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: Science

If you measure something often enough, it becomes science

Water Heater Anode Rod Replacement
The Bradford White AeroTherm heat pump water heater that Came With The House™ has been running for three years. Based on previous experience with the same City of Poughkeepsie water, it was time for a look at the anode rod.

Which, as always, required the Greatest Ratchet with a foot of extensions getting the 1-1/16 inch socket down to the rod:

Water Heater Powered Anode – socket wrench

Remember to:
- Turn off the water heater power
- Shut off the inlet and outlet valves
- Open the drain valve to relieve the tank pressure
- Only then loosen the anode rod
Seeing the first few inches justified extracting the rod:

Water Heater Powered Anode – old rod top

Due to low overhead clearance and inauspicious pipe locations, I had to hacksaw the bottom third off to extract the rod:

Water Heater Powered Anode – old rod overview

Water Heater Powered Anode – old rod bottom

With the rod out, draining a few gallons of water into a pan didn’t produce any notable gravel, so I didn’t do a complete flush. Much to my delight, the drain has a ball valve!

Given that this is a fancy water heater and I no longer regard anode rod maintenance as a fun-filled activity, I installed a Corro-Protec powered anode rod for cathodic protection without all the crud:

Water Heater Powered Anode – Corro-Protec parts

The wall wart proclaims 15 mA with a green LED indicating it’s hard at work:

Water Heater Powered Anode – Corro-Protec wall wart

The data plate on the back reports 24VDC 15mA, but, being me, I poked at it with a handful of resistors:

Corro-Protec power supply measurements

The electronics could be as simple as a 24 VDC wall wart feeding a 425 Ω series resistor and a transistor switch lighting the LED for currents a little over 6 mA.

A quick ohmmeter check shows the powered rod electrode is open-circuit with respect to the tank, as it should be without much applied voltage. Applying +24 VDC from the wall wart drives 15 mA into the water: the rod is hard at work.

I’ll take a look at it in a year or so just to see what’s going on in there …
2026-08-05
Bee Tunnel Nests: Emergence

On rare occasions I see a small bee or wasp investigating the bamboo tunnel nests at the windows:

Bee Tunnel Nest – wasp investigating

Several of the tubes filled & sealed in early June have served their purpose:

Bee Tunnel Nest – Small A

Bamboo tubes have a paper-thin liner around the edge, but the mud-sealed tubes have obvious small holes chewed through the end caps:

Bee Tunnel Nest – Small B

My assumption that various insects would pick their favorite tube from the assortment seems to be working:

Bee Tunnel Nest – Small C

The medium and large tubes haven’t seen much traffic:

Bee Tunnel Nest – Medium

We’re glad to help!

2026-07-03
New Wildlife
An inch-long Praying Mantis stood guard on a carton delivered to the front door:

Praying Mantis – early instar

We hope to see many more of its kind.

Two views of a one-turn snail found on a lettuce leaf from the garden:
One-turn Snail – right side
One-turn Snail – left side
Mary has developed a Zero-Tolerance Policy for snails & slugs, so this one must start over again from the bottom of the food chain.

With sparrows excluded, the House Wrens eventually began setting up their second nest of the season, with the male proclaiming both he and his lady’s chosen nest are the best in the land:
House Wren – second nesting – 2026-06-30
House Wren – second nest – 2026-06-30
Wrens are on our Most Favored Critter list!

Previous encounters with their ancestors and relatives:
- Mantis
- Snails
- Wrens
2026-07-01
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
Methanol Package Labeling

I am so glad methanol is a liquid, not a crystalline powder, because this could be totally misinterpreted:

Methanol package label

A recent LightBurn forum discussion pointed out methanol is a good solvent for borax to produce dark-brown to black laser engravings in wood. In round numbers, 20% w/w borax will dissolve in methanol at room temperature.

I understand the toxicity warnings and don’t plan to spray it indoors. OK?

2026-06-24
Bamboo Bee Tunnel Nests: In Use!

Just over a month after mounting bamboo bee tunnel nest bundles here & there around the house & yard, they have occupants!

One of the bundles of small (a few mm ID) stalks on the kitchen window:

Bee Tunnel Nest – small A

Another bundle of small stalks on a window a dozen feet away:

Bee Tunnel Nest – small B

A bundle of medium (five to ten mm ID) stalks lashed to a downspout:

Bee Tunnel Nest – medium

Unlike the mud dauber wasps decorating our previous house, these little bees dart in and out without announcing their presence: we’ve never seen them at work.

Assuming a single bee works on each bundle, she apparently starts with the lowest stalk and moves upward after filling & capping it.

Larger bees have yet to discover the bundles of larger stalks out on the trees, but … so far, so good!

2026-06-05
Makergear M2 Platform Flatness Puzzle

The first layer of a short TPU chain (about which, more later) came out vanishingly thin in the middle and much too thick on the ends:

Makergear M2 – TPU first layer

So: let the platform cool, scrape off the wreckage, set the nozzle for Z=2.0 mm, and measure the actual gap at various spots across the platform.

Those results are the top set of measurements:

Makergear M2 – BuildTak flatness check

The bottom set of measurements came from a similar test a few days later, after pulling the BuildTak plate off, doing nothing other than scrutinizing it, reinstalling it, and successfully printing several TPU chains of varying design, none of which had any first-layer problems. The platform is slightly too high along the +Y and -Y edges (rear and front), with no bow worth mentioning.

My measurements are, perforce, done with a cold platform, for obvious reasons, and the TPU prints at 50 °C. I have the uneasy feeling the heater / BuildTak magnetic base can bow upward in the middle while it heats, then flatten out after a while at a stable temperature. The good news: it’s not permanently bent.

More study is needed, including thinwall boxes after letting the platform soak at 50 °C for varying times.

2026-05-19