Wood

One last experimental filament: wood. This filament is a mixture of plastic and fine-grained wood fibers, alleged to produce a wood-like look and feel. Sounded fun, so I ordered a small roll. Long story short: not bad.

The first bit of difficulty with this is that it comes loosely coiled in a bag, secured with a zip-tie, rather than on a spool like other filaments. I think it's because the filament is relatively brittle, so it can't be wound as tightly. OK, but how do you put it on the printer? You could cut off the zip-tie and put it on a spool holder, but you run the risk of it uncoiling all over the place. What I did in the short term was to loosely coil some of it around an empty spool and print from there, putting the main coil back in the bag until it's needed. So far, seems to work all right.

The second potential problem is one I'd been forewarned about, so I was able to get out ahead of it. Word on the street is that the fibers in the filament cause clogging. I replaced the usual 0.4mm nozzle on my printer with an 0.75mm one, and I had no clogging issues at all.

Printing was a little iffy because adhesion seems inconsistent. On my first print, the tall, skinny item I was printing broke off about a quarter of the way up when I pulled it off the plate; the bottom of the piece was stuck to the printing surface more strongly than some of the layers farther up were to each other. On a later print, some of the support material didn't stick at all well to the plate, so the piece came loose and didn't finish successfully. Printing seems to be best on blockier pieces which have a lot of surface area touching the plate.

The filament itself doesn't look all that woody once printing is complete. It's a matte brown which certainly is a wood-like color, and the texture is, indeed somewhere between plastic and wood, but it's not, in itself, all that convincingly woody. It's most like a sort of really thick, dense cardstock. However, here's where another of the wood filament's properties comes in to play. The precise color is sensitive to printing temperature. Higher temps darken the wood fibers. And as it happens, there's a plugin for Cura which takes advantage of this very property. The temperature of the hot end changes during printing, creating light and dark bands, emulating wood grain, and I think that works pretty well. For another piece, I'm considering using a bit of stain and shellac.

So now that I've got that printed out, I thought I'd take stock of where our Castle Panic  set is now. At this point, the walls and most of the towers are stone-painted pieces. The wizard's tower is copper with heavy natural patina. I've also got custom pieces for tar, some painted flame tokens, a monster-themed cup we keep the dead monsters in, and a one-piece dice tower which has nothing to do with Castle Panic, but we use it anyway. At the rate we make new pieces, and at the rate the original set is wearing out from heavy use, I may end up rebuilding the whole game.

Metal!

I recently became aware of some exotic new materials for 3d printing. Notably, I've come across some materials by colorFabb. They're playing with a number of unusual things, but the ones I'm dealing with right now are their copper and bronze filaments. These aren't just colored. They're PLA filament with a substantial addition of copper and bronze powders. The ideas is that with appropriate treatment, they look for-real metallic. So how do they work?

They print quite well in my quick tests, sticking to the usual blue-tape-and-hairspray surface I usually use as well as any PLA with no noticeable warping. The marketing material indicates that the metal content means that they cool faster than regular filament, so they're particularly good for pieces with overhangs. I haven't done anything with exaggerated overhanging material yet, but it at least sounds plausible.

The printed material seems a bit fragile. It doesn't fall apart if you breathe on it wrong, but it does break more readily than 100% PLA. But the big difference I noticed was the weight. Not surprisingly, the metal-bearing filament is a lot heavier. It's not as heavy as an all-metal item would be, but there's definitely some heft. It also feels a bit cool to the touch, a bit like something metallic would.

However, they don't come out looking like metal. The bronze comes out as a sort of sandy light yellowish brown while the copper comes out a red which is definitely in the copper color range, but neither appears metallic.

That's where the post-processing comes in. The first step is to sand the surface of the print smooth, optionally hit it lightly with a little black paint to create the illusion of a dark patina, and finally rub with a brass polish.

(That bit on the right is a late Warring States-era dagger axe, the first in a series of historically accurate polearm hair sticks I'm making for Stephanie.)

So far, it's coming out OK, but not great. I'm getting a definite metallic sheen, which is definitely understated in the photo but still not all that impressive. Clearly, I need a better sanding and buffing technique. I've seen a Dremel used with some buffing heads, but in my tests, I've been gouging the plastic pretty badly with it. However, the steel wool I'm using isn't getting outstanding results. Finely detailed pieces are also a problem. I'm having a difficult time with all the corners and little protrusions. I gave up on the retro spaceship from the first picture and printed a little sword in the copper to see if that would work better. There is one interesting thing, though: within a few minutes, the bronze head on the dagger axe was already developing a pale green patina. So, yeah, actual metal.

That's nifty, but there's one other notable thing about this filament. It's expensive. It's really expensive. It costs significantly more by weight than regular PLA, and it's much denser, so the same weight gets you a fraction as much length. All told, it's more than an order of magnitude costlier than plain PLA on a meter-by-meter basis. So it's neat for specific artistic effects, but run test prints with cheaper stuff first to make sure they're absolutely perfect. Mistakes with the metal-bearing filament are costly.