Category: Science

If you measure something often enough, it becomes science

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
House Sparrow vs. House Wren vs. Entrance Reducer

A friend gave Mary a small-bird birdhouse, which immediately attracted the attention of a pair of House Wrens:

Bird House entrance reducer – wren exiting

The vertical black bar is a DIY Birdsaver cord.

The entrance hole was 1-½ inch ⌀, a bit larger than the 1 inch ⌀ preferred by wrens and entirely suitable for the pair of House Sparrrows who also took an interest in the property:

Bird House – sparrow inside

This led to considerable discussion and displays of outright hostility:

Bird House entrance reducer – wren vs sparrow

Sparrows and wrens disagree on nestbuilding materials, with the wrens hauling twigs into the box and sparrows hauling them back out again.

Because wrens have better PR agents than sparrows, I intervened by taking the box apart:

Bird House – nest base sticks

Although I realize that’s a lot of work for a small bird, I dumped the contents off the patio and set about reducing the entrance hole:

Bird House – interior cleared

Because birds aren’t too fussy about looks, I sawed off half an inch of 1 inch (ID) CPVC pipe and glued it in the hole:

Bird House entrance reducer – interior glue

The outside looks marginally better:

Bird House entrance reducer – exterior glue

The sparrows continued to approach the hole at full throttle, deploying landing gear and speed brakes at the last possible moment:

Bird House entrance reducer – sparrow approach

But they no longer fit through the hole and eventually gave up trying. The wrens resumed hauling twigs, although we’re not certain they’ll finish the project, as birds tend to build several partial nests before selecting the final one.

We hope this will end on a happier note than last year’s Wreath Robins.

2026-05-13

PolyDryer Humidity: April-ish

	2026-04-16
Filament	%RH	Weight – g	Wt gain – g	Gain %
PETG White	14	–	–	–
PETG Black	14	–	–	–
PETG Orange	22	52.5	2.5	5.0%
PETG Natural	15	–	–	–
PETG-CF Blue	23	55.4	5.4	10.8%
PETG-CF Gray	18	–	–	–
PETG-CF Black	14	–	–	–
PETG Blue	10	–	–	–
TPU Clear	14	–	–	–
TPU Black	14	–	–	–

Most of the PolyDryer boxes had the same humidity as before, so I didn’t disturb them. When the humidity starts to rise, then we’ll see what’s going on in there.

The PETG Orange meter continues to misbehave and has been glitching from 22% to 30%. The indicator card shows the humidity is around 10% inside and the relatively low weight gain suggests there’s not much water to be adsorbed.

The PETG-CF Blue spool is new and, once again, shows filament does not arrive bone-dry in the factory wrapper.

Those two boxes now have alumina beads.

Dehydrating the jar of wet silica gel on the induction cooktop (set for 405 °F) sweated it down from 532 g to 503 g over the course of four hours, with nearly all of that change in the first two hours.

Obligatory photo from a while ago, because it looks pretty much the same now:

Silica gel beads - drying — Silica gel beads – drying

2026-04-20

Basement Air Filter Box: Ewww!

Late last year I assembled four air filters and a fan quintet into a box filter:

Basement Air Filter Box – installed

Running continuously for three months made the air filters look like this (with an unused filter on top for comparison):

Basement Air Filter Box – 3 months – A

I have not stretched the image contrast, so the new filter isn’t the pure white in the top picture, but it’s still about the same white as the cardboard frame. The floor is, indeed, painted gray.

Looking at the pleats in the other direction to show I’m not making it up:

Basement Air Filter Box – 3 months – B

The inside surface of the filters has the same gray appearance. The fans are, unsurprisingly, immaculate.

Totally did not expect that!

The filters sport a MERV 13 rating and snag “most smoke” from the passing air, so they’ve been collecting any fumes not sucked out of the laser cutter, along with whatever arises from other Basement Shop™ activities.

So I’ll buy another set of filters, build another box, and see what accumulates during the next three months.

2026-04-08