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.
They might be Art
Engraving the vector SCP warning label geometry into yellow-on-black Trolase reduces the handwork to wiping off the dust:
The alert reader will note two missing holes due to an unfortunate oversight while rearranging the layout. One can adroitly fix such errors if the cut shapes don’t move, which is how it worked out:
With the obverse done, another fixture aligns them for a branding pass on the reverse:
This is starting to make sense in a peculiar sort of way …
Scaling the vectorized SCP warning labels to fit 4 inch cork disks produces a stack of Danger Zone coasters:
I particularly like the Cognitohazard and Autonomous Object symbols. The Nonstandard Spacetime symbol comes in dead last; if you make one, use very little kerf offset.
Come to find out yellow is utterly unforgiving of smudges / smoke stains; orange is better, albeit non-canon. I cut them face-up through a layer of blue masking tape, which worked surprisingly well, except for a few areas where I didn’t apply enough paint: the chipboard fibers became one with the tape.
The cork disks arrive pre-cut with a PSA sheet, so using a jig for better alignment with the assembled chipboard layer would be a Good Idea™. These were assembled by feel, which is good for about half a millimeter.
A better process: cut an array of the shapes from a large yellow sheet, fit the black inlays from the back, stick the whole affair to a large cork sheet, then cut the circular outlines where small misalignments wouldn’t matter.
In production, it would make more sense to cut all the pieces from blank white chipboard, paint them in groups, then assemble everything.
Best: having me realize nobody else wants coasters.
Embiggening the SCP symbols used on the yellow vinyl-on-acrylic version improves their proportions:
The black-on-white look come from vinyl PS atop GITD tape atop some transparent red acrylic, which looks a whole lot better in its natural environment:
Making those ten samples requires 15 minutes of laser time (mostly kiss-cutting the patterns at maybe 5 mm/s) and another 25 minutes of weeding and primping. I’m not convinced this is an economically feasible activity, but I really like the results.
Nah, I’m still not getting my ears punched.
A small coaster laser-cut from scraps of EVA craft foam:
It’s all of 60 mm OD, so not particularly practical, but it (and its predecessor, a complete botch) helped show the laser kerf in EVA foam is an astonishing 0.6 mm, when cut at 125 mm/s with maybe 30 W.
The white outer shape is the nominal size, so holes are 0.3 mm larger on all sides than the pattern. The tan inner shapes get a 0.6 mm outset (!) to make them larger, which definitely squared up the horn tips. The fit is snug, but another 0.1 mm might be even better.
The pieces stick to a 60 mm circle cut from cork with a PSA layer, which makes it entirely too bendy.
If you wanted to do this for real, all the patterns would require tweakage to make the smallest features about 2 mm. The huge kerf ate the 1 mm struts around the central white disk and the tan circles should clear the horn stems by 1 mm, so that’s just barely enough.
More tinkering produced a full set of SCP warning labels in vector format suitable for laser cutting:
The faint blue corresponds to the LightBurn tool layer, because you’ll want to assign your own cutting parameters.
The circumscribing circle provides a convenient way to snap the pattern into something else, because the symbols in the middle are not necessarily centered around their geometric midpoint.
Suiting action to drawings:
The acrylic fire shows they’re called Danger Zone earrings for well and good reason!
Anyhow, weeding the black vinyl produces crisp results:
The fallout shelter symbol (top right) should have a circle around it, but that’s in the nature of fine tuning. It’s also not part of the SCP canon, but it kinda goes along with the radiation warning sign.
They’re cut from transparent amber non-edge-lit acrylic with black vinyl PSA patterns:
Still not enough to get me to go full-frontal Mr Clean.
The LightBurn SVG layout as a GitHub Gist:
I have no explanation for the different stroke widths, other than that SVG files seem to maintain a memory of every transformation applied to any object. LightBurn doesn’t use the stroke widths, so it should work out just fine.
With the geometry set up, cutting earrings with surface coatings is just a matter of tweaking a few settings:
From left to right:
UV lights up the edge-lit samples:
And UV powers up GITD tape something fierce:
Cutting the central pattern out of the GITD earring might make it look even better, but I like the subtle presentation.
If it’s flash you want, then retroreflective tape is your fashion friend:
The bolder kiss-cut lines in the middle earring might suffice, but the cutouts on the right definitely look more distinctive. Perhaps the kiss-cut perimeter line would set the pattern off a little better.
Assuming PSA vinyl sticks to itself and GITD tape well enough to survive normal handling, that would make multicolor earrings an option:
On the left: blue PSA vinyl on GITD tape. On the right: green PSA vinyl on red PSA vinyl on black acrylic. Peeling the PSA vinyl is tedious and I’m still not good enough to avoid small nicks in the underlying layer.
GITD FTW:
Now, to work on more patterns …
Some geometry review and a bit of fiddling with LightBurn produced regularized patterns suitable for laser cuttery:
A key trick: circumscribe the figure with a circle on a tool layer, then group the whole mess together, so that the center of the circle coincides with the desired center of the figure. In particular, the geometric center of an equilateral triangle is not at the center of its vertical extent:
The dark blue layer engraves the surface, the red layer cuts through 3 mm acrylic, and the light blue layer is the tooling.
I like the edge-lit ones, although the simplicity of laser-cut clear acrylic is hard to beat:
Wearing them in a place flooded with UV radiation would set you apart:
The careful observer will note stress cracking in the two clear earrings in the middle row. Those came from the vintage paper-covered acrylic sheet and I used alcohol to clean off the not-quite-vaporized glue just to see if isopropyl alcohol would behave differently than denatured alcohol. Nope, the cracks appear instantly.
Peeling the paper and engraving the bare surface produced the clear-frosted earring in the upper right, with the radiation symbol cut out of the sheet. Engraving without surface protection tends to deposit vaporized acrylic dust everywhere, so it would require hand cleaning without the cutouts.
The cutouts get 0.1 mm inward offsets to slightly increase the wall thickness around that central circle.
One combination I didn’t try: engrave the triangle perimeter for emphasis and cut out the symbol for contrast with edge-lit acrylic.
Dropping other symbols into place should be straightforward, with the center of the circumcircle as the snap target.
The LightBurn SVG layout as a GitHub Gist:
The Smell of Molten Projects in the Morning 
