Every hackerspace needs a laser cutter. Unfortunately, they can be very expensive. Deals like the one Hacklab.to got don’t happen very often. However, there are factories in China turning out laser engravers and selling them on eBay for relatively cheap. We found a local distributor that appears to buy them directly from China, make sure they work, and resell them.

We received our laser in good shape. It came with a 240V blower (now junked), a 240V pump (also junked) and a 120->240 stepup transformer (now unnecessary) to power both of them. It also came with MoshiDraw 6 and a USB copy protection dongle.

It didn’t take us long to decide that MoshiDraw wasn’t going to work for us – the software and manual are badly translated and it doesn’t support vector motion (essential for cutting). The interface between MoshiDraw and the controller may be some subset of HPGL, but not in any useful way. Feeding HPGL directly from a file to the laser resulted either in nothing happening or in unpredictable, inconsistent behaviour, even when the file was produced by MoshiDraw itself.

At this point we decided to follow the route Hacklab.to took, and replace the internal driver electronics with a board that can read step and direction signals from LinuxCNC

Once that decision was made, there were two options: build a controller, or buy one off the shelf. There are dozens of commercially available stepper driver boards. They can be expensive, and most of them have more features than we need. Also, just buying a drop-in solution is no fun, so we decided to build one.

The driver is basically just a double implementation of the reference design for the Allegro A3982 plus an optocoupler to activate the laser and a connector for the end stops.

I chose the A3982 because it has a translator built-in (translates step/direction signals into the right sequence for driving a stepper), and because it’s available in SOIC which meant I could use an SOIC to DIP adapter when breadboarding the circuit and when building it on perf-board. If I were to get a PCB made, I would probably use one of the Allegro chips that supports 1/4, 1/8 or even 1/32 steps (only available in TSSOP or smaller). Be sure to read the A3982/83/84 FAQ if you decide to use the chip.

The only hard part of configuring LinuxCNC is the end-stop/home sensor settings – it takes a bit of thought and experimentation to get the right combination of approach direction, inversion of signals, identification of the signals, and so on.

We chose to use the Spindle ON signal to activate the laser because it’s the one that makes the most sense, and it should allow for PWM output when we decide to work out computer control of laser power. We initially routed that signal to parallel port pin 1, but discovered that pin to be active low – meaning that it is held high until LinuxCNC starts and takes control of the parallel port, possibly resulting in the laser being activated unintentionally.

Here are the important parameters for our laser:
Motor steps/rev: 400
X Leadscrew Pitch: 0.626 rev/in (determined empirically)
Y Leadscrew Pitch: 0.626 rev/in

Home X and Home Y signals in LinuxCNC are connected to the optical end stops on the gantry. Both signals are set to invert, and the Home Latch Direction is set to “same”.

The end result is that we have a laser that can easily cut 5mm acryclic, 1/4″ hardboard, 1/4″ poplar, and etch nicely on many materials.

The idea is this: buy a Power Wheels car, mod it to make it MOAR AWSOME, and race it against teams from other hackerspaces. Very simple.

We got ourselves a used Extreme Dune Buggy, and let Jason go at it with the Sawzall.

There was much drilling, lathing, cutting, grinding, and welding.

The organising people announced the Early Bird Challenge a few weeks ago – post a video of your car driving 150 feet, powered by the motor you intend to race with. We didn’t quite get the points, but we did post a video:

Peter took some really nice pictures of his chess set and posted them on the facebook. His pieces are really nice – very clean and sleek. Each piece is made out of two pieces of acrylic fitted together at 90°. Here’s the thingiverse link.

A few years ago, I bought travel Settlers of Catan so that I could bring it with me on trips. Even the travel set is fairly big though, so I just used the cards and port pieces out of the box, and made my own tiles and cardboard pieces. The cardboard pieces are pretty awkward though, and I’ve never really been pleased with them. Today, I made up a little gcode file to cut out tiny roads, settlements, and cities.

If you want to build your own, check out the thingiverse project.

Dictionary of Communications Technology, 2nd edition

The polymer clay is on the left, and the crayon is on the right.

Here’s a cropped version of the last photo showing detail of the polymer clay. To apply it, I put a small amount of clay on my finger and rubbed it in. It fills really nicely and is easy to clean up. Not sure how well it will stay in though. If you can pull the clay out of the etch by pressing more clay on it.


Here’s the detail of the etch filled with crayon. It’s not terribly even, and is a bit harder to clean up afterwards. I tried using a room temperature crayon as well as a crayon I stuck into warm water. The warmth of the wax didn’t seem to make much difference, though I didn’t get the wax very hot. This method doesn’t really work for spots where the etching is wide.

Both methods make a huge difference in the legibility of the etching. It remains to be seen how durable they are. Other suggestions I’ve read include leaving the protective sheet on the acrylic while etching, painting, then removing the protective sheet. Unfortunately, this acrylic came with a paper protective sheet which bursts into flame if you try this. I’ll post updates on durability once they’ve been out in the field for a couple weeks.

http://en.wikipedia.org/wiki/Three-dimensional_chess

Unfortunately the contest closes tomorrow at noon, and I just started the project today. I don’t have any skill with using 3-D computer drafting programs, and I don’t think I will be able to learn Google sketchup proficiently in a matter of hours. So, I drew my designs out by hand and posted them here.

The reason I chose to create new chess pieces is because 3-D chess is a ‘new’ sort of game, like the next evolution of chess. I find it odd to think of Captain Kirk and Mr. Spock playing a game of 3-D chess, using pieces such as a rook, bishop, etc. Can you imagine Captian Kirk trying to explain what a Bishop or a Rook was? I’m thinking that the chess pieces of the future would be something completely new,  with a new and unique culture derived from centuries of living in space.

So, I have replaced the traditional chess pieces with pieces based on a space faring theme. I have tried to use simple geometric shapes, so that they can be easily reproduced on a 3-D program such as Google Sketchup, and easily rendered in a 3-D printer, just as traditional chess pieces were designed to be easily made on a lathe. I consider these designs as ‘open source’, and I encourage other people to use them, copy them, alter them, etc.

The primary set I had designed here is intended to represent humans. The ‘King’ piece is meant to represent the planet Earth, or perhaps an Earth colony such as the moon of Titan, or perhaps the Sol system. 3-D chess players could play each other by proxy, with each board in a different location representing a different star system. The Sol system that Earth is part of might be in Toronto, Alpha Centauri in Pittsburgh, Tau Ceti in Brooklyn, Rigel, etc. All could be played in different locations remotely.

The only thing which makes a 3-D chessboard part of a particular solar system is the name/ designation which the King piece has. When placed on the board, a king piece which represents Tau ceti might be called the Tau Ceti system, at least for the individual player.

3-D chess games that were won or lost could be marked out on a star map, etc. Humans can and will come to inhabit other solar systems, and of course other solar systems can be conquered. Those that become proficient in 3-D chess might end up making many ‘Solar’ (Orbital Defence System or ODS) pieces to place on their boards, or even as trophies of their battles in a display case.

When I become more proficient with Google sketchup, Blender and so forth, I will add more chess sets to represent different species of aliens.  Mechanicals, Mutants, Cyborgs, Insectiod, Cephalods, Felinoids, etc. All of these have the potential to be interesting chess pieces. This makes it a lot more fun since you can have humans versus humans, humans versus robots, robots versus insects, and so forth. This would especially appeal to anyone that likes to collect minatures, since you could have dozens of different sets.

With that, I present my designs for the human set.

HUMANS:

Soldier: (Pawn)

Absolutely essential for winning any battle is the ability to hold and defend land. This is where the Soldiers come in. Also known as ‘grunts’ or redshirts, a soldier is also part technician and part colonist.  Despite their small size, they are an equal match for any piece on the board.  Their moves are limited however.



“They do the flyin’, we do the dyin’.”

Build: The pawn is a sphere which rests on a disk ‘neck’.  This sits on an ‘L’ shaped piece to represent the shoulders. A triangle which is folded at a 90 degree angle to represent the torso and legs. Two rectangles at the base have been chosen to represent the feet, though they aren’t necessary. The whole piece rests on a coin sized disk. The pawn is 1 and a half inches high.

"I hope I don't buy it on my next shipment."

Transport: (Knight)

This ship was designed to transport troops and materials from planet to planet, or from orbit to the planet’s surface. They are too slow and heavy to pass through a jump gate, but they are the only game piece which can jump over other pieces. They travel in an ‘L’ pattern.

Build: The basic shape of this rocket is a cylinder with a pointy top, and four stabilization fins at the base. The piece rests on a disk about the size of a quarter. This piece is 2 inches high. The plans for building this piece already exist on ‘Thingaverse’.

"This is Lima charlie one, over!"
Transmitter: (Bishop)

In any battle, the uninterrupted transmission of encyrpted data is vital for logistics. The vast distances of space were once considered a problem, until the invention of the subspace Transmitter. Through the distortions of tachyon fields, these transmitters are able to send messages at faster than light speeds. However, they can only travel in a diagonal direction, and their transmissions can be intercepted.

Build: This is based on the ‘Traffic cone’ in the Thingaverse, with the addition of a bowl shaped ‘radar dish’ on top. A pyramid shape was chosen to serve as the antenna for the dish.

"Prepare for entry into sub-space."

Gate: (Rook).

The vast interstellar distances prevented many ships from making the journey, until the invention of the Hyperspace jump gate. By folding time-space in on itself like a tightly coiled spring, they were able to shorten travel distances immeasurably. Despite their massive size however, these gates are unable to transport any ships larger than two person fighter craft. They also close again after an indefinite time, sometimes leaving those who travel through them hopelessly stranded.  They also have to travel in perfectly strait horizontal lines.

Build: As a gate, this piece should look like a ring, an ellipse, or a torus such as the one pictured here. When building a ring, it should be two inches high and no more than an inch at the base. Spaceships entering and departing from the gate might add more visual interest.

Zzzzzzzzzzzzzzzzzzzzzzzzzzzzzrrrrrrrrrrrrrrrrrt!

Death Ray: (Queen)

Once considered ‘The Peace ray’, these matter disintergrator beams are the most destructive force known to current technology. Using the dense heart of a collapsed star, they must be located on an object with at least the mass of a large moon in order to work. Fortunately, they are so expensive to construct and maintain that each Stellar military force only has one in it’s arsenal. In effect, what they do is to obliterate their target’s molecular structure, while creating a rift, and then inserting themselves in the time-space location of any target they destroy. These pieces can travel in any direction they choose.

Build: To achieve the visual effect of a spherical planet shooting a Death ray from it’s surface, I have placed a sphere on top of a series of interlocking disks which descend in size as they go up. A cylindrical dowel forms the ‘trunk’ of this cone. Alternately, a sphere on a long rod can be made, with a spring placed over the rod. The piece is 3 inches tall, with a 1 inch base.

"This is it! Fight to the last breath!"

Orbital Defense Systems/ Star: (King)

When everything else has failed, the Orbital defense systems represent the planet’s last line of defence. Fortunately, they are fairly formidible. A network of defense sattelites projects a forcefield around the planet, preventing an enemy from landing or using energy weapons.  This force sheild jams all enemy frequencies, making the use of a transmitter or even a Death ray impossible. The only way to penetrate this sheild is to locate and take out the ‘key’ sattelite. Once this happens, the defence grid is down and the planet is vulnerable. This sattelite defence system can travel one square away in any direction.

Build: A sphere rests on four pillars. This might be similar to the ‘chair’ tutorial in Google Sketchup, or it might be an enlongated rectangular block. I have shown this piece resting on two legs with no middle, to give the impression of a planet floating in space. The spherical planet has a ring around it. This ring could either represent the rings of Saturn (of which the moon Titan might be a future colony), or it might be a Dyson ring during later stages of extraterrestrial colonization. If one is planning a multi-system game of proxy 3-D chess, this piece might have the name of a planet or system. In fact, the sphere in the middle might represent the star or sun, rather than an inhabitable planet.

I have no idea who made it or where it came from. The interweb mentions it a few times, but there doesn’t seem to be any information about it.

A moment of inspiration hit, and I decided it would be neat/fun/educational to build it into a sort of glorious MIDI-controlled monophonic electronic tinny-sounding synthesizer.

Opening the case revealed that each button simply connects a pin on the controller chip (under the black blob) to the positive side of the batteries – there isn’t even a matrix, unlike most music and computer keyboards.

I soldered 30AWG wire-wrap wire to each trace, labeling them with the solfège names printed on the keys so that I could connect them in the correct order. Then I connected the wires to a microcontroller and programmed it to play a simple tune.

With the proof of concept done, I moved on to the next step.

It turns out that reading MIDI using a microcontroller is very easy. I used the circuit and code (with a little modification) from here to read MIDI signals from my keyboard and turn on LEDs.

The final step was to combine the two circuits into one MIDI-controlled, Arduino-powered, piezo-speaker-somethinged monophonic synthesizer:

The fun in this project was in building it and seeing it work, rather than in having it once it’s done. I would be just disassembling it to reuse the parts, but in this case my cousin (who makes electronic music) is interested in it, so I’m going to rebuild it on perfboard in a proper case, with a jack for audio output, and maybe some interesting stuff to use up the remaining four pins on the microcontroller. More on that later.

Peace,
Adina

http://books.google.com/books/serial/ISSN:01617370?rview=1&source=gbs_navlinks_s