Category Archives: seej

I Can’t Print This On My Replicator


Fused deposition modeling (or fused filament fabrication, if you want to avoid a nastygram from the legal eagles at Stratasys) is the process by which Makerbot Replicators, Afinia H-Series printers, Cubify Cube 3Ds, Repraps, Rostocks, and too many homebrew printbots to enumerate turn STL files from electrons into objects.

In FDM/FFF printing, the device lays down a layer of melted plastic, moves its build platform downward a tiny bit, and then repeats the process until the model’s completely built.

I’ve had my Replicator 1 for about a year now and I think it’s safe to say that I’ve put it through its paces. I’m pretty good at 3D printing with this particular FDM printer. I understand and work around its limitations, paying close attention to the 45-degree rule. FDM printers generally can’t print too large an overhang from one layer to the next; gravity interferes and the print fails with often hilarious results.

A few months ago I designed a model that I knew had no real hope of ever printing on an FDM printer. I wanted to see what Shapeways was capable of printing for under 20 bucks, so I built a Voronoi Seej bloxen and sent it over to them. A few days later this showed up in the mail:


You’re welcome to give it a shot yourself: just download the model. I’d be interested to see your results.

A cutaway view demonstrates why the Voronoi bloxen fails on an FDM printer. Most of the model’s OK, but it violates the 45-degree rule in a big way right at the top of the block.


The print at the top of the post was my first try at printing this bloxen on my Replicator. Those tiny Voronoi cells on the bottom of the model make it really hard to keep the bloxen on the platform. If any one of those little filament loops should detach from the platform, it’ll eventually get caught on the print head and catch another loop, and another, and another, and once your model is touched by His Noodly Appendage, it’s done for. Ramen.

Those little loops need to stick fast to the HBP So it’s back to FDM Printing 101: using a raft.

After a new slice, the Replicator had no problem keeping the base of the bloxen on the build platform.


A few minutes later it looks like the Voronoi pattern is holding up well. The mortises on the bottom of the bloxen are printing just fine. I’m starting to think this print might just succeed…


…aaaaand the 45-degree rule rules its ugly head and the print starts to fail as predicted right at the top of the bloxen.


As fails go, this one isn’t spectacular. Enough filament fell into the gaps to provide a scaffold for the top layers. The bloxen is still a fairly solid print, certainly usable in a Seej match.


So. Another failed print. But there’s still hope for those of us who haven’t been able to secure $30 million in venture capital funding. I’ve been corresponding with Dean Piper, inventor of the mUVe 1 printer. Dean took up the challenge of printing the Voronoi bloxen, and his resin-based printer knocked it out of the park:


I feel like home 3D printing is in the VHS vs. Beta stage of its history. On one side we’ve got superior market penetration of FDM printers, but resin-based machines like the mUVe are going to be the bots to watch in the next few months.

Erk. Almost forgot: this post is the latest in my continuing one-man crusade to make “Voronoi” the word of the year for 2013.

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The Quickstone Challenge


download

It’s been some time since I posted a new Seej model. I got tied up with work for couple of months and then I got on to making Magic: The Gathering Tokens, and new Seej work kind of fell by the wayside.

Plus I’ve been working on getting the Forge going, and the Scrying Pool, and I’ve been dusting off my long-unused PHP chops, and also managed to develop cubital tunnel syndrome in my left arm to match the carpal tunnel in my right.

So here’s a quickie as I dip my toes back into the moat. I’ve designed the Quickstone bloxen with paper-thin walls and internal supports to print as rapidly as possible.

Look at the red bloxen in the photo above and you’ll see the backlit mortises self-inverting to become tenons.

My best print time on a Replicator 1 with default firmware and ReplicatorG is 27 minutes.

There have got to be übernerds out there with pimped out RepRaps who can smoke that. I’m particularly interested to see how quickly someone with a b9Creator, Form1, or mUVe can do it. The internal supports on the Quickstone are built for the limitations of an FDM printer, but could probably be deleted if you didn’t have to worry so much about gravity during the printing process.

Can you knock Lao Zheng off the mountain?

First, visit The Forge and download the Quickstone bloxen. (It’s buried under Forge -> Seej Models -> Fortifications.) Then email me with the deets on your slicer, your printer, and your results. Pics or it didn’t happen.

Here are the settings I used:

Replicator1 Dual (using single head)
Infill: 0%
Layer Height: .3mm
Shells: 1
Feedrate: 75 mm/s
Travel Feedrate: 75mm/s
Print Temperature: 240°C
HBP Temp: 110°C
ABS Natural

A few rules:

  • We’re on the honor system here. No fibbing.
  • Cram as many 1:1 bloxen into your build area as you like, and measure your time in bloxen per minute.
  • Slicing time is not included in your total.
  • The bloxen must print in one piece.
  • The bloxen must be usable in a Seej match. If it can’t withstand a firm squeeze, it’s no good.
  • you can modify the bloxen’s geometry, but under the terms of the CC license you must make derivatives available to others. I can host your model in The Forge, or I’ll link to the site of your choice.

Have at thee!

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An Emerging Symbiosis

I’ve read plenty of articles that boil down to, “What is LEGO going to do in The Future, when anyone, ANYONE! can print their own LEGO kit in their basement?”

One can swap LEGO with whatever $manufacturer you choose: Tinkertoys, Lincoln Logs, K’Nex, Colt Firearms. (The 3D printing of firearms is a topic I’ll visit sometime soon, but for now let’s stick to things you can buy at Toys R’ Us.)

The implication of these articles is often that $manufacturer is ultimately screwed. Sooner or later, The Future will arrive and $manufacturer‘s revenue stream will dry up as we all print their products willy-nilly in our living rooms.

I see things differently.

This afternoon my son was playing with the new K’Nex set graciously provided by Grandpa and Grandma. He couldn’t find the one gray piece he needs to finish his roller coaster, so I volunteered to print him one.

Thingiverse doesn’t have the specific piece I need. Nor should they; K’Nex owns the rights to their designs and they deserve to profit from them. They’ve invested the capital in building their factories and hiring designers, and it’s their right to enjoy the fruits of their efforts. Thingiverse probably doesn’t want or need the legal headaches associated with hosting knockoff models of popular toys.

(I just realized I’m making arguments similar to those made by drug companies. Maybe there’s a path to The Future where designs go “generic” after a couple of years so that $manufacturer has an incentive to continue creating new ones? I digress.)

So Thingiverse doesn’t have the piece I need, but they do have pieces from the Universal Construction Kit, which lets one link toys that weren’t designed to be linked– Tinkertoys to Lincoln Logs, Duplo to K’Nex, and so on.

So I grabbed a K’nex -> Duplo connector, did a little vertex surgery, and now I have the piece I need as a 3D model.

knex

To print!

This is what I got, printed in red ABS. Note the difference between my bootleg copy and the original. Cue sad trombone.

knex_fail

You could argue that the MakerBot Replicator is *the* top-of-the-line home 3D printer. There are others in its price range that have more or less the same capability, and if you go an order of magnitude more expensive you can get yourself a small industrial quality prototyper with superior resolution.

Part of this failure is surely inability to configure my printer settings properly, but I think a larger part of it is that the Replicator just can’t print this precisely yet. K’Nex parts are cast in ABS, which effectively means they’ve got molecular-level resolution. No way I can get that on my desktop in 2013.

A further limitation of the additive printing process is those overhangs– even if I could get the resolution right, gravity would pull those long grooves down and make the part significantly less K’Nex-able.

You might get around this by printing the entire piece as a column, but my experience in printing toothpicks vertically is that they tend to fail.

So K’Nex gets a pass until the resolution of home 3D printers increases. Maybe the Form1 will be able to do it. We’ll have to wait until the Form1 is out in the wild to see. I’m hopeful, because right now a lot of my ideas are limited by resolution and gravity.

What about lower-resolution objects, like Tinkertoys? Tinkertoys are well-within the resolution range of the Replicator. I’ve already made a couple of Tinkertoy-compatible items.

apple

There’s nothing stopping me from printing a Tinkertoy clone right now except time, but the manufacturing process that makes Tinkertoys at gets them to the toy store (or, in my case, Amazon) is so much more efficient than a Replicator that it just doesn’t make sense, it can’t *ever* make financial sense to print these toys at home unless the price of plastic feedstock drops to near zero.

(Ultra-low-cost feedstock might happen with a descendant of the Filabot Reclaimer, but it’s not here now.)

So I don’t see home fabrication of toys taking off anytime soon, but here’s what is happening. People are using their 3D printers to extend the capabilities of their existing toys.

gears This is the emerging symbiosis: traditional manufacturing is now and likely will forever provide the base of the mass-market toy experience, cranking out LEGO bricks and Lincoln Logs by the millions. Home-based 3D printers will make small production runs for niche items– gears that extend your Tinkertoys, wacky Lincoln Logs accessories, and the like. Over time, $manufacturer will adapt to the proliferation of high-resolution home printers by offering certified premium models, guaranteed to be interoperable with their mass-manufactured cousins.

zheng3_penny_catapultIn short, I think 3D printers aren’t going to kill the toy industry, they’re going to make it much more creative. And haven’t even mentioned new toys like Dutchmogul’s Pocket Tactics, or my pet project, Seej.

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Seej bloxen, Ransom

I put this model on Thingiverse a couple of days ago but forgot to put it up on the blog. This is a hollow bloxen for Seej with an articulating door. Players place small wager items inside their own ransom bloxen. Winner takes all.

ransom

Some of the Ransom Bloxen’s design DNA comes from this dice plinth, in particular the flagstones on the base.

ransom_underside

I’ve carved out geometry for an articulating door hinge, but the Replicator’s resolution is too low for it to print; we’re in the sub-millimeter range here. Note that the tiny (and skeuomorphic) rivets print just fine though.

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Casting about for new ideas.

I’ve been using my MakerBot to make things to make other things, and here’s my first effort: sidewalk chalk molds in the shape of Seej bloxen. Casting with plaster is a lot of sloppy fun, especially for the under-12 set.

I’m not an expert caster, but here’s what I’ve come up with to get a consistent product out of this mold.

First, liberally smear all interior surfaces of the mold with a lubricant of your choice. I used petroleum jelly, but I imagine anything greasy would work: Murphy Oil Soap, a little EVOO, liposuction byproducts, whatever you have around your workspace. This will help you remove the finished product from the mold at the end of the process.

Mix the plaster and water according to the instructions on the package, generally about 2 parts plaster to one part water. Add a little pigment and mix well. Let the plaster sit for a minute or two once it’s mixed.

Snap the two halves of the mold together and fill it about 2/3 full with plaster. Tap the mold on your work surface a few times to remove air bubbles and make sure it gets into all the corners. Fill the mold up to the bottom of the mortises, and gently insert the tenons.

A little bit of plaster will bloop out. Wipe it off, tap tap tap the mold on the work surface, and then elastic band it together.

If you’re not using any pigment, let the mold sit for about 45 minutes before removing it. If you’ve mixed some powdered paint into the plaster, let things sit for at least 90 minutes. Four hours is too much, it’ll make the bloxen difficult to get out of the mold.

While you’re waiting, call your grandma. She misses you, and you never use all your minutes anyway.

Remove the base of the mold first, and then one side. It might help to gently wedge the mold apart with a screwdriver or chisel.

Getting the bloxen out of the second half of the mold can be a little tough. I recommend tapping the mold smartly on your work surface a few times and then wiggling the block out. Putting the mortises back into the plaster bloxen might give you some leverage, too.

Then let the bloxen rest until you’re ready to use it. A day or so of resting will give you a dandy piece of sidewalk chalk.

Using the finished products for their intended purpose might mean you have to go outside for a few minutes. May cause interaction with small children, who have germs.

Temporarily discontinue use of vitamin D supplements if you frequently leave the house for extended periods of time.

Download these models for free from Thingiverse.

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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.

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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.

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