Tag: Art-ish

They might be Art

Smashed Glass Coaster: Conformal Perimeter
Snugging the perimeter around the smashed glass fragments definitely improves the result:

Smashed glass coaster – top view A

It’s just under 100 mm = 4 inch across the longest dimension and surprisingly glittery:

Smashed glass coaster – top view B

The coaster is a five-layer sandwich half an inch thick:

Smashed glass coaster – edge view

From the top:
- Clear acrylic: 1.5 mm = 1/16 inch
- Black acrylic: 1.5 mm = 1/16 inch
- Clear acrylic: 3.2 mm = 1/8 inch
- Mirror acrylic: 2.7 mm
- Cork: 2.7 mm cut from a standard round coaster base
The smashed glass pieces sit atop the mirror, so the trick is making the layers around it add up to the same thickness. This is not possible by adding the nominal dimensions, because cast acrylic sheet thickness isn’t well controlled; I’ve finally written the actual (metric!) thickness on the sheets so I can select which 1/8 Inch sheet has the proper thickness.

A chipboard template (seen atop the finished coaster) verified the glass pieces fit easily within their openings:

Smashed glass coaster – top view – fit template

I laid the clear frame on the mirror, poured generous epoxy puddles along the middle of the fragment openings, eased the glass in place, and gently pressed the slabs down to get a uniform epoxy layer, with the excess oozing under the frame all around. Then lay the black frame around the glass atop the clear, squirt more epoxy along the gaps around the glass, pour more epoxy atop the fragments, ease the top sheet in place paying considerable attention to coaxing the bubbles along to the edge, align the sides, and wait.

The epoxy cured while stuck atop a styrofoam pillar to let it drain smoothly off the edges:

Smashed glass coaster – epoxy curing

I encouraged the epoxy out of the acute corners, as shown by the larger puddles, over the next few hours until the epoxy stiffened up. Those puddles also show the transparent black tint, to the tune of four drops in 8 ml of epoxy, which turned out to just barely suffice for the job. The whole assembly sat level while curing, but the layers didn’t remain aligned even after gently shoving them around while the stack cured.

The black epoxy joins nicely with the black frame layer to conceal most of the remaining bubbles. A different color frame with matching epoxy might looks less ominous, but colors more transparent than dark gray would likely reveal the bubbles.

It Would Be Nice™ if the acrylic sheet on the top had a transparent plastic film cover, but it arrived with brown paper on both sides. Despite that, I spattered only a few tiny drops on the bare surface and managed to scrape most of them off without further damage.

Overall, I think the conformal perimeter looks much better than the polygonal outline smashed glass coasters.
2022-09-02
Smashed Glass Earrings: Sample Set
The POC earrings had a pair of 1.5 mm acrylic disks epoxied around the glass fragment, with the “gold” ring captured in a rebate around the rims. That process was both tedious and messy, so I tried laser-engraving a deeper rebate into a 3 mm sheet, then epoxying the fragment and the ring in place:

Earrings – epoxy curing

They’re stuck to a strip of Kapton tape to keep the epoxy off the bottom surface of the glass, while aligning it with the surrounding disk.

Peeling the protective film / plastic off reveals the acrylic disk:

Earrings – 25 20 16 12 mm first look

They all required more effort to remove the epoxy remaining around the ring, but it worked out better than I expected.

A lighter background shows off their internal structure:

Earrings – 25 20 16 12 mm set

A closer look at the pairs:
As always, glooping clear epoxy around the edges fills many of the internal cracks and reduces the glittery aspect of all those glass-to-air-to-glass interfaces, but I don’t see another good way to keep the fragments under control.

The results may not be up to a “fine jewelry” standard, whatever that may be, but a slipcase box definitely improves the presentation:

Earrings – presentation case

If I had the courage of my convictions, I’d go for the Mr Clean look myself, but …
2022-09-01

Layered Paper Coaster: GCMC Test

A few more attempts at layered paper construction, done with plain white Art Paper of various vintages:

The middle one comes from a version of the original GCMC marquetry shape generator, tweaked to produce just the frame SVG, called by a Bash script to change the sash width, and imported into LightBurn for laser control:

LightBurn - Marq-6-0.6-0.0mm — LightBurn – Marq-6-0.6-0.0mm

I generated the plain disk for the bottom by deleting all the inner shapes.

The left and right coasters use LightBurn’s Offset tool to reduce the size of the interior holes on successive layers:

LightBurn - Marq-8-0.40-20.0mm-Layers — LightBurn – Marq-8-0.40-20.0mm-Layers

Although the GCMC version turned out OK, you’ll note it lacks the central disk, as I was unwilling to tweak the code enough to make the disk diameter vary with the kerf width.

Applying the LB Offset tool requires selecting only the inner shapes (it has an option to ignore the inner shapes) and applying the appropriate offset. Because the tool remembers its previous settings, it’s straightforward to step the offset from 1.0 mm to 7.0 mm on successive patterns.

Applying glue (from a glue stick!) to the bottom of each disk, aligning them atop each other, and pressing them together becomes tedious in short order. If I had to do a lot of these, I’d be tempted to add three wings (not at 120° angles!) around the perimeter with holes for pegs, then stacking the layers in a fixture to ensure good alignment. A polygonal perimeter would simplify trimming the tabs.

Spray adhesive might be faster, but each layer would have sticky edges and the finished coaster would become a dust collector par excellence.

I like the overall effect, but …

The OpenSCAD source code as a GitHub Gist:

	#!/bin/bash
	# Layering paper cutouts
	# Ed Nisley KE4ZNU – 2022-08-21

	Flags='-P 4 –pedantic' # quote to avoid leading hyphen gotcha

	SVGFlags='–svg –svg-no-movelayer –svg-opacity=1.0 –svg-toolwidth=0.2'

	# Set these to match your file layout

	ProjPath='/mnt/bulkdata/Project Files/Laser Cutter/Coasters/Source Code'

	LibPath='/opt/gcmc/library'

	ScriptPath=$ProjPath
	Script='Marquetry Layers.gcmc'


	[ -z "$1" ] && leaves="6" \|\| leaves="$1"
	[ -z "$2" ] && aspect="0.50" \|\| aspect="$2"
	[ -z "$3" ] && center="0.0mm" \|\| center="$3"

	numlayers=8
	sashmin=2.0
	sashstep=2.0
	sashmax=$(echo "$sashmin+$sashstep*($numlayers-1)" \| bc)

	echo min: $sashmin step: $sashstep max: $sashmax

	for sash in $(seq $sashmin $sashstep $sashmax) ; do

	fn=Marq-$leaves-$aspect-$center-S$sash.svg
	echo Output: $fn

	gcmc $Flags $SVGFlags –include "$LibPath" \
	-D "NumLeaves=$leaves" -D "LeafAspect=$aspect" -D "CenterDia=$center" \
	-D "Sash=${sash}mm" \
	"$ScriptPath"/"$Script" > "$fn"

	done

view raw layers.sh hosted with ❤ by GitHub

	// Marquetry Layers
	// Ed Nisley KE4ZNU
	// 2022-08-21 layered paper test piece

	layerstack("Frame","Leaves","Rim","Base","Center","Tool1"); // SVG layers map to LightBurn colors

	//—–
	// Library routines

	include("tracepath.inc.gcmc");
	include("varcs.inc.gcmc");

	FALSE = 0;
	TRUE = !FALSE;

	//—–
	// Command line parameters

	// -D various useful tidbits
	// add unit to speeds and depths: 2000mm / -3.00mm / etc

	if (!isdefined("OuterDia")) {
	OuterDia = 120.0mm;
	}

	if (!isdefined("CenterDia")) {
	CenterDia = 20.0mm;
	}

	if (!isdefined("NumLeaves")) {
	NumLeaves = 8;
	}

	if (!isdefined("Sash")) {
	Sash = 4.0mm;
	}

	if (!isdefined("LeafAspect")) {
	LeafAspect = 0.50;
	}

	// Leaf values

	LeafStemAngle = 360.0deg/NumLeaves; // subtended by inner sides
	LeafStemHA = LeafStemAngle/2;

	LeafOAL = OuterDia/2 – Sash – (Sash/2)/sin(LeafStemHA);

	LeafWidth = LeafAspect*LeafOAL;
	L1 = (LeafWidth/2)/tan(LeafStemHA);
	L2 = LeafOAL – L1;
	// message("Len: ",LeafOAL," L1: ",L1," L2: ",L2);

	LeafTipHA = to_deg(atan(LeafWidth/2,L2)); // subtended by outer sides
	LeafTipAngle = 2*LeafTipHA;

	// message("Width: ",LeafWidth);
	// message("Tip HA: ",LeafTipHA);

	LeafID = CenterDia + 2*Sash;
	LeafOD = LeafID + LeafOAL;

	// message("ID: ",LeafID," OD: ",LeafOD);

	// Find leaf and rim vertices

	P0 = [(Sash/2) / sin(LeafStemHA),0.0mm];

	m = tan(LeafStemHA);
	y0 = -(Sash/2) / cos(LeafStemHA);

	if (CenterDia) { // one sash width around center spot
	a = 1 + pow(m,2);
	b = 2 * m * y0;
	c = pow(y0,2) – pow(LeafID/2,2);
	xp = (-b + sqrt(pow(b,2) – 4ac))/(2*a);
	xn = (-b – sqrt(pow(b,2) – 4ac))/(2*a);
	y = xp*tan(LeafStemHA) – (Sash/2) / cos(LeafStemHA);
	P1 = [xp,y];
	if (FALSE) {
	message("a: ",a);
	message("b: ",b);
	message("c: ",c);
	message("p: ",xp," n: ",xn," y: ",y);
	}
	}
	else { // force sharp point without center spot
	P1 = P0;
	}

	P2 = P0 + [L1,LeafWidth/2];
	P3 = P0 + [LeafOAL,0mm];

	P4 = P3 + [Sash/sin(LeafTipHA),0.0mm];
	P5r = P4.x * sin(LeafTipHA) / sin(180deg – LeafStemHA – LeafTipHA);
	P5 = rotate_xy([P5r,0.0mm],LeafStemHA);
	P6 = rotate_xy(P4,LeafStemAngle);

	t2 = pow(tan(-LeafTipHA),2);
	a = 1 + t2;
	b = -2 * t2 * P4.x;
	c = t2 * pow(P4.x,2) – pow(P3.x,2);

	xp = (-b + sqrt(pow(b,2) – 4ac))/(2*a);
	xn = (-b – sqrt(pow(b,2) – 4ac))/(2*a);
	y = (xp – P4.x)*tan(-LeafTipHA);
	// message("p: ",xp," n: ",xn," y: ",y);

	P4a = [xp,y];
	P6a = rotate_xy(P4a,LeafStemAngle – 2*atan(P4a.y,P4a.x));

	if (FALSE) {
	message("P0: ",P0);
	message("P1: ",P1);
	message("P2: ",P2);
	message("P3: ",P3);
	message("P4: ",P4);
	message("P4a: ",P4a);
	message("P5: ",P5);
	message("P6: ",P6);
	message("P6a: ",P6a);
	}

	// Construct paths

	LeafPoints = {P1,P2,P3,[P2.x,-P2.y],[P1.x,-P1.y]};

	if (P0 != P1) {
	StemArc = varc_ccw(P1 – [P1.x,-P1.y],LeafID/2);
	StemArc += [P1.x,-P1.y];
	LeafPoints += StemArc;
	}

	RimChord = length(P4a – P6a);
	RimThick = OuterDia/2 – Sash – length(P5);

	RimPoints = {P4a,P5,P6a};
	RimArc = varc_cw(P4a – P6a,P4a.x);
	RimArc += P6a;
	RimPoints += RimArc;

	//— Lay out the frame

	linecolor(0xff0000);

	layer("Frame");

	if (CenterDia) {
	goto([CenterDia/2,0mm]);
	circle_cw([0mm,0mm]);
	}

	repeat(NumLeaves;i) {
	a = (i-1)*LeafStemAngle;
	tracepath(rotate_xy(LeafPoints,a));
	}

	repeat(NumLeaves;i) {
	a = (i-1)*LeafStemAngle;
	tracepath(rotate_xy(RimPoints,a));
	}

	linecolor(0xff0000);

	goto([OuterDia/2,0]);
	circle_cw([0mm,0mm]);

view raw Marquetry Layers.gcmc hosted with ❤ by GitHub

2022-08-26

Acrylic Coasters: Edge Finishing, Round 4

Lacking a 4-jaw chuck for the lathe, this should suffice:

Coaster Epoxy Rim – chuck-in-chuck setup

Which is just the Sherline 4-jaw chuck chucked in the lathe’s 3-jaw chuck, with both chuck Jaw 1 positions lined up and marked on the acrylic disk fixture. The picture is a recreation set up after the fact, because I lack a good picture of the overall scene.

Now it’s easy enough to center the fixture, stick the coaster in place with reasonable accuracy, then tweak the Sherline chuck to center the coaster:

Coaster Epoxy Rim – turning setup

Because the bottom layer is a laser-cut disk, eyeballometrically aligning its edge to a simple pointer worked surprisingly well:

Coaster Epoxy Rim – locating mirror edge

Turning the OD down to match the bottom disk meant I could finally get decent results with zero drama:

Coaster Epoxy Rim – turned samples

From the bottom, this one has a 3 mm mirror, the 3 mm fluorescent green frame + petals, and a 1.6 mm top sheet:

Coaster Epoxy Rim – turned 6 petal mirror

This one has a 3M double-sided tape with low-surface-energy adhesive layers between the mirror and the fluorescent blue frame + petal, with epoxy between the top layer and the frame.

Coaster Epoxy Rim – turned 4 petal

If I never tell anybody, they’ll think the slightly granular look of the tape was deliberate; it looks OK to me.

And, for completeness, the crash test dummy from the start of this adventure:

Coaster Epoxy Rim – turned 6 petal black

I don’t know how to avoid the bubbles, as the usual torch-the-top and pull-a-vacuum techniques pop bubbles at the epoxy-air interface. These bubbles are trapped under the top acrylic sheet, even though I was rather painstaking about easing the layer down from one side to the other while chasing bubbles along.

Maybe I can define bubbles as Part of the Art?

Definitely fancier than chipboard, although not nearly as absorbent.

2022-08-25
Layered Paper Coaster

A long-forgotten pad of Art Paper in assorted colors came to the surface:

Layered Coaster – tweaked

An angled view shows off the layering a little better:

Layered coaster – side view

Done manually with LightBurn’s Offset tool: shrink the frame’s interior openings (which lie outside the frame) by 1 mm per step, then cut each shape into a different color. The black layer is a complete disk, stuck atop a plain chipboard disk for stiffening.

In the cold light of day, I think I offset the green layer by 2 mm.

It’s not a particularly useful coaster, because you want a flat surface under your drink, but it does look pretty. Nowhere close to that good, but I like it.

The next time around, I’ll automate the process by stepping the sash width by 1 mm and saving each SVG image separately.

2022-08-18
Chipboard Thickness

Yes, there really is a difference between 35 mil and 57 mil chipboard:

Chipboard coaster – 35 mil white vs 57 mil kraft

The thinner leaves (0.92 mm) have one delicate white surface that presents much better color when scribbled with fat-tip colored markers. The thicker frame (1.45 mm) is ordinary kraft chipboard which seems much more durable and looks terrible when colored.

The difference is obvious:

Chipboard coaster – plain vs white

Although it may be a case of gilding the dandelion, a durable kraft frame sets off the petal colors and, being slightly thicker, may also protect them from immediate destruction by sweaty drinks.

We’re talking artsy coasters here, not cheap disposable junk. Right?

Riiiight!

2022-08-12
Smashed Glass Coaster #2: Mirror Base FTW

Glass fragments bedded on clear epoxy atop a white base looked OK, albeit minus most of their glitter due to epoxy filling their cracks:

Glass Coaster – fragment edge detail

Filling the cracks with black epoxy makes them stand out:

Smashed Glass vs epoxy – magnified comparison

So I assembled a coaster from shattered glass in a clear surround with black epoxy atop a mirror base:

Smashed Glass Coaster 2 – mid-layer glass pour

Each fragment sits on a blob of black epoxy that eventually oozed out to fill the gap between the mirror and the transparent layer. You can see the oozing start around the two fragments in the upper left.

A top layer of black acrylic sits flush with the upper surface of the glass, seen here with the protective paper in place before pouring black epoxy into the gap around the perimeter of each fragment:

Smashed Glass Coaster 2 – masked top

Peeling the paper away exposes an almost perfect surface, with the epoxy forming a slight curve between the black acrylic and the glass:

Smashed Glass Coaster 2 – overview

The mirror doubles the number of glass cuboids and their glittery gaps:

Smashed Glass Coaster 2 – fragment detail

All in all, it turned out well, but the epoxy pouring and leveling is tedious.

It might be possible to assemble a coaster upside-down, with the black layer stuck to something like Kapton tape and the fragments carefully aligned in their openings to make the entire top surface a plane. The tape should keep the epoxy from oozing out of the gaps, although a perfect seal may be impossible.

Then fill the gaps with black epoxy, lay the clear middle layer in place, run a dollop of epoxy on each fragment, lay the mirror in place, and hope there’s enough epoxy to fill all the gaps and not enough to make a mess around the perimeter.

With a bit of luck, that wouldn’t require so much hand finishing.

The next coaster must have a perimeter shrinkwrapped around the fragments, if only to break the low-vertex-count polygon tradition.

2022-08-11