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

Tour Easy Running Lights: Updated Lights
With the new battery mount & buck converter box installed on Mary’s bike, I updated the running light circuitry to match the ones on my bike. The original wiring just supplied 6.3 V from the headlight circuit, but now the four wire ribbon cable from the electronics box carries 6.3 VDC from the buck converter and a 6 VDC signal going high when the DPC-18 display’s “headlight” output goes active. The latter goes into an optoisolator pulling down Pin 2, telling the running light to stay on continuously.

The optoisolator sits next to the Arduino Nano’s Reset button:

Tour Easy Running Light – unified light top

The black wire barely visible below the optoisolator jumpers Pin 3 to ground, telling the firmware that this is the front running light.

The black & white wires from the top of the optoisolator connect directly to the ribbon cable entering on the other side:

Tour Easy Running Light – unified light bottom

The gray wrap of clear silicone tape mummifies the wire-to-wire soldered connectors.

The firmware now pays attention to the jumper input, so I need only one source file for both front and rear lights:
```
    if (digitalRead(PIN_POSITION) == HIGH) {
        Blinks = String("i e  ");             // rear = occulting
        Polarity = true;
    }
    else {
        Blinks = String("n e  ");             // front = blinking
        Polarity = false;
    }
```
It just doesn’t get much easier than that!

The Arduino source code as a GitHub Gist:
2024-07-05
LightBurn Slot Resizing

LightBurn includes a Slot & Tab Resizer tool that automagically finds and resizes joints to adapt a design for whatever material thickness you might be using. To judge from the LightBurn forum threads, it doesn’t deal well with random designs fetched from the Interwebs, which suggests those designs were either never intended for laser cuttery or just badly laid out.

So I fetched a sheep from a typical sketchy source and attempted to resize its slots:

Sheep DXF import – slot resize problem

The tool looks for rectangular shapes within the Tolerance of the Old Material Thickness width, then marks their narrow ends with red highlights and their length with blue. Obviously, not all of the slots we humans see count as slots.

A closer look at one of the body shapes with a slightly larger Tolerance shows some of the problems:

Sheep DXF import – body

Using the Node Editor tool reveals two stray nodes near the bottom of the second slot from the left:

Sheep DXF import – slots

Zooming in and blowing out the contrast:

Sheep DXF import – slot bottom

Manually deleting those nodes doesn’t solve the problem, because two more errant nodes lurk at the top of the slot:

Sheep DXF import – slot top

You probably didn’t notice those at first glance, either. Those nodes may be very close together, but they still confuse the issue.

Rather than tracking down and deleting / adjusting those nodes one by one, you can apply the Optimize Shapes tool to squash the superfluous nodes into straight lines:

Sheep DXF import – optimized

Don’t smooth the shapes or fit them to arcs at this point, because both of those operations will round off the corners.

That may still leave a few nodes requiring manual intervention, as on the face shape:

Sheep DXF import – optimized leftover

But at least the problem becomes tractable:

Sheep and dinosaur flock

As the Bard put it, all’s well that ends well.

2024-07-03
LED Light Switch: FAIL 2

Another switch for the temporary basement LED light strips failed the same way:

T8 LED power switch – failure 2

As always with such things, I suspect the only reason it has a UL mark on the back is because somebody else hasn’t missed theirs yet.

So I got a three-pack of inline switches with cute little indicator lights and set about replacing all of them:

Inline T8 power switch – internal

These switches carry absolutely no regulatory approval markings, although they do claim to carry 10 A at 250 V, which I take with another load of salt.

At least here in the US-of-A, a 240 VAC outlet has two “hot” wires carrying 120 VAC 180° out of phase, which means both conductors must be switched. Despite the voltage rating, only the L path goes through the clicky switch, with the N path along a strap just below the switch toggle. Using it on a 240 VAC circuit will kill you stone cold dead should you assume whatever it controls is turned off.

I secured the Line and Neutral conductors with crimp connectors, rather than just wrapping the 20 AWG wires around the screw terminals, because the case halves join without perimeter nesting: a bare millimeter of air in the gap between the halves separates the terminals from my fingers. A layer of good electrical tape on each side improved that situation, but not by much.

The complete lack of strain relief clamping on the cords prompted me to route the wires around the screw bosses. After a function check, squirts of hot melt glue anchored the two cords somewhat better.

Aaaaand I secured that loose strap on the right with an (identical to the others!) screw from the Tray o’ Random Screws. The other switches had both screws installed, so this one must have been a QC escape.

They suffice for the purpose, but … caveat emptor!

2024-07-02
Drilled Sunflower Seeds

It seems the best bait for voles is to tie sunflower seeds to the trap trigger, but poking a needle through the seeds tends to split them.

Well, I can fix that:

Sunflower seeds – drilled

This is “shell drilling” of a kind I had not previously encountered:

Sunflower seeds in shell – drilled

Those are #52 drill holes, 63-ish mils in diameter, and pass a standard sewing needle with ease.

The traps have been baited and deployed amid a plague of voles and I await customer feedback …

2024-07-01
Laser Test Paper: Outdoor Testing

“Laser test paper” is, of course, intended for testing lasers, but I thought it might make a outdoor plant tag. A while ago I tried some Trolase Thins acrylic for that job:

Plant tags – Trolase Thin – prototypes

Which turned out to be entirely too stiff, which wasn’t surprising given that Trolase Thin is intended for signage stuck on flat or slightly curved surfaces.

Despite being “paper”, laser testing paper is also too stiff:

Laser test paper – outdoor labels – 2024-06-22

The wrinkles and cracks on the left end of the tags shows the plastic coating makes it basically impossible to shape / bend the paper enough to wrap around a plant stem, then push it through the hole (offscreen to the left). I was not surprised too much by this discovery.

Those two strips now hang outside the kitchen window (left end upward), where they’ll get enough sun and rain to keep a plant happy, and I’ll see how well the engraved / damaged plastic coating stands up to that sort of abuse.

For Science!

2024-06-26
CUPS vs. HP Jetdirect 175x: Admitting Defeat

For several decades, a succession of PCs in the basement have served files and shared printers, the former through NFS and the latter through CUPS. When the Epson R380 finally went casters-up, I got an Epson ET-3830 printer with a network interface, leaving only our venerable HP Laserjet 1200 shared through the server.

For reasons I do not profess to understand, whatever magic shared the printers rotted away over the last month (or, more likely, software updates), to the extent that we could no longer reliably print to the Laserjet. Various software tinkerings being unavailing, I dropped just under thirteen bucks to make the problem Go Away™:

HP Jetdirect 175x – installed

It’s a new-old-stock HP Jetdirect 175x print server from the turn of the millennium, with an Ethernet jack on the back and a USB 1.0 (yes, one-point-zero) jack on the front. It’s roughly contemporaneous with the Laserjet and designed to work with it.

The thing started up in DHCP mode, so I had to ask the router where it was on the network. Configuration then amounted to putting it in static (“Manual”) IP mode, assigning an address, and restarting it.

Aim the CUPS servers on our desktop PCs at the new address, fire off a test page, It Just Worked™, and we’re once again printing like it’s 1999.

That was surprisingly easy.

2024-06-21
M5 Tee Nut: Test To Destruction

The mounting block under the electronics box for the new UPP battery has a recess for an M5 tee nut:

UPP Battery Mount – Block 5 Show View

As with the Terry frame mounts, I glued the modified tee nut in place with JB Plastic Bonder urethane adhesive, did a test fit on the bike, discovered the whole affair had to sit about 10 mm forward, put the new frame measurement into the OpenSCAD code, and ran off a new block.

Which gave me the opportunity to perch the old block atop the bench vise with the tee nut aimed downward between the open jaws, run an M5 bolt into the nut, and give it a good thwack with a hammer:

UPP Battery Mount – M5 insert adhesive test

Although the urethane adhesive didn’t bond uniformly across the tee nut, it had enough grip to tear the PETG layers apart and pull chunks out of the block.

As with the tee nuts on the Terry bike, this one will be loaded to pull into the block, so it will never endure any force tending to pull things apart, but it’s nice to know how well JB Plastic Bonder works.

I chiseled the PETG and adhesive debris off the tee nut, cleaned it up, slathered more Bonder on the new block, and squished the nut in place. After I get the electronics box sorted out, the whole affair will never come apart again!

2024-06-20