Monthly Archives: September 2012

Seej in Education

Here’s a couple of photos of a Skype call I did with a Colorado high school Engineering class this afternoon. These students are designing and 3d printing engines of war for use in an in-class Seej tournament, date to be determined.

I’m the tiny pale dude trapped inside the MacBook Pro.

This looks like a clever band of rogues– I’m looking forward to seeing what designs they come up with. We chatted about 3d design for about half an hour and bounced some ideas around. The conversation really picked up when I suggested someone design and field a robot flamethrower.

Won’t someone please design an Open Source robot flamethrower?

More pix as I get ’em. These students are your engineering future, world. And they can’t wait to blow some stuff up.

Exploring the .thing file format

TL;DR summary: Scientists! And I like this file format.

These tokens are available as a pay-what-you-like download!


Buy this on Selz


Our house has its share of boardgames and several of them use tokens similar to these. One not-so-subtly encourages the consumption of sugar, and another suggests that dropping a load of dishes, no matter how well-intentioned and helpful the original intent of the carry, might shoot one down a slide of pain, shards, and ignominy.

I took the opportunity to replace the original tokens with images of scientists that have influenced me: Neil deGrasse Tyson, Carl Sagan, and Jane Goodall.

None of these icons of icons are wearing pants, which is OK because like the rest of us even great scientists have moments of pantslessness.

I had some trouble deciding which scientists to include in the set, because so many deserve recognition. The trick lies in distilling a person’s essence to an image that can be recognized when printed as a 3D cartoon. You could argue that, say, Michael Faraday contributed more to human understanding of the universe than Jane Goodall, but since he had the misfortune of living his entire life pre-television, almost no one knows what he looks like.

Dr. Goodall’s a tough illustration to do in the first place because she’s got the face of an everywoman– she could just as easily be your helpful neighbor next door, provided your neighbor totes binoculars and strokes chimps.

I think many science nerds of my generation have imprinted on Carl Sagan’s wide lapels and turtleneck, the same way today’s padawans will imprint on Tyson’s (more fashionable, IMHO, even given post-80’s style inflation) Celestial Vest.

Ok, on to the technical– if you came here from Thingiverse, this is what you’re here to read:

My usual workflow is Maya 2009->Wavefront .obj format -> Netfabb Studio Basic-> .STL -> ReplicatorG-> MakerBot print test -> zip -> Thingiverse.

Simple models can usually skip the Netfabb step– that’s just there to fix any polygon problems that Maya’s cleanup didn’t catch.

Still, that’s a lot of steps to get a model from concept to distribution, especially if a model has a lot of pieces like the Zheng3 Penny Catapult.

MakerWare simplifies this process by bundling all the .obj files into a single archive. All you have to do to peek inside a .thing is rename it from .thing to .zip and then open it up. There’s a .json file inside that contains translations, scales, and other metadata for each model, and an amusingly-named UNIFIED_MESH_HACK.STL where all of your
pieces are combined into one monster STL.

Why a .json file? Beats me. I can’t see anything in there that couldn’t be accomplished with half a dozen other plaintext file formats. The almighty oracle says that .json is used primarily to transmit data between a server and web applications, so I wouldn’t be bowled over with shock if somewhere down the road MakerBot integrated MakerWare, Thingiverse, and a paid premium model service.

But that’s just some random dude speculating about the future. Don’t hold me to anything.

Anyway, thought I’d give this new format a try for my new Scientist Game Token models, since they’ve got six separate pieces. If you want to print these models individually, you should be able to open the .thing file and import the .obj files into your slicer of choice. Failing that, Meshlab can convert them for you once they’re extracted.

Arranging the models is easy; drag and drop everything onto MakerWare. Click and drag to move them around, and CTRL-C/CTRL-V to duplicate the base model twice.

I managed to arrange the pieces nicely after a minute or two of fussing around, and along the way I came up with a feature list that would make the process smoother:

auto-layout: somebody smarter than me has to figure out a way to automatically lay out the pieces in their most efficient configuration with a single click.
• snap model to grid
• snap-align multiple models: this would be handy for making sure Neil DeGrasse Tyson’s base centers on his body. Aesthetics are important, even at the printing stage.
• drag to multi-select models: I was surprised that this wasn’t there already. One can shift-select models though.
• a keyboard shortcut to deselect everything
• nudge model using arrow keys

I imagine features like these will be forthcoming. After all, it’s a beta.

I’d also like to be able to easily add a plain-text annotation to a .thing file so I can include printing instructions and other notes. And a pony. I’d really like a pony.

I almost forgot: you can download these models here. They’re free and distributed under a Creative Commons ShareAlike license.

MakerWare Beta, First Impressions Update

Yesterday I had a little trouble with MakerWare holding my USB ports hostage, and I promised an update when it was resolved.

MakerBot Support got back to me within hours, and it was an easy fix. MakerWare runs a background service called conveyor: turning this service off (Services -> Stop Conveyor) freed up the USB ports and now I can run ReplicatorG again.

Relaunching MakerWare gets you this error dialog:

So I’m guessing that conveyor doesn’t actually control Makerbot’s not-yet-released heated conveyor belt, but rather is the service responsible for running multiple simultaneous slices?

I might give MakerWare another shot this weekend and see if I can get a print going. Updates as they happen.

MakerWare Beta: First Impressions

TL;DR summary: I’m avoiding this software for now. It’s borked my USB port and made my Replicator shake violently using MakerWare’s default settings for PLA printing.

I can still print from the SD card, so I’m not completely dead in the water.

Frustrating and kludgetastic, but I’m sure I’ll get to learn something about the inner workings of USB drivers by the time all this is done.

On the plus side, MakerWare has some nice usability improvements over existing software, even if it needs a little UI love. Miracle Grue is insanely speedy slicing software.

My goal is to evaluate this software as a 3D printing hobbyist who’s big on ease of use and good UI design. Also keep in mind that MakerWare’s still in beta, so I wasn’t expecting a flawless performance.

Ok, on to my experience. I’m using a MacBook Pro running 10.6.8.

Startup: Launches quickly and automatically recognizes that I have a Dual Extrusion Replicator connected. Nice.

Navigating around the virtual build platform is easy. Wacom tablet support would be nice: a middle-click and drag to zoom in and out would replace the scroll wheel functionality that I don’t have.

(After 12 years of exclusive Wacom tablet use I find it amazing that anyone can or would make art with a mouse.)

I’d prefer to see the MakerBot branding moved to the title bar rather than taking up screen real estate, but that’s a quibble.

I’ve decided to use one of my Seej models as a test. I chose the Rubble Bloxen because I know the mesh is pretty dense: I sculpted it out of banana bread and then scanned it with Autodesk’s 123DCatch. Lots of polygons for the software to chew on here.

I import the bloxen and click “Make It.” This creates the slicing dropdown.

I choose “High Quality” settings and then (mostly by instinct) click the Advanced tab. The default settings for PLA seem a bit hot to me, but that’s an easy change: Just drop the extruders to 190° and the HBP to 65°. Easy peasy mac and cheesy.

It’d be nice to be able to save my preferred options as a preset, but I don’t see that functionality yet.

I hit the “Make It” button and I get a Slicing progress bar that hangs at 0% with no apparent way to cancel. The rest of the app seems responsive, though: I can still move the bloxen around the virtual platform, rotate it, etc.

The rubble bloxen is a complicated model, though. Maybe it crashed Skeinforge? Let’s try this with something different.

I quit and reboot, and my slice windoid is still there. This feels buggy. (Keep reading, it isn’t.)

I load up an example STL: Mr. Jaws. Click “Make It” and the Slicing dropdown appears again, with default settings. It’s a little disappointing that the settings I added last time haven’t stuck.

Still, it’s a Beta, so let’s not get too worked up about it.

Now I have a second slicing windoid, that’s also stuck at zero percent. Let’s try this again, one more time.

While I’m poking around doing other things, I notice that one of the windoids has started updating its progress bar! This must be the rubble bloxen finally getting its slice on after five minutes.

The software’s not buggy, it’s actually continued a slice after a quit and restart. Very cool.

I’ve blundered into cancelling a slice. Got to click the Bot’s icon in the lower right corner. This doesn’t make a lot of sense to me. The Bot isn’t doing the slicing, my laptop is! Putting a cancel button on the slicing progress bar would be more intuitive.

Ok, so I cancel everything out and start fresh with a single model, the Rubble Bloxen again.

Import the STL. No problems there. I’ll move it around a bit just for fun.

I disagree with the function names “Move” and “Turn.” It feels a little dumbed-down and non-technical. I’m imagining I’ve just bought a cutting-edge piece of 3d printing hardware, and I want to feel like I’m using some massively powerful software with it. “Move” and “Turn” feels too toylike for a prosumer device. Give me translate, rotate, and scale, please.

I rotate the bloxen just to explore the UI a little. Makes sense, easy to use, no surprises. Free rotation is easy, but it would be nice to constrain the model to 45° rotation increments by shift-dragging.

Same goes for duplicating the bloxen: I’d like to be able to option-drag the block to duplicate it, but that’s Photoshop reflexes talking. Not a major feature requirement, and Copy/Paste does the job.

Being able to reset the SRT values is a nice touch.

I hit “Make It” again, and this time I’m going to use Miracle Grue for slicing. Bre Pettis was pretty stoked about a rapid slicing algorithm in the launch webcast, so let’s see if this is it.

Wow! That progress bar that stalled at zero with Skeinforge goes from zero to printing in less than ten seconds with Miracle Grue.

My first print goes straight to la-la-land and fails. So I click “Make It” again.

I have to re-enter my settings.

I hit “Make” and the second print fails, too. I suspect that my extruder head travel settings are too fast, so I check and sure enough the defaults are set way, way higher than I’ve been used to.

My HBP doesn’t appear to be warming to 65° like I told it to, either. Strange. It’s stuck at 16°.

After six attempts I finally gave up trying to print something. I hop over to ReplicatorG to see if something’s up with my Makerbot. Can I print a rubble bloxen with ReplicatorG?

Uh oh. It looks like MakerWare is hogging the serial port even after a quit. Unplug? Replug? No. Reboot? Still no. Shut down and restart? Uh oh. No.

I can’t use ReplicatorG over USB anymore. This is a problem. I launch MakerWare just to see if it still works. Sure enough, it does. Connects to the Replicator no problem. I try a test print, using the default Medium settings on Mr. Jaws.

It prints. But the print is so violent that I end up canceling it after two minutes, just so I don’t have to recalibrate my HBP. It’s literally shaking the Replicator and tabletop.

This behavior might be OK with a heavily-reinforced Replicator 2, but my little plywood buddy looks like it’s having a seizure. Cancel, cancel, cancel.

I’m done. MakerBot support has been very responsive in the past, so I’ll post an update once they get back to me.

Welcome students!

The flashing bank of indicator lights on this blog’s control panel just started going crazy, which means that we’ve got another Seej tournament on our hands, somewhere in the world.

If you’re an engineering student and you’ve got a Seej-related assignment, welcome! I’ll be happy to help in any way I can. Ask questions in the comments below, or email me privately at jim@zheng3.com if you want to keep your opponents from discovering your nefarious plans.

Or find me on Twitter, I’m @Zheng3_Jim.

D&D Dice Box

UPDATE! You can Download this model for free and print it yourself on a 3D printer. Or zip on over to Pinshape and download version 2.0, which includes a secret trapdoor!

Plinth is one of those words that doesn’t come up very often in conversation very often, unless one is a student of art history or architecture. It’s included as one of the basics in my Tuttle Learning Chinese Characters book, 础 (chu, third tone) as a foundational character, but I can’t see where I’d work it into my pidgin asking for extra towels at a Beijing hotel.

There’s a lot of Dungeons and Dragons going on these days at Casa de Zheng (or, as they say in Stuttgart, Zhenghaus,) so naturally we’ve got a proliferation of dice sets.


Dice arrive from the comic book store in these clever little boxes. I can’t print in transparent plastic (yet) so for now I’m limited to printing customized plinths for lil’ necromancers.

Failing a Save Against Platonic Love

My kids have started playing Dungeons and Dragons (they got into my trove of old Second Edition gear and haven’t stopped reading the Player’s Handbook since) and so with all the dice rolling I’ve had polyhedra on the brain for the last month or so.

Dungeons and Dragons dice are a subtle gateway to the study of geometry. They’re the Platonic Solids, something I didn’t realize until well after my first exposure to them in 3rd grade.

Designing these Dodecanode connectors (which you can download for free here) has started me on an adventure into the Underdark of less-than-basic geometry.

I struggle with arcane lore from long-forgotten tomes; dihedral angles taunt me from the shadows and the golden ratio remains tantalizingly out of reach beyond that door.

I’ve become dimly aware of the existence of Schläfli symbols, which might as well be Sindarin for how well I understand their runes.

I thought I was doing well when I relearned how to compute a vector cross product creating Cryptstone Challenge, but I’ll have to level up before I return to explore this maze of twisty passages, all alike.

Design notes: this is printed with PLA on a MakerBot Replicator. You’ll note that the Replicator (and every printer like it– Ultimakers, RepRaps, etc) has trouble printing shapes with too extreme of an overhang. Look closely at the cruciform bores.

The vertical bores print just fine, so I’ve included two models in the zip archive. Grab yourself a package of craft sticks and have a good time building.

Beware a nascent interest in geometry though– it’ll sneak up on you, and that’s a journey from which few return unchanged.