Optical Tach Addresses The Need For Spindle Speed Control

January 28, 2018 by Dan Maloney 8 Comments

With CNC machines, getting the best results depends on knowing how fast your tool is moving relative to the workpiece. But entry-level CNC routers don’t often include a spindle tachometer, forcing the operator to basically guess at the speed. This DIY optical spindle tach aims to fix that, and has a few nice construction tips to boot.

The CNC router in question is the popular Sienci, and the 3D-printed brackets for the photodiode and LED are somewhat specific for that machine. But [tmbarbour] has included STL files in his exhaustively detailed write-up, so modifying them to fit another machine should be easy. The sensor hangs down just far enough to watch a reflector on one of the flats of the collet nut; we’d worry about the reflector surviving tool changes, but it’s just a piece of shiny tape that’s easily replaced. The sensor feeds into a DIO pin on a Nano, and a small OLED display shows a digital readout along with an analog gauge. The display update speed is decent — not too laggy. Impressive build overall, and we like the idea of using a piece of PLA filament as a rivet to hold the diodes into the sensor arm.

Want to measure machine speed but don’t have a 3D printer? No worries — a 2D-printed color-shifting tach can work too.

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Make Your Own Current Clamp Probe

January 27, 2018 by Al Williams 12 Comments

If you want to measure AC or DC current with an oscilloscope, a current clamp is a great way to do it. The clamp surrounds the wire, so you don’t need to break the connection to take your measurements. These used to be expensive, although we’ve seen some under $100, if you shop. We don’t know if it was cost or principle that motivated [Electronoobs] to build his own current clamp, but he did.

This probe design is little more than a 3D printed case, an old power supply toroid, and a conventional alligator clamp to make the business end. The sensor uses a ferrite core and a hall effect sensor. The ferrite toroid is split in half, one half in each side of the clamp. An opamp circuit provides a gain of 100 to boost the hall effect sensor’s output.

In addition to building a homebrew probe, the video also shows a teardown of a Hantek current probe and explains the theory behind the different kinds of current probes, including some tricks like using a compensation winding to prevent core magnetization.

Does it work? You bet. After calibration, it did just fine. It’s not as pretty as a $100 unit, but beauty is in the eye of the beholder, and we are suckers for homebrew gear so we will say it is certainly more interesting. If you have a fair junk box (and a 3D printer), this probe could be made very inexpensively. The hall effect and a BNC connector are likely to be the most expensive parts. Even if you bought everything and used a non-printed case, we would be hard-pressed to think you’d spend more than $25.

If you want to see how the big boys do it, Keysight had a good break down last year. We’ve seen other homebrew builds for current probes and some of them are very accurate.

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Indexing Chuck Not Required

January 25, 2018 by Brian McEvoy 15 Comments

Becoming accomplished with a lathe is a powerful skillset, but it’s only half of the journey. Being clever comes later, and it’s the second part of the course. Patience is in there somewhere too, but let’s focus on being clever. [TimNummy] wants a knobbed bolt with critical parameters, so he makes his own. After the break, there is a sixty-second summary of the linked video.

Making stock hardware is a beginner’s tasks, so custom hardware requires ingenuity or expensive machinery. Adding finger notches to a bolthead is arbitrary with an indexing chuck, but one isn’t available. Instead, hex stock becomes a jig, and the flat sides are utilized to hold the workpiece at six intermittent angles. We can’t argue with the results which look like a part that would cost a pretty penny.

Using material found in the workshop is what being clever is all about. Hex brass stock comes with tight tolerances on the sides and angles so why not take advantage of that?

[TimNummy] can be seen on HaD for his Jeep dome light hack and an over-engineered mailbox flag. Did you miss [Quinn Dunki]’s piece on bootstrapping precision machine tools? Go check that out!

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Printed It: Rubber Band PCB Vise

January 24, 2018 by Tom Nardi 31 Comments

If you’ve ever worked on a small PCB, you know how much of a hassle it can be to hold on to the thing. It’s almost as if they weren’t designed to be held in the grubby mitts of a human. As designs have become miniaturized over time, PCBs are often so fragile and festooned with components that tossing them into the alligator clips of the classic soldering “third hand” can damage them. The proper tool for this job is a dedicated PCB vise, which is like a normal bench vise except it doesn’t crank down very hard and usually has plastic pads on the jaws to protect the board.

Only problem with a PCB vise is, like many cool tools and gadgets out there, not everybody owns one. Unless you’re doing regular PCB fabrication, you might not take the plunge and buy one either. So what’s a hacker on a budget to do when they’ve got fiddly little PCBs that need attention?

Luckily for us, we live in a world where you can press a button and have a magical robot on your desktop build things for you. Online model repositories like Thingiverse and YouMagine are full of designs for printable PCB vises, all you have to do is pick one. After looking through a number of them I eventually decided on a model designed by [Delph27] on Thingiverse, which I think has a couple of compelling features and more than deserves the few meters of filament it will take to add to your bench.

Of course the best part of all of this is that you can customize and improve the designs you download, which is what I’m about to do with this PCB vise!

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Ancient Insect Scales Analyzed With Help Of Nose Hair

January 21, 2018 by Roger Cheng 15 Comments

Scientists working to advance the frontier of knowledge frequently also need to invent their tools along the way. Sometimes these are interesting little hacks to get a job done. Recently some researchers found ancestors of moths and butterflies older than any previously known by analyzing tiny scales found alongside ancient pollen. They needed a tool to manipulate these scales: separating them from surrounding debris, transferring them to microscope slides. The special tool was a needle tipped with a single human nostril hair.

As ancient insects were the published paper‘s focus, their use of nose hair tipped needle was only given a brief mention in the “Materials and Methods” section. Interviews by press quoted researchers’ claim that nose hair has the right mechanical properties for the job, without further details. Not even a picture of the tool itself. What properties of insect scales made them a good match with the properties of nose hair? Was there a comprehensive evaluation of multiple types of hair for the task? Would we regret asking these questions?

Novel approaches to fine-tipped tools would be interesting to examine under other contexts, like the tweezers we use to build surface-mount electronics. As SMD parts continue to shrink in size, will we reach a point where hair-tipped tools are the best DIY alternative to an expensive pick-and-place machine? It would be another creative approach to deal with the challenges of hand-built SMD. From simple but effective mechanical helpers, to handy 3D printed tools, to building hybrid Manual + CNC pick-and-place more affordable than their fully automated counterparts.

[via Washington Post]

The (Unnecessary?) Art Of Connector Crimping

January 20, 2018 by Tom Nardi 54 Comments

The “Completion Backwards Principle” is a method of reasoning through a problem by visualizing the end result and then working your way backwards from that point. The blog post that [Alan Hawse] has recently written about the intricacies of crimping wires for plug connectors is a perfect example of this principle. The end result of his work is the realization that you probably shouldn’t bother crimping your own connectors, but watching him work backwards from that point is still fascinating. It’s also the name of a rock album from the 80’s by The Tubes, but this is not a useful piece of information in regards to electrical wiring.

Of course, sometimes people do silly things. Even though there are pre-crimped wires available online for a pittance, you might still want to do your own. With this in mind, [Alan] has put together an exceptionally detailed and well-research post that gives you all the information you could possibly want to know about crimping what is often erroneously referred to as the “JST connector”.

He starts by showing off some common examples of this connector, which if you’ve ever opened a piece of consumer electronics will be like looking through a High School yearbook. You might not know their names without reading them, but you definitely remember what they look like.

We’re then treated to an array of macro shots showing the scale of the pieces involved. If getting up close and personal with metal bits that are only a few millimeters long is your kind of thing, then you’re really going to love this part.

Finally, the post is wrapped up with a few words about the kind of crimping tools that are available on the market, and then a demonstration of his personal crimping method. While some tools would have you crimp both sets of “wings” at the same time, [Alan] tells us he finds taking them on individually leads to better results in his experience.

If this this little taste has left you hungry for a true feast of hyper-specialized knowledge, be sure to check out the Superconference talk by [Bradley Gawthrop].

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Getting To Know An 18th Century Hacker

January 19, 2018 by Tom Nardi 11 Comments

Here at Hackaday we tend to stay pretty close to the bleeding edge in tech, not by any conscious effort, but simply because that’s what most hackers are interested in. Sure we see the occasional vintage computer rebuild, or reverse engineering of some component that was put into service before most of us were born; but on the whole you’re way more likely to see projects involving the latest and greatest microcontroller to hit AliExpress than ones involving the once ubiquitous vacuum tube.

But occasionally it’s nice to take a step back from the latest and greatest, to really look at what makes the hacker spirit without the all modern trappings of blinking LEDs and Wi-Fi connectivity. We make and explore because it’s something we are passionate about, and while today most of us are doing that with a soldering iron or a compiler, that hasn’t always been the case. In the video below, historic interpreter and woodworker [Bill Maddox] talks about what draws him to 18th century technology. His tools may look foreign to us, but the passion he shows while talking about his creations will be familiar to anyone who’s ever set foot in a hackerspace.

Even with a vastly different set of interests than the modern hacker, [Bill] runs into some very familiar problems. When the highly specialized tools he needed to work like an 18th century craftsman weren’t available, he decided to make his own. But to make his own tools he needed to learn how to forge, and after he forged his hand tools he moved on to forging chisels for the lathe he decided to build.

Whether or not we ever take a knife to a piece of wood and try to carve out a spoon, it’s impossible to watch [Bill] speak about his creations and not see him as a kindred spirit. Like many of us, he’s honed skills in a niche that the everyday person takes for granted. Makes you wonder what people from 300 years in the future would think of us if they could peer back through the centuries.

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