Mindstorms Morse Key Writes to Drawbot

[Jason Allemann] built a Mindstorms Telegraph Machine that packs so many cool details that HaD is about to have a fit.

First off, It’s a drawbot able to write letters, a difficult feat given a lack of native stepper motors and the limited gear options for Mindstorms.  Trying to draw letters with servos typically makes for some ugly letters. And how does the drawbot know what to write? You code them in with Morse code. The second video after the break shows [Jason]’s setup. He has a Mindstorms touch sensor with a LEGO Morse key attached to it. He simply taps on the key and the EV3 Intelligent Brick interprets his dots and dashes and translates them into letters.

Next off, [Jason]’s printer is built using one EV3 set. It’s one thing to build a cool Mindstorms robot with whatever you have in your parts bin, but the gold standard is to make a project that can be built with only one EV3 set. That way, anyone with the set can build the project. Precious few really cool projects can be built with just one set–[David Gilday]’s MindCub3r Rubik’s cube solver comes to mind. Dude, this is another one.

Last off, [Jason] breaks down how to build it, providing full LDraw building steps and EV3 code on his site. Even better, he shows how to supersize the project by adding a second EV3 brick, which can connect to the drawbot’s EV3 brick via bluetooth and serve as a standalone CW key. He shows off this part in the second video.

Icing on the cake, [Jason] even built a Morse reference book, done appropriately in 100% LEGO.

Hackaday loves innovative LEGO projects, like this game-playing robot and this LEGO exoskeleton.

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Drawbot software aims to do it better than the rest


There are plenty of drawbot projects out there, many of which come with their own special software in tow. While some of these packages are easier to use than others, [Dan Royer] is pretty sure he can do it better.

Looking for a fun and engaging way to teach STEM subjects in schools across the country, [Dan] developed a relatively simple drawbot which can be constructed by a wide range of age groups. While he is trying to get schools to purchase his robot kits, we’re guessing that our readers would be more inclined to build their own.

So what does [Dan] have to offer that might interest you? Well, he says he has developed some drawbot software that’s pretty darn easy to use. Rather than multiple applications generating machine-specific code, his software will transform your picture into a line drawing in one easy step. The app uses a traveling-salesman algorithm to generate drawings with nary a crossed line in sight before outputting the resultant machine instructions in easy-to-use GCode.

We don’t have a drawbot of our own handy to test his software out, so if you do happen to give it a shot, let us know how it worked for you in the comments.

Drawbot produces portraits… very slowly

This robot artist, the Drawbot, produces images using an Arduino and Processing. A piece of paper is attached to a wall as a stylus connected to a couple of stepper motors scribbles out patterns that gradually become the image seen above. Each drawing is different and can take several weeks of constant operation to finish. That must have made debugging a real problem for [Harvey] during development. We wonder if this would work with homemade pencils?

Making Spirographs with LEGO and Math

Master LEGO builder [Yoshihito Isogawa] has been on a roll lately, cranking out a number of robots that make drawings reminiscent of the classic Spirograph toy. For instance, he built an elegant drawbot out of LEGO elements, seen above. At first glance the monicker “spirograph” seems wrong, because where are the gears? However, [Yoshihito] has them stashed underneath the sheet of paper, with magnets controlling the pens.

His drawbot consists of a platform (cleverly, an inverted LEGO plate) upon which a sheet of paper is laid. One or two pen holders, each with a pair of magnets underneath, rest on the sheet of paper. Beneath the plate, two pairs of spinning magnets rotate around a double layer of 11×11 curved racks, which then play the role of the classic spirograph rings. An EV3-controlled motor powers the whole thing.

He also makes use of an obscure part–the 14-tooth bevel gear, last manufactured by LEGO in 2002 and even then it was mostly sold in part assortments intended for the education market. It’s so obscure LEGO doesn’t even provide the gear in their online building program LEGO Digital Designer, though (of course) the LDraw folks re-created it — it’s brick 4143 in the library, seen below.

Spirograph Gear Math

This gear becomes important in spirograph-style projects because tooth count is everything. There really aren’t that many spirograph designs that can be made with LEGO, because there are a limited number of gears and they mostly have the same tooth counts–the smaller ones sport 8, 12, or 16 teeth, medium-sized ones 20 or 24 teeth, and larger ones 36 or 40 — see a pattern? Such predictability may be great for a building set, but it doesn’t engender a lot of spirograph diversity.

When you compute the number of vertices in a spirograph shape, you take the least common multiple of the two gears (or sets of gears) and divide by the small gear. So a 60-tooth turntable turning a pair of 14-tooth gears has an LCM of 420, and you divide by 28 to get the number of vertices: 15. Remove one of those smaller gears and the vertices increase to 30. The challenge in creating new shapes with a LEGO spirograph lays in swapping in new gears, just like the original toy, and having more ways to come up with unusual gear ratios makes for more interesting drawings.

Another that makes the 14-tooth gear so alluring to [Yoshihito] is that it’s one of the few LEGO gears with a number of teeth not divisible by 4. Among other things this means the gear meshes with an identical gear at 90 degrees. Usually the gears have the same number for each quarter of the circumference and meshing becomes a matter of jogging one gear a scosh. This can be a problem because LEGO axles have a “plus” shaped profile, and you may not want everything on that axle tilted as well — having a 90-degree solution makes a lot of sense.

[Yoshihito] designs LEGO robots out of Isogawa Studio and has written several books on advanced LEGO techniques, published by No Starch. He specializes in small and elegant mechanisms — finding the perfect set of elements that work together effortlessly. You can see an example in the gear assembly to the right — a pair of the aforementioned 14-tooth bevel gears, turned into a normal gear with the help of that golden spacer, none other than a One Ring from LEGO’s Lord of the Rings product line. You can find videos of his projects on YouTube.

[Yoshihito] has released a number of variants of the spirographing drawbot. What’s next? Maybe a harmonograph?

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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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These Sands Of Time Literally Keep Time

Hour glasses have long been a way to indicate time with sand, but the one-hour resolution isn’t the best. [Erich] decided he would be do better and made a clock that actually wrote the time in the sand. We’ve seen this before with writing time on a dry erase board with an arm that first erases the previous time and then uses a dry erase marker to write the next time. [Erich]’s also uses an arm to write the time, using the tip of a sea shell, but he erases the time by vibrating the sandbox, something that took much experimentation to get right.

To do the actual vibrating he used a Seeed Studio vibration motor which has a permanent magnet coreless DC motor. Interestingly he first tried with a rectangular sandbox but that resulted in hills and valleys, so he switched to a round one instead. Different frequencies shifted the sand around in different ways, some moving it to the sides and even out of the sandbox, but trial and error uncovered the right frequency, duration, and granular medium. He experimented with different sands, including litter for small animals, and found that a powder sand with small, round grains works best.

Four white LEDs not only add to the nice ambience but make the writing more visible by creating shadows. The shells also cleverly serve double duty, both for appearance and for hiding things. Shells cause the arms to be practically invisible until they move (well worth viewing the video below), but the power switch and two hooks for lifting the clock out of the box are also covered by shells. And best of all, the tip that writes in the sand is a shell. There’s plenty more to admire about the cleverness and workmanship of this one.

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Founding A Company In Shenzhen For Eight Days

Nadya Peek is one of the hackers that should require no introduction for the regular Hackaday reader. She is a postdoc at the Center for Bits and Atoms at the MIT Media Lab. She’s responsible for Popfab, a CNC machine that fits in a suitcase and one of the first implementations of a Core XY stage we’ve seen. Nadya has joined the ranks of Rudolf Diesel, Nikola Tesla, Mikhail Kalashnikov, and George W.G. Ferris by having a very tiny piece of the Novena laptop bear her name. She’s built cardboard CNC machines, and taken the idea of simple, easy to build printers, routers, and drawbots worldwide.  She just defended her thesis, the gist of which is, ‘How to rapidly prototype rapid prototyping machines.’ She’s also one of this year’s Hackaday Prize judges, for which we have the utmost appreciation.

This year, the organizers of the Fab 12 conference on digital fabrication in Shenzhen turned to Nadya and her team to bring their amazing experience to conference attendees. A workshop was in order, but Nadya didn’t have time to organize the logistics. The conference organizers made a deal: the Center for Bits and Atoms would teach a workshop, but getting all the materials and electronics was the responsibility of the organizers.

Upon arriving at the Shenzhen Sheridan, Nadya found the organizers didn’t hold up their end of the bargain. The cardboard, motors, electronics, and glue were nowhere to be found. A “rider” doesn’t quite translate from English, it seems. This is Shenzhen, though, where you can buy all the cardboard, motors, electronics, and iPhone clones you could imagine. What was the solution to this problem? Founding a company in Shenzhen for eight days.

Half a tourist’s guide to Shenzhen and half a deconstruction of what goes into cardboard CNC, Nadya’s talk for the 2016 Hackaday SuperConference covers what happens when you have a week to build a company that will build machines that build machines.

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