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

Craft Stick Plant Markers: Laser Fixture

Converting craft sticks into plant markers should be a mass-production process, which means a fixture is in order:

Craft Stick Markers – fixture first fill

Admittedly, making ten markers at once barely qualifies as “mass production”, but you (well, I) can think of it a proof of concept.

The basic shape comes from a 0.25 mm outset around the measured size of a craft stick (150×18 mm), plus an alignment target:

Craft Stick Plant Markers – fixture cut layout – array base

A good rule of thumb says never do any more work than absolutely necessary, so the rest of the fixture comes from linear arrays replicating the stick slots and targets:

Craft Stick Plant Markers – fixture cut layout – full

The two strips over on the left (with a common cut down the middle) get glued to the underside of the fixture:

Craft Stick Markers – fixture rail gluing

They’re exactly 5 mm apart to bracket one of the knife-edge bars supporting the fixture. The bar is upside-down to put its flat side upward:

Craft Stick Markers – fixture target detail

Yes, the fixture is made of chipboard, mostly because it’s about the same thickness as a craft stick and it’s cheap & readily available. Each target gets an ink blot to make it more conspicuous; there is also a tiny hole burned through the chipboard at the center to mark the other side for the strips.

Two knife-edge bars (sharp side up) support the sticks near their ends, well out of the cutting path, to prevent scorch marks:

Craft Stick Markers – fixture overview

It’s worth noting the knife-edge bars are 5 mm wide and the platform spaces them on 3/8 inch = 9.525 mm centers. Not 10 mm, not 9.5 mm, exactly 3/8 inch. Kinda like the platform leadscrews: a 4 mm lead thread driven by a belt with 0.2 inch pitch. Only in America.

This doodle captures the key dimensions down there in the corner to work out where the strips should go:

Craft Stick Plant Markers – fixture vs laser bar spacing doodle

Now, to convert names from a garden map into plant markers …

2023-04-25
Trail Camera: Skunk

We’ve never seen a skunk by day, so this was a bit of a surprise:

Skunk by night

We occasionally smell a skunk by night, but this critter seems peaceable enough:

Skunk by night – detail

Skunks usually have a striped back, so this one’s pure white fur will be easy to identify should we meet again, ideally at a mutually respectful distance.

2023-04-24
Plant Markers: Craft Stick Edition

Inspired by a LightBurn forum post I ~~can no longer find~~ once again tracked down, I tried my hand at ~~popsicle~~ craft stick plant markers:

Plant Markers – craft stick tests

You’d have only one name on the end of each stick, with the uncut section jammed into the ground: these are test pieces to demonstrate capability.

Wood is better than acrylic because it checks all the eco-friendly attribute boxes. Admittedly, craft sticks don’t exactly grow on trees, but we seem to ignore such externalities in nominally eco-friendly products.

Bonus: a recurring revenue stream from the replacement market!

The design, such as it is, involves subtracting the letters from a rectangle maybe half a millimeter short of their top & bottom extents and a few millimeters longer than their length. Using a chonky font with generous letter spacing may prevent prompt disintegration by weathering:

Plant Marker – craft sticks – LB layout

Engraving the letters marks their uncut sections outside the rectangle, although we know laser char on wood-ish materials fades in sunlight. The two big sticks have Radish engraved with varying density; the darker version looks better against a lighter background never found in an actual garden.

Mary thinks they might be a nice fundraiser for the next Master Gardener Plant Sale.

Outdoor field tests seem appropriate …

2023-04-21
Techie Temptations

I walked up to a sign-in kiosk with an interesting difference:

Kiosk app update

If they ask a question on a public-facing device, they must expect a response. Right?

This interesting assembly sprouted from an upstairs wall:

Wash hose valve

The brass fitting seems intended for a braided hose leading to a nozzle, but there was no corresponding floor drain in the room. I’m sure the shutoff valve in the bottom elbow was turned off.

Back in the motel, I attempted to plug in my charger:

USB sockets vs AC plug

The currently trendy black-on-black design scheme doesn’t work well in the low-light environment of a motel room. The white plastic tabs in those USB sockets were the only visible parts of that whole assembly.

As the saying goes, “Without temptation, there can be no virtue.”

Sometimes I am sooo tempted …

2023-04-20
Subaru Forester Gas Tank Capacity, Experimental Measurement Thereof
According to the manual, which I have hitherto had no reason to doubt, our non-turbo 2015 Subaru Forester has a 15.9 gallon fuel tank:

Subaru Forester – Fuel Capacity Chart

One screen shown on the dashboard’s Multi-Function Display gives the current mileage and estimated range:

Forester – MPG Range

Dividing those two numbers gives you 13.97 gallons, the current fuel level. As you’d expect, should the average miles per gallon change, the range will change accordingly.

The trip odometer says we have driven 72.8 miles since I filled the tank. Dividing that by the average mpg gives 2.3 gallons, so the tank could possibly hold 16.2 gallons, which, given all the averages involved, is reasonably close to the 15.9 gallons shown in the manual.

Being that type of guy, I have a spreadsheet tallying each fillup since the car was new:
- 8.1 gal average
- 7.5 gal median
- 13.9 gal maximum
Long ago, my father taught me to fill the tank when the needle got halfway down and I’ve been doing so ever since. As a result, we have only rarely seen the Low Fuel Warning Light:

Subaru Forester – Low Fuel Warning Light info

A concatenation of unavoidable events put us southbound on I-87 when that light went on. Given the estimated range of 70-ish miles, I planned to refuel at the New Baltimore Service Area, about a dozen miles ahead.

The engine shut down and all the dashboard warning lights lit up with the Service Area Ahead sign in view:

Out of Gas – Service Area Ahead

All the “facilities” are blank because they’re rebuilding the whole place, with the gas station remaining open.

So I slapped the shifter into neutral and we drifted slowly along the shoulder, under the bridge visible ahead, and eventually came to a halt at the beginning of the exit lane.

There was only one thing to do:

Out of Gas – Walking On

Some storytelling later:

Out of Gas – Walking Back

Just because I could:

Refueling – GPS Track

For what are, I trust, understandable reasons, I started the tracker after I began hiking and forgot to turn it off before driving away.

After figuring out the devilishly complex spring-loaded anti-spill spout on the gas can, we drove 1500 feet to the Service Area:

Out of Gas – Service Station

As usual, I filled the tank until the nozzle automatically shut off, for a total of 13.554 gallons in two transactions:

Pump Receipts

Now, it is possible the Forester fuel system has another 2.3 gallons tucked away somewhere, but if that reserve doesn’t make the wheels go around, it’s not doing me the least bit of good.

The fact that I’ve occasionally added just short of 14 gallons suggests the estimated remaining capacity depends strongly on the average mileage up to that point and I have come very very close to running out of gas on several occasions.

As far as I can tell, the usable fuel capacity is a scant 14 gallons and the Low Fuel Light goes on with, at most, a dozen more miles in the tank.

This is the second time in more than half a century of driving I’ve run out of gas.

My father was right and I shall henceforth mend my wayward behavior.
2023-04-17
Tour Easy Running Light: Heatsink Machining
Having acquired some thick-wall (1 inch OD, ¾ inch ID) aluminum tube, making the LED heatsink and lens holder for a running light generates a lot less scrap. A new doodle gives the dimensions in a rather Picasso-ish layout:

Running Light – dimension doodles

The back end of the tube gets turned down to 23 mm OD and cleaned up to 19 mm ID, then scored to give the epoxy something to grip:

Front Running Light – Heatsink shell scoring

The front end gets bored to 22.5 mm for the lens holder and has its OD cleaned up to 25 mm:

Front Running Light – finished shell

Clean up the end of a ¾ inch rod to 19 mm OD, knurl it a little to increase the OD ever so slightly and improve its griptivity, slice off a bit more than 10 mm, butter it up with JB Weld epoxy, and shove it into the shell with its front end aligned and its back end sticking out:

Front Running Light – epoxied plug in shell – rear

Face off the back end and the front end looks fine as assembled:

Front Running Light – epoxied plug in shell – front

Grab it in the Sherline mill’s three jaw chuck to:
- Drill & tap the M3 central hole for the stud holding the circuit plate to the back end
- Drill 1.6 mm blind holes for the circuit plate pins
- Drill 2 mm through holes for the LED wires, 60° apart
Which looks like this from the front:

Front Running Light – drilled heatsink – front

And like this with the circuit plate screwed & glued to the rear:

Front Running Light – circuit plate mounted

Clean up the OD of some ¾ inch PVC pipe to 25 mm, bore it out to 23 mm.

While the Sherline is set up, drill a pair of 2 mm holes in the lens holder for the wires, aligned so they’ll match the heatsink holes.

Because we live in the future, laser-cut the rear cap from some edge-lit acrylic with a black inner disk:

Front Running Light – PVC tube – end cap

Cutting that cap with the notch included is now trivially easy, compared to the previous machining.

Now for some circuitry …
2023-04-14
Laser-engraved Polycarbonate: Color!

Prompted by a LightBurn forum discussion, this was completely unexpected:

Polycarbonate engrave – 400mm-s 20pct 0.1mm – brushed

The color is apparently a side effect of the CO₂ laser vaporizing the plastic, because it emerged during the engraving process.

Polycarb tends to get all melty when cut, so it’s not particularly good for laser machining. Indeed, the engraving produced filaments of (presumably) melted / condensed plastic that I brushed off after taking this picture:

Polycarbonate engrave – 400mm-s 20pct 0.1mm – as cut

If you could put up with the filaments and the poor cut edges, it might be useful for front panel legends and suchlike.

2023-04-13