Monthly Archives: April 2014

All That Glitters: A Tale of Shock and Au

In second grade I was exposed to the concept of Raw Umber when I laid covetous eyes on the well-to-do kids’ crayons, with the sharpener in the back and the 64 colors and the full-priced hot lunch with no unintended seasoning of classism sprinkled on top.

I made do with reliable BROWN, but was at least primed for fifth grade when I had some mental connection to the Umber Hulk in the 1st Edition Dungeons and Dragons Monster Manual.

Everyone sees color differently; every printing press and every monitor is a little different from its siblings, and so other industries have put tremendous time into standardization of color. PANTONE is the gold standard for print, and even the crummy, now-archaic NTSC made at least some effort to keep colors consistent across platforms.

The world needs PANTONE for 3D printing filament.

gold variants

OK, so check this out. My Faire Play Kickstarter was a success, and now I’m into printing rewards for backers. I used up my first two rolls of this gold PLA printing Athena Makeover Kits. It’s the gold you see all of the Faire Play photos to date. Unfortunately the distributor I was using seems to have run out of this particular gold and I can’t find another roll anywhere.

So I picked up a new spool off Amazon. The vendor used the same stock image of “GOLD PLA FILAMENT 1.75” as the earlier filament, so I says to myself, “Self, just how different can these be?”

I’m used to some variation between batches of filament, but these colors are wildly different. The leftmost spear is the new gold, which looks more like Butterscotch to me.

Butterscotch is kinda gold, I guess? But definitely doesn’t match the original gold used in the aegis and center spear.

These weapons are going to be used to arm Barbie dolls. Can you imagine the Queen of Fashion wearing an outfit that doesn’t match? Horrors.

This will not stand. So Butterscotch gets relegated to the noble, but inglorious role of prototyping feedstock. The world needs ditch diggers too, Danny.

I try again, with a new gold filament. This is the rightmost spear. Still not a match. It’s a more lustrous, metallic gold, but still wildly different than the gold I’ve been using.

So it’s back to Amazon to twiddle my supply chain again. This time I print some winged boots:

gold boots

Nope. Completely different, once again. This time: same distributor as my first two rolls, different tone. Original gold on the left, newest gold on the right.

I like the antique look of this one, so I’m going to call it Burnished Gold.

I’m making excellent progress on printing the fifty or so Athena Makeover Kits that I need to ship to backers. Everyone’s kit will be an internally-consistent match in one of three gold tones.

No Butterscotch, though. It be fugly.

Shucks. Now that I’ve been chewing the cud of this blog post, I’m convinced that somebody’s gotta dig this ditch and create a standard.

I can’t think of anyone else dumb enough to try it, so 毛遂自荐。 I’ll volunteer. Filament manufacturers. Start sending me samples and I’ll develop and curate a color standard. I’ve always wanted to learn SQL anyway.

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.