You Can Build Anything Out Of What Is Holding Your 97 Eagle Talon Together

April 7, 2018 by Brian Benchoff 29 Comments

We all know it, we all love it, and the guy parked outside of the 7-11 covered his car in it. What is it? Polyester body filler, better known by the almost generic trademark, Bondo. There’s a lot more you can do with Bondo than fairing in that sweet body kit, bro, and [Eric Strebel] is here to show you how far you can push the mechanical properties of polyester body filler.

We didn’t always have polyester body filler. In the days before OSHA, auto body workers would use a torch, bricks of lead, and a grinder. You can check out a video of the era before OSHA here. Needless to say, vaporizing and grinding lead in your shop isn’t the greatest idea, and there had to be a better way. This led Robert ‘Bondo Bob’ Spink to invent a much less toxic auto body filler that we now know as Bondo.

For the beginning of the demonstration, [Eric] mixes up a cup of polyester body filler with a few special additions: he’s using printer ink to get his mixture to something other than that one shade of pink we all know. Although Bondo is a bit too thick to cast, he did manage to put a little bit of it in a square mold, a PVC pipe, and applied a little to foam and wood. It’s enough for a demonstration, but for the actual ins and outs of machining Bondo we’re going to have to wait until [Eric]’s next video. Until then, you can check out this introduction below, or look at his previous work on free-form sculpting of uncured Bondo.

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Using Moiré Patterns To Guide Ships

April 7, 2018 by Steven Dufresne 27 Comments

[Tom Scott] ran across an interesting visual effect created with Moiré patterns and used for guiding ships but we’re sure it can be adapted for hacks somewhere. Without the aid of any motors or LED animation, the image changes as the user views it from different angles. When viewed straight on, the user sees vertical lines, but from the left they see a right-pointing arrow and from the right, they see a left-pointing arrow. It’s used with shipping to guide ships. For example, one use would be to guide them to the center point of a bridge. When the pilots see straight, vertical lines then they know where to steer the ship.

US patent 4,629,325, Leading mark indicator, explains how it works and how to make one. Two screens are separated from each other. The one in front is vertical but the one behind is split in two and angled. It’s this angle which creates the slants of the arrows when viewed from the left or right. We had to convince ourselves that we understood it correctly and a quick test with two combs showed that we did. See below for the test in action as well as for [Tom’s] video of the real-world shipping one.

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[Ben Krasnow] Tests Novel Plasma

April 3, 2018 by Steven Dufresne 18 Comments

When [Ben Krasnow] sees an interesting phenomenon he pursues it with a true scientist’s mentality, though it doesn’t hurt that he also has the skills and the workshop. This time he’s produced a glowing plasma by impacting fused quartz and other materials with a high-speed water jet.

The jet of pure water emerges from a 0.004″, or 100 micron, diameter sapphire orifice with a flow rate of around 2 milliliters per second giving a speed of 240 meters per second. It collides at 90° with a dielectric material where the plasma is produced as a toroid surrounding the collision point.

There’s been very little research into the phenomena but a proposal from one research paper which [Ben] found is that the plasma is a result of charging due to the triboelectric effect. This is the same effect which charges a balloon when you rub it against your hair, except that here there are water molecules running across a clear dielectric such as fused quartz. This effect results in a positively charged anode downstream of the collision while the water near the point of highest shear becomes conductive and conducts negative charge to the point of smallest curvature, producing a cathode. The electric field at the small-radius cathode acts like a short point with a high voltage on it, ionizing the air and forming the plasma. If this form of ionization sounds familiar, that’s because we’ve talked it occurring between the sharp wire and rounded foil skirt of a flying lifter.

[Ben] found support for the triboelectric theory when he substituted oil for the water. This didn’t produce any plasma, which is be expected since unlike water, oil is a non-polar molecule. However, while the researchers tried just a few dielectric materials, [Ben] had success with every transparent dielectric which he tried, including fused quartz, lithium niobate, glass, polycarbonate, and acrylic, some of which are very triboelectrically different from each other. So there’s room here for more theorizing. But check out his full video showing his equipment for producing the waterjet as well as his demonstrations and explanation.

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Autodesk Introduces Serpentine Router For Eagle

April 1, 2018 by Brian Benchoff 26 Comments

Since Autodesk acquired Eagle a few years ago, they’ve been throwing out all the stops. There is now a button in Eagle that flips your board from the front to the back — a feature that should have been there twenty years ago. There’s parametric part generation, push and shove routing, integration with Fusion 360, and a host of other features that makes Eagle one of the best PCB layout tools available.

Today, Autodesk is introducing something revolutionary. The latest version of Eagle (version 8.7.1) comes with a manual serpentine routing mode, giving anyone the same tools as the geniuses at Nokia twenty years ago.

An exclusive first look at Eagle’s new serpentine routing mode

The new serpentine routing mode is invoked via the SNAKE command. This brings up serpentine routing interface, where you can add nets and place your serpentine router. Click anywhere on the screen, and you can route around pads and traces to collect all the vias, hopefully netting a high score.

There are some tricks to this new mode. Control and Shift change the speed of serpentine routing, and the current zoom level changes the initial speed. As you route between vias, the serpentine router grows longer, making routing significantly more difficult, but if you’re up to the task you’ll eventually get a ‘You’re Winner’ screen.

This is just the innovation we’ve been looking for from Autodesk since their acquisition of Eagle. It’s not push and shove routing, and it’s not parametric part generation. Serpentine routing is the next big thing in EDA tools, and already this routing mode is on the upcoming feature list for KiCad. The KiCad version of serpentine routing will be pronounced, ‘sneak’.

Thermoelectric Generator Shines Where The Sun Doesn’t

March 31, 2018 by Dan Maloney 81 Comments

For off-grid renewable electricity, solar seems to make sense. Just throw some PV panels on the roof and you’re all set to stick it to the man, right? But the dirty little secret of the king of clean energy is that very few places on the planet get the sort of sunshine needed to make residential PV panels worth their installation cost in the short term, and the long-term value proposition isn’t very good either.

The drearier places on the planet might benefit from this high-power thermoelectric generator (TEG) developed and tested by [TegwynTwmffat] for use on a wood burning stove. The TEG modules [Tegwyn] used are commercially available and rated at 14.4 volts and 20 watts each. He wisely started his experiments with a single module; the video below shows the development of that prototype. The bulk of the work with TEGs is keeping the cold side of the module at a low enough temperature for decent performance, since the modules work better the higher the difference in temperature is across the module. A finned heatsink and a fan wouldn’t cut it for this application, so a water-cooled block was built to pump away the heat. A successful test led to scaling the generator up to 10 modules with a very impressive heatsink, which produced about 120 watts. Pretty good, but we wonder if some easy gains in performance would have come from using heat sink compound on the module surfaces.

Using thermal differences to generate electricity is nothing new, but a twist on the technique is getting attention lately as a potential clean energy source. And who knows? Maybe [TegwynTwmffat]’s or one of the other Hackaday Prize 2018 entries will break new ground and change the world. What’s your big idea?

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The Internet Of Three-Pointers

March 30, 2018 by James Hobson 1 Comment

When tossing something into the rubbish bin, do you ever concoct that momentary mental scenario where you’re on a basketball court charging the net — the game’s final seconds ticking down on the clock — making a desperate stretch and flicking some crumpled paper perfectly into the basket only for no one to notice your awesome skills? Well, now you can show off how good you are at throwing out garbage.

Well, not strictly garbage. The genesis of this IoT basketball hoop was in fact an inflatable ball on [Brandon Rice]’s desk that he felt would be more fun to fidget with if he could keep score. The hoop and backboard were laser cut on his Epilog cutter, and sport a Particle Photon to track and upload his running point tally to the Internet. An Arduino and IR sensor detect objects passing through the hoop — ultrasound proved to be too slow to keep up with [Rice]’s shots.

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Improving Controls For A Camera Slider Kit

March 28, 2018 by Steven Dufresne 10 Comments

We’ve all gone through it. You buy a kit or even an assembled consumer item, and it’s either not quite right or it’s only a part of what you need. Either you do a fix, or you add to it. In [Jeremy S. Cook’s] case, he’d been working for a while with a camera slider kit which came with just the slider. He’d added a motor and limit switches but turning it on/off and reversing direction were still done by manipulating alligator clips. Now he’s put together some far better, and more professional-looking controls.

He started by replacing the DC motor with a servo motor modified for continuous rotation. Then he built a circuit around an Arduino Nano for controlling the motor and put it all in a carefully made box which he bolted to the side of the slider. A switch built into the box turns it on and off, and a potentiometer sets the direction of the slider. While not necessarily new, we do like when we see different approaches being taken, and in this case, he’s using magnets to not only hold the case’s cover on for easy access, but also a couple of them to hold the 9-volt battery in place. Check out his construction process and the new slider in action in the video below.

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