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: Photography & Images

Taking & making images.

Layered Paper: Inkjet Printer Skew
The Summer 2026 issue of Living Bird from the Cornell Bird Lab had a downloadable set of paint-by-number images that seemed tailor-made for laser-cut layered paper, so I laid out a test piece with targets in the corners:

Page 5 – Printed page test piece

Print that on fancy paper, drop it into the Letter cutting fixture, align the printed targets with the layout using the same technique as with the punched cards:
- Position the laser head at the center of a target in the LightBurn workspace
- Skootch the fixture to put the corresponding printed target under the red dot pointer
- Position the laser head at another target
- Skootch the other printed target to match
- Iterate until both align properly
I find that’s faster / easier / no less accurate than Print and Cut.

Then Fire The Laser:

Page 5 – Test piece – cutting

That’s cut over honeycomb, rather than empty space, because there’s not much paper left when the cutting is done and the remaining pieces distort the lacework:

Page 5 – Test piece – as cut

That layer (with binary code 0001) goes under the top black mask hiding the remaining colors on the lacework. The wing feathers and details seemed too small for slots cut into paper, so printing them finessed the issue.

I had aligned the fixture at the upper-right target:

Page 5 – Printed page test piece – cut top-right

And the lower-left target:

Page 5 – Printed page test piece – cut bottom-left

The printed lines are about 0.3 mm wide, so the cut alignment is off by that much in both X and Y.

The lower-right target is spot on:

Page 5 – Printed page test piece – cut bottom-right

But the upper-left target is off by nearly a millimeter in Y:

Page 5 – Printed page test piece – cut top-left

As well as I can measure, the printed image is slightly distorted, perhaps by the printer’s feed rollers skewing the paper slightly on its way through the printer. The laser-cut holes are, again as well as I can measure, dead on.

The punched card process required scaling the composited PNG image by 97%×97.9% so the image matched the laser-evaporated holes. This distortion seems different, but different paper and printer settings surely affect the outcome.

On the whole, though, the first test piece came out OK:

Page 5 – Test piece – stack oblique view

Those chonky feet need some attention.

Maybe three out of four ain’t bad …
2026-08-20
Hiatus

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:

Cat on deck

It’s neighborhood cat supervising rodents from the deck.

The crappy picture quality comes free with a phone camera zoomed entirely too tight.

2026-07-20
New Wildlife
An inch-long Praying Mantis stood guard on a carton delivered to the front door:

Praying Mantis – early instar

We hope to see many more of its kind.

Two views of a one-turn snail found on a lettuce leaf from the garden:
One-turn Snail – right side
One-turn Snail – left side
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:
House Wren – second nesting – 2026-06-30
House Wren – second nest – 2026-06-30
Wrens are on our Most Favored Critter list!

Previous encounters with their ancestors and relatives:
- Mantis
- Snails
- Wrens
2026-07-01
Prusa MK4: Camera Mount Bird’s Nest

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:

Prusa MK4 – Bird Nest – A

~~(The camera in the lower right doesn’t yet record videos, so you must imagine what I saw.)~~ I forgot capturing this screenshot:

Prusa MK4 – Bird Nest – platform camera

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:

Prusa MK4 – Bird Nest – B

This was entirely my fault, as I’d ignored PrusaSlicer’s warning about inadequate adhesion for the camera mount link standing in the corner:

Prusa MK4 – Camera Mount Links – slicer preview

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.

2026-05-21
Prusa MK4 Camera Lighting
Although the Raspberry Pi camera has a good view of the Prusa MK4’s extruder, there’s not much light under there:

RPi Camera Mount – image

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:

Prusa MK4 – Extruder sidelight – COB LEDs

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:
- Unsolder the pins
- Crunch off the surprisingly precise 27.4 Ω SMD resistor
- Clean up the rubble
- Wire the panels directly in series, ignoring their bridge rectifiers
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:

Prusa MK4 – Extruder sidelight – installed

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:

Prusa MK4 – Extruder sidelight – front view

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:

Prusa MK4 – Extruder sidelight – camera overview

A staged scene with the shop lights turned off:

Prusa MK4 – Extruder sidelight – low-light view

Call it Good Enough™ for the purpose.
2026-05-20
RPi Camera RTSP Setup
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 LAN
- framerate need not be as high as you think
- nopreview prevents a preview picture while starting
- width and height do the obvious thing, but don’t try to be too clever
- roi picks the image from a specific part of the camera sensor, so you can adjust the image layout if you have a rigidly fixed camera
- hdr doesn’t do anything for cheap RPi cameras
Putting 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:
2026-05-18
House Sparrow vs. House Wren vs. Entrance Reducer

A friend gave Mary a small-bird birdhouse, which immediately attracted the attention of a pair of House Wrens:

Bird House entrance reducer – wren exiting

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:

Bird House – sparrow inside

This led to considerable discussion and displays of outright hostility:

Bird House entrance reducer – wren vs sparrow

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:

Bird House – nest base sticks

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:

Bird House – interior cleared

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:

Bird House entrance reducer – interior glue

The outside looks marginally better:

Bird House entrance reducer – exterior glue

The sparrows continued to approach the hole at full throttle, deploying landing gear and speed brakes at the last possible moment:

Bird House entrance reducer – sparrow approach

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.

2026-05-13