The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Things around the home & hearth
Spotted at the local library:
Putting the downspout inside the building probably made architectural sense, but I’d much rather have that pipe on the outside of the wall where a leak wn’t be so expensive.
It hasn’t leaked yet, but in a few months I won’t be surprised to learn my tax dollars were hard at work fixing the ensuing water damage.
Taken at maximum zoom through a grubby windshield, so the picture quality isn’t up to contemporary standards.
This is what happens to an uncoated plywood coaster with fairly deep laser engraving after about half a year of use:
The poor thing went all potato chip:
I swapped it for one with polyurethane sealant, much like those fancier coasters with the same layout, and we’ll see if it survives longer …
Today looks like a good day to fire up the snowblower and clear the driveway:
One of the bolts holding the muffler on the engine worked its way past its rebuilt locking plate and will require attention before getting out there.
Fortunately, it looks like a good day for shop projects …
We buy olive oil in large bottles, then fill smaller bottles for easier handling. The caps on those bottles were never meant to last as long as we keep them and the thin, deeply drawn aluminum tends to crack after a while.
So I conjured a cap cover from the vasty digital deep:
Which looks exactly like you’d expect when printed in black PETG:
You can see the raggedy edge of the original cap just inside the cover’s rim. A snippet of double-sided tape holds the cover in place, after de-oiling the cap with alcohol.
Having gotten one to fit, I made enough for All The Bottles:
Only two of those see regular service: one in use and another filled when the first is nearly empty. The remaining pair huddle in the back of the shelf against future need.
The OpenSCAD source code produces those fancy knurls with BOSL2’s textured cyl() :
// Shower soap dish
// Ed Nisley - KE4ZNU
// 2026-01-17
include <BOSL2/std.scad>
/* [Hidden] */
HoleWindage = 0.2;
Protrusion = 0.1;
NumSides = 5*3*4;
$fn=NumSides;
ID = 0;
OD = 1;
LENGTH = 2;
WallThick = 1.0;
BaseThick = 2.0;
CapOD = 36.0;
CoverOA = [CapOD,CapOD + 2*WallThick,20.0 + BaseThick];
//----------
// Build it
render()
difference() {
cyl(BaseThick,d=CoverOA[OD],chamfer1=1.0,anchor=BOTTOM) position(TOP)
cyl(CoverOA[LENGTH] - BaseThick,d=CoverOA[OD],
texture="trunc_pyramids",tex_size=[2,6], style="convex",
anchor=BOTTOM);
up(BaseThick)
cyl(CoverOA[LENGTH],d=CoverOA[ID],anchor=BOTTOM);
}
Our house came with several single-LED night lights featuring a transparent light guide / reflector:
The plate had snapped off one of them and, being me, I wondered if I could replace it with something similar.
Years passed.
Obviously, this must be made from a transparent substance, which 3D printed things are not, but after some fiddling with parameters I thought the result might be informative.
The guide plate is a section of a spherical surface, here approximated by a BOSL2 spheroid():
The original is 3 mm thick, but 2 mm worked out better for my purposes by reducing the amount of infill:
The intricate base latches into the lamp’s plastic case:
The result is, at best, translucent, because it’s definitely not transparent:
The zigzag pattern seems to come from the icosohedral approximation to the sphere, because it follows the surface tesselation.
Getting the base shape right required several iterations, each printed with the model cut off just above the bottom of the guide plate:
The first two attempts needed attention from a flush cutting pliers before fitting into the case, but they don’t call it rapid prototyping for nothin’.
The original and replacement plugged into an outlet strip:
While you can see the vague outline of the strip behind the printed light guide, it’s definitely lacking in detail:
The striations throw more light into the room than the original:
Fiddling with the 3D printing parameters might make it more transparent, but it’s going back into the box it came from after giving me a better idea of which parameters to tweak the next time around.
The OpenSCAD source code as a GitHub Gist:
| // Nightlight light guide | |
| // Ed Nisley – KE4ZNU | |
| // 2026-01-13 | |
| include <BOSL2/std.scad> | |
| Layout = "Show"; // [Show,Build,Plate,Base,Pipe] | |
| /* [Hidden] */ | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; | |
| NumSides = 10*3*4; | |
| $fn=NumSides; | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| function ChordRadius(m,c) = (m^2 + (c^2)/4) / (2*m); | |
| PlateThick = 2.0; | |
| PlateOA = [60.0,50.0,PlateThick]; | |
| PlateRound = 5.0; | |
| PlateTaper = 1.0; | |
| PlateAngle = atan(-2/60); // original plate angle, far end closer to wall | |
| PlateM = 2.4; | |
| PlateRadius = ChordRadius(PlateM,PlateOA.x); // light guide plate | |
| echo(PlateRadius=PlateRadius); | |
| WallThick = 2.0; | |
| MountOA = [23.4,17.0,5.5]; | |
| MountRadius = ChordRadius(4.3,MountOA.x); // base arc in housing | |
| echo(MountRadius=MountRadius); | |
| PipeThick = 5.0; | |
| //———- | |
| // Define shapes | |
| // Oddly intricate base fitting into housing | |
| // Replete with magic numbers | |
| module Base() { | |
| difference() { | |
| union() { | |
| intersection() { | |
| cuboid([MountOA.x,MountOA.y,5.5],anchor=BOTTOM); | |
| back(6.5) | |
| tube(MountOA.z,or=MountRadius,wall=1.5,anchor=BOTTOM+BACK); | |
| } | |
| for (i=[-1,1]) | |
| right(i*18.5/2) | |
| back(11.5) | |
| cuboid([1.8,8.0,MountOA.z],anchor=BOTTOM+BACK); | |
| for (i=[-1,1]) | |
| right(i*22.0/2) | |
| cuboid([1.4,2.0,MountOA.z],anchor=BOTTOM+FRONT); | |
| fwd(5.0) | |
| cuboid([11.0,10.5,MountOA.z],anchor=BOTTOM+FRONT); | |
| } | |
| down(Protrusion) | |
| for (j=[-1,1]) | |
| fwd(j*(1.5 + 10.0)/2) | |
| cuboid([7.0,10.0,MountOA.z + 2*Protrusion],anchor=BOTTOM); | |
| up(3.1) | |
| back(7.5) | |
| cuboid([MountOA.x,25.0,MountOA.z],anchor=BOTTOM+FRONT); | |
| } | |
| } | |
| // Light guide plate | |
| module Plate() { | |
| xrot(PlateAngle) | |
| zrot(90) yrot(90) | |
| left(PlateOA.x/2) | |
| down(PlateM + PlateThick/2) | |
| intersection() { | |
| up(PlateRadius) | |
| difference() { | |
| spheroid(PlateRadius,style="icosa"); | |
| spheroid(PlateRadius – PlateThick,style="icosa"); | |
| } | |
| cuboid(PlateOA + [0,0,2*PlateThick],rounding=PlateRound,edges="Z",anchor=BOTTOM); | |
| } | |
| } | |
| // Light pipe between base & plate | |
| // Magic numbers to fit case opening | |
| module Pipe() { | |
| difference() { | |
| intersection() { | |
| fwd(3.0/2 – 0.2) | |
| cuboid([MountOA.x,MountOA.y,PipeThick],rounding=0.5,edges="Z",anchor=BOTTOM+FRONT); | |
| back(6.5) | |
| cyl(MountOA.z,r=MountRadius,anchor=BOTTOM+BACK); | |
| } | |
| down(Protrusion) | |
| back((1.5 + 10.0)/2) | |
| cuboid([7.0,10.0,1.0 + Protrusion],anchor=BOTTOM); | |
| } | |
| } | |
| module Assembly() { | |
| Base(); | |
| up(MountOA.z) | |
| Pipe(); | |
| up(MountOA.z + PipeThick) | |
| Plate(); | |
| } | |
| //———- | |
| // Build things | |
| if (Layout == "Base") | |
| Base(); | |
| if (Layout == "Plate") | |
| Plate(); | |
| if (Layout == "Pipe") | |
| Pipe(); | |
| if (Layout == "Show" || Layout == "Build") | |
| Assembly(); | |
A SquidWrench meeting discussion about printing transparent objects prompted me to conjure a soap dish from the vasty digital deep:
They’re all done in “natural” PETG with sufficient variations in speed, temperature, extrusion multiplier, and fill pattern to stock the shower & tub:
The single-thread sidewalls came out reasonably translucent in all the variations, but the baseplate remained stubbornly white-ish, even at 20 mm/s and 250 °C with 100% infill. The seams where the extruder retracts and lifts to the next layer remain conspicuous, with a scarf joint forming the white slab in the left-rear dish.
Quite a while ago, I’d considered making soap dishes with shattered-glass bottoms, but came to my senses. These have some key advantages:
They’re also test pieces for the whole transparency thing, so it’s all good.
The OpenSCAD source code as a GitHub Gist:
| // Shower soap dish | |
| // Ed Nisley – KE4ZNU | |
| // 2026-01-13 | |
| include <BOSL2/std.scad> | |
| /* [Hidden] */ | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; | |
| NumSides = 3*3*4; | |
| $fn=NumSides; | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| WallThick = 0.6; | |
| BaseThick = 2.0; | |
| //DishOA = [80.0,40.0,20.0]; // standing used Dove | |
| DishOA = [90.0,50.0,30.0]; // standing Dove | |
| //DishOA = [100.0,65.0,30.0]; // half-bar | |
| DishTaper = [10.0,10.0]; | |
| CornerRadius = 15.0; | |
| DrainOA = [10.0,DishOA.y,3.0]; | |
| DrainOC = DishOA.x/3; | |
| //———- | |
| // Build it | |
| difference() { | |
| union() { | |
| linear_extrude(BaseThick) | |
| rect([DishOA.x,DishOA.y] – DishTaper,rounding=CornerRadius); | |
| rect_tube(DishOA.z,wall=WallThick, | |
| size1=[DishOA.x,DishOA.y] – DishTaper,size2=[DishOA.x,DishOA.y], | |
| rounding=CornerRadius,anchor=BOTTOM); | |
| } | |
| for (j=[-1,1]) | |
| right(j*DrainOC/2) | |
| up(BaseThick) | |
| cuboid(DrainOA,rounding=1.0,anchor=BOTTOM+BACK); | |
| } |
As a reminder for the next time in this rodeo, the latches holding the temperature adjustment knob on the Delta 17 Series dual-handle bath / shower faucet look like this:
I am unable to apply enough force to the smooth edge of the knob opposite the handle to un-latch it, so I jammed a small prydriver into the gap and twisted enough to pop the latch, at the obvious risk of scarring the chrome plating.
A better approach would involve a plastic prydriver intended for consumer electronics case cracking.
For the record:
Ideally, I won’t need any of that information again.
The Smell of Molten Projects in the Morning 