Machine Shop – Page 13 – The Smell of Molten Projects in the Morning

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

New Dryer Vent

After the deck stain cured for a few days, I replaced the dryer vent:

The alert reader will note it’s held to the siding with four stainless steel 4 mm socket-head cap screws, for which I’m not going to apologize one little bit.

They fit into a quartet of threaded wood inserts driven into the siding, because the previous vent had small steel screws that pulled out many years ago.

I used a 4-¼ inch oscillating hole saw to embiggen the original 4.000 inch hole through the wall that doesn’t fit contemporary “4 inch” dryer vent pipe. The 4.000 inch hole in the interior seal plate also needed embiggening.

We must add a filter bag of some sort, as the dryer really wants to coat the deck in fuzz, but that’s in the nature of fine tuning.

There are no other pictures, as this was a ten minute job that burned an entire afternoon …

2025-10-07

Mostly Removing Acrylic Scratches

Some time ago I made a simple guide / carrier to help select & arrange smashed glass fragments to fit within a given diameter:

Coaster Layout - selected fragments — Coaster Layout – selected fragments

The laser-engraved guide lines confused GIMP’s edge detection to no end.

It came from a large sheet of 1 mm acrylic, formerly a poster cover, bearing scars of its long history in the “might be useful someday” stash. I wondered if I could remove enough scratches and scuffs to ease GIMP’s workload.

Stipulated: I am a cheapskate.

Laser-cut a suitable sheet and sand both sides with 220 grit paper to what looked like a uniform surface:

Acrylic polishing - 220 — Acrylic polishing – 220

Continue scrubbing with 400, 800, 1000, 1500, and 3000 grit papers:

Acrylic polishing - 3000 — Acrylic polishing – 3000

Massage it with Novus Polish 3, 2, and 1:

Acrylic polishing - Novus 1 — Acrylic polishing – Novus 1

At best, it’s more translucent than transparent and definitely not an optical-quality polishing job:

Acrylic polishing - translucency — Acrylic polishing – translucency

Fortunately, I need not care about the edges, because it goes in a square frame with a circular cutout.

Tape it into that cardboard frame, scan it against a black background, and blow out the contrast to show I should have started with 100 grit paper and paid more attention to that “uniform surface” thing:

Acrylic polishing - scratches — Acrylic polishing – scratches

In use, though, it doesn’t look all that bad:

Fragment layout - 5in Set B - scan tweaked — Fragment layout – 5in Set B – scan tweaked

Come to find out those glittery cracks between all the cuboids still confuse GIMP’s edge detection, but at least hand-tracing the outline is easier without all the lines.

The entire “polishing” series as a slideshow for your amusement:

Acrylic polishing – 220
Acrylic polishing – 400
Acrylic polishing – 800
Acrylic polishing – 1000
Acrylic polishing – 1500
Acrylic polishing – 3000
Acrylic polishing – Novus 3
Acrylic polishing – Novus 2
Acrylic polishing – Novus 1

FWIW, those fragments turned out nicely:

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

Glow In The Dark Pool Sandals

For reasons not relevant here, after Having Been Advised to not walk barefoot on our wood floors, I picked up a pair of beach / pool sandals with comfy soles. Although they have a white logo, they’re black and essentially invisible in the dark when I need them most.

Start by taking a photo of the logo on the clamped-flat upper strap:

UnderArmour logo – flattened

Use GIMP to select the white area, clean it up a little, convert the selection into a path, export it as an SVG file, import into LightBurn, scale to match reality, and Fire The Laser:

UnderArmour logo – GITD tape cutting

That’s a roll of glow-in-the-dark tape which is almost certainly a lethal combination of PVC and phosphorescent stuff, so hold your breath while it cuts.

It’s “actually a “kiss cut” through the tape, but not through the backing paper, letting the whole thing hang together after the operation.

Peel-n-stick on the (still flattened) sandals, expose them to light, and It Just Works:

UnderArmour logo – glowing

The fit isn’t perfect, perhaps due to insufficient flattening, but it’s close enough for my simple needs.

2025-10-02