MK4 – Page 6 – The Smell of Molten Projects in the Morning

3D Printed Smashed Glass Coasters: Fragment Outlines

Because all smashed glass fragments are different, the problem boils down to locating their borders in order to create recesses to hold them.

The fragments, being slightly green-tinted glass, have very low contrast against any background color. This picture shows the result of applying GIMP’s Select by color tool with a reasonable color tolerance:

Printed Fragment Coaster - 5 inch - GIMP mask — Printed Fragment Coaster – 5 inch – GIMP mask

Fiddling with the tolerance trades off more trash outside the fragments with less accurate selection inside them. While it’s possible to clean up the ensuing mess, it’s incredibly tedious and more trouble than just tracing the edges manually using a stylus and graphic tablet. For the record, a white background produces similar results.

I began tracing the fragments with meticulous attention to following their exact outline, which certainly produced angular shapes:

Smashed Glass paths - quick mask — Smashed Glass paths – quick mask

It also takes approximately forever and is way tedious.

The intent was to apply a uniform offset to those outlines in OpenSCAD, but it turned out the fragment edges aren’t exactly perpendicular to the scanner platform and the protruding glass extends beyond any reasonable offset; determining how unreasonable the offset must be requires cutting a fitting template:

Printed Coasters - fit test — Printed Coasters – fit test

Incidentally, the dark smudge in the bottom fragment isn’t dirt, it’s the Ford logo above the identification numbers for that particular window:

Printed Coasters – glass fragment logo

You’ll note the rather sloppy fit inside the template.

However, the little glass shard sticking out on the upper right side does not match a corresponding template notch. You’re looking at the top of the fragment, but the scanner was looking at the bottom and that shard angles outward toward the top, where it was out of focus and I didn’t notice it.

Although that fragment fit its recess, such things eventually cause problems:

Printed Coasters - fragment misalignment — Printed Coasters – fragment misalignment

The chipboard template isn’t as tall as the printed recess, which means some of those protruding shards can wiggle through.

Protip: Avoid the temptation to just press a fragment into its ill-fitting recess, as shattered glass doesn’t have much strength. AFAICT, only air pressure holds the shards in place (they’re not windshields and not laminated), so you must handle them like they’re made of ahem glass.

The scans produce 300 DPI images, so each pixel is 0.085 mm across and half a millimeter is about 6 pixels wide. I tried tracing the fragments with the center of a 12 pixel circular GIMP brush, so the outer edge of the brush painted a 0.5 mm margin around the fragment, but keeping the middle of the brush on the edge was entirely too fussy.

I eventually settled on a 6 pixel brush, painted it just outside the margin, and paid more attention to shadows that might be shards protruding toward the top:

Printed Clutter Collector - fragment GIMP selection — Printed Clutter Collector – fragment GIMP selection

That works out well with the fragments on the desk to resolve any issues.

The garish red in those screenshots is GIMP’s Quick Mask mode allowing you (well, me) to paint the selection with either black or white to mask or select the pixels.

After painting the entire perimeter of the fragment, use the Bucket Fill tool to pour white into the interior and select the entire fragment. This is much easier than scribbling over the fragment, which is what I did until I realized I was working too hard.

Get out of Quick Mask mode, convert the selection to a Path, then export the path (or paths) to an SVG file.

The initial test piece was a round coaster:

Smashed glass printed coaster - detail — Smashed glass printed coaster – detail

But a conformal perimeter is much more interesting:

Smashed Glass 3D Printed Coaster - Set B — Smashed Glass 3D Printed Coaster – Set B

However, an interesting perimeter requires an interesting fragment layout …

2025-10-15

3D Printed Smashed Glass Coasters: Optimization

A pair of 3D printed smashed glass coasters for a friend:

Printed Coasters - in use — Printed Coasters – in use

The black PETG coaster under the French Press:

Printed Coasters - black PETG finished — Printed Coasters – black PETG finished

The white PETG coaster under the mug:

Printed Coasters - white PETG finished — Printed Coasters – white PETG finished

They’re considerably improved from the first attempt:

Smashed glass printed coaster - front view — Smashed glass printed coaster – front view

More details to follow …

2025-10-14

Baseboard Radiator Sleds

Cleaning the baseboard radiator fins before moving the houseplants back to their winter abode by the living room window made sense, so I took the trim covers off and vacuumed a remarkable accumulation of fuzz off the top and out from between the fins. The covers had an equally remarkable accumulation of sawdust along their bottom edge, apparently deposited when the previous owners had the floor sanded before they moved in a decade ago.

If you happen to live in a house with baseboard radiators, I’m guessing you never looked inside, because nobody (else) does.

Anyhow, the radiator fins should rest on plastic carriers atop the bent-metal struts also supporting the trim covers, so that they slide noiselessly when the copper pipe expands & contracts during the heating cycle. Over the last six decades, however, the plastic deteriorated and most of the carriers were either missing or broken to the point of uselessness:

Baseboard Radiator Sled - old vs new — Baseboard Radiator Sled – old vs new

The shapes on the bottom are replacements made with a 3D printed base (“sled”) and a chipboard wrap around the radiator preventing the fins from contacting the strut:

Baseboard Radiator Sled - OpenSCAD show — Baseboard Radiator Sled – OpenSCAD show

Although it was tempting to 3D print the whole thing, because plastic, I figured there was little point in finesse: chipboard would work just as well, was much faster to produce, and I need not orient the shapes to keep the printed threads in the right direction.

The Prusa MK4 platform was just big enough for the number of sleds I needed:

Baseboard Radiator Sled - printed — Baseboard Radiator Sled – printed

The sleds along the left and right edges lost traction as the printing progressed, but everything came out all right.

The OpenSCAD program also produces 2D SVG shapes for the chipboard wraps and adhesive rectangles sticking them to the sleds:

Baseboard Radiator Sled - OpenSCAD SVGs — Baseboard Radiator Sled – OpenSCAD SVGs

Import those into LightBurn, duplicate using the Grid Array, Fire The Laser, then assemble:

Baseboard Radiator Sled - assembly — Baseboard Radiator Sled – assembly

The slits encourage the chipboard to bend in the right direction at the right place, so I didn’t need any fancy tooling to get a decent result.

A few rather unpleasant hours crawling around on the floor got the struts bent back into shape and the sleds installed under the fins:

Baseboard Radiator Sled - installed — Baseboard Radiator Sled – installed

Protip: Gloves aren’t just a good idea, they’re essential.

The trim cover presses the angled chipboard where it should go against the fins. The covers carry shadows of the plastic carriers, suggesting the clearance was tighter than it should have been and thermal cycling put more stress on the plastic than expected. We’ll never know.

Although I’ll make more for the other baseboards as the occasion arises, I hope to never see these again …

The OpenSCAD source code as a GitHub Gist:

	// Baseboard radiator sled
	// Ed Nisley – KE4ZNU
	// 2025-10-11

	include <BOSL2/std.scad>

	Layout = "Sled"; // [Show,Build3D,Build2D,Sled,Wrap,Glue]

	/* [Hidden] */

	HoleWindage = 0.2;
	Protrusion = 0.1;

	Gap = 5.0;

	Radiator = [25.0,62.0,50.0]; // X = support base, YZ = radiator element

	SledBase = [Radiator.x + 10.0,Radiator.y,1.0]; // support under wrap
	Runner = [SledBase.x – 2.0,3.0,1.6]; // bars contacting radiator support

	GlueOA = [SledBase.x,SledBase.y] – [2.0,2.0]; // glue sheet

	Wrap = [SledBase.x,Radiator.y + 1.0,Radiator.z + 1.0]; // chipboard wrap around radiator
	WrapFlat = [Wrap.x,Wrap.y + 2*Wrap.z];
	WrapThick = 1.2;
	WrapSlit = 0.4;

	//—–
	// Sled base

	module Sled() {

	cuboid(SledBase,rounding=2.0,edges="Z",anchor=BOTTOM)
	position(TOP)
	for (j=[-1,1])
	fwd(j*SledBase.y/3)
	cuboid(Runner,rounding=Runner.z/2,edges="Z",anchor=BOTTOM);

	}

	//—–
	// Glue sheet
	// Export as SVG for laser cutting

	module Glue() {

	rect(GlueOA,rounding=2.0);

	}

	//—–
	// Radiator wrap
	// Export as SVG for laser cutting

	module Wrap() {

	difference() {
	rect(WrapFlat,rounding=2.0);
	for (j=[-1,1])
	fwd(j*Wrap.y/2)
	rect([Wrap.x/2,WrapSlit]);
	}

	}

	//—–
	// Build things

	if (Layout == "Sled")
	Sled();

	if (Layout == "Glue")
	Glue();

	if (Layout == "Wrap")
	Wrap();


	if (Layout == "Show") {
	xrot(180)
	Sled();
	color("Yellow",0.6)
	Glue();
	up(1)
	color("Brown") {
	cuboid([Wrap.x,Wrap.y,WrapThick],anchor=BOTTOM);
	for (j=[-1,1])
	fwd(j*Wrap.y/2)
	cuboid([Wrap.x,WrapThick,Wrap.z],anchor=BOTTOM);
	}
	}

	if (Layout == "Build3D") {
	Sled();
	}

	if (Layout == "Build2D") {
	left(GlueOA.x/2 + Gap/2)
	Glue();
	right(Wrap.x/2 + Gap/2)
	Wrap();
	}

view raw Baseboard Radiator Sled.scad hosted with ❤ by GitHub

2025-10-13

Dryer Vent Filter Snout

The first step in adding a filter bag to the dryer vent requires a convenient way to attach it. Because we live in the future, a couple of hours of 3D printing produced something that might work:

It’s made of TPU, which is bendy enough to ease two tabs into the two outermost slots you can see and a corresponding pair of tabs into slots on the wall side.

The solid model shows the part snapped inside the vent:

Clothes Dryer Vent Filter Snout - OpenSCAD show — Clothes Dryer Vent Filter Snout – OpenSCAD show

The flared bottom takes something like three hours to print (TPU likes slooow extrusion), so I did the top ring first to verify the tab fit:

Clothes Dryer Vent Filter Snout - OpenSCAD build — Clothes Dryer Vent Filter Snout – OpenSCAD build

Both parts come from hull() surfaces wrapped around quartets of thin circles at the proper positions; the difference() of two slightly different hulls produces thin shells.

A thin layer of JB PlasticBonder urethane adhesive, which bonds TPU like glue, holds the two parts together. I used the tan variant and, while it’s not a perfect match, it definitely looks better than black. Not that it matters in this case.

Mary will sew up a bag with a drawstring holding it to the snout. If everything survives the performance tests, printing the whole snout in one four-hour job will both make sense and eliminate an uneven joint that’s sure to be a lint-catcher.

The OpenSCAD source code as a GitHub Gist:

	// Clothes dryer vent filter snout
	// Ed Nisley – KE4ZNU
	// 2025-10-07

	include <BOSL2/std.scad>

	Layout = "Ring"; // [Show,Build,Ring,Taper]

	/* [Hidden] */

	ID = 0;
	OD = 1;
	LENGTH = 2;

	HoleWindage = 0.2;
	Protrusion = 0.1;

	NumSides = 432*4;
	$fn=NumSides;

	Gap = 5.0;

	// Centers of corner rounding circles

	InnerWidth = 3.0; // wall inside snout
	InnerRadius = 6.0; // inner corner rounding

	RR = [130.0/2 – InnerRadius,91.0/2 – InnerRadius]; // right rear corner
	RF = [112.0/2 – InnerRadius,-(91.0/2 – InnerRadius)]; // right front corner

	CornerCtrs = [[RR.x,RR.y],[RF.x,RF.y],[-RF.x,RF.y],[-RR.x,RR.y]]; // clockwise from RR

	InsertHeight = 7.0; // overall height inside the snout

	TabOC = [73.0,91.0]; // tabs locking into snout

	TabCtrs = [[TabOC.x/2,TabOC.y/2],[TabOC.x/2,-TabOC.y/2],[-TabOC.x/2,-TabOC.y/2],[-TabOC.x/2,TabOC.y/2]];
	TabRadius = 5.0;
	TabHeight = 3.0;

	TaperHeight = 20.0; // Taper holding filter bag
	TaperRadius = 10.0; // outward to capture bag string
	TaperWidth = 2.0; // wall width

	TaperCtrs = CornerCtrs + [[0,-(TaperRadius – InnerWidth)],[0,0],[0,0],[0,-(TaperRadius – InnerWidth)]];

	//—–
	// Clear inside vent opening as 2D shape

	module Opening() {
	hull()
	for (p = CornerCtrs)
	translate(p)
	circle(r=InnerRadius);

	}


	//—–
	// Insert ring locking into vent snout

	module Ring() {

	difference() {
	union() {
	linear_extrude(h=InsertHeight)
	offset(delta=InnerWidth)
	hull()
	for (p = CornerCtrs)
	translate(p)
	circle(r=InnerRadius);
	up(InsertHeight – TabHeight)
	linear_extrude(h=TabHeight)
	for (p = TabCtrs)
	translate(p)
	circle(r=TabRadius);
	}
	down(Protrusion)
	linear_extrude(h=2*InsertHeight)
	Opening();
	}

	}

	//—–
	// Taper glued to ring

	module Taper() {

	difference() {
	hull() {
	up(TaperHeight)
	linear_extrude(h=Protrusion)
	offset(delta=InnerWidth)
	hull()
	for (p = CornerCtrs)
	translate(p)
	circle(r=InnerRadius);
	linear_extrude(h=Protrusion)
	offset(delta=TaperRadius)
	hull()
	for (p = TaperCtrs)
	translate(p)
	circle(r=TaperRadius);
	}
	hull() {
	up(TaperHeight)
	linear_extrude(h=2*Protrusion)
	offset(delta=InnerWidth)
	hull()
	for (p = CornerCtrs)
	translate(p)
	circle(r=InnerRadius – InnerWidth);
	down(Protrusion)
	linear_extrude(h=2*Protrusion)
	offset(delta=TaperRadius – TaperWidth)
	hull()
	for (p = TaperCtrs)
	translate(p)
	circle(r=TaperRadius);
	}
	}
	}

	//—–
	// Build things

	if (Layout == "Ring")
	Ring();

	if (Layout == "Taper")
	Taper();

	if (Layout == "Show") {
	up(TaperHeight)
	Ring();
	Taper();
	}

	if (Layout == "Build") {
	back(55)
	up(InsertHeight)
	yrot(180)
	Ring();
	fwd(55)
	up(TaperHeight)
	yrot(180)
	Taper();
	}

view raw Clothes Dryer Vent Filter Snout.scad hosted with ❤ by GitHub

2025-10-10

Polydryer Humidity: October

Another month of data from all those Polydryer boxes:

	7 Oct 2025			8 Oct
Filament	%RH	Weight – g	Wt gain – g	%RH
PETG White	28	26.6	1.6	19
PETG Black	25	26.6	1.6	20
PETG Orange	29	26.6	1.6	21
PETG Blue	23	26.7	1.7	15
PETG-CF Blue	26	26.6	1.6	23
PETG-CF Black	23	26.4	1.4	20
PETG-CF Gray	30	26.5	1.5	26
TPU	28	26.3	1.3	27
Empty 1 → White	35	26.7	1.7	37
Empty 2	36	27.1	2.1	24

The “PETG White” spool in the top line is nearly empty, so I loaded a new spool into the “Empty 1” box.

The “Empty 1” 35% value on 7 Oct matches the other empty box, the desiccant having pulled the humidity down from the 51% basement level. The weight of the water pulled out seems low compared to “Empty 2”, as they both started with a fresh batch of basement air while changing the desiccant in September.

They’re again filled with 25 g of alumina beads, although I’m beginning to think silica gel does a better job.

A picture of the boxes, thus avoiding WordPress reminding me pictures improve SEO:

PolyDryer PC4 Fitting - Prusa MMU3 setup — PolyDryer PC4 Fitting – Prusa MMU3 setup

2025-10-09

Polydryer Humidity: Another Month of Data

The 25 g of silica gel in each Polydryer box produced these results after a month:

	8 Sept 2025			11 Sept	23 Sept
Filament	%RH	Wt – g	Wt gain – g	%RH	%RH
PETG White	25	27.6	2.6	15	21
PETG Black	22	27.3	2.3	15	20
PETG Orange	21	27.2	2.2	21	23
PETG Blue	19	27.3	2.3	14	15
PETG-CF Blue	24	27.4	2.4	21	22
PETG-CF Black	21	27.3	2.3	15	19
PETG-CF Gray	27	27.1	2.1	24	26
TPU	25	27.4	2.4	22	24
Empty 1	51	no gel	n/a	27	30
Empty 2	35	27.9	2.9	19	28

The humidity levels seem higher than before, with a bit under 10% weight gain.

The two “Empty” boxes show the difference between ambient basement humidity and letting 25 g of silica gel work on the box for a month. Comparing the latter’s weight gain with the other boxes shows occupying (much of) the interior with (relatively) dry filament reduces the desiccant’s workload.

The beads in the “Empty 2” box were definitely darker after soaking up an entire box full of 50 %RH air:

Polydryer - 37%RH meter - empty — Polydryer – 37%RH meter – empty

The meter reads 37%, rather than 35%, due to being out of the box for a few minutes.

They’re the darker swirl in the pan of beads:

Silica Gel regeneration - starting bead colors — Silica Gel regeneration – starting bead colors

That’s an accumulation of beads from a few months, not just what you see in the table.

I used an induction cooktop to heat the cast-iron pan. Some fiddling with the cooktop’s constant-temperature mode got the beads to 200 °F with a 460 °F setting in about an hour. Setting the cooktop to 50% in constant-power mode worked better, as the beads reached 220 °F in an hour and 230 °F after another hour.

The bead weights at various stages:

Start = 531 g
+1 hr at constant temperature = 491 g
+ 1 hr at 50% constant power = 483 g
+ 1 hr ditto = 480 g

The 41 g weight loss is 8.5% of the dry weight, roughly what you’d expect from the humidity readings.

After reloading the meters with 25 g of alumina beads, the 11 Sept humidity readings are slightly lower and the 23 Sept readings are roughly comparable.

2025-09-26

Fitbit Charge 5 Charging Stand

My Fitbit Charge 5 has become fussy about its exact position while snapped to its magnetic charger, so I thought elevating it above the usual clutter might improve its disposition:

FitBit Charge 5 stand - installed — FitBit Charge 5 stand – installed

The Charge 5 now snaps firmly onto its charger, the two power pins make solid contact, and it charges just like it used to.

The solid model comes from Printables, modified to have a neodymium ring magnet screwed into its base:

Fitbit Charge 5 stand - solid model section — Fitbit Charge 5 stand – solid model section

Which looks about like you’d expect;

FitBit Charge 5 stand - added magnet — FitBit Charge 5 stand – added magnet

A layer of cork covers the bottom and it sits neatly atop the USB charger.

The OpenSCAD source code punches the recesses and produces the bottom outline so LightBurn can cut the cork:

// FitBit Charge 5 Stand - base magnet
// Ed Nisley - KE4ZNU
// 2025-09-05

include <BOSL2/std.scad>

Layout = "Build";       // [Build, Base, Section]

module Stand() {
  difference() {
    left(38/2) back(65/2)
      import("Fitbit Charge 5 Stand.stl",convexity=10);

      down(0.05)
        cylinder(d=12.5,h=5.05,$fn=12);
      up(5.2)
        cylinder(d=3.0,h=10.0,$fn=6);
  }
}

//-----
// Build things

if (Layout == "Build")
  Stand();

if (Layout == "Base")
  projection(cut = false)
    Stand();

if (Layout == "Section")
  difference() {
    Stand();
    down(0.05) fwd(50)
      cube(100,center=false);
}

2025-09-24