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.

Author: Ed

DIY CPAP Mask Liner
Mary cut out a simple cloth liner for her ResMed F20 CPAP mask (a.k.a. “cushion”) and snipped away at the fabric until it felt about right. I scanned the result and turned it into a bitmap mask (which is entirely different from a CPAP mask):

Mask liner – scanned

Given that as a start:
- Import the scanned image into LightBurn
- Fair a few curves around the perimeters by hand, rather than attempting to trace the thing
- Rationalize the sizes
- Make it symmetric
- Cut a few prototypes while tweaking the fit
Which leads to a pattern like this:

CPAP Mask Liner – F20 knit – spline fit

The rectangular upper part forms a simple eyeshade that also keeps minor leaks from disturbing her sleep. Your mileage may vary, depending on how much you toss and turn during the night.

We found the fit depends on the fabric, with woven fabric requiring a taller opening:

CPAP Mask Liner – F20 knit woven – LB layout

The engraved legend verifies I used the proper design for the fabric:

Laser cut CPAP Mask Liner – F20 – knit fabric

The opening has tabs holding it in place while cutting, at least until we get this down to a routine.

Then make enough for a while:

Laser cut CPAP Mask Liner – F20 – production

The usual woodstove odor vanishes after half a day sitting atop the clothes washer. Putting them in a mesh bag and tossing them into the regular wash refreshes them after use.

The LightBurn SVG layouts as a GitHub Gist:

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2023-02-22
Shower Faucet Handle Rebuild & Tightening

The shower faucet handles have been getting looser, but once a decade seems reasonable. This time around, however, the setscrews had dug themselves so far into the splined plastic fittings that they had run out of thread:

American Standard Shower Handle rebuild – gouged setscrew sockets

Wipe out the crud, clean out what’s left with alcohol to encourage stick-to-it-ivity, and fill the cavities with JB Kwikweld epoxy:

American Standard Shower Handle rebuild – epoxy fill

When it cures, file a flat across the sockets:

American Standard Shower Handle rebuild – flatted

Reinstall in reverse order with a dot of NeverSeez on the setscrews for good measure.

Just so you don’t have to look it up, this is what the cold water faucet innards looked like a decade ago:

Shower faucet valve stem

Ought to be good for another decade, right?

2023-02-21
World War II Dog Tag Layout

Quite some time ago, I hammered out G-Code to engrave ersatz dog tags for a Cabin Fever demo:

Cabin Fever Dog Tag

A dozen years later, making a World War II dog tag is a whole lot easier:

John Q Public – WWII dog tag

Well, “easier” if you allow laser engraving in white-on-black Trolase using a font intended to mimic a typewriter.

Close enough, methinks.

Which comes from a simple layout:

John Q Public – WWII dog tag – LB layout

The outline traces a scanned image of my father’s tag, fitting a few hand-laid splines around the curves:

John Q Public – WWII dog tag – spline curves

I generated a random serial number based on my father’s draftee status (he was in his early 30s during his South Sea Island tour) and state of residence; my apologies to anyone carrying it for real. His blood type was A and (I think) the religion code marks him as “Brethren”, a common group in my ancestry.

Given the outline, various plastics, and a laser, other effects become possible:

WWII dog tag outline test

It might come in handy for something, someday.

The LightBurn SVG layout as GitHub Gist:

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2023-02-20
Dunkin’ Drive-Through: Triumph of Hope Over Experience

The bollard at the newly opened Dunkin’ stands upright once again:

Dunkin drive-through corner bollard – repaired

I can’t tell whether the bollard stands in more concrete this time, but the gray pipe to the left of the gas meter is definitely new.

In round numbers, it took less than a week for the first impact, a week for the first repair, and … we shall see.

The white disk just behind it is a rat trap, with a subtle explanatory sign directly above it. The building has three such traps, so they’re apparently trying to stay ahead of a known problem; we find similar traps around most commercial establishments.

2023-02-17
Lift Chair Foot Risers
The fuzzy felt feet on the lift chairs raised them enough to slide both floor lamp bases underneath with the backs in the upright state, but reclining the chair with the light more than halfway back along the side of the chair crunched the lamp base.

Rather than print taller fuzzy feet, which takes a long time, I knocked out two quartets of laser-cut risers:

Lift Chair Foot Riser – installed

They’re six layers of 3 mm MDF or plywood:

Lift Chair Foot Riser – assembled

The LightBurn layout makes one riser:

Lift Chair Feet Extenders – LB layout

The upper two discs become two rings and two pads, with the lower two disks forming the middle layers. The ring ID clears the chair foot and the pad OD fits into the existing printed fuzzy felt foot. The two cuts making that happen leave the thinnest imaginable ring of MDF in place.

The tiny circles cut holes for 11 mm snippets of 1.1 mm hard steel wire aligning the layers:

Lift Chair Foot Riser – locating pins

Assembly sequence:
- Tap two pins into a ring
- Butter the ring with yellow wood glue
- Slide the other ring over the pins
- Butter
- Slide a disk over the pins
- Drive a pin into a pad
- Butter
- Slide the other pad over the pin
- Butter
- Slide a disk over the pin atop the pads
- Butter one of the disks
- Slide the disks together over all three pins
- Tap all pins below their surface
Make two and clamp them together to ensure everything sticks firmly.

Repeat to make four risers

Install, recline, and enjoy not hearing a mysterious crunch from the lamp base.

The alert reader will note the 6 mm stack of two pads leaves a slight gap above the printed foot. Turns out the recess is 5 mm deep and I decided to just live with a 1 mm gap down there.
2023-02-16
Flypower Wall Wart: FAIL

The IR sensor on the under-cabinet LED lights I installed half a dozen years ago became increasingly flaky. Its wall wart power supply was on the hot side of uncomfortably warm, so I had an obvious culprit.

The data plate says it’s UL Listed, which is comforting:

Flypower LED wart – data plate

The open-circuit output of a 12 VDC power supply should not look like this:

FlyPower 12V 1A – no load

The horizontal scale is 100 ms/div, so those ramps seem much more languid than you might expect from a 60 Hz wall wart.

Adding a 16 Ω load to draw maybe 750 mA got its attention:

FlyPower 12V 1A – 16ohm load

The average may be 12 V with too-large dips at the expected 120 Hz, but looky at all the hash riding the output!

No wonder the IR sensor was having such a hard time. When the LEDs are off the voltage ramps between 16 and 5 V. When it eventually turns on the supply has impossible noise levels.

So I cracked the case and extracted the electronics:

Flypower LED wart – components

Those caps over there on the left rear don’t look healthy, do they?

Flypower LED wart – failed caps

No. No, they don’t and you shouldn’t be able to see the wiring inside the inductor between them, either.

Probing the Box o’ Wall Warts produced a similar-ish wart that only required harvesting and splicing the teeny coax plug from the failed adapter to put the LED strips back into normal operation.

The identical supply for the identical LED strips on the other side of the kitchen continues to work fine and feel only warm-ish, so I’ll let it be.

2023-02-15
Universal Socket to Quarter-Inch Hex Adapter Stack
Being that type of guy, I wanted to salvage a loooong square-head bolt from the utility pole stub formerly holding up the mailboxes, which would require a few gazillion turns of its square head with the Adjustable Elephant Wrench. After verifying I couldn’t just hammer the mumble thing through the pole, I gave a few turns of the Universal Socket on a ratchet:

Universal Socket Wrench

It’s intended for goobered hex heads up to 1-¼ inch, but the pins slide down around pretty much anything that sticks out and jam against the shell, so it’s handy for those last-ditch extraction events.

After verifying doing this by hand would occupy me until just before the heat death of the universe, I followed Mad Phil’s signal connector adage: “If you can get to BNC, you can get to anything.”

Some rummaging produced this unsteady mechanical ziggurat:

Universal Socket to quarter-inch hex – adapter stack

From bottom to top:
- Universal Socket with ½ inch square drive socket
- 1/2 inch square drive to ¾ inch hex
- 19 mm (close enough to ¾ inch) 12-point socket to ⅜ inch square drive socket
- ⅜ inch square drive to ¼ inch square drive socket
- ¼ inch square drive to ¼ inch hex drive
Then stick the teeny end into the hand drill, rig engines for reverse running, and whine away on that bolt, which obligingly backed right out.

After the fact, I found the obviously missing ¼ to ½ inch square drive adapter hiding in the Drawer o’ Sockets:

Universal Socket – short adapter stack

Which doesn’t make any more sense, but is less likely to fall apart under normal use.

Aaaaand one more adapter makes this possible:

Improper square drive adapter stack

That’s a 50 mm socket turned by ¼ inch hex drive in four easy steps, although I’m reasonably sure it still won’t get the idler bogies off my armored personnel carrier.

The stray adapter steps down from ½ square to ⅜ square, should a need for a breaker bar occur during eyeball surgery.
2023-02-14