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.

Author: Ed

Humidifier Lid Hinges
The humidifier that Came With The House™ had a lid with two broken plastic hinges that I figured I could never replace, but while cleaning out the fuzz for the upcoming season I found one missing piece stuck inside the lid. Given a hint, I glued it back in place:

Humidifier Hinge – outlined

There’s a strip of duct tape around the outside holding the fragment in place while the adhesive cured.

A manual curve fit to the image in Inkscape produced the red outline, which gets saved as a plain SVG and fed into OpenSCAD to create a solid model:

Humidifier Hinge – solid model

The cylinder doesn’t exactly fit the end of the hinge, but it’s close enough. The straightforward OpenSCAD code making that happen:
```
// Humidfier Hinge Replacement
// Ed Nisley KE4ZNU
// 2024-10-20

HingeThick = 10.0;
PinLength = 10.0;

ScrewOD = 2.0;

NumSides = 2*3*4;
Protrusion = 0.1;

difference() {
    union() {
        translate([0,0,HingeThick])
            cylinder(d=6.0,h=PinLength,$fn=NumSides);

        linear_extrude(height=10.0,convexity=5)
            translate([-3.1,-8.0])
                import("Humidifier Hinge - ouline.svg");
    }

    cylinder(d=ScrewOD,h=4*(HingeThick + PinLength),center=true,$fn=8);
}
```
The pin has a hole for a M2 screw, but contemplation of the broken pieces suggested the pin wasn’t the weakest link, which later experience confirmed.

Figuring I’d need only one hinge, I made a spare for fitting:

Humidifier hinge – on platform

The unmodified part fit just about perfectly, whereupon a completely ad-hoc fixture involving a pair of laser-cut MDF slabs, a craft stick epoxy mixer, and more duct tape held it in place while the adhesive cured:

Humidifier hinge – fixturing

The hinge pin turned out to be half a millimeter too long, which is easily fixed, and it worked fine:

Humidifier hinge – installed

That’s more duct tape wrapped around the perimeter to hold the pieces in place, should it break again.

Which, I regret to report, occurred on the way up the stairs from the Basement Shop™ when the lid slipped from my grasp, fell away from the rest of the humidifer’s top panel, and jammed open:

Humidifier hinge – break

The PETG-CF part held together, the adhesive remained bonded to both pieces, but the original plastic fractured just below the joint. A closer look from the other side shows the break:

Humidifier hinge – break detail

The other hinge broke about where it did before.

So the humidifier remains in service with the lid in status quo ante and a small bag inside holding the fragments for the next return to the shop.

Drat!
2024-10-28
Worst Deck Staining Job Ever

This looks about as awful as I expected:

Worst deck staining job ever

The previous owners replaced the deck two years ago, but the contractor installed more than half the planks with the grain cupped upward. The job was so bad the contractor replaced the most egregiously warped planks (over by the door and out of sight on the right) under warranty, but left all the other mis-oriented planks in place, presumably because they weren’t that bad yet.

The bare wood must age for a while before staining, so the shelf of painting supplies held a year-old gallon can as a reminder, with about two inches of stain / preservative in the bottom. I applied it to the “new” planks with pleasing results that absolutely do not match the rest of the weathered wood. With nothing to lose and plenty to gain, I applied the rest of the potion to the worst of the upside-down planks, producing the egregiously bad result you see above.

Given how the stain weathered to oblivion over the course of the last year, I expect all those planks will become roughly the same shade of ugly by next summer, when I might possibly be motivated to slather another gallon over the deck.

A friend observes: Houses are trouble.

2024-10-25
Laser Cutter: Focus Ramp Tests
A few ramp tests with various Focus Distance + Home Offset settings as noted:

Ramp Test Targets – 14-17 mm

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:

KT332N Autofocus settings

What they mean:
- Home Offset = distance to retract after the autofocus “pen” = switch activates so the tip of the pen clears the material
- Focus 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 button
- Homing Speed = how fast the platform moves while focusing
Getting the focus right really makes the laser cut like it should!
2024-10-24
Dancing With The Stars Quilt: First Wash

Mary recently finished a multi-year quilt project:

Dancine With The Stars quilt – detail

The overall pattern is “Dancing With The Stars” and it involves more intensive detail work than I have ever deployed on anything I’ve ever done:

Mary with quilt on ping-pong table

Washing the quilt required a generous handful of Color Catchers to prevent the bold colors from bleeding into the lighter fabrics:

Dancing With The Stars quilt – color catchers

The sheets on the left came from the wash and the ones on the right came from a separate rinse cycle. We didn’t expect the “average” color to be brown, but there it is. We were both mightily relieved when they performed as expected!

Now, to send it away …

2024-10-23
EBL Bucked Lithium AA and AAA Cells

A new kitchen scale eats a quartet of AAA alkaline cells every month, so a set of bucked lithium AAA cells make sense:

EBL AAA first charge – 2024-09-11

The cells claim 1200 mA·hr capacity, because it looks much more impressive than 1.2 A·hr, and deliver 900 mA·hr at 500 mA, likely higher than the scale’s actual load current.

The old Sony DSC-H5 works well with the light box and gets a pair of bucked lithium AA cells to replace the tired Eneloops:

EBL AA first charge – 2024-10-17

They claim 3000 mA·hr and deliver 2.5 A·hr at 500 mA: nearly perfect, considering some of the junk I’ve gotten over the years.

Now, to see how they behave in real life …

2024-10-22
Gizo Spiders: Leg Splice

This being the season for decorative spiders, two more appeared:

Gizo spider assortment

Wedding photographers have trouble getting the proper exposure for both the bride and the groom, too.

Only one of the 32 legs came loose from the platform:

Gizo spider – failed leg

The upper part of the leg captured the loose segment and glommed it into a blob:

Gizo spider – failed leg – detail

Fortunately, one of the clearance test pieces was an isolated leg and joint, so I amputated the grisly mess, matched the cut in the test piece, and hot-melt-glued the pieces together:

Gizo spider – spliced leg

Not quite perfect, but good enough for the purpose.

Given the 3% failure rate, I think the legs show such small contact areas really do justify a brim. Adding a brim to the main body would mess up the joints, but I think PrusaSlicer can add brims to specific parts. More study is needed.

Orange eyes for the win!

2024-10-21

Laser Cutter: Focus Ramp Fixture

After figuring out the Ruida focus settings, a focus ramp fixture seemed like a good thing to have around:

Ramp Test Fixture - setup — Ramp Test Fixture – setup

The solid model shows a bit more detail:

Laser Focus Ramp Fixture - solid model — Laser Focus Ramp Fixture – solid model

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:

Ramp Test Fixture - laser line — Ramp Test Fixture – laser line

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:

Ramp Test Targets - 15 16 mm — Ramp Test Targets – 15 16 mm

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 + 25.0),10.0,8RampHeight]; // very tall to cut through everything

	Body = [(Slot.x + 210.0),30.0,3RampHeight]; // extend Z to reach baseplate

	FocusPillarHeight = (RampHeight/2) + Body.z/3; // match Z at center of body

	BasePlate = [(Body.x + 2Magnet.x + 25.0),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);
	}

view raw Laser Focus Ramp Fixture.scad hosted with ❤ by GitHub

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view raw Target Layout – LightBurn.svg hosted with ❤ by GitHub

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.

2024-10-18

Author: Ed

Humidifier Lid Hinges

Worst Deck Staining Job Ever

Laser Cutter: Focus Ramp Tests

Dancing With The Stars Quilt: First Wash

EBL Bucked Lithium AA and AAA Cells

Gizo Spiders: Leg Splice

Laser Cutter: Focus Ramp Fixture