This 3D Cable Printer Remixes the Delta

When last we ran into [Daren Schwenke] he was showing off his 6-color delta printer that changes colors seamless mid-print. Right now he’s working on a printer that uses tensioned cables to precisely move a toolhead while maintaining enough solidity that [Daren] can tap on the toolhead without it budging at all.

It’s much more simple a rig than a gantry-style 3D printer, with a chassis shaped like a geodesic polyhedron consisting of fiberglass trusses (those driveway markers) secured by 3D-printed lugs, all controlled by a Beaglebone Green and four steppers. A key element of the build is the central steel rod, a 4′ repurposed garden stake which serves to stabilize the whole toolhead. In terms of  build diameter it can scale from around 200 mm to 600 mm. [Daren] aims to using Machinekit’s tripod kinematics for control and he also learned a bunch from RepRap’s Flying SkyDelta project.

For more 3D-printing goodness, be sure to check out [Daren]’s aforementioned 6-color delta.

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The Triple Delta Robot Arm (and Leg)

delta By now you’d think we’ve seen just about every means of robotic actuator possible. We have Cartesian bots, Stewart platforms, SCARA bots, Delta bots, and even some exceedingly bizarre linkages from [Nicholas Seward]. We’re not done with odd robotic arms, it seems, and now we have Delta-ish robots that can move outside their minimum enclosed volume. They’re fresh from the workshop of [Aad van der Geest], and he’s calling them double and triple Deltas.

Previous Delta robots have used three universal joints to move the end effector up and down, and side to side. They’re extremely fast and are a great design for 3D printers and pick and place machines, but they do have a limitation: the tip of a single Delta can not move much further than the base of the robot.

By adding more parallelograms to a Delta, [Aad] greatly increases working volume of a his robots. One of the suggested uses for this style of bot is for palletizers, demonstrated in the video below by stacking Jenga blocks. There is another very interesting application: legs. There’s footage of a small, simple triple Delta scooting around the floor, supported by wire training wheels below. It makes a good cat toy, but we’d love to see a bipedal robot with this style of legs.

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Automated Phone Cracker/App Tester Steps it Up a Notch

delta bot cracks your passwords

Delta robots like this automated phone tester are awesome: high speed, accuracy, and mesmerizing to watch. [Justin Engler], a security researcher from ISEC Partners (also speaks at DEFCON on occasion) needed a robot to help with repetitive testing. He contacted the folks over at Marginally Clever to see if they could help him out, and they came up with this slick delta robot.

Normally they build these robots out of plywood, but [Justin] requested a bit more of a modern look, and although it looks blue, it’s actually clear acrylic: they haven’t removed the protective film yet.  The robot is quite functional, but [Justin] plans on upgrading it in the future to increase the top speed. It currently has a built-in camera, using OpenCV to watch the log-in screen as it tries every combination as quickly as possible.

Stick around to see it in action!

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Build and Control Your Own Robot Army


[Sarah Petkus] has a simple dream. She wants to build and command her own delta robot army. It all began with an illustration she drew of a woman hovering over a field of flowers. The flowers in this case had incandescent light bulbs as blooms. [Sarah] decided to create her image in the real world as an interactive art installation. Her first attempts at moving light flowers were based on a pulley system, which was unreliable and not exactly the graceful movement she imagined. Eventually [Sarah] discovered inverted delta robots. She changed her flower design to a delta, and began building her own delta robots out of parts she had around the house.

A chance meeting with the folks at SYN Shop hackerspace in Las Vegas, NV kicked the project into high gear. [Sarah] switched from using R/C ball links as joints to a simple ball bearing joint. She created her entire design in CAD software and printed it on the hackerspace’s 3d printer. She now has six working prototypes. The robots are all controlled via I2C by an Arduino compatible Nymph board. Six robots doesn’t exactly constitute an army, so [Sarah] had to find a new way to fund her project. She’s currently setting up a project for Kickstarter. [Sarah] will be selling kits for her robots, with the proceeds going toward the realization of her dream of a field of robotic light bulb flowers – Assuming the deltas don’t become sentient and try to take over the world first. [Sarah] posts progress updates to her blog, and has a dedicated site (which we featured on Sunday as part of a Links post) for information about her upcoming Kickstarter campaign.

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Super-precise light painting from a delta robot


The points of those geometric shapes line up perfectly thanks to the delta robot arm controlling the light source. The source is a simple LED that can be switched on and off as it moves. A camera is set up in a dark room to keep the shutter open while the arm moves. We’re assuming that all of the light for the stationary objects in this image comes from the LED as well.

[Sick Sad] built the delta bot for just for this purpose. Check out the video below to see, and perhaps more importantly hear, the thing in motion. Seriously, the whine of the stepper motors is pretty awesome on this one.

The delta concept uses a central head on three arms angled down from above. If the LED is also pointed down it won’t light up the hardware and that’s why it doesn’t show up in the image. We’ve seen similar accuracy when using this style of machine for 3D printing. But if you don’t want to build a complicated machine you can try this out with a simple string plotter.

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3D printing with a delta robot that seems to simplify the concept

This 3d printing delta robot really seems to solve a lot of the hurdles faced by previous offerings. With other delta printers we’ve looked at the motor control of the three arms is usually a it complicated. On this build the motors can just be seen in this image at each corner under the build platform. Each motor has a belt that loops from the bottom to the top for the machine, driving an arm along two precision rods.

It’s also interesting to note that the printer head doesn’t have a motor mounted on it for feeding the filament. Instead, the motor is mounted remotely. You can see it above the soda can in this image. It feeds the filament through a hollow tube spanning the gap between the extruder and the motor. This acts as a Bowden cable. With less mass to move this may make it easier to control the location of the print head.

After the break you can catch a clip of the team showing off the speed and dexterity of the delta bot, followed by a printing demo.

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[Pythagoras], a Delta Robot for Drawing

[Pythagoras] is a delta robot built originally using RC servos. Humbly, [Aaron] “concedes” that the first version of his delta robot using hobby servos was easy to build. As anyone who has built any kind of robot knows though, there is definitely a lot of work involved in even the simplest robot. Coordinating three axes and programming it to draw a picture is a really great accomplishment.

The second version, however is currently in development and uses stepper motors instead of servos. These upgraded motors should make the robot faster, more controllable, and more accurate. This version is at least somewhat working as evidenced by the time-lapse video after the break.

Although the title page listed above is a little sparse on build details, if you dig deeper into the page, there are actually 15 articles about the ‘bot, so be sure to poke around. Continue reading “[Pythagoras], a Delta Robot for Drawing”