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.
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 …
Just to see what happened, I dumped a few of those beads:
Into a few drops of water in a bottle cap:
After a few days, it was obvious only the larger beads changed color and, no matter what the description said, they were not going to become any color I would recognize as green.
While the larger ones did get darker, the smaller ones must have already been at their limit of adsorption and remained at the same shade.
For humidity levels under about 20%, I think changing the desiccant every month or so is the only way to be sure.
Tuck a neatly laser-cut disk into a flimsy cardboard tube:
Put a big conical center in the tailstock:
Whereupon the tube remains nicely tubular on both ends and aligned along the chuck axis:
Which is why you save all that scrap material …
Yes, it’s the core from a toilet paper roll, which is way cheaper than burning through tumblers / mugs / shot glasses / whatever while figuring this stuff out.
Contemplating a 0.8 mm nozzle to print more-transparent things, I ran off an Official MK4 Nozzle Replacement Tool to stabilize the heater block while applying a wrench to the nozzle:
For obvious reasons, it doesn’t fit with the inlet scoop I installed as part of blinging the MK4:
Removing the scoop is a matter of removing those two cap screws, which is no big deal, but a little flush-cutter action made that problem Go Away forever:
Yeah, I should have modified the solid model. Maybe next time.
A version of the tool fits extruders covered with an Official Prusa Silicone Sock thermal insulator, but they were out of stock when I was in the mood. My heater wears a knockoff sock:
Unlike the Official Sock, there’s no way to get a wrench on the nozzle with that one installed, but removing the sock is no big deal.
I apparently installed the nozzle / heater block slightly higher than specified, so the tool didn’t quite fit. Loosening those two thumbscrews and lowering the nozzle to fit the tool solved that problem. Fortunately, the automatic bed leveling routine corrects for nozzle height differences on the fly.
The scoop is back on the fan, the sock once again surrounds the heater, and I can easily swap in the 0.8 mm nozzle when the time comes.
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);
}
The process of switching the laser cutter from “normal” operation to the Ortur YRC-1 rotary and back again requires a checklist:
Which looks like this:
The same thing as a PDF will be more printable or readable.
Previous posts cover what goes into making it work:
Home Offset and Focus DistanceNotes:
Rotary.lbset and Linear.lbset files live on a file server with daily backups. Such backups will come in handy when you inadvertently overwrite one of those files with the other one. Trust me on this.Rotary.lbset file does not have Rotary Mode enabled, because the KT332N does not home the Y axis in that mode. If your rotary lacks a home switch, then it doesn’t matter and you’re on your own.[Reset] button that allegedly does a power-on reset and reloads all the changed Machine Settings. This sometimes does not work as expected: power-cycling the controller is the only way to be sure.[Origin] at the foot of the pad’s base for more elbow room.Move window does not accept formulas, so you must divide the workpiece diameter by two. Using a focus stick to verify the ensuing nozzle-to-workpiece distance is a Good Idea™.Job Origin dot must be on the top row, because the KT332N does not go into regions with negative coordinates. With the chuck on the left and the [Origin] just to its right, the upper left dot locks the LightBurn selection to the physical limits.[Use Selection Origin] puts the Job Origin at the upper left (per the dot) of whatever you’ve selected, not everything on the LightBurn workspace. [User Origin] then locks the selection to the [Origin] set on the controller.As the saying goes, it works for me …
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(); | |
The Smell of Molten Projects in the Morning 