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: Laser Cutter

Star Quilting Ruler Salvage: Laser Recutting

Mary picked up a pair of Star quilting rulers from the Quilting Guild’s “exchange” table:

Star quilting ruler – finished

They’re 1/4 inch laser-cut acrylic slabs dating back to the turn of the millennium, when laser cuttery wasn’t nearly as common as today. Apparently, the (now long gone) Gadget Girls had a problem with their laser: the larger star had eight of its ten lines not cut completely through the acrylic. The protective paper on the back had small perforations along a few of the lines, but nothing for most of them.

Well, I can fix that.

Lay the slab on the platform and lock it in place so it cannot move:

Star quilting ruler – laser setup

That’s with the original bottom side facing upward, so the laser beam will hit the uncut part of the lines.

Focus the laser atop some scrap 1/4 inch acrylic, then verify the red dot pointer is exactly concentric with the CO₂ beam by firing a test pulse, as in this punched card:

Red dot vs printed target vs laser spot alignment

Adjust as needed.

Jog the laser to put the red dot pointer exactly at a star point:

Star quilting ruler – laser point alignment

Hit Get Position in the Laser window so LightBurn knows where the laser head is located.

I’ve added the targets I normally use for LightBurn’s Print and Cut alignment to its Art Library, so I dragged one to the workspace, then hit Move to Laser Position to snap the target directly onto that point of the star.

Repeat for vertices along the star, then draw a multi-segment line = path between the target centers:

Star Ruler Re-cutting – LightBurn layout

That’s one continuous path from the upper right, counterclockwise around the star, ending in the center right. The missing pair of lines (and the vertex between them) were already cut, so I didn’t need to locate them.

The camera view shows the alignment, although IMO the camera simply isn’t capable of such finicky alignment:

Star Ruler Re-cutting – LightBurn layout overlay

As a confidence builder, I selected each target, moved the laser to that point, then fired a test pulse to verify the hole hit the vertex. In most cases, I couldn’t see the hole because it was within the original cut.

My 60 W laser can’t cut through 1/4 inch = 6 mm acrylic in a single pass, so I use a 10 mm/s @ 60% pass to get most of the way through and a 20 mm/s @ 60% pass to complete the cut. That seemed excessive for a mostly cut path, but a single 20 mm/s @ 60% pass didn’t completely clear the uncut sections.

So I used the normal two-pass cut and the star lifted right out:

Star quilting ruler – victory

Happy dance!

Although it is not obvious from the pictures, the star is not symmetric: it fits into the sheet in only one of its ten possible orientations. I will never know if that was a deliberate stylin’ decision or the result of hand layout before CAD spread throughout the land.

I managed to locate the vertices so accurately that the repeated cuts left edges indistinguishable from the original cuts on the two free sides, which was a pleasant surprise.

Mary promises to do something with those stars when she’s done with her current project(s). She may want the slab of acrylic around the large star trimmed into a smaller and more manageable decagon, in which case I will suddenly have a bounty of thick fluorescent green acrylic.

2026-03-26
Laser-Cut Egg Carton Sprouter
Mary has been using Styrofoam egg cartons to sprout seeds for this year’s garden veggies:

Egg carton sprouter – hand cut

I looked at those artisanal holes and offered to make sprouters with precisely calibrated laser-cut holes.

After the laughter died down, this happened:

Egg carton sprouter – lid detail

Each egg compartment has a drainage hole in the bottom:

Egg carton sprouter – on platform

The LightBurn layout has four shapes in three virtual arrays:
- Drain holes: 3 mm circle, 6×3 array
- Top vents: 25×15 mm oval, 2×1 array
- Side vents: concentric 3×4 & 2×3 mm ovals, 2×4 array
Which looks like this:

Egg Carton Sprouter – LightBurn layout

Because this isn’t a high-precision operation, I align the patterns to the carton using the camera:

Egg Carton Sprouter – LightBurn camera alignment

The two halves of the unfolded carton aren’t the same height, which means the top and bottom patterns have different focus levels and must be cut in two operations.

The laughter made it totally worthwhile.
2026-03-16
Punched Cards: Apollo Eagle Card Layout
With some lessons learned from the first pass, the bottom layer of the Apollo Eagle gets a reversed card for the white tail feathers:

Apollo Eagle – Layer 1 card layout

Which looks like this just after cutting the outline:

Apollo Eagle – Layer 1 as cut

Gently removing the scrap from the edges reveals the eagle:

Apollo Eagle – Layer 1 cutout

The top two layers also come from a reversed card, with those shapes arranged to put the holes in attractive places:

Apollo Eagle – Layer 7 8 card layout

The five layers in between as a slide show:
Apollo Eagle – Layer 2 card layout
Apollo Eagle – Layer 3 card layout
Apollo Eagle – Layer 4 card layout
Apollo Eagle – Layer 5 card layout
Apollo Eagle – Layer 6 card layout
It took a while to get over cutting up all those nice cards.

Some deft glue stick work produces a layered eagle:

Apollo Eagle – assembly overview

I managed to get a dark bottom in the nostril, which turned out weird:

Apollo Eagle – head detail

All in all, though:
- Fewer layers are better
- The head came out OK-ish
- The bottom layer card arrangement is too fussy
- The olive branches still look weird
- The claws are still ugly
- The tail needs more contrast, perhaps two layers
- Having horizontal card splices aligned on successive layers is bad
More study is definitely in order …
2026-03-11
Punched Cards: Paper Matters

Using different card colors makes it easy to find your program deck in the Comp Center’s output bins:

Punched Cards – paper color vs smoke stains

The smoke stains on the bottom orange card came from the same LightBurn settings used with the purple (violet?) and blue (teal?) cards: 400 mm/s, 35% power, and assist air enabled.

The conventional wisdom is that you *do not* use assist air while engraving, to avoid pushing the smoke / soot down onto the material, and I’ve generally followed that rule. Apparently evaporating holes in the other colors doesn’t generate much smoke and I had no reason to notice the air was enabled.

The upper orange card differs from the lower one only in having the assist air turned off, so I have definitely learned my lesson!

Readers of long memory will recall the dual-path assist air setup that pushes 2 l/m through the nozzle when the LightBurn layer has AIR disabled, specifically to keep smoke out of the nozzle and away from the lens; that gentle breeze doesn’t push smoke into the paper.

FWIW, that’s why I run a set of test cards before I do anything fancy for the first time.

2026-02-27
Punched Cards: Layered Apollo Eagle
What with punching the Apollo 11 CSM source code into the cards, converting the mission’s eagle into a layered shape made some sense.

The original Apollo 11 mission patch:

Apollo 11 mission patch – rescaled

After considerable faffing, a few of the fifteen layers look like this in GIMP:

Apollo 11 Patch – eagle layers

Each layer is a connected white region defining the cut perimeter, which will expose some part of the layer(s) below it in the stack. The small squares in the corners provide a bounding box to make all the layers snap to the same location.

Then:
- Select each layer’s shape + corner boxes with GIMP’s Color Select tool
- Convert the selection to a path
- Export paths as SVG files (all fifteen of them!)
- Import SVGs into LightBurn & arrange neatly
- Put outlines on a cut layer, corner squares on a tool layer
- Burn each layer separately
Testing the concept with packing paper looked surprisingly good:

Apollo 11 Eagle – layer test piece

A few key layers on punched cards:

Apollo 11 Eagle – card partial test piece

The changes for each of those iterations required tweaking the original layer images to eliminate obvious-in-retrospect problems, recreating the SVG files, and importing into LightBurn. This is a relentlessly manual process.

Then I ran a full-up test of all fifteen layers on cards punched with the Apollo source code.

Cutting the head layers from face-down cards made them sufficiently white, although it’d be nice to have a different beak color and darker eyes :

Apollo 11 Eagle patch – layer test – head

I must arrange the cards with text to put more holes in the wings, although too many will cause fragile feathers:

Apollo 11 Eagle patch – layer test – wing

The white tail should be also done with face-down cards, more holes, and the three-way joint between the cards shifted under the tail layers to its left:

Apollo 11 Eagle patch – layer test – tail

The feet and olive branch were a total faceplant, as successive layers did not register accurately enough to overlay the leaves:

Apollo 11 Eagle patch – layer test – feet

Not to mention those ug-u-lee claws.

The wing layers need more rounding along their edges, perhaps with some thin cuts to emphasize the feathers.

On the whole, though, I think it turned out well.

Things to do:
- Registration holes / pins up to the top layer
- Remove speckles on all the layers
- Arrange cards for more hole density where needed
- Better glue application
- Different card colors?
2026-02-19
Cheap HD USB Camera: Base Disassembly
A brace of cheap HD USB cameras may improve the scenery around here during video meetings. They were $16, marked down from an absurd $130:

HD USB Camera price history

Some poor schlubs certainly dropped more than twice the price of a Genuine Logitech camera on these critters, but a nearly total lack of demand must have had some effect.

They do take their stylin’ cues from Logitech, although the speckled pattern on a shiny plastic sheet is amusing:

HD USB Camera – styling vs Logitech C920

Unsurprisingly, the lens is fixed / manual focus. What looked like focus rings were in different positions on the two cameras:

HD USB Camera – lens focus notches

It turns out the rings were not glued in place, perhaps because they have absolutely no effect on the camera’s focus. Maybe there’s another camera model where they rotate the lens in a threaded socket, but this ain’t that.

The front panel has three pores:
- A red Power LED is always on when it’s plugged in
- A green On the air LED lights up when the camera is selected; I have no idea what the WiFi-ish glyph is supposed to represent
- The “advanced noise canceling microphone” sits behind a pore offscreen left; the claim seems dubious.
Because these may go into smaller spaces, I dismantled the base to see what was involved. Most of the screws lie underneath thin foam sheets:

HD USB Camera – ball mount interior

The lower plate has a tripod mount and a folding bracket:

HD USB Camera – baseplate interior

The camera body has a ball mount with a few degrees of movment:

HD USB Camera – ball mount detail

Reassembled and stuck inside the laser cabinet with some good double-sided foam tape, it definitely produces a better image than the previous camera:

Platform camera view

Whatever noise cancellation the mic may provide is irrelevant in there: nobody’s listening.
2026-02-17
Punched Cards: Almost Automated Punching
With a printed card in a fixture and aligned to the punch pattern, all that’s left is to Fire The Laser:

Punched cards – laser fixture – cut

When the card drops free, then:
1. Remove card from fixture
2. Insert next card
3. Import next SVG file
4. Verify alignment
5. Fire The Laser
The gotcha lies in Step 3, which requires mousing & clicking through a tedious file selection dialog. For whatever reason, Windows / LightBurn does not remember your place in the file directory, so you must not only remember which card you just punched, but maneuver to the next card in the sequence.

It turns out there exists a lightly documented SendUDP.exe command-line program to send a file to the running LightBurn instance, which will (in the case of an SVG file) import it and center the layout at the middle of the workspace.

Which means a Windows batch file can feed SVG files, one at a time, in order, to LightBurn. Before importing the file, however, LightBurn verifies you want to blow away the previous layout:

LightBurn – Confirm import

Tapping D lets the import proceed.

The feed-lb.bat batch file:
```
@echo off
for %%f in (%1) do (
    echo Sending: %%f
    "c:\Program Files\LightBurn_Prerelease\sendudp" "%CD%\%%f"
    pause
)
echo Done!
```
Because the SVG files have convenient sequential names, this does what’s needed:
```
…snippage…>.\feed-lb.bat Cards\Tests\test-?-lb.svg
Sending: Cards\Tests\test-1-lb.svg
Press any key to continue . . .
Sending: Cards\Tests\test-2-lb.svg
Press any key to continue . . .
```
Set up the process:
1. Start LightBurn with the proper layer defaults
2. Start a Command Prompt
3. Get to the proper directory
4. Run feed-lb.bat aimed at the SVG files
5. Align the first card
6. Click in LightBurn window
7. Alt-S to start cutting
When the cutting is done, the loop continues:
1. Replace / align card
2. Click the Command Prompt window
3. Hit (almost) any key to send the next file
4. Click the LightBurn window
5. D to discard old layout / import next SVG
6. Alt-S to start cutting
7. Iterate
Assuming you don’t spend too much time aligning a card, punching it can take up to four minutes. This process is definitely not competitive with an experienced operator on a real IBM 029 keypunch machine, but it’s as good as it gets in the Basement Shop.

One wrinkle: The imported SVG file uses LightBurn layer colors, so the various shapes appear on those layers with their default speed / power cut settings. It’s your responsibility to make the cut setting defaults match the cardstock, because that’s the only way (short of per-card clicking) to make it happen.

Another wrinkle: the Command Prompt window opens at your Windows home directory, thus requiring a little setdir.bat file in there to get you where you want to go:
```
@echo off
z:
cd "\Project Files\Laser Cutter\Punched Cards\Programs\"
dir
```
Now it’s just a matter of punching and stacking cards:

Punched cards – storage trays

It’ll take a while before I’m ready for the next step …
2026-02-11