Hackaday Links: February 9, 2014

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Here’s a quick tip to extend the usefulness of your multimeter. It’s a set of mini test hooks soldered to alligator clips with a short hunk of stranded wire in between. You can buy mini test hooks that go right on the metal probes of your meter, but the weight and bulk of the meter probes and cords sometimes get in the way. This rig allows more flexibility because of that wire.

Staying on the theme of test equipment tips, here’s a simple way to make a Y-connector for logic analyzers. [Thomas] uses a dual-row pin header, shorting each pair of pins so that both rows are connected. When this is plugged into a pin socket it leave two pins for connecting your test equipment and the rest of the project hardware.

After seeing our feature of a 3-wire Character LCD [Chad] wrote in to mention he built a 1-wire version using an ATmega328.

If you’re going to be in Anaheim this week you can stop by the ATX-West expo and see a 3D printer with a 1m x 1m x 0.5m printing area. [Thanks Martin]

Speaking of 3D printers, here’s a big delta robot (seven feet tall) outfitted for alternative material printing. It’s printing a CT scan of ribs and a heart in hot glue. This seems to be a popular material for more artistic uses. We just saw a hexapod which deposits hot glue as it roams.

The weaponized quadcopter post from Tuesday was a controversial one. The really bad part of it was the laser, which strapped to anything is extremely dangerous. But the other hack may have just been poorly executed. Hackaday alum [Jeremy Cook] wrote in to mention that fireworks and quadcopters can be used more responsibly. He strapped a sparkler to his quadro and used it to make light graffiti. You may remember that [Jeremy] wrote an introduction to light graffiti for us back in November.

Is a LEGO 3D printer by definition self-replicating?

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LEGO parts are plastic. 3D printers make parts out of plastic. So the transitive property tells us that a LEGO 3D printer should be able to recreate itself. This one’s not quite there yet, mostly because it doesn’t use plastic filament as a printing medium. Look close and you’ll probably recognize that extruder as the tip of a hot glue gun. If all else fails you can use the machine as a precision hot glue applicator.

The instructions to make your own version include the design reference and a few ideas for getting the most out of the glue dispenser. For the design phase [Matstermind] used LEGO Digital Designer. It’s basically CAD with the entire library of LEGO parts available as building blocks. from there he assembled the machine which is controlled by an NXT brick. He goes on to link to a few different printing mediums. There’s instructions for using crayons to make colored glue sticks, as well as a method of printing in sugar using the hot glue extruder.

We remember seeing one other LEGO 3D printer. That one didn’t use an extruder either. It placed blocks based on the design to be printed.

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Tearing apart a hot glue gun for a 3D printer

If you’re building a 3D printer, the most complicated part is the extruder. This part uses a series of gears to pull plastic filament off of a spool, heats it up, and squirts it out in a manner precise enough to build objects one layer at a time. [Chris] made his own extruder out of a hot glue gun and made it so simple we’re surprised we haven’t seen this build before.

The basic operations of a plastic extruder – pushing a rod of plastic through a heated nozzle – already exists in a hot glue gun available for $3 at WalMart. To build his printer, [Chris] tor apart the hot glue gun and mounted the nozzle on a piece of plywood. The hot glue sticks are fed into the nozzle with the help of a 3D printed gear and a stepper motor driver.

After the break, you can see [Chris]‘s hot glue gun RepRap printing a 10cm cube. It’s not fast, but the quality is exceptional, especially considering he made it out of a hot glue gun.

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Climbing robot glues it’s own feet to the wall

The problem of gripping all surfaces has always plagued the field of climbing robotics. But if you don’t care about damaging the wall, why not just let the robot glue its feet to the surface. That’s exactly how this robot does it, using a couple of climbing feet in conjunction with a hot melt glue gun wielding arm. It seems to be a predecessor of the hot glue 3D printing robot which we saw last week.

Check out the video to get a full overview of the climbing process, but here’s the gist of it. The legs and arm are able to pivot around the central axis of the robot, parallel to the climbing surface. Once one leg is glued in place the robot swivels around it so that the body is directly above that leg. From there it reaches up with the arm to deposit some glue on the wall, then moves it out of the way so the other foot can be pressed against the hot adhesive. When the newly attached foot has cooled sufficiently, the lower foot is reheated to free it from the wall. At this point the whole process repeats.

We’re still fond of vacuum-based climbers like this parachute-equipped robot. But the design of the hot-glue arm on this guy is something that might make it into one of our own projects someday.

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Hot glue appendages may be predecessor to the flow metal of the T-1000

The T-1000 was the shape-shifting robot from T2 (the second Terminator movie). It was so amazing because it could assume the form and texture of anything; humans, piercing weapons, inanimate objects. This robot doesn’t even compare, except for one small trait. When it needs a tool, it can build it as its own appendage. This really is nothing more than making tools with a 3D printer. However, the normal boxy infrastructure is missing.

The print head is mounted on a single robot arm, and the tool is printed using hot melt glue in order to stick to a plate which makes up the business end of robot arm. In this case the robot needed to transport some water. It sets down the plate, uses the hot melt extruder to print a cup on that plate, then picks it up again and uses it to move water from one bowl to the other. You can see it all in the video clip below the fold.

Sure, it’s just baby steps. But hot melt glue sticks are light weight, and don’t require much energy to melt. This makes for a perfect combination as a portable tool shop.

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Flux paste applicator gun

[Luciano] didn’t want to drop a lot of cash into a flux and solder paste applicator so he built his own for about $5. He re-purposed a hot glue gun which you can usually find at a dollar store. After removing the heating element he inserted the body of a syringe. The plunger has been modified to use a knitting needle inside of some plastic tubing. After taking the picture above he made an improvement by adding a milliliter scale to the plunger, allowing you to meter out the paste and also gauge how much remains.

Polycarbonate fish uses three servos to swim

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[Amnon] is learning the hard way that water and electronics don’t always like to play nicely together. He’s been working on creating a swimming fish that uses three servos to flex a sheet of fish-shaped polycarbonate. This photo doesn’t really do the project justice but you can get a better idea of what he’s accomplished by watching the videos after the break.

The three servos along with some distance sensors for obstacle avoidance are all controlled by a PIC 16F877A microcontroller. [Amnon] tried out three different waterproofing methods; coating the device in varnish, dipping it in hot glue, and dipping it in epoxy. The first two resulted in water damage to the electronics, but the third managed to work. It kept the water out, but also prevents reprogramming of the controller.

Although not successful, we would have loved to see the process of dipping the fish in a churning vat of molten glue. Once perfected, this may be the perfect platform for carrying our weapons of doom.

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