Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
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:
SCP Earrings – GITD in action
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.
A small coaster laser-cut from scraps of EVA craft foam:
Biohazard foam coaster
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.
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:
SCP Earrings – black on yellow – cutting
The acrylic fire shows they’re called Danger Zone earrings for well and good reason!
Anyhow, weeding the black vinyl produces crisp results:
SCP Earrings – black on yellow – overview
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:
SCP Earrings – black on yellow – detail
Still not enough to get me to go full-frontal Mr Clean.
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.
Danger Zone Earrings – GITD and PSA vinyl – UV light
And UV powers up GITD tape something fierce:
Danger Zone Earrings – GITD radiation
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:
Danger Zone Earrings – retroreflective
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:
Danger Zone Earrings – multilayer PSA vinyl
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.
Some geometry review and a bit of fiddling with LightBurn produced regularized patterns suitable for laser cuttery:
Danger Zone Earrings – radioactive – handful
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:
Danger Zone Earrings – radioactive – LB layout
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:
Danger Zone Earrings – radioactive – white light
Wearing them in a place flooded with UV radiation would set you apart:
Danger Zone Earrings – radioactive – GITD UV
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.
Then I traced them into LightBurn vectors suitable for engraving, added hanging holes, and fit a perimeter cutout. This being a test, I took a number of shortcuts resulting in slightly off-center engravings and ignored a number of image botches (most notably in the Inconsistent Topology figure.
A quick painting fixture kept (most of) the rattlecan paint off the edges:
SCP Warning Labels – fixture clamping
The acrylic is old enough to have brown paper protective layers, rather than fancy plastic sheets. I peeled various combinations and shot various sides with purple:
SCP Warning Labels – purple coat
Remove some, flip others over, and hit ’em with yellow:
SCP Warning Labels – yellow coat
I expected purple markings over a yellow background to look best:
SCP Warning Labels – purple over yellow
But the inverse version seems more contrasty (ignore the off-center cutout):
SCP Warning Labels – yellow over purple
I think the purple-on-clear version would look better with edge-lit acrylic:
SCP Warning Labels – purple over clear
The 0.15 mm line spacing seems too coarse, but trying to get a perfectly flat engraved bottom seems futile.
A second coat of paint on the engraving would definitely boost the contrast.
If you were going to do this for real, you’d definitely recreate the images with vectors right from the start, using the original images as inspiration.
All in all, I like ’em, but there’s some improvement required before anybody else does!
Cutting or engraving patterns on earrings should go more smoothly with a fixture:
Earring fixture – demo install
That’s a serving suggestion, using the Biohazard test pieces, which also helped align the top and bottom layers while gluing:
Earring fixture – clamping
That used all my little clamps: obviously I need more!
The bottom layer (red) is MDF for strength and the top layer (orange) is chipboard because that’s all it needs:
Earring fixture – LB layout
The little tab along the top ensures alignment using the jump ring cutout. The central hole will let me cut through the earring, should that be necessary.
The two strips over on the left get glued on the bottom, spaced to align along one of the aluminum knife blade rails, as with the craft stick fixture. With that lined up, any two of the four targets will serve to align the template with the fixture using LightBurn’s Print-and-Cut tool, as with the craft stick template.
The Smell of Molten Projects in the Morning 
