The voltage (yellow) and current (green, 100 mA/div) waveforms look downright tame compared to some of the other chargers!
I made a cursory attempt to crack the case open, but gave up before doing any permanent damage. Hey, that UL listing (and, presumably, the interior details) means they’re three times the price of those Anonymous chargers!
Nothing prizewinning, but better than no picture at all:
Garage Robin – recovered image
Note that you start by copying a reasonable chunk of the partition from the Memory Stick / (micro)SD Card first, to prevent a bad situation from getting worse.
Now I can remember the easy way the next time around this block …
I built a small plywood work table for the drill press:
Drill press – scarred vise table
Obviously, that was a long time ago. It’s a plywood scrap with a small cleat screwed to its bottom, upon which one can position / clamp / hold / finagle smallish workpieces without worrying about drilling into the surface.
The mill vise under the plywood grips the cleat and the whole affair rides on a Sears “Drill Press Milling Attachment Stock No 27585” which is basically a simple XY table with hand dials. It’s not rigid enough for actual milling (which you should never do on a drill press, anyway, because the end mill will pull itself out of the Jacobs chuck), but it’s good for tweaking the position before you drill something.
One should never hand-hold workpieces while drilling.
So I can see the actual current waveform of a Glass Tile box running from a bench power supply:
Tiles 2×2 – bench supply – 50 mA-div
The top trace is the firmware heartbeat from the Arduino Nano, the middle trace is the SK6812 LED data stream, and the bottom trace is the USB current at 50 mA/div. The current steps downward by about 10 mA (just after the data burst) when one of the tiles changes color and and LED shuts off.
The current probe reveals some mysteries, such as this waveform from a dirt-cheap USB charger:
Tiles 2×2 – anon white charger – 50 mA-div
I wonder why it’s ramming 100 mA current spikes into the circuit, too. At least now I can see what’s going on.
I’ve been putting this type of support structure inside screw holes & suchlike for years:
Browning Hi-Power Magazine Block – solid model – Generic 1 – support detail
It’s basically a group of small rectangles rotated around the hole’s axis and about one thread thickness shorter than the overhanging interior.
I’ve found that incorporating exactly the right support structure eliminates Slic3r’s weird growths, eases removal, and generally works better all around.
So doing this for the baseplate of the Glass Tile frame came naturally:
Glass Tile Frame – octagonal support
This OpenSCAD snippet plunks one of those asterisks in each of four screw holes:
if (Support)
color("Yellow")
for (i=[-1,1], j=[-1,1])
translate([i*InsertOC.x/2,j*InsertOC.y/2,0])
for (a=[0:45:135])
rotate(a)
translate([0,0,(Screw[LENGTH] - ThreadThick)/2])
cube([Screw[OD] - 2*ThreadWidth,2*ThreadWidth,Screw[LENGTH] - ThreadThick],center=true);
The “cubes” overlap in the middle, with no completely coincident faces or common edges, so it’s 2-manifold. Slic3r, however, produces a weird time estimate whenever the model includes those structures:
Slic3r – NaN time estimate
NaN stands for Not A Number and means something horrible has happened in the G-Code generation. Fortunately, the G-Code worked perfectly and produced the desired result, but I’m always uneasy when Something Seems Wrong.
Messing around with the code produced a slightly different support structure:
Glass Tile Frame – quad support
The one thread thick square on the bottom helps glue the structure to the platform and four ribs work just as well as eight in the octagonal hole:
Fin = [Screw[OD]/2 - 1.5*ThreadWidth,2*ThreadWidth,ScrewRecess - ThreadThick];
if (Inserts && SupportInserts)
color("Yellow")
for (i=[-1,1], j=[-1,1])
translate([i*InsertOC.x/2,j*InsertOC.y/2,0]) {
rotate(180/8)
cylinder(d=6*ThreadWidth,h=ThreadThick,$fn=8);
for (a=[0:90:360])
rotate(a)
translate([Fin.x/2 + ThreadWidth/2,0,(ScrewRecess - ThreadThick)/2])
cube(Fin,center=true);
}
Which changed the NaN time estimates into actual numbers.
One key difference may be the small hole in the middle. The four ribs (not two!) now overlap by one thread width around the hole, so they’re not quite coincident and Slic3r produces a tidy model:
Glass Tile Frame – quad support – Slic3r
The hole eliminates a smear of infill from the center, which may have something to do with the improvement.
In any event, I have an improved copypasta recipe for the next screw holes in need of support, even if I don’t understand why it’s better.
Which looks like this with the LEDs and brass inserts installed:
Glass Tile – 2×2 array – interior
The base holds an Arduino Nano with room for wiring under the cell array:
Glass Tile Frame – base – openscad
Which looks like this after it’s all wired up:
Glass Tile – 2×2 array – wiring
The weird colors showing through the inserts are from the LEDs. The red thing in the upper left is a silicone insulation snippet. Yes, that’s hot-melt glue holding the Arduino Nano in place and preventing the PCBs from getting frisky.
Soak a handful of glass tiles overnight in paint stripper:
Glass Tiles – paint stripper soak
Whereupon the adhesive slides right off with the gentle application of a razor scraper. Rinse carefully, dry thoroughly, and snap into place.
Tighten the four M3 SHCS and it’s all good:
Glass Tile – 2×2 array – operating
So far, I’ve had two people tell me they don’t know what it is, but they want one:
However, just because you can do something doesn’t mean you should:
Glass Tile Frame – 6×6 cell array – openscad
Something like this might be interesting:
Glass Tile Frame – 2×6 cell array – openscad
In round numbers, printing the frame takes about an hour per cell, so a 2×2 array takes three hours and 3×3 array runs around seven hours. A 6×6 frame is just not happening.
