Automating 3D Printers With Robots

3D printers were never meant to be used for production. They’re not manufacturing machines, they’re prototyping machines. That doesn’t mean 3D printers can’t be used in a manufacturing context, it’s just very hard – you’d need someone manning a fleet of machines, or some sort of ‘automated build platform’ that won’t be invented for exactly fourteen years.

In the absence of someone paid to watch printers print, [Mark], [Robert], and [James] at tend.ai have created a way to manage a fleet of printers with a robot arm. It’s a robotic arm that automatically monitors the LCD on a rack full of 3D printers, plucks the finished prints off the bed, drops the parts in a box, and starts another print.

Tend.ai is in the business of cloud robotics, and have designed a system that takes any robotic arm, any webcam, and provides the backend for this robotic arm to – wait for it – tend to other machines. As a demo, it works well. Parts are picked up off of the machines, dropped into boxes, and another print run started.

As a tech demo for a cloud robotics platform, you can’t do much better than this. As a way to automate a fleet of 3D printers, I can only wonder how this robot arm system would work with large, flat printed parts. A robotic gripper could always be replaced with a spatula, I guess.

You can check out the demo and the ‘how they did it’ video below.

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Taming Robot Arm Jump with Accelerometers

Last fall, I grabbed a robot arm from Robot Geeks when they were on sale at Thanksgiving. The arm uses servos to rotate the base and move the joints and gripper. These work well enough but I found one aspect of the arm frustrating. When you apply power, the software commands the servos to move to home position. The movement is sufficiently violent it can cause the entire arm to jump.

This jump occurs because there is no position feedback to the Arduino controller leaving it unable to know the positions of the arm’s servos and move them slowly to home. I pondered how to add this feedback using sensors, imposing the limitation that they couldn’t be large or require replacing existing parts. I decided to try adding accelerometers on each arm section.

Accelerometers, being affected by gravity when on a planet, provide an absolute reference because they always report the direction of down. With an accelerometer I can calculate the angle of an arm section with respect to the direction of gravitational acceleration.

Before discussing the accelerometers, take a look at the picture of the arm. An accelerometer would be added to each section of the arm between the controlling servos.

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Hackaday Prize Entry: A Low-Cost Robot Arm

Robot arms are cool, and to judge from the SCARA arms and old Heathkit robots tucked away in a cupboard of every computer science department in every university in the world, they’re still remarkably educational. You can learn a lot about control systems with a robot arm, or you could build a clone of the old Radio Shack Armatron; either way, you’re doing something very cool. Right now, there aren’t many educational robot arms available, and the ones you can get are tiny. For [Jonathan]’s Hackaday Prize project, he’s building a low-cost robot arm with a one meter reach.

There’s a reason you won’t find many large, low-cost robot arms: the square cube law. An ant can carry many times its own body weight, but if you scaled that ant up to the size of a human, its legs couldn’t support itself. Likewise, a small, handheld robot arm will work perfectly well with hobby servos, but scaling this up requires big heavy stepper motors.

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Project Giant Robot Arm

[Antoniopenamaria] is working on a giant robot arm. The beauty is, he’s posting a step-by-step guide (translated) of his entire journey from start to finish.

Why does he want to build a giant robot arm? Well, the idea originally came to him a few years ago when he was soldering something together and thought, “Man, I could really use another hand!”. So he got out a Meccano set, and built a mini robot arm. Nothing fancy, but it worked. From there, he decided to program it, and was able to teach it to move things from point A to point B… as he continued to expand on his little project, the vision grew, and now he’s working on project D.I.M.E.R. — a giant robot arm.

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Robot Clock Writes Time Over and Over and Over

We’ve seen quite a few clocks that write the time out with a pen or marker. If you think about it, this really isn’t a great solution; every whiteboard marker will dry out in a day or two, and even if you’re using a pen, that’s still eventually going to run out of ink.

[ekaggrat] wanted a drawing clock that didn’t have these problems, and after taking a look at a magnetic drawing board, was struck with inspiration. The result is a clock that will perpetually write the time. It’s a revision of one of his earlier builds and looks to be much more reliable and mechanically precise.

A clock that writes time needs some sort of surface that won’t degrade, but can be written to over and over again. Whiteboards and glass won’t work, and neither will anything with ink. The solution to this problem was found in a ‘magnetic writing board’ or a Magna Doodle. These magnetic writing boards have a series of cells encapsulating iron filings. Pass a magnet over one side of the board, and a dot of filings appear. Pass a magnet over the opposite side of the board, and the filings disappear.

[ekaggrat]’s time-writing robot consists of a small Magna Doodle display, a robotic arm controlled by two stepper motors, and two solenoids on the end of the arm. The kinematics come from a helpful chap on the RepRap forums, and with the ATmega644 and two stepper drivers, this clock can write the time by altering the current flowing through two solenoids.

A video is the best way to experience this project, and you can check that out below.

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Hackaday Prize Semifinalist: An Affordable Robotic Arm

Industrial robot arms are curious devices, found everywhere from the back of old engineering classrooms where they taught kinematics in the 90s, to the factory floor where they do the same thing over and over again while contemplating their existence. For his Hackaday Prize entry, [Dan] is building a big robot arm. It’s not big enough to ride on, but it is large enough to automate a few processes in a reasonably well-equipped lab.

This is not a tiny robotic arm powered by 9 gram hobby servos. For the bicep and tricep of [Dan]’s arm, he’s using linear actuators – they’re high precision and powerful. A few months ago, [Dan] tried to design a hypocycloid gear but couldn’t get a $3000 prototype to work. Although the hypocycloid is out, he did manage to build a strange differential pan/roll mechanism for the wrist of the arm. It really is a thing of beauty, and with the engineering [Dan] has put into it, it’s a very useful tool.

If you’d like to meet [Dan]’s robot arm in person, he’ll be at the 2015 NYC Maker Faire this weekend. Check out [Dan]’s Hackaday Prize video for his robot arm below.

The 2015 Hackaday Prize is sponsored by:

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Human Gestures Control this Robot Arm

[Ray Kampmeier] just finished writing some code to allow him to control his robotic arm using force-sensitive hand gestures! He calls it the Robo Marionette.

He’s using a MeArm 4 DOF robotic arm, a Sensel touch interface, an Arduino Uno, and a servo shield for the Arduino to control the MeArm. All the code you need is available on his GitHub, but unfortunately the Sensel touch interface isn’t actually available to the public yet.

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