Ever try signing your name with a mouse or a trackball? Not so easy. You could buy a graphics tablet with a pen. [Rahul Ramakrishnan] has a different approach. He took two 10-turn pots, and attached some strings and a washer. A pencil goes through the washer, and a BeagleBone Black reads the pots to determine what it is drawing on the paper. A couple of retractable badge lanyards keep tension on the string.
This ingenious design would be easy enough to replicate with any microcontroller that can read the two pots. The only awkward part is the need to press a button down when you want the device to treat the pencil as down (see the video below). It would probably be easy to rig up some switch on the pencil to make operation a little smoother.
Continue reading “Back to the Drawing Board”
[Maurice] recently built a clock that draws the time (Google Doc) on a white board. We’ve seen plenty of clock hacks in the past, and even a very similar one. It’s always fun to see the different creative solutions people can come up with to solve the same problem.
This device runs on a PIC16F1454 microcontroller. The code for the project is available on GitHub. The micro is also connected to a 433MHz receiver. This allows a PC to keep track of the time, instead of having to include a real-time clock in the circuit. The USB connector is only used for power. All of the mounting pieces were designed in OpenSCAD and printed on a 3D printer. Two servos control the drawing arms. A third servo can raise and lower the marker to the whiteboard. This also has the added benefit of being able to place the marker tip inside of an eraser head. That way the same two servos can also erase the writing.
The communication protocol for this systems is interesting. The transmitter shows up on [Maurice’s] PC as a modem. All he needs to do to update the time is “echo 12:00 > /dev/whiteboard”. In this case, the command is run by a cron job every 5 minutes. This makes it easy to tweak the rate at which the time updates on the whiteboard. All communication is done one-way. The drawing circuit will verify the checksum each time it receives a message. If the check fails, the circuit simply waits for another message. The computer transmits the message multiple times, just in case there is a problem during transmission.
Some of our more
senior experienced readers may remember a toy called the Spirograph. In case you don’t, it’s a geometric shape drawing toy. The way it works is a plastic disc with gear teeth around the perimeter and various holes on its face is spun around a plastic ring with gear teeth on the inside. A pencil is inserted in one of the holes in the disc and, when spun around the inside of the ring, draws different complex shapes called hypotrochoids.
This was fun enough to keep a kid entertained for a few minutes. It took a while to make a complete shape and sometimes it was easy to mess up (especially if the hole chosen for the pencil was near the outside of the disc). [Darcy] thought it would be neat to combine the Spirograph’s drawing style with modern technology. The result is called the Art-O-Matic and it draws some pretty wild art, you guessed it, automatically.
Click past the break for more!
Continue reading “Art-O-Matic Is Spirograph’s Young Hip Offspring”
[David] has created a four cable drawing machine for the Telus Spark Science Centre in Canada. Hackaday has featured [David’s] unconventional drawing contraptions before, specifically his center pivot pen plotter. The drawing machine is a new take on a drawbot, and could be considered to be close cousins with [Dan’s] SkyCam. The premise is simple: A stepper motor with a reel of string is placed at each corner of a square. The strings for all four motors come together at a center weight. When all four strings are taut, the weight is lifted off the drawing surface. When a bit of slack is added into the strings, gravity pulls the weight down to touch the sand.
It’s at this point that a simple premise becomes a complex implementation. Moving the weight in one direction is a matter of reeling out string on one motor, and reeling in string on the other. But what about the two “un driven” strings? They have to be slack enough to allow movement in the driven direction, but not so slack that the weight can dig in and tumble on the sand, causing a tangle. To handle some of these questions, [David] called on [Kevin] to write some software. [Kevin] created a custom kinematics module for LinuxCNC to control the drawing machine. The drawing machine runs on Gerber Code, similar to a CNC. Simply feed the machine Cartesian coordinates, and [Kevin’s] module converts to steps.
Continue reading “Four Cable Drawing Machine Pulls Our Strings”
If you own an oscilloscope, sooner or later the urge to see something other than signals on the screen will strike. Some people ignore the urge and go about their normal business while others give in, spending hours carefully crafting images, games, and more. The process is time consuming and tricky as our own [Kevin Dady] discovered, but rewards come in the form of geek cred and are hard to pass up.
[Alex] wanted to draw on his oscilloscope, but decided that he would try something other than the microcontroller-based solutions we have seen in the past. He figured the easiest and most accessible way to draw on the scope was with sound, so he whipped up a small application he calls Rabiscoscopio to do most of the work for him.
He starts off by drawing an image using a single line, saving it as an SVG file. This image is converted into an audio file by Rabiscoscopio, which can then be fed directly into his oscilloscope from his PC. That’s all there is to it – it really doesn’t get much easier.
While you could claim that [Alex] is cheating his way through the oscilloscope drawing process, we think his application rocks – after all, hacking is about making your technology work for you rather than the other way around.
Give Rabiscoscopio a try and post the results here or in our Flickr stream – we’d love to see what you guys come up with.
In the meantime, check out the video below to see [Alex’s] attempt at replicating the Garoa Hackerspace logo on his scope.
Continue reading “Rabiscoscopio – Oscilloscope drawing made easy”
[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”
Back in the 80’s, there used to be a kid’s toy that would allow you to replicate an image by tracing a pre-drawn picture in one panel, while a mechanical arm laid down ink in another. We’d be hard-pressed to remember what the thing was called, but this Electrographic Enlarging Sketchifier would be a wonderful modern day stand-in.
flickr user [Imajilon] constructed this cool motorized pantograph out of tongue depressors, rivets, foam core board, and a handful of electronic components. Despite its bargain basement bill of materials, this thing is pretty darn cool. An optical sensor “views” an image and drives a simple FET circuit, replicating the picture automatically using an electrically driven pen mechanism.
Looking through her flickr stream, we thought the results were quite impressive. She does plan on making a second version of the Sketchifier with a smaller light sensitive area, which should allow her to resolve even smaller features of the source drawing.