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.
Taking & making images.
Seeing as how I’m in the midst of several long-attention-span, heads-down projects that don’t produce continuous dopamine hits, a cat picture must suffice for a few days:
It’s neighborhood cat supervising rodents from the deck.
The crappy picture quality comes free with a phone camera zoomed entirely too tight.
An inch-long Praying Mantis stood guard on a carton delivered to the front door:
We hope to see many more of its kind.
Two views of a one-turn snail found on a lettuce leaf from the garden:
Mary has developed a Zero-Tolerance Policy for snails & slugs, so this one must start over again from the bottom of the food chain.
With sparrows excluded, the House Wrens eventually began setting up their second nest of the season, with the male proclaiming both he and his lady’s chosen nest are the best in the land:
Wrens are on our Most Favored Critter list!
Previous encounters with their ancestors and relatives:
Having just set up the camera to watch the Prusa MK4’s platform, this situation caught my eye while sitting in the Comfy Chair at my desk:
(The camera in the lower right doesn’t yet record videos, so you must imagine what I saw.) I forgot capturing this screenshot:
The nozzle was busily adding to the tangle, so I shut the printer off and trotted to the Basement Shop™ to find two more parts lying dead on the workbench:
This was entirely my fault, as I’d ignored PrusaSlicer’s warning about inadequate adhesion for the camera mount link standing in the corner:
That’s the PrusaSlicer preview after adding a wider brim and painting more support structures on all three parts. Given larger footprints, the next attempt completed without drama, which is the normal outcome.
Moral of the story: Tall skinny parts need more surface area on the platform than you think, even with excellent adhesion.
Although the Raspberry Pi camera has a good view of the Prusa MK4’s extruder, there’s not much light under there:
There’s also not much room for a lighting fixture on the printer where it must mount, so I modified a trio of nominally 12 V / 4 W COB LED panels:
Their “4 W” rating seems aspirational, at best, as a 12 VDC supply pushes only 75 mA through the panel, so they tick along at 900 mW. If you expect cheap eBay / Amazon components to live up to their specs, dream on.
The modifications:
The 15 LEDs on each panel are arranged in five parallel chains of three LEDs for a total forward drop of 8.3 V, so putting three panels in series works with the MK4’s 24 V power supply.
Stick them onto the MK4 power supply case with foam tape and wire them directly to the 24 V terminals:
There’s very little clearance between the machine frame and the X Axis carriage on the threaded rod. Putting the LEDs in a 3D printed case and routing the wires lower on the column would be nice touches:
The panels start at 30 mA when cold and drop to 25 mA as they warm up in the 63 °F = 17 °C Basement Shop. Each panel dissipates 250 mW: bright enough for the task, dim enough to avoid overpowering the camera’s limited dynamic range, and definitely within whatever power rating they should have.
Looking over the camera’s shoulder in normal shop lighting suggests it’s about right:
A staged scene with the shop lights turned off:
Call it Good Enough™ for the purpose.
The rpicam.cfg file holding the parameters for the Raspberry Pi watching the Prusa MK 4 printer:
bitrate=2000000
framerate=15
timeout=0
nopreview=
codec=libav
libav-format=mpegts
width=1280
height=720
rotation=180
roi=0.00,0.00,1.0,1.0
hdr=auto
The RPi camera for the wren nest is just taped to the window, but has a configuration providing a bigger picture:
bitrate=2000000
framerate=15
timeout=0
nopreview=
codec=libav
libav-format=mpegts
width=1920
height=1080
roi=0.00,0.00,1.0,1.0
hdr=auto
The useful pieces:
bitrate sets the average data rate, which may be too high for comfort outside your immediate LANframerate need not be as high as you thinknopreview prevents a preview picture while startingwidth and height do the obvious thing, but don’t try to be too cleverroi picks the image from a specific part of the camera sensor, so you can adjust the image layout if you have a rigidly fixed camerahdr doesn’t do anything for cheap RPi camerasPutting all the fiddly config in a file reduces the command line invocation to a mere jawbreaker:
rpicam-vid --config rpicam.cfg -o - | cvlc stream:///dev/stdin --sout '#rtp{sdp=rtsp://:5886/wrens}' &
Although you’d want to set that up to run automagically when the RPi starts up, for now I just fire it off as needed through an SSH session, with the ampersand letting it run after that terminal session closes.
The RTSP port (5886) and stream (wrens) can be anything you like, which comes in handy when squirting streams through port-forwarded firewall pinholes using a router that cannot handle different external and internal port numbers.
Useful background info:
A friend gave Mary a small-bird birdhouse, which immediately attracted the attention of a pair of House Wrens:
The vertical black bar is a DIY Birdsaver cord.
The entrance hole was 1-½ inch ⌀, a bit larger than the 1 inch ⌀ preferred by wrens and entirely suitable for the pair of House Sparrrows who also took an interest in the property:
This led to considerable discussion and displays of outright hostility:
Sparrows and wrens disagree on nestbuilding materials, with the wrens hauling twigs into the box and sparrows hauling them back out again.
Because wrens have better PR agents than sparrows, I intervened by taking the box apart:
Although I realize that’s a lot of work for a small bird, I dumped the contents off the patio and set about reducing the entrance hole:
Because birds aren’t too fussy about looks, I sawed off half an inch of 1 inch (ID) CPVC pipe and glued it in the hole:
The outside looks marginally better:
The sparrows continued to approach the hole at full throttle, deploying landing gear and speed brakes at the last possible moment:
But they no longer fit through the hole and eventually gave up trying. The wrens resumed hauling twigs, although we’re not certain they’ll finish the project, as birds tend to build several partial nests before selecting the final one.
We hope this will end on a happier note than last year’s Wreath Robins.
Under the plausible assumption the security / surveillance cameras along the Walkway Over the Hudson aren’t the cheapest junk available from a randomly named Amazon seller, this came as a surprise during a recent Walkway At Night stroll:
The IR LEDs emit just enough red light to be dimly visible to the human eye, but appear much brighter to a silicon detector. I think the long gap at the bottom right is a sensor of some sort, so the array of 18 LEDs has two deaders, one near death, and six more fading away.
The necklace lights on the Mid-Hudson Bridge are once again in good repair:
They were showing fixed white light, rather than a moving color display, but it’s still a nice effect.
The Smell of Molten Projects in the Morning 