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.

Category: Oddities

Who’d’a thunk it?

Dutchess Rail Trail: Beaver Lodge & Dam

A beaver family built their lodge next to the Dutchess Rail Trail:

Beaver Lodge – DCRT N of Golds Gym – 2020-02-23

It’s just to the right of the fence post, on the far side of the pond.

Dutchess County’s aerial survey in 2016 showed a dry-ish area west of the rail trail, with a culvert to the north:

Beaver Lodge – DCRT N of Golds Gym – 2016 CIR image

We went back the next day and stopped at the culvert. Their dam spans the entire near side of the pond, upstream of the ditch (just above my hand) leading to the culvert:

Beaver Lodge and Dam – DCRT N of Golds Gym – 2020-02-25

The helmet camera pictures look west from the rail trail, with the lodge in the northernmost open area. The wide-angle camera lens exaggerates the distance, but the lodge is only about 35 feet from the fence.

A stand of birch trees near the lodge now looks like a combination buffet and construction yard. When beavers discover ferrocement, their structures will become much more obvious.

Go, beavers, go!

2020-02-29
The Return of High-Reliability / High-Availability Trash Cans

Five years ago, robotic trash cans were a thing on Vassar’s campus, including this duo in front of Vassar’s library:

Vassar Library – Trash and recycling containers

That was then, this is now:

Vassar Library trash cans

I infer the robotics did not work out as anticipated.

2020-02-23
Frozen Fire Hydrant, One Year On

It seems reporting a frozen hydrant to the local fire company didn’t produce any meaningful action:

Frozen hydrant – Sheldon at Rt 376

We didn’t have any fires in the neighborhood where it might have been a problem, but I’ll try the water department this year …

Oddly, the water department repainted most of the fire hydrants along most of the roads last year. This one apparently didn’t qualify, for whatever reason, despite being only slightly off Rt 376 on Sheldon:

Frozen hydrant – Sheldon at Rt 376 – Google Streetview

When it’s not frozen, it’s not obvious …

2020-02-22
High-Impact Driving

We spotted this near our usual parking spot during a recent grocery trip:

Adams crash – stone wall

The bush was pretty well uprooted, suggesting the vehicle stopped atop the bush after demolishing the wall.

Wondering how it got there, I looked across the parking lot:

Adams crash – reverse view

Yes, that’s a dead lamp post. The impact dislodged its concrete base by about four inches:

Adams crash – lamp pole detail

The greenery came from another eviscerated bush:

Adams crash – bush debris

I expected to see tire gouges in the grass, but … nope.

The bush got a haircut, although the right half seems undamaged:

Adams crash – bush detail

The boulder won its disagreement with the vehicle, although there’s surprisingly little shattered plastic and other debris along the trail:

Adams crash – boulder detail

The impact dislodged the boulder, which came to rest about four feet from its origin:

Adams crash – overview

The damage lies along a straight line from the middle of the Adams entrance intersection to the wall impact:

Adams crash – trajectory

There are no obvious skid marks, undercarriage scrapes, or gouges in the grass anywhere along the trajectory, suggesting the vehicle remained mostly airborne and ballistic during the whole event, and even the three (!) curbs involved have no marks.

The nice lady at the Adams Customer Service counter didn’t know what happened and, as usual, the Poughkeepsie Journal (newspaper) has nothing to say.

I did not check for a high-clearance pickup truck with tall tires and severe front-end damage in the body shop across the street, although one seems a likely suspect. Whatever the vehicle may have been, it was definitely traveling at the usual (tautological) “high rate of speed” …

2020-02-02
CAMtool V3.3 vs. The Fat Fingers of Death

As is my custom, the day before showtime I talked my way through a final full-up dress rehearsal, with the HP 7475A plotter and the CNC 3018XL running their demo plots. As if to justify my attention to detail, the 3018 refused to home, with its X axis motor grinding in a manner suggesting something had gone terribly wrong with its driver.

OK, I can fix that™.

Turn off the power, verify the leadscrew turns smoothly by hand, check all the connections & connectors, then pull the DRV8825 PCB to see if anything looks obviously wrong. It didn’t, so I carefully re-plugged the driver and moved the whole affair to the Electronics Workbench for further study.

I turned on the scope and Tek current probes, then turned on the 3018 power supplies, whereupon a great cloud of Magic Smoke emerged from the CAMtool board and filled the Basement Laboratory with the acrid smell of Electrical Death.

It seems I carefully and meticulously re-plugged the DRV8825 PCB into its socket exactly one pin too high, which, among other Bad Things, connects the +24 V motor power supply to the driver GND pin.

Obviously, this did not end well:

CAMtool V3.3 – blown stepper fuse

The fuse, put under considerable stress, vented smoke & debris in all directions across the board; note the jets above the white motor connector. Surprisingly, the 1 kΩ resistor just below it is in fine shape, as is the rather blackened electrolytic cap.

The fuse measures the same 150-ish mΩ as the fuses in the other two axes, but I doubt it’s actually a fuse any more.

Astonishingly, the Arduino clone on the board worked fine, so I could extract the GRBL configuration.

Memo to Self: Never plug things in with your head upside down!

2020-01-30
Alkaline Battery Packaging

Apparently, we’ve burned enough cargo aircraft and killed enough people to require careful attention to detail in battery packages:

Amazon alkaline AAA packaging

These “Ships from and sold by Amazon” alkaline AA cells arrived by UPS. They now fall under reasonable requirements to prevent shorting and damage, although the cardboard box wasn’t sturdy enough to prevent them from breaking free laterally.

One might quibble about the “Health & Personal Care Item” description, but, yeah, better battery packaging seems like a good idea.

2020-01-11
Scrap EEPROMs

A quartet of defunct 64 KB EEPROMs (*) emerged from a box of microscope doodads, so I stuck ’em under the stereo zoom scope for final pictures.

The oldest one, an MCM68764, came from Motorola with a 8313 date code. The next three, all TMS2764JL-25, came from TI with date codes in 84 and 85, so they have slightly different layouts.

MCM68764C EPROM

TMS2764JL-25 A EPROM

This one is rotated 90° counterclockwise:

TMS2764JL-25 B EPROM

TMS2764JL-25 C EPROM

The hideous compression artifacts come from the original Pixel 3a images, because they’re (digitally) zoomed in all the way, plus bonus optical distortion from the quartz windows. The chips definitely look better in person, although the (optical) magnification isn’t nearly enough to show the tiniest details.

(*) Uh, they’re just EPROMs. It’s been so long since I’ve typed it that the extra “E” just stuttered right out. That’s my story and I’m sticking with it … at least I got the image names right!

2020-01-05