Category: Science

If you measure something often enough, it becomes science

All’s Well Who Ends Well

Eventually this happened:

Negative COVID tests

Three weeks, more or less, from my exposure to clearing the hurdle. Mary, being tougher than I, got it done in two.

For the better part of the first two weeks I was in bed ten hours every night, plus an hour or two of afternoon nap (no milk & cookies, drat), plus dragging around the house getting nothing done.

No major health problems, good blood oxygen levels throughout, no loss of smell apart from what you’d expect during three days of complete nasal blockage, and we’re both feeling OK-ish now.

However, we are making more than the usual number of stupid mistakes, which is one way we know we’re not really OK yet.

Back to the Basement Shop, with considerable caution …

Memo to Self: That was the first time in four years you didn’t wear a mask in close quarters. Don’t ever do that again.

2025-09-23
Wasp Blower: Carnage

The day after I set up the Wasp Blower, the carnage was terrible to behold:

Wasp Blower – carnage

Two weeks later, the blower is chopping up two or three wasps each day.

As far as I can tell, the blower killed essentially every wasp leaving the nest and most of the returning foragers:

Wasp Blower – shattered wasps

After two weeks, (nearly?) all of the eggs remaining in the nest have hatched, the larvae / pupae have starved for lack of incoming food, and I’ve put out ant bait traps to discourage scavengers.

The plan is to keep running the blower until a week goes by without any kills, then seal the crack under the door sill.

I have no idea how the queens (Yellowjacket wasp nests have multiple queens!) are doing in there, but they must be getting pretty hungry and, we hope, will not survive the winter.

This makes me feel awful, but not nearly bad enough to regret dealing with the critters.

2025-08-28
Switchyard Hum

For reasons not relevant here, I walked along IBM Rd to the end of Sand Dock Rd and back, passing the switchyard serving the IBM Poughkeepsie site:

Street View – 1 Sand Dock Rd

The overall capacity is surely in the tens of megawatts and there’s an overwhelming hum coming down that driveway:

Switchyard hum

Those peaks and the corresponding lines in the waterfall show the equipment emits acoustic energy all the way up to about 480 Hz, call it the eighth harmonic of 60 Hz.

Transformer steel has low magnetostriction, which produces most of the noise at even harmonics of the 60 Hz power line (because each cycle has two current maxima). The spectrogram shows the switchyard handles enough current to emit plenty of odd harmonic energy, with a notable peak at 180 Hz.

For comparison, standing a few feet from the transformer behind a medical office building along IBM Rd:

Transformer hum

No 180 Hz energy from that transformer!

Moving a few feet further away dropped those peaks into the background.

Even with my deflicted ears, I think can hear the switchyard hum from a considerable distance along the road, so maybe the background isn’t as quiet as I think.

2025-08-14

PolyDryer Humidity: 30 Days Later

A month after the last desiccant change, the silica gel looks like this:

Polydryer - 30 day beads — Polydryer – 30 day beads

The top cup contains fresh-from-stock dry (regenerated) silica gel beads and the others, left-to-right and top-to-bottom, come from PolyDryer boxes:

Material	%RH	Weight – g	Increase – g	Water gain – %
PETG White	14	26.8	1.8	7.2
PETG Black	20	26.8	1.8	7.2
PETG Orange	13	26.8	1.8	7.2
PETG Blue	15	26.9	1.9	7.6
PETG-CF Blue	19	27.4	2.4	9.6
PETG-CF Black	28	27.3	2.3	9.2
PETG-CF Gray	27	27.1	2.1	8.4
TPU Clear	13	26.8	1.8	7.2
Sum of weights		215.9		8.0
Measured weight		216.3		8.1

I expected some correlation between the indicated humidity and the weight of adsorbed water vapor, but that’s not the case.

The bottom row suggests there’s also little-to-no correlation between bead color and humidity, at least at this low end of the scale.

The indicator cards tucked into the boxes roughly correlate with the meter reading, but they’re much easier to interpret in person.

The old chart of adsorption vs. relative humidity suggests the results are plausible, with the 27-ish %RH being higher than you’d expect from 9-ish % adsorption:

So they’re all set up with 25 g of fresh silica gel, although the boxes no long have the same humidity meters they started with. This likely makes little difference, as I have no way to calibrate them.

2025-08-01

Polymaker PolyDryer Desiccant: Trust, But Verify
The startup ritual for a PolyDryer box’s humidity meter includes:
- Opening a small sealed bag containing …
- The DO NOT EAT desiccant, to be cut open and …
- Poured into the meter box
Which looks like this:

Polydryer – 14 pctRH – meter – white PETG

However, the desiccant packets for the most recent pair of boxes (intended to simplify changing the desiccant in the collection feeding the MMU3 atop the Prusa MK4 3D printer) produced this:

Polydryer – as-received desiccant

The silica gel in the left cup looks OK-ish, maybe a little dark, but the fresh-from-the-bag beads in the right cup are crying out for regeneration after having adsorbed about all the water vapor they can.

If you were using that silica gel in its original DO NOT EAT bag, where you can’t see what it’s telling you, you might wonder why it wasn’t doing such a great job of drying the box + filament. The same could happen with a bag of non-indicating gel, along the lines of what I was using a decade ago.

So I dumped both in the Needs Rgeneration bottle and filled both meters with 25 g of fresh silica gel.
2025-07-31
Snowflake Coaster: One Year Later

After more-or-less constant use under a cup in the bathroom, a Snowflake Coaster has reached the end of its life:

Snowflake coaster – 1 yr use

The acrylic flake is fine, but the wood has mildewed:

Snowflake coaster – 1 yr use – detail

It’s second from the left in the bottom row:

Snowflake Coaster – assortment

All except the pair in the left column had a coat or two of rattlecan clear, which suggests wood-ish coasters need something much more durable, along the lines of clearcoat epoxy. No surprise there!

2025-07-14
Newmowa NP-BX1: 2025 Batteries
A new sextet of NP-BX1 batteries for the Sony AS-30V helmet camera arrived:

Newmowa NP-BX1 – 2022 vs 2025

The traces:
- Blue = 2025 batteries
- Red = 2022 batteries when new
I don’t know what the bump in the middle of the new battery discharge curve means. Something weird in the chemistry, I suppose. Getting good batteries from Amazon surely remains a crapshoot and I now have four chargers.

Recharging all six batteries required 5488 mA·hr, just over 900 mA·hr apiece. Running the camera on a one-hour bike ride burns 600-ish mA·hr, so that’s comforting.

Comparing the new results with the 2022 batteries tested last month:

NP-BX1 – Newmowa 2022 in 2025-06

The upper traces appear in red in the first plot, the lower curves come from three years of use.

I’ll deploy the two best 2022 batteries (D and F) in the SJCAM M20 keeping watch from the Forester’s dashboard.
2025-07-08