3D Printing

I haven't posted in ages, but that may begin to change.  3d printing has consumed most of my "me time" over the last few months, and hopefully designs and research will start ending up here.

I first learned about 3D printing at the Crash Space hackerspace in Culver City two years ago.  My first real design was of kids sandals done using Sketch-up and printed on Crash's Makerbot Cupcake.  With only a 4" print area, I had to print the sandal in two parts and chemically weld it together with acetone.  The end result wasn't really usable as footwear as they were both too stiff and too slick on the bottom, but my youngest did wear them for a bit.




I'm still pursuing the footwear idea, but my current printer is too small for a single-piece adult sized shoe.  As a result, I've begun working on a large scale printer.  The rough design is in my head, but I won't know if it will work until it is built.

Solar Oven

I've been interested in solar power for a while, and not just in using the sun to generate electricity via solar panels, but also in the use of solar heat (e.g. Stirling Engines, etc).  I read about solar box ovens as a cooking solution for places where resources are scarce, and was intrigued by how easy they seemed to build.

These ovens work using the greenhouse effect.  Sunlight enters an enclosed space and the light is converted into heat and trapped in the oven, cooking the food.  Two boxes are used to create insulation and minimize heat-loss.  Tinfoil reflects the light/heat and cooking is done in dark containers which will absorb rather than reflect the heat.  Glass or high temperature plastic (e.g. baking bags) is used to create the window through which the sunlight enters.  The temperature inside gets high enough to cook food but not burn wood or paper.

Two weeks ago I looked up the instructions, and since the kids were otherwise occupied and I had two appropriately-sized cardboard boxes at my disposal, I decided to give it a shot.

The first thing you need is some decent sized cardboard boxes, where the smaller box is about 1 or 2" smaller in all dimensions.  The instructions recommended they be at least 15x15".  I used an old speaker box and a paper box.

You'll also want a roll of tinfoil, a large piece of cardboard (3" bigger than the footprint of your big box on all sides), newspaper or a few cardboard tubes, a bottle of non-toxic white glue, a box cutter, a pencil, and a turkey oven bag. Clamps are also helpful.

The first thing to do is to close up the large box, and center the smaller box on top, then trace the outline (see below).  Then cut through the lid and flaps of the large box so the smaller one can fit snuggly into the hole.

Next, line the inside of both boxes with tinfoil, shiny facing towards the center of the box.  Use lots of non-toxic white glue.  I assume white glue is used because it won't melt or give off fumes. I used about half a bottle.  You want the entire inside of the box (bottom, sides, remainder of the inside-top of the outer box to be lined with foil.

Here's the finished inner box.  Note that in my case, there were no top flaps. Normally you'd use the top flaps to help connect the inner box & outer box.  Since I couldn't do that, I left lots of spare tinfoil sticking out the top.

The top of the inner box should be flush the top of the outer box, so you have to put some kind of spacers between the two.  I had a really strong cardboard tube in a kind of curvy v-shape, so I measured the height difference and cut it into a number of pieces with a saw.  I then glued them in place in the bottom of the outer box (below).  You can also use newspaper or cardboard tubes cut to size.

Now you can slide the inner box into the outer box.  If your inner box has flaps, fold them out and glue them down.  Since mine didn't, I folded the extra foil over and glued it down.  The results are below.  Note that I did not put any additional "insulation" between the boxes, but I think it would work better if you do (e.g. crumpled newspaper).

The next step is to make the lid. For this you can either use the top to your outer box if you have one, or you can make your own lid with a large sheet of cardboard, which is what I had to do.  Turn the oven upside down onto the center of the cardboard and trace it.  You'll need 3" or so of overhang around the whole thing.   Cut tabs so that you can fold the cardboard into a lid, and glue the edges together.  It helps to use clamps here.  Next, cut a flap the size of the inner box into the lid.  This will be a reflector, so only cut it on three sides.

Line the inside of the flap with foil, since the goal is to reflect light into the opening.   You can use a piece of coat hanger to hold the flap open.   This is visible in some of the pictures below.

The last part of the solar oven is the window.  You can use a sheet of glass, but it's much safer and lighter to use a turkey oven bag.  The large sized Reynolds oven bag was perfect for my lid.  Glue the bag closed (run a line of glue along the inside edge, and then press down with something heavy like a stack of National Geos. Try to make sure the bag is sealed with no air inside, and flat. Wrap the edge in wax paper so if glue leaks out the bag isn't stuck to your furniture workbench (no honey, I definitely did not do this on our buffet).

When that is dry, glue the bag to the inside of the lid, sealing it all the way around.  Here's what it looked like when dry.

You can optionally make a "drip pan" by cutting a piece of cardboard that fits into the oven, gluing foil to one side, and then painting the foil black with non-toxic paint.

Now we're ready to cook!

There's no better way to break in an oven than with brownies.  The first thing I did was "preheat" the oven by leaving it in the sun for an hour with a few bricks inside.  The bricks help keep the oven hot after you open the lid to put the brownies in.  They're resting on some black construction paper that was on my "drip pan."

We used regular brownie mix and put it into a dark cupcake tin.  Dark pans work best because they'll absorb rather than reflect the light and heat.  The cupcake tins also mean more surface area vs a flat pan.  Once the oven was hot, we quickly opened the oven and lowered them in.  Remember to use oven mitts!

Here's the oven with the brownies cooking.  When the sun moved, I noticed that the front (left, in the picture) side of the pan was falling into the shade, and the brownies on that side were not cooking as fast.  To fix this you can quickly remove and rotate the lid 180 degrees and turn the oven to face the sun again.  The result is like rotating the pan, but this way you don't have to remove the pan from the oven.

The finished product!  Of course, since the oven doesn't get as hot as a real oven, you have to let things cook longer.  Ours cooked for about 90 minutes, and we checked them using the "clean toothpick" method.  They could have cooked for another 15-30 minutes since the bottoms were not quite done, but then the "mushy part" was the kids' favorite. 

Energy ideas

Idea #1: a hollow plastic ring containing a spherical magnet. The ring is wrapped with wire, and oriented horizontally, so that as the ring is jostled, the magnet rolls around and generates a current.

Idea #2: find some material that generates electricity when flexed (e.g. piezoelectric cable). Ideally, the material could be stiffer than normal piezoelectric cable, and generate more electricity. Mount the cable on trees (from trunk up along the branches) in a windy area. The wind can already flex the thick tree branches, so the idea is to harness this movement and convert it into electricity. Not terribly efficient, but it means power generation without replacing the trees with windmills.

GPS to GPS communication

My normal caveat #1: this may already exist. The idea involves taking a regular GPS unit but adding a 2-way radio that (among other things) allows the GPS to communicate with other units. This means your GPS can relay its route to other GPS units so that your friends can see exactly where you are and where you are going. For example, if you're backpacking and part of your group falls behind, they can still see where you went and follow your exact route.

Map scrolling using motion sensors

Rather than pushing arrow buttons to scroll a map left, right, up, or down, a motion sensitive device could be tilted in the direction the user wants to scroll. The larger the tilt, the faster the scroll. Shaking the device could restore the display to the starting point or user's current location.

Fingerprints for recommendations

A number of audio fingerprint technologies exist today and are used for things like radio monitoring, copyright filtering, and content identification (e.g. Shazam). To over simplify, these technologies work by generating a fingerprint from acoustic information of a track, and then determining whether there is a fingerprint of known content that is similar enough within a confidence threshold that the track can be reliably identified. This is probably already being done (I haven't read up on the literature) but it seems to me that you might end up with a half-decent recommendation engine if you ignore the high confidence hits and instead look at the medium-low confidence hits (aka near misses). Because recommendation engines can be pre-generated and speed is not a problem, you could only pair songs that had multiple "near misses" at different points in time.

Sythesizing high-resolution audio...

I don't remember enough information theory to know whether this is even possible, but I was wondering whether one could create a high(er)-resolution audio recording from multiple low resolution sources. Specifically, imagine a bunch of fans recording a concert using the video cameras on their cell phones. The resulting audio would be pretty lousy on a per-recording basis, but if you put them all together, would it be possible to subtract out the crowd noise and reproduce a higher fidelity version? Theoretically, it seems that the same signal processing techniques (if they exist) could be used to take multiple low resolution images and synthesize a higher resolution image.

Crowd music

A device with a microphone, speaker, and accelerometer. The device's software is programmed with basic music rules (rhythm, melody, musical keys, harmonies, etc.). A single device will make random melodic music in a single voice to the beat that you shake it. Additional devices listen to the music being made and make something complementary in the appropriate key, also to the rhythm to which they are shaken. The software will compensate for slightly out-of-sync rhythms, but will allow off-beats, double beats, and other beats that would sound complementary. Each device will pick an octave and voice so that the combined music is comprised of interesting and musically appropriate layers.

A collection of these devices should make interesting music when "played" together.

A phone service that...

A service that you can call and vocally give the name of a Wikipedia entry and have it read the entry to you so that you can get information about different topics from your phone. Would require basic navigation for following links. The tone of voice might vary to indicate a link, the speaker might vary, or the system might say "link".

Digital sheet music for concerts

Here's the idea: sheet music on a digital display (LCD, OLED, eInk, etc.) instead of on paper. The unit listens to what you are playing using digital fingerprints of the music and automatically turns the page for you when you get to the right spot. Could show you where you are in real time (no more losing your place, if anyone actually has that problem), and would let you skip around.

Sustainability as a metric of ethics?

Been wondering whether there are any ethics systems that measure the viablity of an act based on whether it leads to a sustainable society or not. Basically, you judge the fitness of an action by asking "what if everyone did the same thing" and if the result is an unstable society then the act is judged as unethical. This applies at the macro level (what if every country acted in the same way), too. Would this be where evolutionary pressures lead, because stable societies would be more likely to advance (less time spent warring internally or externally) then unstable societies (more time fighting for survival)?

Crowd protection device

Kind of a riff on the rave idea below, I was thinking about how people get killed when crowds press forward without regard to fallen individuals and wondered if technology could help by signaling when someone has fallen down. For example, imagine a watch that can detect when the wearer removes it or falls down (e.g. using an accelerometer). Suppose this watch also has the ability to notify similar devices in the area when one of these two events occurs, and those watches continue to spread the message outward. Then if everyone in a crowd was equipped with such a device and someone fell, the watches would alert people to stop moving forward (e.g. by vibrating and playing an audio message). Because the message propagates locally, and entire densely packed crowd would be alerted as the message spread from watch to watch. This might work to control low-speed crushes occurring at organized events like the Haaj (spelling?), sporting events, etc. It probably wouldn't make much difference in case of a fire.

Interactive Rave Lights

Got this idea while watching the visualizations on my computer. Ravers have been twirling glowsticks for some time, but I haven't heard of any type of wearable interactive lights. The idea is to recreate the visualizations that you see in an MP3 player on the dance floor, using devices that pulse to the beat, but that also react to other devices in proximity. For example, a necklace would probably work best because, worn outside of the clothes, it can "see" 360 degrees around you. The devices might pulse at a specific frequencies (different devices at different frequencies?) and talk to other local devices using IR. A specific device might be designated the "center" and devices around it would pulse slightly later in time, at a lower brightness. This might continue outward for some number of hops. The effect, if seen from above, would look like a wave spreading outward. A given device might respond to different frequencies in different colors, and then you could have overlapping waves of color. Different algorithms would produce different effects. Would be cool to see this in action and a simple program could probably model what it would look like on a computer screen.

Kid-friendly furniture

Was looking at the Crate and Barrel (or Crap in a Barrel, as I call it) catalog and much of the furniture is downright unsafe for a house with kids. Glass, sharp metal corners, unstable designs, etc. Seems to me that there is an opportunity for furniture designs that take kids into account. For example, no sharp corners or glass, slight padding under tables (to prevent painful head-banging) and possibly on edges, no small pieces to fall out and become choking hazards (like the screw covers that are common on many chairs), built in earthquake straps for book cases, etc. Sometimes I wonder if having straps or a low-height bar across the front of a shelf would prevent books from spilling out during an earthquake. Another important factor is ease of cleaning.

Language Game

Here's an idea for a computer or console game intended to make learning a language interesting.

Imagine a fantasy-world game where the foreign language is used to cast magic spells. A microphone is needed to record what the user says. The game would teach the player to say phrases or sentences to activate spells. Introductory phrases such as those relating to time, location, or acquiring things lend themselves to this concept. For example, learning to ask about location or directions might conjure up a map, or saying "I am from ..." might return the user to that location. Other sentences might be used to activate objects. A user might have a magic bag that only opens when the user says "My name is ...". Basic written text would serve as the "magic language" to teach new spells at higher levels, or serve as in-game puzzles. Sentences or short poems could also be used for "magical combat". For instance players might freeze an opponent by saying "The weather today calls for snow and wind."

In games, the concept of "leveling up" is common, where the player gains more abilities over time as their character progresses (e.g. learning new skills, spells, etc.). This would work well with a language based game because the player would naturally learn more over time, leading to more sophisticated spells and puzzle challenges.

P2P-based web search engine

Web search engines are currently the domain of large corporations like Yahoo, Microsoft, and Google. However, one can imagine an open-source, distributed, P2P based search engine. Traditional P2P systems like Gnutella use distributed searching to locate files, and the web is nothing more than a collection of HTML files. The P2P-based web search engine envisioned here would take the functions that would typically be running on Yahoo, Google, etc. servers and distribute them to clients running on end-user systems. You might think of this as Gnutella for web content.

An ideal client for a distributed web search engine might be one of the existing browsers like Firefox. In that case, a new ranking system could be used based on the number of times a specific page is actually visited (e.g. as opposed to the number of times a given paged is linked to, as used by Google). This information would, of course, need to be anonymized.

Privacy screens

Portable devices (PDAs, phones) are widely used for business. An obvious side-effect is that business is increasingly conducted in public places, rather than just in the office. Especially on public transportation, privacy may be a growing concern. One solution is protective film that makes device screens impossible to read except for someone looking straight onto the display. Alternatively, privacy screens may be built into the device during manufacturing. Note that 3M is a manufacturer of privacy screens for PCs.

Parts that tell you when they are failing

Maybe five or six years ago I a radiator hose blow-out, just beyond the top of the "grapevine" pass on California's interstate 5. Apparently the radiator hose had been weakening over time and eventually split down the middle. A few years after that, the same thing happened again, just driving around town. I started to wonder why we don't have car parts that notify you when they start to fail.

For example, the government is working on clothing for military personnel that can identify when they are torn/pierced due to a fine mesh of wires or fiber optics. Some kind of simple version of this, built into parts that frequently fail (fan belts, radiator hoses), would save a lot of grief for just a few more cents of cost per part. The system could use passive RF for communication (ala RFID) with the car so no wires would be necessary. If the belt/hose expanded and broke the wire mesh, the part would report back possible failure to the car when queried. The mechanic would be able to identify the failing part, back in the shop, using the same mechanism.

Possible problems include ensuring the failure warning system itself does not become a source of false positives. Also, possible privacy concerns from RFID, but I think there are ways to solve this using proximity and/or generic part IDs rather than globally unique IDs. Cost of the monitoring system in the car would need to be low.

Mobile phone mapping

This is the first post with any real idea. Mobile phone systems are now required to be able to locate 911 callers so that responders (police, ambulance) know where to go when they get a call. The data about where mobile phone users are can be used in a number of interesting ways. By tracking the location of users over time, one could construct a real-time traffic map. For example, this could be used for traffic flow purposes (i.e. what routes are congested, what is the best way home tonight) . Furthermore, it can be done anonymously - it is only necessary to know a given phone's location over time, not any information about the phone's user.

Though I've had this idea for a while, I haven't committed it to "paper" until now. I think an East-Coast university or phone company may have just announced a plan to study this as a possibility just last week.

Dead Sea

Attempting to enter text via PSP. UI is lame: D-pad navigates phone style alpha grid. Should allow use of analog stick as well. Maybe over qwerty or ring of letters.