked about putting a board under the machine and making the laser move up and down easily. But I still didn’t have an air assist. Since then I found a great way to add it that will work for many laser cutter setups.

I didn’t design any of these modifications, but I did alter them to fit my particular circumstances. You can find my very simple modifications to other designs on Thingiverse. You’ll also find links to the original designs and you’ll need them for extra parts and instructions, too. It is great to be able to start with work from talented people and build on each other’s ideas.

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CNC Chainsaw

You can spend a lot of time trying to think of a clever title for a post about a CNC chainsaw. But you’ll finally realize, what else can you say but “CNC Chainsaw?” [Stuff Made Here] actually built such a beast, and you can watch it go in the video embedded below. A custom chainsaw on a Tormach robotic arm. So it is more like a robot using a chainsaw than a conventional CNC machine.

Instead of an XY motion, the machine uses what the video calls an “apple peeler” method and uses the Minkowski algorithm to adjust for the size of the chainsaw. The video is an odd juxtaposition of advanced topics like the Minkowski and basic things like G code.

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When The Right Tool Is Wrong

I’m a firm believer in using the right tool for the job. And one of the most fantastic things about open-source software tools is that nothing stops you from trying them all. For instance, I’ve been going back and forth between a couple, maybe three, CAD/CAM tools over the past few weeks. They each have their strengths and weaknesses, and so if I’m doing a simpler job, I use the simpler software, because it’s quicker and, well, simpler. But I’ve got to cut it out, at least for a while, and I’ll tell you why.

The first of the packages is FreeCAD, and it’s an extremely capable piece of CAD/CAM software. It can do everything, or so it seems. But it’s got a long shallow learning curve, and I’m only about halfway up. I’m at the stage where I should be hammering out simple “hello world” parts for practice. I say, I should be.

Fortunately/unfortunately, some Hackaday readers introduced me to KrabzCAM through the comments. It’s significantly less feature-full than FreeCAD, but it gets the job of turning your wife’s sketches of bunnies into Easter decorations done in a jiffy. For simple stuff like that, it’s a nice simple tool, and is the perfect fit for 2D CAM jobs. It’s got some other nice features, and it handles laser engraving nicely as well. And that’s the problem.

Doing the simple stuff with KrabzCAM means that when I do finally turn back to FreeCAD, I’m working on a more challenging project — using techniques that I’m not necessarily up to speed on. So I’ll put the time in, but find myself still stumbling over the introductory “hello world” stuff like navigation and project setup.

I know — #first-world-hacker-problems. “Poor Elliot has access to too many useful tools, with strengths that make them fit different jobs!” And honestly, I’m stoked to have so many good options — that wasn’t the case five years ago. But in this case, using the right tool for the job is wrong for me learning the other tool.

On reflection, this is related to the never-try-anything-new-because-your-current-tools-work-just-fine problem. And the solution to that one is to simply bite the bullet and stick it out with FreeCAD until I get proficient. But KrabzCAM works so well for those small 2D jobs…

A hacker’s life is hard.

Hacking The Ortur Laser With Spoil Board, Z-Height, And Air Assist

Last month in my hands-on review of the Ortur Laser I hinted that I had done a few things to make it work a little better. I made three significant changes in particular: I anchored the machine to a spoil board with markings, I added a moving Z axis to adjust focus by moving the entire laser head, and I added an air assist.

Turns out, you can find designs for all of these things all over the Internet and I did, in fact, use other people’s designs. The problem is the designs often conflict with one another or don’t exactly work for your setup. So what I’ll tell you about is the combination that worked for me and what I had to do to get it all working together. The air assist is going to take a post all by itself, but some of the attempts at air assist led to some of the other changes I made, so we’ll talk about it some in this post, as well.

One of the modifications — the spoil board mount — I simply downloaded and the link for that is below. However, I modified the moving Z axis and air assist parts and you can find my very simple modifications on Thingiverse. You’ll also find links to the original designs and you’ll need them for extra parts and instructions, too.

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