Machine Shop – Page 87 – The Smell of Molten Projects in the Morning

Coaster Generator: Simple Petals

Having figured out how to intersect a line with a circle, I figured I could do it twice to put arcs on both the inside and the outside of each petal:

Chipboard coaster - double arcs — Chipboard coaster – double arcs

As before, scribbling markers on plain chipboard makes for a … subdued … coaster, so I tried chipboard with one white surface:

Chipboard coaster - plain vs white — Chipboard coaster – plain vs white

Much better.

Clamping the coaster produces a flatter result:

Chipboard coaster - clamping — Chipboard coaster – clamping

With the risk of squishing excess glue through the kerf:

Chipboard coaster - excess glue — Chipboard coaster – excess glue

That’s the same coaster as in the first picture, carefully arranged with light reflecting off the flat glue surface. In real life, the nearly transparent glue doesn’t look nearly so awful, but smoothing much less glue than seems necessary across the bottom disk suffices.

The geometry doodle with the arcs:

Chipboard coaster - double arc petal geometry doodle — Chipboard coaster – double arc petal geometry doodle

I suppose I should refactor the code with a quadratic solver returning a list of roots, but copypasta suffices for now.

The GCMC and Bash source code as a GitHub Gist:

	#!/bin/bash
	# Simple petals test piece
	# Ed Nisley KE4ZNU – 2022-07-01

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

	SVGFlags='-P 4 –pedantic –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='Simple Petals.gcmc'

	[ -z "$1" ] && petals="6" \|\| petals="$1"

	fn=Petals-$petals.svg
	echo Output: $fn

	gcmc $SVGFlags \
	-D "NumPetals=$petals" \
	–include "$LibPath" \
	"$ScriptPath"/"$Script" > "$fn"

view raw petals.sh hosted with ❤ by GitHub

	// Simple Petals Test Piece
	// Ed Nisley KE4ZNU
	// 2022-07-12 Simplest possible petals

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

	//—–
	// Library routines

	include("tracepath.inc.gcmc");
	include("tracepath_comp.inc.gcmc");
	include("varcs.inc.gcmc");
	include("engrave.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 = 100.0mm;
	}

	if (!isdefined("CenterDia")) {
	CenterDia = 25.0mm;
	}

	if (!isdefined("NumPetals")) {
	NumPetals = 6;
	}

	if (!isdefined("Sash")) {
	Sash = 5.0mm;
	}

	// Petal values

	PetalAngle = 360.0deg/NumPetals; // subtended by inner sides
	PetalHA = PetalAngle/2;

	PetalOD = OuterDia – 2*Sash;
	PetalID = CenterDia + 2*Sash;

	PetalOAL = OuterDia/2 – Sash – (Sash/2)/sin(PetalHA);
	//message("petalOAL: ",PetalOAL);

	// Find petal vertices

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

	t1 = tan(PetalHA);
	sc = (Sash/2) / cos(PetalHA);

	if (P0.x < PetalID/2) {
	a = 1 + pow(t1,2);
	b = -2 * t1 * sc;
	c = pow(sc,2) – pow(PetalID/2,2);
	xp = (-b + sqrt(pow(b,2) – 4ac))/(2*a);
	xn = (-b – sqrt(pow(b,2) – 4ac))/(2*a);
	y = xp*t1 – sc;
	if (FALSE) {
	message("a: ",a);
	message("b: ",b);
	message("c: ",c);
	message("p: ",xp," n: ",xn," y: ",y);
	}
	P1 = [xp,y];
	}
	else {
	P1 = P0;
	}

	a = 1 + pow(t1,2);
	b = -2 * t1 * sc;
	c = pow(sc,2) – pow(PetalOD/2,2);

	if (FALSE) {
	message("a: ",a);
	message("b: ",b);
	message("c: ",c);
	}

	xp = (-b + sqrt(pow(b,2) – 4ac))/(2*a);
	xn = (-b – sqrt(pow(b,2) – 4ac))/(2*a);
	y = to_mm(sqrt(pow(PetalOD/2,2) – pow(xp,2)));
	//message("p: ",xp," n: ",xn," y: ",y);

	P2 = [xp,y];

	PetalWidth = 2*P2.y;

	P3 = [PetalOD/2,0.0mm];

	if (FALSE) {
	message("P0: ",P0);
	message("P1: ",P1);
	message("P2: ",P2);
	message("P3: ",P3);
	}

	// Construct paths

	PetalPoints = {P1,P2};

	OutArc = varc_cw([P2.x,-P2.y] – P2,PetalOD/2);
	OutArc += P2;
	PetalPoints += OutArc;

	if (P0 != P1) {
	PetalPoints += {[P1.x,-P1.y]};
	InArc = varc_ccw(P1 – [P1.x,-P1.y],PetalID/2);
	InArc += [P1.x,-P1.y];
	PetalPoints += InArc;
	}
	else {
	PetalPoints += {P0};
	}

	//— Lay out the frame

	linecolor(0xff0000);

	layer("Frame");

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

	repeat(NumPetals;i) {
	a = (i-1)*PetalAngle;
	tracepath(rotate_xy(PetalPoints,a));
	}

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

	//— Lay out internal pieces for oriented cutting

	// baseplate

	layer("Base");

	relocate([OuterDia + 2*Sash,0]);
	goto([OuterDia/2,0]);
	circle_cw([0mm,0mm]);

	// central circle

	if (CenterDia) {
	layer("Center");

	relocate([OuterDia/2 + Sash,-(OuterDia – CenterDia)/2]);
	goto([CenterDia/2,0mm]);
	circle_cw([0mm,0mm]);
	}

	// petals

	layer("Petals");

	repeat(NumPetals;i) {
	org = [PetalWidth/2 – OuterDia/2,-(OuterDia + Sash)];
	relocate([(i-1)*(PetalWidth + Sash) + org.x,org.y]);
	tracepath(rotate_xy(PetalPoints,90deg));
	}

	// Debugging by printf()

	if (FALSE) {
	layer("Tool1");
	linecolor(0xff1f00);

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

	goto(P0);
	circle_cw([0mm,0mm]);

	goto([0,0]);
	move([OuterDia/2,0]);

	goto([0,0]);
	move(OuterDia/2 * [cos(PetalHA),sin(PetalHA)]);

	goto(P2);
	move_r([0,-PetalWidth/2]);

	}

view raw Simple Petals.gcmc hosted with ❤ by GitHub

2022-07-21

Onion Maggot Flies vs. Sticky Traps: Round 2

Mary decided the second round of sticky traps had collected enough Onion Maggot Flies (and other detritus) to warrant replacement, so this season will have three sets of cards.

The two sides of each card after about a month in the garden:

VCCG Onion Card A – 2022-07-17
VCCG Onion Card B – 2022-07-17
VCCG Onion Card C – 2022-07-17
VCCG Onion Card D – 2022-07-17
VCCG Onion Card E – 2022-07-17
VCCG Onion Card F – 2022-07-17

There are many flies that look (to me) like Onion Maggot Flies, in contrast with the first round of cards which had far fewer flies after about six weeks in the bed.

Some could be Cabbage Maggot Flies, but my fly ID hand is weak.

One of the frames screwed to a fence post suffered a non-fatal mishap, so I made and deployed a seventh trap. We’re pretty sure the garden has enough flies to go around.

2022-07-20

Wheelbarrow Wheel Transplant

The rubber in pneumatic tires / tubes rots when left out in the open for a year or three, so I volunteered to replace the dead-flat tire (on the wheelbarrow I rebuilt last year) with the “flat free” solid foam tire+wheel harvested from an irreparably damaged wheelbarrow. Which, as it turned out, had lost one bearing and the remaining bearing wasn’t in good shape:

Wheelbarrow Wheel - victim bearing — Wheelbarrow Wheel – victim bearing

The bearings in the pneumatic wheel were in comparatively good shape:

Wheelbarrow Wheel - donor bearing — Wheelbarrow Wheel – donor bearing

So I knocked the good bearings out, cleaned up / re-lubed them with squirts from my lifetime supply of genuine Mobil Vactra No. 2 Sticky Way Oil, and ~~hammered~~ tapped them into the solid-tire wheel.

Whereupon I discovered the two wheels have different hub lengths and, unfortunately, the axle clamps in the recipient wheelbarrow lacked enough adjustment range.

Well, I can fix that:

Wheelbarrow Wheel - axle clamp cutting — Wheelbarrow Wheel – axle clamp cutting

I briefly considered cleaning and repainting the wheel, but came to my senses when I considered the tire’s condition:

Wheelbarrow Wheel - transplanted — Wheelbarrow Wheel – transplanted

I suppose when the tread flakes off, the interior foam will rapidly erode, but we’ll burn that bridge when we encounter it.

The alert reader will have immediately noted the grease fitting on that rusty wheel: you’re supposed to periodically fill the entire hub with sufficient grease to push the crud out of the bearings. IMO, that’s so deep in silk purse territory as to be irrelevant.

The remaining useful parts from the defunct wheelbarrow will, most likely, come to good use next year …

2022-07-19

Laser Kerf Width Test Pattern / Coaster Generator

Before trying to make decorative coasters from colorful acrylic, I figured a few practice sessions in chipboard would be in order:

They’re colored with wide tip Sharpies of various ages and, as the yellow and uncolored sections show, chipboard never gets very bright. On the other paw, chipboard is also known as “beer mat”, so at least I have the right general idea.

The patterns come from a GCMC program producing SVG figures for LightBurn to apply kerf compensation:

Chipboard coasters - cut and color — Chipboard coasters – cut and color

It’s obviously too late to have me color within the lines.

The overall frame in the upper left and the base plate in the upper right get the kerf compensation, which (for chipboard) turns out to be +0.15 mm outward (thus making the holes smaller and the diameter larger). If I were doing marquetry, I’d want to arrange each piece on a separate wood veneer sheet with proper grain orientation and similar fussiness, but that’s not the point right now.

Without compensation, the pieces have a drop-in fit with an obvious gap:

Coaster - chipboard - no kerf comp — Coaster – chipboard – no kerf comp

Adding a mere 0.15 mm on each side produces a very snug fit:

Coaster - chipboard - frame 0.15 out — Coaster – chipboard – frame 0.15 out

In fact, the pieces go in from the back and require ~~hammering~~ gentle tapping to persuade all the corners into place.

Protip: putting a dark color on the frame and around the edges conceals many flaws.

Increasing the compensation to +0.20 mm means the pieces no longer fit and, when eventually battered into the frame, the surface becomes a concave-upward dish.

With the (colored) pieces in the frame, I covered the base plate with a thin layer of good old Elmer’s Yellow Wood Glue, dropped the top over it with some attention to good alignment on all sides, and clamped the assembly between two planks for a while. Obviously, you’d want to make more than one at a time, but they’re rather labor intensive.

The GCMC program produces the patterns from the coaster’s dimensions:

Outer diameter
Number of leaves around the center
Center spot diameter
Sash width (it’s really a muntin, but quilters say sash)
Leaf aspect ratio (max width / overall length)

Due to the relentless symmetry, finding the points describing half a leaf and half the sector between two leaves suffices to generate the entire coaster by various rotations around the center. The code performs no error checking whatsoever, so some dimensions emit a hard crash rather than a coaster.

A geometry doodle with some incorrect values:

Poinr P1 (where the leaf snugs against the circular sash around the center spot) sits at the intersection of a line and a circle, so the code solves a quadratic equation with grisly coefficients:

  a = 1 + pow(tan(LeafStemHA),2);
  b = -2 * tan(LeafStemHA) * (Sash/2) / cos(LeafStemHA);
  c = pow((Sash/2) / cos(LeafStemHA),2) - pow(LeafID/2,2);
  xp = (-b + sqrt(pow(b,2) - 4*a*c))/(2*a);
  xn = (-b - sqrt(pow(b,2) - 4*a*c))/(2*a);
  y = xp*tan(LeafStemHA) - (Sash/2) / cos(LeafStemHA);
  P1 = [xp,y];

Given the geometry, the “plus” root is always the one to use.

A doodle working out that intersection, as well as for P5 out at the widest part of the leaf, carrying some errors from the geometry doodle:

Both of those doodles have errors; the GCMC source code remains the final arbiter of coaster correctness.

The Bash and GCMC source code as a GitHub Gist:

	#!/bin/bash
	# Marquetry test piece
	# Ed Nisley KE4ZNU – 2022-07-01

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

	SVGFlags='-P 4 –pedantic –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/Marquetry/Source Code'

	LibPath='/opt/gcmc/library'

	ScriptPath=$ProjPath
	Script='Marquetry Test Piece.gcmc'

	leaves="NumLeaves=$1"
	aspect="LeafAspect=$2"

	fn=Marq-$1-$2.svg
	echo Output: $fn

	gcmc $SVGFlags -D "$leaves" -D "$aspect" \
	–include "$LibPath" \
	"$ScriptPath"/"$Script" > "$fn"

view raw marq.sh hosted with ❤ by GitHub

	// Marquetry Laser Cuttery Test Piece
	// Ed Nisley KE4ZNU
	// 2022-07-01 Simplest possible mandala

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

	//—–
	// Library routines

	include("tracepath.inc.gcmc");
	include("tracepath_comp.inc.gcmc");
	include("varcs.inc.gcmc");
	include("engrave.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 = 5;
	}

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

	if (!isdefined("LeafAspect")) {
	LeafAspect = 0.40;
	}

	// Leaf values

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

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

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

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

	// Find leaf and rim vertices

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

	if (P0.x < LeafID/2) {
	a = 1 + pow(tan(LeafStemHA),2);
	b = -2 * tan(LeafStemHA) * (Sash/2) / cos(LeafStemHA);
	c = pow((Sash/2) / cos(LeafStemHA),2) – pow(LeafID/2,2);
	// message("a: ",a);
	// message("b: ",b);
	// message("c: ",c);
	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);
	// message("p: ",xp," n: ",xn," y: ",y);
	P1 = [xp,y];
	}
	else {
	P1 = P0;
	}

	P2 = P0 + [L1,LeafWidth/2];
	P3 = P0 + [LeafLength,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));
	// message("P4a: ",P4a);
	// message("P6a: ",P6a);

	// message("P0: ",P0);
	// message("P1: ",P1);
	// message("P2: ",P2);
	// message("P3: ",P3);
	// message("P4: ",P4);
	// message("P5: ",P5);
	// message("P6: ",P6);

	// 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");

	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]);

	//— Lay out internal pieces for oriented cutting

	// baseplate

	layer("Base");

	relocate([OuterDia + 2*Sash,0]);
	goto([OuterDia/2,0]);
	circle_cw([0mm,0mm]);

	// central circle

	layer("Center");

	relocate([OuterDia/2 + Sash,-(OuterDia – CenterDia)/2]);
	goto([CenterDia/2,0mm]);
	circle_cw([0mm,0mm]);

	// leaves

	layer("Leaves");

	repeat(NumLeaves;i) {
	org = [LeafWidth/2 – OuterDia/2,-(OuterDia + Sash)];
	relocate([(i-1)*(LeafWidth + Sash) + org.x,org.y]);
	tracepath(rotate_xy(LeafPoints,90deg));
	}

	// rim

	layer("Rim");

	repeat(NumLeaves;i) {
	org = [-Sash,-(OuterDia + 2*Sash + RimChord/2)];
	relocate([(i-1)*(RimThick + Sash) + org.x,org.y]);
	tracepath(rotate_xy(RimPoints,180 – LeafStemHA));
	}


	// Debugging by printf()

	if (FALSE) {
	layer("Tool1");
	linecolor(0xff1f00);

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

	goto(P0);
	circle_cw([0mm,0mm]);

	goto([0,0]);
	move([OuterDia/2,0]);

	goto([0,0]);
	move(OuterDia/2 * [cos(LeafStemHA),sin(LeafStemHA)]);

	goto(P2);
	move_r([0,-LeafWidth/2]);

	}

view raw Marquetry Test Piece.gcmc hosted with ❤ by GitHub

2022-07-18

Lawn Chair Re-strapping: Countdown Hold

I planned to replace the vinyl straps on our set of (salvaged) lawn / patio chairs and made a pair of rivets for one long-missing strap:

The overall project is on indefinite hold, as a Steel-blue Cricket Hunter (*) has decided at least one of the chairs is an ideal place to start a family:

Lawn chair - wasp nest under construction — Lawn chair – wasp nest under construction

The patio under the chair is littered with blades of grass and twigs that didn’t quite fit through the 5 mm vent hole in the tube, but that long stem went in just fine:

Lawn chair - wasp nest grass stem — Lawn chair – wasp nest grass stem

We have seen the wasp airlifting crickets near the chair, so provisioning has begun. The cricket seemed not only larger than the hole, but also larger than the wasp; we assume the wasp knows what she’s doing.

The new wasp will hatch this year, pupate over the winter, then hatch and emerge next summer, but I plan to replace the straps after the construction season ends.

I have no idea how to clean out whatever’s accumulating in there …

(*) I learned them as Steel-blue Cricket Killer, but the crickets are just paralyzed, not completely dead.

2022-07-15

Bathroom Sink Pop-up Drain Rod Status

Three years later, the bathroom drain stopper once again disconnected from the pop-up rod and gave me a chance to inspect how the brass is surviving:

After five years, the epoxy plug is either creeping out of the end or the end is corroding back a bit, but there’s plenty more where that came from.

The original steel rod disintegrated after nine years, so it’s still a horse race.

2022-07-13

High Impact Art: Practical Smashed Glass Coaster

The proof of concept coaster might suffice for a shot glass, but my morning tea comes in a 20 ounce mug with a much larger footprint.

So, back to the Basement Shop, where a laser-cut and -engraved layout guide helps arrange and carry some suitable fragments:

Glass Coaster - Layout tray — Glass Coaster – Layout tray

As before, scan the bottom of the fragments and wrap selections around them:

Coaster Layout - selected fragments — Coaster Layout – selected fragments

Apply the usual operations to get a suitable mask:

Coaster Layout - fragment masks — Coaster Layout – fragment masks

Fire the laser to cut the chipboard test template holding the fragments, then a white octagonal acrylic base plate and a transparent acrylic layer surrounding the fragments, and:

Glass Coaster - base epoxy setup — Glass Coaster – base epoxy setup

Mix up some pourable epoxy, smooth it over the base plate, squish the transparent layer atop it, use the tape (sticky side up) to hold the two layers in alignment, and gently insert the fragments:

Glass Coaster - fragment epoxy — Glass Coaster – fragment epoxy

I eased some epoxy around the perimeter of each fragment with a pipette in an attempt to reduce the glass-sliver hazard:

Glass Coaster - fragment epoxy detail — Glass Coaster – fragment epoxy detail

Yes, that’s on top of the protective paper, because then I can whisk the paper off to reveal the pristine surface around each fragment:

Glass Coaster - fracture filling — Glass Coaster – fracture filling

As with the smaller coaster, the epoxy penetrates the fractures and reduces the shattered appearance. Mary suggests tinted epoxy would produce an interesting effect and I’ll try that the next time around.

Because the smashed glass came from our neighbor’s lawn, it carried a bit of dirt and debris onto the playing field:

Glass Coaster - fragment edge detail — Glass Coaster – fragment edge detail

Seen through the edge of the coaster, the uneven surface of the epoxy fill around the fragments shows up clearly:

Glass Coaster – fragment edge profile

The top of the glass stands half a millimeter above the transparent acrylic. I knew that would happen and wanted to see how the bottom of the mug interacted with the epoxy-coated sides:

Glass Coaster - first test — Glass Coaster – first test

As it turned out, the epoxy coating wasn’t quite good enough to prevent tiny slivers from chipping off and, in the cold light of day, the pale-green-ish tinted glass didn’t stand out well against the white background.

So I taped up the perimeter, leveled the base, mixed up another batch of epoxy, added two drops of opaque black dye, and poured just enough to level the surface with the glass:

Glass Coaster - black epoxy pour — Glass Coaster – black epoxy pour

Introducing the meniscus to Mr Belt Sander put a bevel around the edge and finished it off well enough:

Glass Coaster - second test — Glass Coaster – second test

The Squidwrench logo looks a bit battered after three and a half years of trips through the dishwasher, although I didn’t expect it to last nearly this long.

There’s still a slight upward tilt around the perimeter, but it meets my simple requirements and the fragments definitely look better in black. The white base sets off the fragments, but a clear plate takes advantage of their transparency; a mirror sheet might be even more interesting.

2022-07-12