Tag: Design

Moving in to Fab Lab Tuyuryaq

Sunrise on Bristol Bay in Togiak, Alaska

Hackerspaces and FabLabs get started in lots of different ways. Often it’s a group of friends that already have a lot of tools and decide to rent a space to pool their resources. Others are built into institutions, like universities and libraries.

Fab Lab Tuyuryaq (that’s the Yu’pik spelling of Togiak) has a more peculiar start: it’s one of a few labs around the world that was established out of an NSF grant as the result of a research proposal. I wasn’t around for the years of coordination since a 2010 FabLab demonstration at a convention of the Alaska Federation of Natives. It was the meeting of minds between tribal council members of Togiak, and people from the University of Alaska and University of Illinois that got the ball rolling on a grant proposal that would finally get funding in 2014. I was asked to take the lead on ordering the equipment and materials to fully stock a lab within our budget and finally to fly out and unbox, assemble, and test all the equipment.




After flying from Chicago to Anchorage on a 737, I took a little Saab 340 turboprop where they hand out earplugs instead of snacks for the 90 minute trip to Dillingham, and finally, one of the daily cargo planes took me over the Alaskan marshes to Togiak. I got to peak over the pilot’s shoulder on that one. Just me and a bunch of Amazon Prime packages in the back.

The space was perfect for the lab: the backbone of a traditional canoe hung from the ceiling, and the building was situatued in the middle of downtown, right between the post office and the general store. At first it was packed full with dozens of boxes large and small that had been shipped over the past few months, but over the course of the first week it took the shape of a computer lab. Local handymen built sturdy hardwood tables and stools, and other furniture was rummaged from the local ‘Office Depot’ — an abandoned school down the street that was full of tables and chairs and other office supplies, open for the picking if you’re friends with the mayor.




Before it was a FabLab, this space was occupied by the local Boys and Girls club, so groups of kids knew it well and would knock on the doors after school. Though it was often a nuisance to supervise a bustling building of middle schoolers, I was glad to teach them how to use the sticker cutters and 3D printers — they showed up almost every day wanting to make something and I’m not the kind of person that says ‘no’ to people who want to learn.

But sometimes they were interrupting and just wanting to play games. Once when it was getting out of hand, a young girl noticed that I wasn’t as bossy as I was 5 minutes ago, and she hypothesized, “You’re one of those people that just gets quiet when you’re upset, huh?” And I nodded my head yes and she decided to take over for me and raised her voice to tell people to clean up after themselves. Keep taking command, Piccola!

Another night, I finally met some of the older kids that were going to high school there. They were quiet, but picked up skills really quickly. It was crowded when it was getting close to curfew, and a police officer stopped in to see why so many people were crowded in the building. After a quick tour of the lab he revealed he went to art school in Phoenix before getting a job as a policeman in Alaska, and he said he hoped he would get to use the equipment too.




Consider this a draft. I want to sit down and flesh this idea out, but:

Equally well equipped as the electronics hobbyists and inventors in Shanghai, Chicago, the investment of fabrication equipment may be an equalizing factor in bringing the same opportunities to rural and dense urban areas.

A big idea with establishing this lab is it may allow locals to develop skills that can be paid to remote workers. Instead of learning a skill and getting hired to leave the town, locals could bring income into the community by working from the lab.

Some replacement parts for salvaged work tables. Feet and cable guides.


Digital embroidery was really popular. I love setting up classrooms with sewing machines. A couple of kids in any group have likely dealt with threading a sewing machine so they can become helpers very quickly.




Some fun with broken glass:


Playing with broken glass: Laser etchings make ghosts over Togiak

A picture we received a few months after setting the lab up, a village elder’s portrait laser etched into a whale bone.


A couple of examples of Bristol Bay locals using 3D scanning and printing before this lab was set up. Bones from a whale carcass are being meticulously scanned in full color with a NextEngine laser scanner. A machinist explained to me how useful it is to print a block of plastic to test dimensions. The plastic is much easier to machine or just sand down until it fits than using a block of steel. Once he’s happy with the fit, he can machine it manually from a block of steel.



Building Brackets around the C-LEG prosthetic

This is Part Three. See: Part One, Part Two

Started out with some photogrammetry to capture the geometry of the C-LEG, which will hopefully allow me to 3D print a bracket that fits the contours of the the C-LEG precisely.

This first scan was enough to play around with, but ultimately the glossiness and the bright sunlight caused enough gaps and distortions that I had to do a photoshoot later that night using our CNC machine as a light box. The even lighting from the LED rope was just the trick.

The next step was selecting a portion of the C-LEG’s surface to extrude into a form fitting shell. Blender was used to create a mirror image of the scan, and MeshLab was used to align the two sides and fill in the holes so I had a reconstruction of the entire CLEG (Agisoft was only able to reconstruct one side of it — I could of went back and tried another photoshoot, but decided it would be faster to just duplicate the half that worked). In the video you can see the mesh of the whole C-LEG next to the original scan.

Blender and MeshLab were used back and forth here: Blender allowed me to select a portion of the mesh freehand and export as a separate STL. MeshLab allowed me to offset this surface using ‘Uniform Mesh Resampling’ and then construct a volume around the surface using Uniform Mesh Resampling with ‘Absolute Distance’ checked off. This created an excessive and messy edge, however, so I brought it into Blender to perform a boolean intersection, extruding the surface that I selected earlier outward to overlap with the portion of the new mesh that I wanted to keep. With that cut performed, I used MeshLab one last time to perform a ‘Surface Reconstruction: Poisson” to smooth the corners. To cut a slit in the back of the model I used Tinkercad, because it’s quicker to align and subtract a cube, knowing what I know.

And it actually clipped on the way I had hoped, wrapping around the edges — but there was a considerable gap. The inner diameter of the print was 60mm, while the C-LEG is 55mm wide, so I uploaded the STL to tinkercad at 91% of the original size to continue to prototype #2:

I used some cylinder, cube, and hexagon shapes to throw together clamps that I can add nuts and bolts to for this print, to see if I can really clamp down on the C-LEG enough to hang some weight off of it.

Ended up printing copies at 93% and 96% of original size. It is not a perfect fit, but once tightened down with bolts, holds on pretty well. This one cracked due to the nut turning against the plastic — the white ABS must have shrunk more than the grey ABS, which had holes big enough for the nuts to sink into without forcing it.

Designing brackets for cLeg cosmetic fairings

A continuation of: Blending and Bending Prosthetic Leg Fairings

I wanted to design a 3D printable file that would allow me to clamp my acrylic fairings to the cLeg. Luckily Kay and Gabe created a pretty solid model of the cLeg itself so I could use its contours in my design. Again, I had to cut the model down manually in Blender because netfabb does an awful job of exporting STL (hadn’t yet investigated if this is an actual or a free-demo-imposed limitation of the software).

I also used Blender to multiply the scale by 1,000 before importing into Tinkercad.

I like Tinkercad because it makes it super easy to perform boolean functions on complex stuff like our leg here. If you’re a tinkercadder, try ungrouping the model so you can see how I made a cross section of the leg: Tinker This

And I went on to improvise a way to screw two parts together — this is very much a test fit, to see if the idea makes any sense, to see if screwing two plastic pieces on with pressure is enough to keep it from falling off.

I went back and forth about 3D printing holes for nuts and bolts, but decided I would drill it out of the finished plastic — “machining” is way more accurate than printing for this kind of thing.

OK, the original Kinect scan was not very dimensionally accurate…I guess I could have compared measurements of the model with measurements of the object, that’s what I get for trusting technology -.- I can still use the blocks of plastic for practice fitting, though. They don’t clamp around the c-Leg, but I tested screwing the pieces together and drilling into the plastic to insert a brass threaded insert, and with a few taps of a hammer that turned our really nice.

Of course, the chunky tinkercad design isn’t so fashionable, but it served its purpose to confirm that I need to press the shape of the leg more accurately (the front fairing doesn’t sit flush with the printed model at all) and that countersunk M5 screws will do a nice job of securing the fairing to the bracket, though I’ll have to play with melting a countersink so the head of the screw doesn’t stick out the back.

Continued here: Building Brackets around the C-LEG prosthetic 

Blending and Bending Prosthetic Leg Fairings

From Kinect scan to laser cutting

Opened the original scan in Blender, selected the portion of the scan we’re concerned with. Separated it from the rest of the mesh and exported as stl.

Used Netfabb to repair the mesh and cut into a top and bottom portion.

Found out netfabb decimates the mesh upon export, from 27000 triangles to 24000 triangles, and manages to make it pretty rough, so it looks like this in 123D Make.

Inspected the files before and after repairing in Netfabb…

Used MeshLab’s Filters → Remeshing → Surface Reconstruction to “Shrinkwrap” the model and fill in gaps and holes without losing the smoothness of the scan.

Used this guide to split the part in two using Blender’s newish “Bisect” function.

Played around with different options in 123D Make…

Drew a circle in Blender against the scanned cLeg and stool, confirmed that the units of the scan are in meters. (The circle is .355 units wide and in real life the stools are too.) But, since many programs interpret these STL units as mm, our objects are 1000 times too small. Let’s scale them up.

Settled on a slicing pattern in 123D Make. Used the Modify Form feature to hollow out the leg and picked out the Radial Slices construction technique. The arrangement has some collisions at the bottom, but I don’t want a closed model anyway, so will do some hand-tuning in Inkscape. Exported the model to Blender to check that the cLeg would sit inside it okay.

Using Inkscape to layout the the pieces onto less than 4 sheets of plywood… (nesting is apparantly a difficult problem for computers, and not one that many softwares implement, certainly not free ones. just have to eyeball it)

123D Make is sadistic and exports the objects as groups of thousands of lines instead of a single vector, so editing the exported PDF is really really slow. (It takes 20 seconds to select a text object and type in a new number. I counted.) Learned things:

On the left: the highlighted list of numbers 4,000 characters long describes a single path. On the right side, two coordinates of a single line segment are surrounded by markup. The file containing 2 objects takes 73 lines of text. The file exported by 123D Make takes up 6151 lines of text for the same object. Inkscape modifies this information in memory every time you move something.

Inkscape operates with SVG, which is plain text, ASCII, one character equals one byte. When a path is exported as 677 individual paths, each one of those line segments has 8 lines of markup surrounding it in the SVG file (between the g tags, with information for position and stroke and fill attributes). So what could be saved (and manipulated in memory) as 20 bytes if it was appended to the list of nodes in a single path instead takes 389 bytes to be kept in memory as a standalone object.

I found this forum post describing how to select all the separate objects, Path → Combine them into a single object, and in node edit mode you can select all nodes and click Join Selected Nodes and it simply merges overlapping nodes. Hallelujah!

So to downsize the files enough that they’re not a pain to work with:

Open the PDF. I learned that if you check the “import via Poppler” option Inkscape can detect the colors of the stroke (otherwise imported PDFs have “undefined” color unless you adjust it yourself). So check that box. CtrlA, CtrlU to ungroup everything. Click a blue line segment. Edit →Select Same →Stroke Color. Path →Combine. F2 (Edit Paths by Node). CtrlA. Wait for a minute. Join Selected Nodes (one of the buttons in the node edit toolbar, 3rd from the left, just after the delete node button. It might take a few minutes for Inkscape to chew on this one. It will probably become unresponsive. Let it do its thing. In my case this trimmed the file size by 97% and I could then translate and rotate and rearrange the objects without any lag.

Two hours later…have my minified cut file, fitting on 1.5 sheets instead of 4. I’ve trimmed the tops and bottoms off the vertical slices so the end result will be open.

20 minutes of lasering + 10 minutes of assembling: Hey I made a thing!

Met up with Shawna and learned the design constraints: how the leg has to move, what areas can’t be covered, etc. We picked out a pattern she wouldn’t mind having wrapped around her leg:

I took a few measurements of the wooden positives and drew the outer shape of the fairing in inkscape by hand (using auto-smooth of course!). A few booleans later I had my cut file, which took about 20 minutes apiece. To get the part ready to shape against the mold, I stuck it in our convection oven to bake at 300F for about 5 minutes (don’t worry, we keep one oven for circuit boards and plastics and a different oven for foods 🙂

So the process was: semi-soften the plastic in the oven, then roughly fold it over the wooden form, then stick the whole wooden form in the oven. If you let it soften all the way when it’s sitting on the metal it’ll stick to the metal. Better to have it roughly on the wood form when it reaches maximum droopiness. When it’s as soft as rubber, we take it out and push the plastic against the form, holding it in place as it cools.

I’m pretty happy with the second prototype. I think the next step is 3D printing some bracket system, and maybe taking more time to plan out how the plastic will fold against the form — this was pretty heavily eyeballed.

Continued with a rough prototype of a bracket here: Designing brackets for cLeg cosmetic fairings 

The Artistic Side of Shenzhen


Imagine my surprise when I learned of a 2-week international jazz festival happening in this city, with artists from Italy, Russia, China, all over, and just my luck it was only the second day! I ended up only catching this one show, “Second Approach”, before leaving the city — a Russian trio of piano, upright bass, and singer. It was exciting to be in this kind of music venue all of a sudden, full of young Chinese jazz fans shouting for an encore.




This whole neighborhood, OCT, really surprised me after staying in the middle of the overcrowded concrete center of Shenzhen. “Overseas-born Chinese Town” is basically a reverse Chinatown, a place where people from all over the world have settled in China but brought international culture back with them. So there are patisseries and cafes and art galleries nestled among some of the most creatively-repurposed warehouses I’ve seen — giant wooden structures that let you slide down from the 2nd to the sidewalk framed by impressive and modern murals. I was pleasantly reminded of Arcosanti — a city whose architecture encourages you to climb onto roofs.





With graphic design firms and art galleries sharing renovated warehouses with shops of creative, handmade one-off goods, it reminded me of the parts of the American rust-belt whose economies are reinvigorated by the ‘creative industry’ — software, design, and technology firms, where money is made with ideas and services instead of physical goods. Many of these new businesses occupy the old warehouses of Pittsburgh, Cincinnati, Chicago and so on, and is often referred to as a post-industrial economy.

Well in OCT, these renovated warehouses are neighboring factories and shipping warehouses where business couldn’t be better. A large part of everything the world consumes is manufactured here. Foxconn is just up the road. With that, OCT struck me as a strange post-industrial utopia surrounded by the ultra-industrial reality of the world’s factories. (I expressed this while walking with some new friends, so I had to explain the notion of being “post industrial” to some people who lived in the most industrious city I’ve ever seen).





Oh my god that astronaut is fixing his flying saucer I love this place.

Hedgehog Programmer

Feb 25, 2015


This week, we all made a FabISP. Knowing we could make any shape we wanted on the Roland Modela, I didn’t think much of making a rectangle circuit board. I brought the ‘traces’ png into Inkscape, traced bitmap, and modified some of the traces to have more curves, and to fit the silhouette of a hedgehog. Just by switching what parts of my image were visible or transparent, I could make my traces file and my cut-out file for the Modela.


Burlap-Resin Composite Boat


Searching youtube for how-tos on composites, there’s lots of videos on boat-making. So I decided, what the heck, why not get started with my boat making career. I made a really rough boat-like shape in Blender and applied a subsurface division modifier to smooth it down. The only foam I had on hand was 3/4″ thick, so I scaled the model and split it into 3 layers, set them side by side in Blender, and import the whole thing into MeshCAM.

MeshCAM generatered the gcode for our 1′ by 3′ CNC machine using a 1/4″ ballnose. Milling through insulation foam with a 1/4″ bit was a real treat — I cranked the speed up to the max and watched it cut like butter. After freeing the individual slices from the foam, I just hot glued them together.

I stacked 4 layers of SuperSap soaked burlap over the foam boat form, wrapped it up in release plastic, layered felt on top of that, and stuck the whole thing in a vacuum bag. We tried using our shopvac and then our smoke sucker, which sucked the bag tight against the form, but didn’t put any pressure on it. So, I ended up setting it in the sink under a trashbag filled with water, which visibly put a lot of pressure on the form.

After unpacking the form, and ripping out the foam (it did not go without a fight), I optimistically set it in the sink full of water, where it promptly sank. It’s totally permeable to water. Gabe’s frisbee floated a lot better. I’ll probably coat it with another layer of resin and let it cure without putting pressure on it. I figure the resin would be more solid with a two part mold, filled with resin (not squeezing the resin out of the burlap). Next time!



Update, a couple of weeks later: after pouring super-sap resin over the hole-ridden burlap boat with multiple applications and slowly spinning the boat upside down, rightside up, to keep the resin moving for about a half hour and cured in the air, the boat is sea-worthy! Unfortunately, the excess resin did slowly seep down to edge of the composite and pooled there, leaving me with heavy chunks of resin that’s just weighing the boat down. I can’t think of a good way to remove this except for a hacksaw.

I’ve also figured out that I’m not a great boat designer. The shape of my hull gives very little displacement, and the boat sits pretty low in the water without any weight (except for the aforementioned excess resin). I’ll look forward to designing a boat worth sticking a motor or sail into later on in life. In the meantime, here’s my burlap boat floating in Lake FabLab (our perpetually flooded parking lot).

–

Original Blender file with subdivision surface.

STL Export, scaled up to millimeter units.

Being Treated to Shenzhen


Shenzhen has been a pretty wacky experience. As soon as we got out of the subway station, we were literally greeted by a dance troupe. At first it seemed like maybe they were just street performers or just practicing for some cheerleading competition, who knows, big city, right? Except it was a pretty empty part of town and we were the only audience. And after they finished dancing they took a picture with us and walked away. It was super bizarre and disorienting and at the same time effective at welcoming us to the everything-will-happen attitude of Shenzhen.

The luxury tour bus provided by Tsinghua university was a big step up from taking the subway everywhere in Hong Kong, although it was always a little unnerving having little information on what the plan was, where we were going, how long we were going to be on the bus, that was always a mystery.

Basically, a cheerful woman meets us at the subway station and says she has a bus for us outside, and we gladly duck into the air conditioning. She welcomes us to China and introduces us to her co-workers (tho at this point we don’t know anything about her company) and one of her coworkers sings a song a capella over the bus’s PA. OK. We spend an hour driving on the highway through the city and the scale of this place become apparent. Unlike every other city I’ve been in where you drive out of the city center and the building get shorter, it seems that pretty much any residence here is required to be 40 stories high. Just endless high rises, with new ones being constructed right beside them. The only way you know you’re ‘downtown’ is when the high rises are covered in animated LED displays.

So we make it to Harbor School after weaving our way through a construction site with big signs for ‘special economic zone’ and I’ve written a separate blog about it cause it was awesome:

https://medium.com/p/e3bae07d8be7


And afterwards we had dinner at a great hot pot place, all paid for by our hosts (again, still unclear at this point on why they were treating us so well and who they were. Like I’m sure it was mentioned but I don’t know the name of any of the companies so it didn’t stick.) The next day it became more clear who are hosts were as we toured their factories that are owned by a company that has a partnership with the university. I’ll blog more about the factories separately, but after a few factory tours we ended up at this place:





It’s the showroom for this company 3Nod, and it took a while to figure out what the company did. The 3D room sized screen intro video communicated that they were all about creating a better future (implication: for wealthy people who live in spaceships). But the showroom was full of bluetooth speakers and headphones. Their vision of a smart home was just projector walls (a la Fahrenheit 451, surrounded by TVs…) I liked the style of the furniture, though one of my compatriots pointed out that they’d be pretty useless in practice, unless you can do all of your work via touchscreen.

Also the lights kinda clicked on and off without warning, the screens seemed to react to your gestures but didn’t do a great job (cause it’s Kinect based and it’s unreliable and everyone moved on from arm-wavey-HCI decades ago) so it seemed like their vision of the future was full of glitches and really needless technology stacks. There’s four projectors for that one wall. That’s like 2kW to have a bamboo forest by your couch. It would literally take less energy to just grow bamboo in your living room.

I really liked the couch tho.

Anyway we briefly met with Richard up in his office full of cigars and brandy. Very hollywood personality and attire. He kind of just pitched his company and his personal story to us without any context of why he’d invited a bunch of hackers/makers for a tour. He wanted to meet with Mitch and suggested the rest of us continue a tour of the building and hang out in his office on the top floor where he entertains. So there we were, a dozen idealists walking around gawking at this guy that makes his millions selling headphones with Wil.i.am. Alex took on entertaining us with piano and Jona performed a Chinese tea ceremony.

I noted that even surrounded by ostentatious wealth, sitting on plush couches, people still turn to their smartphones when they’re bored. Nothing all that exciting about it.

Ah, but no one is checking their phones in this last photo — we caught a ride to ShenzhenDIY. Well, the bus got us to the neighborhood but didn’t want to go onto the skinnier streets, so it was a nice walk. First past bustling markets with flashing LED and neon signage, electric bikes and mopeds weaving through people crossing the street, then through a dark alley with unfinished pavement such that a flashlight was necessary not to trip. Up a few flights of stairs in an old concrete building that I later learned housed a clothing factory and a Japanese sword factory (wait what?) we made it to the first real hackerspace of China, a tight community of people excited to meet visitors and share projects and passions. A DIY car chassis sat behind a comfy couch. Guitars and mixing boards sat against the wall. People passed around the microchips they were excited to write programs for. We went in a circle introducing ourselves and an expat member of the space announced in surprise that he is also from San Antonio, and he has never been in a room with so many Texans in China (two people in our tour group in the same room, pretty easy record to beat!)


A couple of friends and I went back the next day thanks to Yuheng opening the space for us to take advantage of the wifi and air conditioning. Here’s his github. He told us he’s writing a programming language with formal syntax to prove logical theorems (it won’t but the first, but it’s still an awesome project to write your own language). He was also interested in the design of spoken languages and introduce me to Toki Pona, an invented language of 120 words. He told us this was the first time he had a conversation with people speaking English which really surprised us and we asked how he learned, he said just talking along with American TV and movies. He also played a pretty mean Nirvana cover with one of the hackerspace’s guitars. Very inspiring dude.

Oh and this is the hackerspace that opened a second space at Harbor School, so they’re reaching out to the wider community and just being awesome.

Parametrically Designed

CNC Plasmascreen Coffeetable

Being a university affiliated FabLab has some perks: we get to pull useful items from University Surplus (one department upgrades their computer lab, other departments call dibs on the old hardware, sometimes really new stuff, sometimes really old stuff).

Nearly all of the computer equipment at CUCFabLab was pulled second-hand this way, then topped off with RAM and upgraded to SSDs. A funny assortment of other supplies end up getting collected: decades old oscilliscopes, a 1980s bandsaw, and this big old 60″ plasma screen display.

It weighs about 100 pounds and is fairly low resolution (not quite 720p if I remember right) and it took up an awful lot of table space, so it quickly got basemented. That was until my Fab Academy assignment was to ‘make something big’ and I remembered that I always wanted a coffee table that was a giant computer screen.




The neat thing about plasma screens is that a lot of the electronics are bonded to the glass (tho I can’t recall where I heard that…) and as a result, they often have a pretty thick slab of glass to start with, so it’s sturdy enough that I don’t feel nervous about setting my laptop and maybe a cup of coffee on the screen (tho a spill of the latter might be fairly disastrous if you don’t contain it before it drips into the edges…).

Putting a big slab of acrylic or glass on top of a large display is often the most expensive part of this kind of object, so avoiding that part altogether meant I just needed a cheap MDF base for the TV to sit on. Like most TVs, there’s the front body of the screen that tries to be thinner while the power supply and mainboard sits in a sort of hump on the backside. So the design of a base that goes up to this edge but leaves room for the hump turns out looking like a pool table.



It was designed using the Rhino plugin Grasshopper, which proved to be a very intuitive interface for parametric design. It is a matter of dictating the size and position of 3 rectangles (the top of the table, the base of the table, and one that can be scaled and moved as a midpoint) and then creating “lofted curves” through each set of corners. This is an automatic function that creates the whole smooth shape pictured without any work on my part. I get to just change the position of the midpoint of the curve until I like the look of the resulting curve. Then I just subtracted a box with the inner dimensions I needed from the larger shape.

After that, I have a program to do the work of planning my assembly as well. The free 123D Make by Autodesk has a great workflow to open your 3D file, type in your material parameters (“I’m using 4′ by 8′ sheets of material 1/2 inch thick”)




I got the pieces cut at the architecture lab with lots of help. I learned that with this slotted construction technique it’s necessary to drill holes at every interior corner (so in the CAD file you select each of these corners and create ‘points’ on a separate layer to export as a drill file). This was about $40 worth of MDF and took less than an hour to cut out on Architecture’s giant fancy CNC machine.

Assembling it took a lot longer. Lots of rubber malleting.



I started playing with processing sketches (like the rainbow above), but it takes up a lot of space and there’s not a good spot for it at the lab, but the TV is unvierstity property so it can’t be taken off campus, so it is hidden in a corner — the interactive processing sketches will wait for now.

The Twenty Dollar 3D Scanner and Cloning Cacti

October 19, 2013


With a newfound ability to take digital design and make physical objects, it’s only natural to find a way to go the other direction. 3D Scanning is the technique that closes the gap in the promise of 3D printers being replicator machines. In fact, the ‘Maker Replicator’ has a companion: the $1400 “Makerbot Digitizer.” Essentially, it’s a motorized turntable, two lasers illuminating either side of the object-to-be-digitized, and a camera with a live feed to the fine tuned software that gives you a 3D model ready to print inside of ten minutes.

Makerspace Urbana has a mission of technology proliferation to people of all classes and creeds, and at $1400, the Makerbot Digitizer is another piece of new technology that’s priced out of reach of the general population. So I was very impressed to see James, a fellow member of Makerspace Urbana, playing with a different set of hardware to achieve the same result — a simple handheld laser and an old webcam (specifically a Playstation Eyetoy — talk about repurposing).

This blue laser isn’t something many people would have sitting around, but can be ordered online for about $10 before shipping. It’s 5mw and 405nm wavelength. A simple filter that can be ordered along with it turns the dot into a sharp straight line. However, any old red laser would work as well (though it would require very dim lights, higher power lasers will work much better), and can be converted from a red dot to a red line using a small plastic cylinder, for instance: a lego lightsaber!

So the components for a 3D scanner can be hacked together (perhaps you have a busted cd or bluray player that could have its laser beam harvested) — but how about the software? James had been using the free trial of DAVID3 laser scanning software. It offered a very intuitive scanning workflow, but would only allow you to save one side of the object at a time unless you pony up hundreds of dollars for a license.

This strategy of digitizing an object works by using a calibration pattern that the software recognizes (that’s the piece of paper with dots printed on it) to determine how far away the background is from the camera. When a laser-line is projected across the object, the line takes the shape of the object. The software compares the form-fitting shape of the laser line with the straight line that hits the background, and creates a “point cloud” representing the one side of the object the camera can see.

The Makerbot Digitizer has the turntable wired up to the computer, so it can scan the object while it rotates. But without this integrated turntable, we have to scan the object one side at a time — and manually piece the point clouds together after the fact. The DAVID3 software automatically aligns these point clouds, but saving the result is a privilege of the paid version.

From left to right: aligning two point clouds, the completed 8-sided point cloud and all its associated noise, and the surface reconstruction ready to print.

But no matter, the free and open source “MeshLab” allows you to align point clouds semi-automatically. For each of the 8 angles captured, you have to give MeshLab some hints as to how they line up, and it uses its fancy algorithms to piece the two together. Here is (someone else’s) video tutorial that shows the whole process.

I used that technique to piece together 8 scans of my cactus, and was able to create a ‘watertight’ mesh, a continuous volume without any holes — using a MeshLab filter called “Surface Reconstruction: Poisson.”

The generated mesh is solid, seamless and ready to print. While the general likeness was captured, I’m not so satisfied with the detail. Perhaps using a higher resolution camera would help, but I think most of the detail was lost in the noise resulting from the laser’s light-scatter — a result of the material bending and blurring the laser-line. So whatever laser scanner you use, the detail you capture will be reliant on how sharply the object reflects the laser.

After trying this method out on a few different objects, I came across 123D Catch : a cloud service that generates meshes from photographs. I’ve found it vastly more practical than setting up and calibrating lasers and cameras — even with a couple dozen pictures from my camera phone I can get very detailed meshes, with the photographic data applied to the surface. You can download the results to use how you please (under a non-commercial agreement), but it is a free service by Autodesk that they can pull anytime. Since then I’ve learned to use Agisoft — equally powerful photostitching software, for $60 with education discount. At least it’s something you can own and run on your own computer!