SandBot Happily And Tirelessly Rolls Patterns In Sand

The patience and precision involved with drawing geometric patterns in sand is right up a robot’s alley, and demonstrating this is [rob dobson]’s SandBot, a robot that draws patterns thanks to an arm with a magnetically coupled ball.

SandBot, SCARA version. The device sits underneath a sand bed, and a magnet (seen at the very top at the end of the folded “arm”) moves a ball bearing through sand.

SandBot is not a cartesian XY design. An XY frame would need to be at least as big as the sand table itself, but a SCARA arm can be much more compact. Sandbot also makes heavy use of 3D printing and laser-cut acrylic pieces, with no need of an external frame.

[rob]’s writeup is chock full of excellent detail and illustrations, and makes an excellent read. His previous SandBot design is also worth checking out, as it contains all kinds of practical details like what size of ball bearing is best for drawing in fine sand (between 15 and 20 mm diameter, it turns out. Too small and motion is jerky as the ball catches on sand grains, and too large and there is noticeable lag in movement.) Design files for the SCARA SandBot are on GitHub but [rob] has handy links to everything in his writeup for easy reference.

Sand and robots (or any moving parts) aren’t exactly a natural combination, but that hasn’t stopped anyone. We’ve seen Clearwalker stride along the beach, and the Sand Drawing Robot lowers an appendage to carve out messages in the sand while rolling along.

Another Drawbot Uses A Pi And Web Sockets

There’s something about art. Cavemen drew on walls. People keep programming drawing robots. One we’ve seen recently is [Andy’s] Drawbot that uses WiFi and WebSockets to draw on just about any flat surface. What’s more, the Johnson County Library has a great write-up about how they built one and if you want a go at it, you’ll find their instructions very helpful. The video below is pretty inspirational, too.

What makes this build especially interesting is that it uses a drive system with two fixed points attached with suction cups.  There are a variety of 3D printed parts — some just for the build and some are older parts repurposed.

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DrawBot Badge Represents the CNC World in Badge Design

Badges come in all shapes and sizes, but a badge that draws on a stack of Post-It notes is definitely a new one. The design uses three of the smallest, cheapest hobby servos reasonably available and has a drawing quality that creator [Bart Dring] describes as “adorably wiggly”. It all started when he decided that the CNC and mechanical design world needed to be better represented in the grassroots demo scene that is the badge world, and a small drawing machine that could be cheaply made from readily available components seemed just the ticket.

Two arms control the position of a pen, and a third motor lifts the assembly in order to raise or lower the pen to the drawing surface. Gravity does most of the work for pen pressure, so the badge needs to be hanging on a lanyard or on a tabletop in order to work. An ESP32 using [Bart]’s own port of Grbl does the work of motion control, and a small stack of Post-It notes serves as a writing surface. Without the 3D printed parts, [Bart] says the bill of materials clocks in somewhere under $12.

We’ve seen similar designs doing things like writing out the time with a UV LED, but a compact DrawBot on a badge is definitely a new twist and the fact that it creates a physical drawing that can be peeled off the stack also sets it apart from others in the badgelife scene.

Make a Plotter Out of Rulers

Instructables user [lingib] made a clever and inexpensive pen arm plotter that uses plastic rulers for arms. An inspiring sight for anyone without a bunch of robot parts lying around,

The electronics are straightforward, with an Arduino UNO and a pair of Easy Drivers to control NEMA17 stepper motors connected to robot wheels, which serve as hubs for the rulers. At the end of the arms, an SG90 micro servo raises and lowers the pen as commanded, shoving the whole pen assembly off the paper with its horn—an elegant solution to an age-old drawbot problem. He even wrote wrote a custom Processing program that allows him to control the plotter from his desktop

[lingib]’s experimented with different kinds of drawing machines, including a drum plotter (video after the break), a V-plotter, as well as a rolling drawbot.

You’ll find tons of Hackaday posts about all types of drawing machines, including vintage plotters, plotters for making circuit boards, and even one built out of cardboard.

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Sandy Poems Drawn by a Robot Named Skryf

If you were lucky at the 2015 World Maker Faire you may have stumbled upon strange writings of poetry on the ground — written in sand.  While at first confusing, if you followed the poetry along you also caught a glimpse of Skryf, a draw bot by [Gijs van Bon].

skryf-drawbot-thumbThe creator was asked to perform poems for a festival about transition and letting go. Naturally, building a robot to write poetry in sand was the downright obvious answer to the question.

I was asked to perform 40 poems during a 10 day festival, and the poems were about transition and letting go. And then I thought the obvious thing to do as an artist is to make a machine that writes those poems with sand. I started writing them, and when the third poem was written, the first one was completely gone, and it was such a beautiful thing.

The robot uses a laptop for input, which is connected to the bicycle carriage. One servo controls the left-to-right movement, and another releases the sand. Forward and back is controlled by the main drive train, which must have been fun to account for (they aren’t servos!)

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A Robot’s Favourite Pen

A test of various pens using a robot

Some people are very picky about their pens. Entire forums exist to discuss the topic of pen superiority. However, it comes down to a personal choice. Some people like gel while others prefer ballpoint.

[Jens] built a drawing robot that produces drawings like the one seen here. It uses several linkages connected to two stepper motors, which give fine control over the pen. With the robot working [Jens] set out to find the best pen for robotic drawing.

Seven pens were tested on the machine, each drawing the same pattern. [Jens] found that gel and rollerball pens work the best on the robot, and started examining the performance of each.

The pens all performed differently, but two winners were chosen to use in the machine. The Pentel Energel Deluxe RTX and the Pilot G-2 07 beat out the competition since they maintained good lines at high speeds.

If you’re looking to build a drawing robot, [Jens]’ research should help you pick the best pen for your application. For inspiration, a video of the robot in action is waiting after the break.

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Building a SkyCam-like camera mount

With the Olympics on there are a lot of really great camera shots shown during the events. One of the best is the overhead view, which is provided by a camera suspended between cables. It’s not new for the Olympics, SkyCam has been around for over twenty years. What is new is [Dan Royer’s] attempts to build his own aerial camera setup.

He’s not starting from zero with this project. [Dan] has done some really great work with the Drawbot. It’s a two-motor, two-axis plotter which uses CNC to draw on a white board. For this project he combined two Drawbots in order to add a third axis. The image above shows the camera mount suspended between the four strings. He’s been working hard on getting the software ready for this kind of addressing. Along the way he broke the strings a few times because he was too far from the kill switch to stop it in time. But what he’s got is a nice start and we hope to see a more illustrative follow-up soon.

One of the things that SkyCam has going for it is a stabilization system. We wonder if a spinning gyroscope would work as well as it did for that balancing bike.