Thursday, September 22, 2016

Iron Dragon

While getting some other things at a craft store, I came across a kit for providing an iron rust finish to any surface. Put on a layer of iron-bearing paint, then squirt on some kind of rapid oxidizer. I thought "Hey, I should print something out for this." And so I did. And this is what I got:




Not bad, I think. It's lightweight plastic, but I'm afraid to drop it on my foot.

The dragon-head door knocker I got off of Thingiverse was, in the event, really hard to treat. It's a very complicated shape, with lots of little nooks and crevices, and both the primer and the iron paint were quite thick, so it was difficult getting it completely covered. The "activator" sprays on, though, so that wasn't a problem.

There was also a problem with printing. The design is perfectly good, but my printer kicked out about an hour before finishing the job. I'm guessing a power fluctuation on our old wiring or something. Anyway, I was able to measure the height of the printed portion with the digital micrometer, fire up netfabb, slice off the unprinted section from the design, print that part off, and superglue it on. It went much better than I expected, and I can't find the seam even though I know exactly where it should be.

Sunday, September 18, 2016

The Burning Bed

...well, a bit warmish, anyway.

A persistent problem in 3d printing is warping, bowing, and curling. The first printed layers in a 3d printed item cool down sooner than the upper layers and shrink, pulling of the print bed and curling up. I've tried all the usual remedies: a combination of painter's tape and hairspray on the print bed to keep everything stuck down, printing with rafts and brims added by the printing software, and so on. And they never really worked out. Here's a typical example:



This is one of the walls from my beloved DIY Castle Panic set. It's lovely, but the bottom curls significantly. The wall portion is about 21mm thick in the middle, but around 19mm at the ends, leading it to rock and spin easily when placed on the board. And that's over a length of under 7cm.

Here it is compared with something I just printed out, the base for a dice tower.


I'd post some kind of comparison of how much it curls over that distance, but here's the thing: it doesn't. There's no notable curve over its 18cm longest dimension. The difference is in the hardware. I finally bit the bullet and got a heated bed for my Printrbot. While it took some work to get all the right settings dialed in (some fiddling to get the self-leveling bed recalibrated, bed temperature to 50C, a layer of glue stick on the kapton tape, and no brims or rafts; they just waste time and filament now), and it's not technically necessary for the PLA filament I usually use, the difference is quite stunning. Indeed, I'd basically recommend that anyone getting into 3d printing spring for the heated bed up front. It makes one of the most annoying problems in 3d printing go away instantly.

Saturday, July 30, 2016

More Coasters


Two more coaster things. First, a Wonder Woman I'd done a while back in marble, but never got around to doing any treatments on.


Not horrible, but the lines dividing the parts of the Ws didn't come out cleanly.

Then another Corian experiment. Rather than the 2.5d engraving I did on previous coasters, this was full 3d, using a design I found on Thingiverse, scaled down suitably.


Two colors of sparkly India ink on this one. Not bad, though I was off by a millimeter or two on the size of the stock I was using. I'm considering filling the carved area with clear epoxy to make a flat surface over the whole thing.

Friday, July 22, 2016

Corian

Earlier this summer, I got a few samples of Corian, the countertop material, from an artist friend to try in the CNC machine. How'd it go?


Quite well. It carves easily and cleanly, and it neither eats bits nor burns out my motor like stone does. The above piece has a small problem with some drifting along the Y axis, but that's a problem with the hold-down solution I was using. Would use again.


Friday, April 22, 2016

Definitely The Light Side

So this was fun. Start with a design from Thingiverse, use netfabb to slice it into bits, print, and paint. The "blade" is a simple separate design, sized to fit in the hilt piece and made from glow-in-the-dark blue filament.


But the pommel? It comes off. It stays quite snugly on the USB plug.


 And I'm sure you can see what's happening.


That's a pair of UV LEDs powered by the USB drive. And since it's the glow-in-the-dark filament, it keeps fluorescing gently for a while after the drive is unplugged.




Saturday, April 16, 2016

Where No Drive Has Stored Before

Another little thumb drive.


The design should have some familiar elements. The disk on top, the nacelles along the sides. Pretty standard original series Starfleet stuff, right? Cute.

Now, let's plug it in (and dim the lights, since this is a new camera which I haven't figured out entirely yet).


This is my first foray into not just casemodding, but actually messing with the electronics. The core of what's going on behind the scenes is in this diagram:

If you look closely into a USB plug, you'll see that there are four contact strips in a row. The two in the middle are where the data comes in an now. The outer ones provide power you can use for your own applications. They're the reason you can charge your phone through the same socket you might use to get upload/download data or plug into accessories. But what I wanted here was to light something up. Unlike earlier drive cases I've made, this one has actual infrastructure, looking a bit like this:


Internally, the case is hollow and divided into three compartments. The center is about the width of the drive itself but a bit longer. The nacelles are hollow as well, just wide enough to accommodate some 3mm LEDs. There are walls dividing them, but I thinned them out where the arrows are in the diagram above, leaving gaps for wires to pass through. Using wire glue (rather than soldering; I'm not a steady hand with the iron and don't want to inadvertently fry the electronics, I connected the "hot" contact to a resistor and the resistor to two wires leading the the LEDs in the nacelles. The ground-end leads from the LEDs were long enough that I could bend them to where they'd make contact in the middle (using a slip of paper to insulate the drive from the bare wires above) and then run a single wire to the ground contact. Took a bit of doing to get everything to work in the tiny space allowed, but, hey, lights.