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
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.
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.
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.
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.
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!
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.
A week after installing 25 g of fresh silica gel, without any outside influence other than using some of the filaments to build things, I recorded the humidity meter reading, the indicator card colors, and the weight gain.
Click on any picture for more dots and to get rid of the captions and their stylin’ photo-blur.
White PETG, gain 0.6 g:
Polydryer – 14 pctRH – meter – white PETGPolydryer – 14 pctRH – card – white PETG
Black PETG, gain 0.8 g:
Polydryer – 21 pctRH – meter – black PETGPolydryer – 21 pctRH – card – black PETG
The (newer) indicator cards with the smaller dots / larger black borders seem less acute than the (older) large-dot cards. The two 28 %RH cards look about right, but the 20 and 21 %RH cards seem more different than the similar humidity would suggest.
Under 20 %RH, all the spots look pretty much the same, but AFAICT any humidity below 20 %RH is Good Enough for 3D printing.
The Blue PETG-CF went directly from its sealed bag into the PolyDryer box, unlike the Black and Gray PETG-CF spools that sat in the 50% RH basement long enough to soak up the ambience. The Blue has outgassed enough water to suggest spools do not arrive “bone dry” from the factory, although the Black and Gray prove the Basement Shop is wetter than the factory.
All of the silica gel together weighed 184.2 on the same scale I originally measured the 25 g quantities that should have totalled 175 g, but the individual measurements total 183.3 g. I don’t trust the scale to be better than ±0.1 g on any measurement, so half a percent is likely as good as it gets.
The silica gel weighed 187 g on the kitchen scale, sweated down to 179 g after 7 minutes in the microwave being defrosted like 1.5 pounds of fish, and, depending on which numbers you believe, released 8 to 10 g of water in the process.
Microwaving something containing so little water means the silica gel absorbs very little of the energy: the dish, glass turntable, and metal walls got absurdly hot. I think using the induction cooktop and cast iron pan makes more sense, even if it takes longer.
With fresh silica gel in place, perhaps waiting two weeks will produce interesting numbers.
The Smell of Molten Projects in the Morning 