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.
Making the world a better place, one piece at a time
Having recently shotgunned Amazon’s selection of colored art paper, this becomes possible:
It’s the same geometry as the plain white layered version, with somewhat more attention to detail, and consists of a dozen layers glued and stacked on an assembly fixture.
The quilt-block version uses simple layering:
No commercial potential, but I like the effect.
An entry from The New Garden Encylopedia, copyright 1936 through 1946, gives recommendations for using arsenical poisons in your garden:
My father always said anybody who talks fondly of The Good Old Days wasn’t alive back then. He was and thought things had definitely improved since then.
Words to live by.
A pair of plant stands from a friend’s collection ended up in Mary’s care and cried out for feet to keep their welded steel wire legs from scratching the floor:
Admittedly, it’s not the prettiest stand you can imagine, but the sentimental value outweighs all other considerations.
The feet are shrink-wrapped around the legs with enough curviness to look good:
With a drain hole in the bottom to prevent water from rusting the wires any more than they already are:
I briefly considered a flat bottom at the proper angle to sit on the floor, but came to my senses; it would never sit at the proper angle.
The end results snapped into place:
Of course the other stand, at first glance identical to the one above, has a different wire size and slightly different geometry, which I only discovered after printing another trio of feet. Changing the appropriate constants in the OpenSCAD program and waiting an hour produced a better outcome:
Living in the future is good, all things considered.
The OpenSCAD code as a GitHub Gist:
| // Wire plant stand feet | |
| // Ed Nisley KE4ZNU | |
| // 2024-11-06 | |
| Layout = "Show"; // [Show,Build,Leg,LegPair,FootShell,Foot,Section] | |
| /* [Hidden] */ | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| TOP = 0; | |
| BOT = 1; | |
| FootLength = 30.0; // vertical foot length | |
| LegRings = // [255.0,350.0,300.0]; // top dia, bottom dia, vertical height | |
| [260.0,312.0,300.0]; | |
| WireOD = //4.6 + 0.4; // oversize to handle bent legs | |
| 5.7 + 1.0; | |
| DrainOD = 4.0; // drain hole in the bottom | |
| LegWidth = // [65.0,9.7]; // outer width at top & bottom | |
| [95.0, 12.0]; | |
| LegAngle = atan((LegWidth[TOP] – LegWidth[BOT])/(2*LegRings[LENGTH])); | |
| StandAngle = atan((LegRings[TOP] – LegRings[BOT])/(2*LegRings[LENGTH])); | |
| WallThick = 3.0; | |
| FootWidth = 2*[WallThick,WallThick] + | |
| [LegWidth[BOT] + LegWidth[TOP]*FootLength/LegRings[LENGTH],LegWidth[BOT]]; | |
| echo(FootWidth=FootWidth); | |
| NumSides = 2*3*4; | |
| Protrusion = 0.1; | |
| //—– Set up pieces | |
| module Leg() { | |
| hull() | |
| for (k = [0,1]) | |
| translate([0,0,k*LegRings[LENGTH]]) | |
| sphere(d=WireOD,$fn=NumSides); | |
| } | |
| module LegPair() { | |
| for (i = [-1,1]) | |
| translate([i*(LegWidth[BOT] – WireOD)/2,0,0]) | |
| rotate([0,i*LegAngle,0]) | |
| rotate(180/NumSides) | |
| Leg(); | |
| hull() // simulate weld for flat bottom | |
| for (i = [-1,1]) | |
| translate([i*(LegWidth[BOT] – WireOD)/2,0,0]) | |
| rotate([0,i*LegAngle,0]) | |
| rotate(180/NumSides) | |
| sphere(d=WireOD,$fn=NumSides); | |
| } | |
| module FootShell() { | |
| difference() { | |
| hull() { | |
| for (i = [-1,1]) { | |
| translate([i*((FootWidth[BOT] – WireOD)/2 – WallThick),0,0]) | |
| rotate(180/NumSides) | |
| sphere(d=(WireOD + 2*WallThick),$fn=NumSides); | |
| translate([i*((FootWidth[TOP] – WireOD)/2 – WallThick),0,FootLength – WireOD/2]) | |
| rotate(180/NumSides) | |
| sphere(d=(WireOD + 2*WallThick),$fn=NumSides); | |
| } | |
| } | |
| translate([0,0,FootLength + FootLength/2]) | |
| cube([2*FootWidth[TOP],10*WallThick,FootLength],center=true); | |
| rotate(180/NumSides) | |
| cylinder(d=DrainOD,h=4*FootLength,center=true,$fn=NumSides); | |
| } | |
| } | |
| module Foot() { | |
| difference() { | |
| FootShell(); | |
| hull() | |
| LegPair(); | |
| } | |
| } | |
| //—– Build it | |
| if (Layout == "Leg") | |
| Leg(); | |
| if (Layout == "LegPair") | |
| LegPair(); | |
| if (Layout == "FootShell") | |
| FootShell(); | |
| if (Layout == "Foot") | |
| Foot(); | |
| if (Layout == "Section") | |
| difference() { | |
| Foot(); | |
| cube([FootWidth[TOP],(WireOD + 2*WallThick),2*FootLength],center=false); | |
| } | |
| if (Layout == "Show") { | |
| rotate([StandAngle,0,0]) { | |
| Foot(); | |
| color("Green",0.5) | |
| LegPair(); | |
| } | |
| } | |
| if (Layout == "Build") | |
| translate([0,0,FootLength]) | |
| rotate([0*(90-StandAngle),180,0]) | |
| Foot(); |
Spotted during Autumn Window Cleaning:
That’s the compression spring inside the curtain rod over the kitchen sink, intended to push the ends against the cabinets on either side. The screw slides along the outer rod and when tightened, backstops the spring against the inner rod.
The end of the spring is apparently intended to twist and jam inside the inner half of the rod, but that seemed so … unesthetic.
Being in the midst of setting up a Windows 11 box for the laser cutter, I used it as an excuse to fiddle with the RDP configuration to get LightBurn running in full screen mode on the monitor atop my desk; more about all that later.
The little pusher block is a hull around a pair of circles the same diameter as the smaller dimension of the inner rod, spaced apart enough to match its width, then laser-cut from a scrap of 1/4 inch acrylic:
Which assembles as you’d expect:
The spring seems much happier pushing against the block, doesn’t it?
Admittedly, this was completely unnecessary, but if you think of it as a side effect of the Win 11 thing, it makes at least a little sense.
Given a 3% failure rate for the tiny footprint of Gizo spider legs, I added 5 mm pads to each foot:
A few rounds of successive approximation and one copypasta hit the right spots:
// Gizo spider footpads
// Ed Nisley - KE4ZNU
// 2024-10-26
pts = [
[24,-23],[28.5,-7],[29.5,14.5],[20,28],
[-24,-23],[-28.5,-7],[-29.5,14.5],[-20,28]
];
translate([14,0,2.8])
import("/mnt/bulkdata/Project Files/Prusa Mk4/Models/Gizo Spider/GizoSpider.stl");
linear_extrude(height=0.2)
for (pt = pts)
translate(pt)
circle(d=5,$fn=2*3*4);
Which was enough to stick the legs firmly to the build platform:
Talk about blank looks:
White filament is particularly susceptible to charred globbing:
Which was, fortunately, completely hidden inside the shell.
Extensive testing showed the pads pushed the error rate below 1.5%:
As before, dots of hot melt glue hold the eyes in place.
All’s well that ends well: just in time, too.
A few ramp tests with various Focus Distance + Home Offset settings as noted:
The bottom test was at 15 mm, which (contrary to previous estimates) seems to center the narrow band round 0.0 mm. Given the depth of field, a millimeter one way or the other likely doesn’t matter, particularly given the mmm lack of flatness in many materials.
The controller settings making it happen:
What they mean:
Home Offset = distance to retract after the autofocus “pen” = switch activates so the tip of the pen clears the materialFocus Distance = distance beyond Home Offset to put the focal point at the surface of the material (or wherever you want)Enable Homing = makes autofocus work at the push of a buttonHoming Speed = how fast the platform moves while focusingGetting the focus right really makes the laser cut like it should!
After figuring out the Ruida focus settings, a focus ramp fixture seemed like a good thing to have around:
The solid model shows a bit more detail:
Centering the autofocus “pen” = switch on the peg in the back puts the beam dead-center in the fixture, with the notches as comfort marks. The top of the peg is flush with the center notch, so the machine should be properly focused at that level after a focus operation.
Obviously, your laser has a different pen location, as will this one the next time I fiddle with anything around the nozzle.
The general idea is to tape a target to the ramp, with some attention to flattening the paper (tape the edges in critical spots as needed) & putting its zero at the center marks, align the fixture to the laser path along the X axis & secure it with a few magnets, then burn a single line at low power along the length of the scale:
The mark will be thinnest in the region with the best focus, which should be centered around the 0.0 mark in the middle. In that photo, the thinnest section runs from about -2.0 to +1.0, although (at least for me) it does take some squinting to be sure.
The ramp has a 1:10 = 5.71° slope to spread 1 mm of vertical focus across 10 mm of horizontal distance. If you’re being finicky, you should rescale the targets to correct the 0.5% cosine error, but IMO it’s irrelevant for this purpose.
A few more tests varying the focus distance by a millimeter:
AFAICT, setting the controller’s Focus Distance to 16 mm is about right. That puts the focal point 18 mm below the nozzle, as shown in the earlier post, and is pretty much what I’ve been using all along.
The OpenSCAD code as a GitHub Gist, along with a simplified target layout in SVG format:
| // Laser Cutter Focus Ramp Fixture | |
| // Ed Nisley KE4ZNU | |
| // 2024-10-10 | |
| FocusPenOffset = [-19,23,0]; | |
| FocusPenOD = 10.0; | |
| RampHeight = 16.0; | |
| RampScale = 10; | |
| RampLength = RampScale * RampHeight; | |
| Magnet = [5.0,60.0,10.0]; | |
| NumSides = 3*4; | |
| Protrusion = 0.1; | |
| RampAngle = atan(RampHeight/RampLength); | |
| echo(RampAngle=RampAngle); | |
| Slot = [(RampLength + 2*5.0),10.0,8*RampHeight]; // very tall to cut through everything | |
| Body = [(Slot.x + 2*10.0),30.0,3*RampHeight]; // extend Z to reach baseplate | |
| FocusPillarHeight = (RampHeight/2) + Body.z/3; // match Z at center of body | |
| BasePlate = [(Body.x + 2*Magnet.x + 2*5.0),max(Magnet.y,FocusPenOffset.y + 2*5.0),3.0]; | |
| BaseRound = 5.0; | |
| //—– Build it | |
| difference() { | |
| union() { | |
| translate(FocusPenOffset) | |
| cylinder(d=FocusPenOD,h=FocusPillarHeight,$fn=NumSides); | |
| difference() { | |
| union() { | |
| rotate([0,RampAngle,0]) | |
| cube(Body,center=true); | |
| linear_extrude(height=BasePlate.z) | |
| hull() | |
| for (i=[-1,1], j=[-1,1]) | |
| translate([i*(BasePlate.x/2 – BaseRound),j*(BasePlate.y/2 – BaseRound)]) | |
| circle(r=BaseRound,$fn=NumSides); | |
| } | |
| cube(Slot,center=true); | |
| translate([0,0,FocusPillarHeight]) { | |
| cube([0.5,2*Body.y,1.0],center=true); | |
| rotate([0,RampAngle,0]) | |
| cube([2*Slot.x,0.5,1.0],center=true); | |
| } | |
| } | |
| } | |
| translate([0,0,-Body.z]) | |
| cube(2*[BasePlate.x,BasePlate.y,Body.z],center=true); | |
| } |
Contrary to what you might think, the targets are not laser cut, although you could use the crosshairs for LightBurn’s Print and Cut alignment.
The Smell of Molten Projects in the Morning 
