Squelching Squigs

Squigs. Sometimes we get them when 3D printing with extruded filament. Usually they’re the result of too steep an overhang in a model; there’s not enough shelf on layer X for the printer to lay down another layer of plastic on layer X+1, and gravity pulls the newly extruded filament downwards.

A squig is born. Small squigs are usually just an aesthetic issue, but larger ones will cause your print to be touched by His Noodly Appendage and then you’ve got a build plate full of plastic ramen. Not good.

I’ve entered into mass production of the Athena Makeover Kit as Faire Play rewards, and I’ve discovered a small problem. Every few prints something on the printer goes to Wally World and the spear’s clip gets all squiggy.

The clip’s strength is compromised and besides, it just looks fugly.

clip squig

Some of these Athena Makeover Kits are destined for the hands of folks who have never seen a 3D print in their lives. We can’t be giving them a bad impression of the technology’s capabilities.

Fortunately, it’s an easy fix. I’ve updated the clip to be just a little thicker at its junction with the shaft, which both makes it sturdier and eliminates the squig spawning grounds.

clip after

I also added a little bullnose between the shaft and clip, because I find 90° angles at transitional edges between volumes to be unlovely.

bullnose

Troubleshooting a Shapeways Print

April Fools’ Day (愚人节) has come and gone and, to the Internet’s credit, most folks weren’t taken in by my last post, Printing With Steel on the PrintrBot Simple. Good on you, clever people.

But now the blog post just lurks there, context-free and malignant, a coldly crystalizing piece of unexploded Internet ordinance, waiting to disembowel the unwary traveler who pays no heed to timestamps.

Also! Faire Play’s funding period is winding down and only a scant five days or so remain before pre-production on Barbie’s parade armor is set to begin.

Shapeways managed to deliver the first metal proof of one of Faire Play’s backer rewards ahead of schedule! I was expecting this steel Aegis Pendant to arrive after the funding period, but we got a little lucky this week.

Here it is, printed in polished gray. I’m impressed with how well Shapeways was able to reproduce the meandros motif on the shield’s face.

pendant

I’m a little less enthused about the stepping patterns on the gorgon’s face, but I think I know how to fix it. First, a simplified explanation of how 3D printers do their thing.

Hobby 3D printers and Shapeways printers’ work on basically similar principles. First, 3D models are digitally sliced up into multiple layers from bottom to top. A print head traces a pattern on an XY plane for each layer, either putting down a thin bead of hot plastic or sintering tiny particles of steel powder into a solid form.

Once the XY pattern for the first layer is completed, the printer moves up one layer and repeats the process.

unforeseen problem The moiré patterns on the gorgon’s face are an artifact of the printing process. If you look carefully you’ll see the divisions between layers, like elevation lines on a topographic map.

macro

Rotating the model 90° on its X axis might mitigate these artifacts. I’m fairly confident that the face of the pendant will be smoother if Shapeways’ printer prints the pendant as if it were balanced on its edge rather than laying on its back. This kind of edge-on printing isn’t possible with a hobbyist 3D printer, but shouldn’t be any problem when the developing print is suspended in Shapeways’ matrix of steel particles.

I’ll check with the gurus at Shapeways and see if this is possible, or if they’ve got some kind of auto-orientation function in their printing software that I can’t do anything about. #staytuned

Printing With Steel on the Printrbot Simple

printrbot

One of the most popular pages on this blog is Calibrating the Printrbot Simple. To be honest I haven’t been using my Simple much lately, what with the hullabaloo surrounding my Barbie-Compatible 3D printed armor Kickstarter. Just don’t have the time.

My mental juice can’t be occupied by all Kickstarter, all the time, so I took a few hours to mess around with Mr. Simple, and I decided to try an experiment that’s long been tugging at my frontal lobes. Can I print something recognizable, in metal, using my Printrbot simple and some clever engineering?

There are hobbyist metal printers on the way. I saw Vader Systems’ prototype at Maker Faire NYC, and can’t wait to get one of these bad boys into the basement at Zheng Labs.

But! Enough wishful thinking. Let’s get down to brass tacks.

I’m using baling wire for this project. You can get this stuff at any hardware store. Just make sure it’s not galvanized, because that can give off some nasty zinc fumes when it’s heated up. Also, I highly advise wearing protective gear.

wire

warning Attempt this project at your own risk! There is an excellent chance that you’ll completely junk your Printrbot, or at least melt the plastic collar at the top of the extruder nozzle. Have a fire extinguisher handy, just in case. Goggles, gloves, the whole nine yards. Be smarter than I was: under no circumstances should you down three mimosas before trying this, no matter how much fun you were having at brunch.

As a precaution, you’ll also want to cover the print bed in fire-retardant tape, unless you’re willing to deal with a flaming Printrbot.

I’m planning on doing this repeatedly, so I replaced the Printrbot Simple’s print bed with a piece of asbestos tile instead. Yay for Open Source!

I just redid the kids’ room with asbestos tile and had some left over. It’s cheap and durable and I can’t believe people just throw this stuff away. Watch this space for a blog post about turning old asbestos tile into cutting boards; I’ll be putting them on Etsy once I’ve cut a dozen of them or so.

Temperature is everything here and you’ll have to move quickly once you start, so be sure to have your gCode pre-generated. Don’t waste time slicing the model before you print.

Preheat the extruder as high as you can get it. I managed to get mine up to 275°C by disabling the firmware safeties and working under heat lamps in the basement. (Printrbot firmware hacking is a topic for another day.)

Even 275°C is way too low for melting steel, so you’ve got to help the Simple across the finish line by heating your baling wire up with a propane torch. Depending on the alloy of your wire that means somewhere around 1400°C, which should be within the range of a hardware store torch.

tip

Start the print and gently feed the hot wire into the Simple’s extruder. I epoxied a steel washer onto the collar of the extruder nozzle to protect it from the hot wire. Don’t lick the glowy part!

The print was a miserable failure, just your typical tangle of filament touched by His Noodly Appendage, ramen. This is what happens when you leave steel prints unattended:

print failure

The second time through I stayed with the print, keeping the propane flame focused on the wire as extruder pulled it in.

feed

With just a little filing and polishing the nose ring looks way better than I expected it to. Not bad for a printer kit that retails for $300, even if I did have to babysit the print the entire time.

yurenjiekuaile

Permit me a brief foray into my other hobby, studying Mandarin Chinese. It’s a remarkably concise language, so cramming the entire One Ring poem (to find them, bind them, yadda yadda yadda) onto the side of the ring is easy peasy lemon squeezy.

You can compress the whole poem into five characters, 愚人节快乐. Way fewer than required in the Black Speech of Mordor.

Flagrant stagecraft alert: I printed the ring and nose separately and welded them together afterwards; I haven’t tried printing anything with support yet.

You can download the STL files for the nose ring in the Baubles section of The Forge, or if you’re impatient or don’t have a 3D printer just grab one from Shapeways.

Pro tip: I found that copying my gCode into OpenOffice, coloring it pure red (#FF0000), and then re-pasting it back into Repetier-Host helped me get the extruder nozzle up to 282°C the second time around.

Faire Play Funding Goal Reached!

Yesterday, thanks to the combined efforts of 238 individual backers, Faire Play reached its funding goal of $5000 USD. I couldn’t be happier, and I’m very excited to begin work on the parade armor.

I’ve created a digital token of gratitude for my backers and social media enablers: the Faire Play Recurve Bow.

doll with bow

You can download the bow and quiver right now, for free, for real, no strings attached, from The Forge. Print it out and send Barbie to the range with Katniss and Merida.

This bow is sculpted from organic, locally-sourced vertices, filtered and purified from the droppings of only the mimsiest free-range borogoves, and it’ll fire a 6″ cosmetic swab across a room with dismissive ease.

The flood of support and media attention that Faire Play has received has convinced me that a not insignificant portion of the world wants to see Barbie wearing and bearing more medieval armor and arms.

I’m a huge fan of Giving The People What They Want, so I’m announcing a modest stretch goal.

If our little community can add another $1000 to the Kickstarter’s original goal, I’ll redesign the bow so that it can be printed as a single piece on Shapeways. Then anyone, anyone! will be able to make their Barbie dolls deadly at a distance with a couple of clicks. My initial tests show that Shapeways should be able to print a bow for less than $10.

During the redesign, I’ll naturally be making the bow and quiver more elegant and lovely than they are now. The quiver in particular will be a fascinating design challenge; to keep printing costs down I’ll have to remove as much material as possible from the design without compromising utility or strength. Fortunately, I live for this kind of thing.

And mascarpone with green apples. I live for that too.

So thanks everyone. This project has been a wonderful experience so far and I’m really looking forward to the next step.

If this is the first time you’ve heard of Faire Play and you’re all like whazzat? here’s the original Kickstarter video. TL;DW: It’s Barbie-Compatible 3D printed medieval armor.

Oooo! One more thing I’ve been meaning to get to! Last week I was interviewed by @dutchmogul and friends for their Go For Rainbow podcast. We talk about design and 3D printing, and eventually segue into discussing video games. Fun stuff, give it a listen.

On Wonky Geometry

The Faire Play Kickstarter is doing great: 17 days and 8% to go! Go give it some love if you’d be interested in seeing Barbie don some 3D printed medieval armor.

The Athena Makeover Kit’s been out in the wild for twelve days now and there are several photos of prints floating around the internet. I’ve collected two of them here.

First: Bill Owens’ print of the AMK with a cut-down spear to fit his printer’s bed, with tunic hand and machine-sewn by Maddy. Nice job, Bill and Maddy!

Bill has made some suggestions for improving the boots, which I’ll be taking into account when I release the final STL files to backers at the end of the Kickstarter.

owens large

Second, Josh Ajima’s hot-pink Aegis print, shown here with a Percy Jackson figure. Love this one.

percy jackson

Josh also made a modification to the aegis clip that will help it fit other Barbie dolls with inflexible wrists. You can download it from Thingiverse. Creative Commons licensing roolz.

5mm clip

Mr. Ajima blogs at DesignMakeTeach.com, and has all kinds of great resources for STEM educators over there.

If you’ve printed an Athena Makeover Kit, Send it my way with as much info about yourself as you care to reveal, and I’ll get the photo up on the blog toot sweet.

Early printers of the AMK might have noticed some fugliness at the intersection of the shield and medusa. To wit:

aegis fail

I’ll fall on my sword for this oversight; my initial prints handled this intersecting geometry just fine, but other folks using different slicing software have had some problems with this. Here’s what it used to look like in wireframe:

bad geometry

See how the medusa is just kind of jammed into the shield face and creates some intersecting geometry? That’ll print, sure, but it’s a less-than-optimal solution to the problem. We here at Zheng Labs prefer to minimize less-than-optimal solutions.

So! Here’s what it looks like now. I’ve welded the vertices together and now the mesh is watertight as the proverbial frog’s ass.

joined geometry

The final print result is now much improved. Go on over to The Forge and Download the latest and greatest model.

aegis better

Can’t wait to see your prints.

Finding Sparky’s Voice

In early February I debated whether to make a promotional video for my Kickstarter. The 3D modeling was done, the armor was printing reliably, and I figured the concept of 3D printed medieval armor for Barbie dolls would just about sell itself to the right crowd of people. Did I really need to invest the time in making a video?

SPOILER: I ended up making the video.

I dithered and hemmed and hawed for a day or two while I weighed the pros and cons of investing even more time in the Kickstarter. Eventually the creative itch won out over the practical hurdles of lighting, shooting, and editing with less-than-professional tools (my vendetta against Apple Motion 5 continues unabated) and after much gnashing of teeth and rending of garments I released this to the world:

I’m glad I did because people really seem to enjoy it. It’s also on Youtube and Vimeo now, BTW.

Acquiring scenery and minifigs for the video wasn’t a problem, but I clearly needed a Big Bad. I rooted though every bookshelf and toybox in the house and came up empty. The Zhengspawn are growing up quickly, and are more interested in playing with software than they are with plastic. Clutter is the enemy, so only the most cherished or useful toys remain in the house.

Candy Crush is also the enemy, but no matter how many stakes, silver bullets, DDT, UV, and Slim Whitman Indian Love Calls I use, I can’t seem to rid Zheng Labs of that particular infestation.

Last year’s purge resulted in an unfortunate paucity of plastic dinosaurs in the storage tubs, just when I needed one the most.

Ever supportive, the Lovely and Talented Mrs. Zheng3 dropped by the local thrift store, popped some tags, and returned with Sparky. She found him in the discount bin for a dollar, on account of his non-functional pushbutton speaker.

Sparky is a generic-looking therapod carnivore with very broad feet. Artistic compromises were clearly made during his design, but I think the size of his forearms pegs him as a reasonable attempt at an Allosaurus, with a little pre-1990′s tail anatomy thrown in for stability’s sake.

sparky full

I’ve spent a lot of time with Sparky, and now I’m curious about his origins. Somewhere on the Internets there’s an expert on cheap plastic dinosaurs who can take one look at Sparky and identify him immediately. Until that person surfaces, our only clue is a “MADE IN CHINA” stamp between his legs, which narrows his origin not at all.

The wear patterns on Sparky’s maw, brow, and toes suggest that he was extensively played with in the past. He’s definitely attacked his fair share of villages. Sparky, at some point in his life, was loved. The discount bin would be too ignominious an end for such a loyal toy.

wear pattern

To the workbench with you, my Jurassic friend.

Whoever sculpted Sparky did some nice work, especially with the reticulated scale patterns on his skin, but the person or people who inserted his speaker botched the job a bit; I think a hole saw was used to access his chest cavity but the opening was messily enlarged with a knife at some point before the speaker was jammed inside.

sparky hole

With some prying and pulling I’m able to extract the speaker assembly, hopelessly mangling it in the process. It uses two LR41 batteries, which are easy enough to come by, if redonkulously expensive when purchased as singletons.

Sparky’s noisemaker is a simple affair. A speaker is connected to a small circuit board, activated by a (gray) plastic plunger that completes the circuit by touching that solder squiggle in the middle.

But wait, you say? How does nonconductive plastic complete a circuit? There’s a circular swatch of black, conductive somethingorother glued to the bottom of the plunger. Any EE’s who swing by, please tell me what this stuff is called, for curiosity’s sake.

If you squint and turn up the contrast on your monitor you can see a dark circle in the southwest corner of the circuit board. That’s where the recording of Sparky’s voice is stored underneath a blob of epoxy. A little more on that later.

speaker

Two fresh batteries later, here’s what Sparky sounded like straight from the factory. Turn your speakers down, it’s a bit unpleasant.

Hmm. That roar sounds familiar. Here’s Godzilla, king of monsters:

Here’s the two of them, side-by-side with a little bit of audio cleanup in Audacity. Sparky is first, followed by Godzilla. Big G is sped up by 90% with an accompanying change in pitch to make Sparky.

waveforms

It appears to me, at least, that someone just ripped off Godzilla when Sparky was made. I’m offended.

A little research tells me that I won’t be able to hack Sparky’s audio chip and record my own roars. Apparently the audio is burned onto an IC at the factory and then covered with a little black blob of epoxy. “Flip-chip” technology, this sorcery is called, and working with it is beyond any magic I possess at Zheng Labs.

I’d love to be able to hack these chips because they show up everywhere, especially in Happy Meal toys.

I do have a toolbox full of electronics, and I might be able to cobble together a replacement roar for Sparky after the Kickstarter is finished. At the very least, I can print him a new bezel for his speaker today.

sparky fixed

Guy can’t be walking around with a nasty hole in his chest, now can he?

Also. All the time I’ve spent on TVTropes? It actually paid off: see how many tropes I managed to cram into one video, and post in the comments below:

I’ll give you the second one for free: Action Girl. Or is it Badass Princess? Reasonable people can disagree.