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.

Category: Home Ec

Things around the home & hearth

Laser-cut Window Screen

Having just cleaned a bunch of gunk out of the bottom of the worm bin, we decided to try a layer of window screen to keep both gunk and worms out of the sump.

A roll of window screen Came With The House™, minus label or provenance, that felt like some sort of plastic, perhaps with a glass core.

The bin has a 19-¼ inch = 488 mm ID with 10 thin support struts around the perimeter. Laying out a circle and cutting it accurately by hand seemed like a chore, even though the screen cut easily with ordinary scissors.

The diameter just barely fit on the laser’s 700×500 mm platform, so I laid it out in LightBurn:

Laser-cut window screen – LightBurn layout

For lack of anything smarter, I applied the same setting as for the faucet gasket material (30 mm/s at 25% of 60 W) and Fired The Laser.

As far as I could tell while the laser was trundling around the circle, absolutely nothing happened other than maybe burning off a coating with a little discoloration on either side of the path.

However, the circle lifted out with zero drama:

Laser-cut window screen

And was a perfect fit in the worm bin.

Color me surprised!

I have no pictures of the happy results, as all this happened in the few minutes between “We should try a screen”, dropping the cut screen in place, and reassembling the bin.

I think the screen would cut just as well with a higher speed. If the screen works and we need another, I’ll run a few tests first.

2026-07-17
Chest Freezer Basket Shims

Our new chest freezer has three baskets sliding along ridges just under the lid, but they seem to be just slightly too short for the ridge spacing. After having a basket fall off the rails once too often, I cut shims from 3 mm white acrylic and stuck them in place with double-sided foam tape to soak up the extra space:

Chest freezer basket shims

Each shim is 300×8 mm with the neatly rounded corners that are easy to do with a laser. They may not look like they grew there, but it’s tidy enough.

Perhaps the situation should have become a warranty claim, but a few minutes applying a tool to material I have on hand made the problem Go Away.

Which is entirely good enough for me and pretty much what I do around here most of the time anyway.

2026-07-15
Shower Mat Hangers

A new Gorilla Grip shower mat defeated the spring-loaded clip its predecessor dangled on between showers, so I applied a contour gauge to the shower stall, copied the shapes to paper, scanned them, then fit some curves:

Shower Mat Hanger – curve fitting

Combine the two to get a model of the shelf, subtract it from a rectangle, and produce a cardboard test piece:

Shower mat hanger – cardboard test 1

Put a hook on the bottom, a small bump on the top, and round the corners:

Shower Mat Hanger – LightBurn layout

Function-test a cardboard pair:

Shower mat hanger – cardboard test 2

They clear the hump along the edge and fit snugly across the front and sloping underside, so make an MVP from 6 mm acrylic:

Shower mat hanger – acrylic

Laser-cut acrylic may be too brittle for the job, but it gets the mat off the floor for drying and we’ll see how this works before doing anything more complex.

2026-07-14

Photo Backdrop: Crossbar Improvement

The instructions for the Photo Backdrop frame (upon which we hang Mary’s quilts for photos) suggest the crossbar fits on like this:

Photo Backdrop - OEM crossbar installation — Photo Backdrop – OEM crossbar installation

The slot in the bottom is wider than the M10 stud, so the crossbar tends to flop around while assembling it overhead. I immediately replaced the wingnut with a chunky knob for better griptitude, but was never happy with how poorly the whole thing fit together.

This is dramatically better:

Photo Backdrop - fitting installed — Photo Backdrop – fitting installed

The crossbar is upside-down from the OEM instructions, but the bottom of the gray plug holds the tube firmly to the tripod while the nut seats firmly on the plug’s flat top:

Photo Backdrop - fitting top view — Photo Backdrop – fitting top view

A snippet of 3M 300LSE adhesive sheet holds the plug in place, so that’s one less thing to fiddle with on each end.

The solid model holds no surprises:

Photo Backdrop Fittings - solid model — Photo Backdrop Fittings – solid model

Of course, it builds with the flat end downward.

The OpenSCAD source code as a GitHub Gist:

	// Photo backdrop fitting
	// Ed Nisley – KE4ZNU
	// 2026-07-01

	include <BOSL2/std.scad>

	Layout = "Show"; // [Build,Show]

	/* [Hidden] */

	ID = 0;
	OD = 1;
	LENGTH = 2;

	HoleWindage = 0.2;
	Protrusion = 0.01;
	NumSides = 324;

	Clearance = 0.3;

	$fn=NumSides;

	Tube = [23.0 – HoleWindage,1*INCH,100.0]; // arbitrary length

	Aperture = [24.0,15.0,100.0]; // oblong nut hole, arbitrary Z

	Washer = [10.5,20.0,1.5]; // M10


	//—–
	// Define things

	module Fitting() {

	difference() {
	union() {
	intersection() {
	xcyl(Tube[LENGTH],d=Tube[ID]);
	cuboid(Aperture,rounding=Aperture.y/2,edges="Z");
	}
	cuboid([Aperture.x,Aperture.y,Tube[OD]/2],rounding=Aperture.y/2,edges="Z",anchor=BOTTOM);
	}
	cyl(Aperture.z,d=Washer[ID]);
	}
	}




	//—–
	// Build things


	if (Layout == "Show") {
	Fitting();
	}

	if (Layout == "Build") {
	up(Tube[OD]/2)
	xrot(180)
	Fitting();
	}

view raw Photo Backdrop Fittings.scad hosted with ❤ by GitHub

2026-07-02

Hose Nozzle Flow Restrictors

Mary wanted less pressure in the spray while watering her plants and I suggested replacing the nozzle’s washer with a flow restrictor:

Hose Nozzle Flow Restrictors – assembled

The 3D-printed TPU base is squishy enough to act as a hose washer:

Hose Nozzle Flow Restrictor Base – solid model

A 1.5 mm thick acrylic orifice plate snapped into the opening takes advantage of the laser cutter’s precision:

Hose Nozzle Flow Restrictors – LightBurn layout

For lack of anything smarter, the holes have areas that are powers-of-two smaller than the nozzle’s 14.2 mm = 158 mm² internal passage: the hole labeled 8 is 158/256 mm² = 0.62 mm² → 0.9 mm diameter.

Rather than figuring each hole’s diameter, just divide the previous diameter by √2 or rescale it by 100%/√2, which LightBurn can evaluate directly in its Numeric Edits fields. The as-cut holes are larger than their nominal size by about 0.1 mm, but any errors that might cause are definitely in the nature of fine tuning while watering the plants.

The nozzle’s Shower pattern (on the left in the picture) has a 6.8 L/minute = 110 ml/s flow through an ordinary garden hose washer. The four smallest aperture plates produced these flows:

Hose Nozzle Flow Restrictors – flow vs dia

The flow should scale with the square of the aperture diameter, which I could bully those points into suggesting, but the measurement accuracy produced by filling a gallon jug while tapping my phone’s stopwatch doesn’t justify anything fancier.

The two smallest apertures reduce the Shower pattern to a very gentle spray requiring far too long to put enough water on the plants. Mary now uses an old plastic sprinkler head with enough holes to produce a dense spray with very little force, with the flow set by fifty feet of PEX pipe running across the width of the house from the town water inlet to the hose bib.

It was a fun exercise and I learned a little more about printing TPU and fitting acrylic parts therein:

Hose Nozzle Flow Restrictors – prototypes

2026-06-29
Gas Furnace Zone Drain Valve Refurbishment

One of the zone valves on the gas furnace developed a slow leak around its actuator stem, so (now that the heating season is definitely over) I’ve been refurbishing all the long-neglected rubbery bits and pieces.

The four zone drain valves showed signs of having leaked in the past, so I took them apart to replace the washers:

Furnace zone drain valve – washers

As you’d expect, the two most-deteriorated washers were on the valves with the most corrosion.

As I expected, the faucet washer assortment on the shelf didn’t have that size. Figuring the size based on the outside diameter produced a description of faucet washer size labels that confirmed my suspicion: it makes no sense whatsoever. In the event of link rot, a lightly reformatted version of his table:

Faucet Washer Sizes

Careful measurement suggested they were 3/8L, which fit perfectly:

Furnace zone drain valve – gaskets

I added the spares and a copy of that table to the washer kit, although I’m certain the next project will involve a washer with yet another nonstandard standard size.

Replacing the washers required dismantling the valves and the first valve produced a gasket that fell out in brittle fragments. Although the remaining three gaskets emerged intact, I picked up some gasket material and laser-cut four new gaskets from the 0.8 mm sheet.

The OD fits into the valve body rebate:

Furnace zone drain valve – gasket installed

Because these valves are closed in operation and even when open won’t operate under any significant pressure, the gaskets aren’t particularly critical, but I dabbed joint compound into the body threads just to be sure.

And, while I was ordering things, I got a set of knobs to replace the sad bent wreckage on their stems.

2026-06-22
Dripworks Mainline Leak: Repair Under Field Conditions

A large gooey puddle helped isolate a leak in the Dripworks main line pipe running the length of Mary’s Vassar Farms plot:

Dripworks Mainline clamp – injured hose joint

Much of the tubing between the transfer barb in the buried pipe and the cross coupling lies on the surface, where it’s subject to missteps. This being just a few feet inside the garden gate, it’s no surprise enough missteps caused the barb to no longer seal properly.

So I pulled the barb out of the pipe and deployed the backup pipe clamp I made after fixing a previous mishap:

Dripworks Mainline clamp – installed

You’re supposed to wrap silicone tape while keeping its surface clean, which is obviously impossible in a hole rapidly filling with water draining from the plumbing but the clamp presses the tape firmly against the pipe and seals the leak.

There is, I regret to say, an 8-32 stainless steel washer lost somewhere deep in the muck.

I punched a new barb into the pipe with slightly longer tubing to the cross fitting, in the hope it’ll be more resilient.

Another clamp with its silicone tape snippet stands ready for duty:

Dripworks Mainline Pipe Clamp – assembled

For the record, the Micromark Cutoff Saw has a 3 mm offset between the side of the vise and the left edge of the blade:

Micromark abrasive cutoff – work offset

I still lack a Round Tuit for improving that vise.

2026-06-19