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.

Tag: Improvements

Making the world a better place, one piece at a time

COVID-19: Elephant Tracks

Getting a post mentioned on Reddit causes a traffic spike:

Elephant Sighting – Reddit traffic spike

It’s nothing like the bedbug impulse, though …

The bulk of the subsequent increase comes from the Fu Mask Templates, although I suspect folks aren’t looking for 3D printed stuff.

As far as my original predictions go, I’m pleased to be somewhat wrong, as the most recent data shows the effect of handwashing, distancing, and general paranoia:

COVID-19 – USA Total Cases and Total Deaths – 2020-04-08

The lowered slope in the Total Cases curve means the cases now increase by a factor of ten every 20 days, rather than every eight, which is a major improvement. Still, it implies whatever seems bad right now will be only 10% of the badness in three weeks.

Folks with better models than my ruler make better predictions:

They assume “full social distancing through May 2020” and, apparently, the virus vanishing thereafter.

The colored area represents the 95% uncertainty range. Among other things, we don’t know what will happen when the (unknown number of) currently infected people need (far) more medical care / equipment / resources than we have available (“open image in new tab” for more dots):

Hospital Resources – healthdata.org projection – 2020-04-09

Given our somewhat … erratic … national leadership, keeping everybody tucked in and the economy turned off for any substantial duration seems unlikely, but there’s no other way to reduce the death toll. The vast majority of the population will not have been exposed to COVID-19 and will, therefore, remain vulnerable to any (infected-but-asymptomatic, thus untested) people arriving from other counties / states / countries.

You know what to do: stay home and wash your hands. You’re buying time for the medical folks to catch up with the situation.

2020-04-12
Clearing the Overgrowth

Our morning task on clear days has been clearing a forsythia overgrowth along the north lot line; the branches tip-root as our neighbor’s bushes creep southward toward the sunlight. The process involves ramming a six-foot octagonal high-carbon / tempered / tougher than nails / rings like a bell steel bar (measuring a generous 1-1/8 across the flats) deep into the dirt under the plant, kicking a 4×4 inch block against the bar, pushing downward with all my weight to pry the plant upward until something deep underground rips, then repeating from all directions until enough big roots break and the mass tears out:

Forsythia root removal

Then it’s on to the next plant.

The turmoil exposed a run of black PVC pipe along the lot line, although one end seemed firmly anchored. More excavation revealed a giant grape vine root growing around the pipe:

Grape root around PVC pipe – top

I had to sever the pipe with an axe on both sides to free the root:

Grape root around PVC pipe – side

The pipe originally carried water from the Mighty Wappinger Creek along the east lot line, 500 feet away and 70-ish feet down, presumably to water the previous owner’s plants. As far as I’m concerned, the remains of that pump will remain on the bottomlands forevermore, but at least we’ve cleared the remains of the plumbing.

Mornings like that make writing CNC code look downright attractive, but I’m developing the cutest little biceps …

2020-04-11
Tek Circuit Computer: Formula Layout

Although Inkscape can lay out simple text in many intricate ways, there seems no way to typeset mathematical equations, even the simple ones involved in the Tektronix Circuit Computer.

So I entered the equations in LibreOffice’s math editor, zoomed in on each equation to the maximum 600%, whacked the little-used PrntScr key, cropped out everything except the equation, and saved it as a PNG file:

Tek CC – Bottom Deck Back – FR formula

Import the PNG files into Inkscape, fiddle with the line spacing to get enough room, and jockey everything into position:

Tek CC – Bottom Deck Back – formula detail

Bit of a kludge, but it looks Good Enough™.

2020-04-10
Homage Tektronix Circuit Computer: Minimally Viable Product, Pickett Variation

This one came out just about perfect:

Tek Circuit Computer – MVP – Pickett Edition – front

The yellow decks may not be authentic, but they definitely look nice; think of it as an homage to Pickett’s Eye-Saver Yellow slipsticks.

The rear has my how-to-operate hints:

Tek Circuit Computer – MVP – Pickett Edition – back

Laser-printing on “inkjet” paper worked fine, although this isn’t fancy Gloss-coated Brochure paper, and the text looks like it should.

The cursor sports a two-pass hairline scribed at 330 g and filled with Lacquer-Stick paint:

Tek CC – Milled PETG cursor – Lacquer-Stik hairline

This time, I had the clear film on top!

Although the picture doesn’t do it justice, the scales are in blue ink, which looks better against the yellow background. I suppose I could do custom colors:

Pilot V5RT cartridge – ink levels

The line width has decreased as the ink level drops: 0.3 mm on yellow card stock and 0.2 mm on glossy white brochure paper. I don’t know if they’re supposed to work like that, but, for this application, narrower lines are definitely better.

2020-04-09
Tek Circuit Computer: Paper Matters, Redux

The back of a Tektronix Circuit Computer’s bottom deck carries instructions and information:

Tektronix Circuit Computer – rear

A separate instruction manual told you how to use the thing, under the reasonable assumption you’d be intimately familiar with slide rules.

In this day and age, the back should carry how-to-use instructions, so I summarized the manual into half a dozen lists:

Tek CC – instructions – first pass

Which looked fine & dandy & ready to print, thereby exposing various typos / inconsistencies / misalignments:

Tek CC – test print – HP Brochure vs ordinary copy paper

Whereupon I (re)discovered just how much paper matters.

The HP Brochure Glossy inkjet paper on the left produces wonderful results with a 0.5 mm Pilot V5RT ball point pen and has coating on both sides. It’s intended for handouts, brochures, and suchlike; the Pilot pens produce identical results on either side.

The same text, printed on plain old 22 pound “multipurpose” paper on the right, looks much better and makes the HP paper looks like something done with crayon on paper towel.

I could try a font with finer strokes, but … ick.

It’s unclear whether Brochure Matte paper would make any difference, nor whether running coated “inkjet” paper through a laser printer would have an … infelicitous … outcome.

Past experience shows the unsteady ziggurat of Linux printing doesn’t respond well to tweakage: when the default settings don’t work, there’s no easy / predictable way to change any particular setting.

For future reference, print the instruction on what will become the back of the bottom deck, mark the center point, tape it to the CNC 3018 platform, touch off XY = 0 at the center, and draw the front scales: everything lines up perfectly without extra fuss & bother.

2020-04-08
PETG Diamond Drag Engraving Tests
The hairline on the second machined cursor looks pretty good:

Tek CC – Milled cursor – unlaminated bottom deck

Based on manually scratching some acrylic, the GCMC code retraced the hairline four times to help the Sharpie stick to the groove. Maybe fewer passes would be better?

Affix a PETG scrap to the milling fixture for some manual CNC action:

PETG – engrave through film

Just to see what happened, I made the first scratch through the protective film and, because it’s hard to tell which side is up, the scratch went through the white film.

Repeat several times with variations in number of passes & downforce:

PETG – engraving test – overview

Manual jogging FTW:
- 2 passes, 300 g, through film
- 2 passes, 300 g, no film
- 1 pass, 300 g
- 3 passes, 300 g
- 4 passes, 300 g
- 1 pass, 260 g
- 1 pass, 330 g
A closer look through the PETG sheet, as you’d see finished hairline, with the scratches in the same order as above:

PETG – engraving test – detail grid

They may be easier to see against a blank background:

PETG – engraving test – detail plain

Or in a hairline’s natural environment:

PETG – engraving test vs Testors sample

The absolute best-looking line is at the top, with the diamond point scribing through the (white) protective plastic film.

Multiple passes average out the waves / glitches / irregularities, at the cost of broadening the hairline.

The bottom hairline suggests a single pass with more downforce produces a broader groove and a finer line of Sharpie ink at the bottom; the top appears more rounded and the bottom more ragged.

Doing one pass with enough pressure to cut through the thinner (?) transparent(-ish) film may produce a better overall result. This will require me to get the orientation right.

The Real Hairline in my K&E Deci-Lon slipstick is a smoothly engraved, neatly half-cylindrical, channel with a smooth thread of red (!) ink / paint / pigment laid along the middle. Obviously, my engraving hand is weak …

The nightmare scenario: engraving a smooth hairline groove, completely backfilling it with paint, sanding (that side of) the cursor smooth to leave the groove’s paint flush with the surface, then polishing the plastic back to full transparency. Even I agree that’s crazy talk, at least for a circular slide rule made with laminated paper decks.
2020-04-07
Beaver Dam: Rising Water

The furry engineers in charge of maintenance laid several layers of branches along the breast of their dam:

Beaver Lodge and Dam – raised dam – 2020-03-31

Their pond is maybe nine inches deeper than a few weeks ago. The rail trail has little danger of flooding, even as the water creeps closer, because the roadbed is higher than the far shoreline.

Go, beavers, go!

2020-04-05