MK4 – Page 7 – The Smell of Molten Projects in the Morning

PolyDryer Humidity vs. Spool Fill

The Basement Shop has 50±5% relative humidity, with the top held down by a hulking dehumidifier (plus a box fan stirring the air) and the bottom supported by being a basement. As a result, the 3D printer filament stabilized at about 50% RH, which seemed to work well enough for PETG.

Adding TPU to the stable called for better humidity control, so I set up a bunch of PolyMaker PolyDryer boxes with Auto-rewind spindles.

After a few weeks, though, I didn’t expect this:

That’s activated alumina desiccant, mostly because it’s reputed to have more capacity and a lower ultimate humidity than silica gel, but it likely doesn’t make much difference.

In addition to 25 g of desiccant in the PolyDryer meter case, I dropped five teabags holding 10 g each in the bottom of the box for more capacity. I measure the desiccant by putting 75.0 g into a cup, putting 25.0 g in the PolyDryer meter box (aided by a Polydryer Desiccant Funnel), 10.0 g into four teabags, and whatever’s left into the fifth teabag, thus eliminating rounding errors in the smaller quantities.

The stabilized humidity inside the boxes seems to depend on the amount of filament on the spool:

Nearly full → 25% to 30% RH
Half full → 20%-ish RH
Nearly empty → 10% to 15% RH

I think the humidity level comes from the filament outgassing water vapor through its (limited) surface area on the outer layer around the spool. The difference between that rate and the desiccant’s ability to remove water vapor from the (unmoving) air in the box sets the stable humidity: more surface area → more water vapor → higher humidity.

After the filament eventually dries out, the humidity should decrease, but diffusion is a slow process. More likely, the humidity will remain stable as the printer pulls filament from the outer layer and exposes the somewhat wetter plastic within.

The heater and fan inside the PolyDryer base unit circulates hot air through the box around the spool, but depends on the desiccant to remove water vapor. Running the base unit for 6 or 12 hours makes little difference in the stabilized humidity, so I think the desiccant is doing the best it can as the filament outgasses more water vapor.

Using Air Exchanger vents seems to make no difference, likely because the desiccant must then pull more water vapor out of the incoming 50% RH basement air. A psychrometric chart says 50% RH air at 60 °F becomes 10% RH air at 120 °F, but moisture in the filament wrapped around the spool can’t escape any faster.

So, for example, a full spool of TPU starting at 25% RH:

PolyDryer humidity - TPU start — PolyDryer humidity – TPU start

Six hours of drying pulls it down to 22%:

PolyDryer humidity - TPU finish — PolyDryer humidity – TPU finish

After sitting overnight it’s back at 25%:

PolyDryer humidity - TPU after 14 hr — PolyDryer humidity – TPU after 14 hr

Admittedly, that was with the vents in place, but the closed box started at 25% RH after sitting around for a week or so following a similar drying cycle.

The desiccant had absorbed 4 g of water since I put it in, so it hasn’t been entirely idle.

Which suggests 75 g of activated alumina desiccant is workin’ hard and doin’ swell in there, with the filament acting as an essentially infinite reservoir of water vapor.

I haven’t noticed any particular difference in PETG print quality and the TPU hasn’t gotten enough mileage to notice much trouble, but reducing the MMU3 buffer clutter was totally worth the effort.

2025-06-02

HQ Sixteen: Nose Ring Lights

We don’t know what the proper term might be for this part of the machine, but it looks sorta like a nose and the lights form most of a ring around it, so I’m going with “Nose Ring Lights”:

The general idea is to put more light on the quilt than the Chin Light, which looked pretty good until the COB LED strip started flickering as the LEDs failed.

Handi-Quilter sells a ring light for machines manufactured a decade later than ours, but it uses a built-in USB jack this machine lacks.

One of two (apparently) unused M4 holes on the left side of the machine frame suggested a mounting point for a 3D printed bracket:

HQ Sixteen Nose Ring Lights - solid model — HQ Sixteen Nose Ring Lights – solid model

The ramp matches the 3° (-ish) mold draft of the machine frame, which I initially ignored by angling the tab, but a tilted frame looked awful; it’s now aligned with local horizontal..

A few iterations got all the pieces & holes in their proper places:

HQ Sixteen Nose Ring lights - iterations — HQ Sixteen Nose Ring lights – iterations

The smaller (rampless) bracket has three LED strips, but a quick test showed more light would be better:

HQ Sixteen Nose Ring lights - bottom view — HQ Sixteen Nose Ring lights – bottom view

The lack of a transparent-ish cover is obviously unsuitable for a commercial product, but the key design goal is to not interfere with spreading as much light as possible across as much of the quilt as possible. The black JB Weld Plastic Bonder blobs keep the 24 VDC supply out of harm’s way, which is as good as it needs to be for now.

The bracket has three sides, because the right side of the machine has all the thread guide hardware. Putting anything over there seemed likely to interfere with either thread movement or fingers making adjustments.

Fortunately, the wider bracket doesn’t stick out too far beyond the machine frame and the doubled LED strips create a much smoother light pool:

HQ Sixteen Nose Ring lights - left front view — HQ Sixteen Nose Ring lights – left front view

Yes, the quilt is focused and the LED frame is blurred.

The larger light-emitting area reduces the shadow under the left rod (supporting the ruler foot) enough to be unobjectionable.

A 0.2 mm layer thickness transforms the smooth ramp into stair steps:

HQ Sixteen Nose Ring Lights - PrusaSlicer — HQ Sixteen Nose Ring Lights – PrusaSlicer

They’re inconspicuous after the bracket is installed.

The Chin Light ran on 12 V and these strips require 24 V, so the OpenSCAD code creates a pair of endcaps for the new supply, which is of course completely different than the old supply. Setting that up must await quilt completion.

The OpenSCAD source code as a GitHub Gist:

	// HQ Sixteen Nose Ring Lights
	// Ed Nisley – KE4ZNU
	// 2025-05-23

	include <BOSL2/std.scad>

	Layout = "Show"; // [Show,Build,NosePlan,PowerCap]

	// Number of side-by-side LED strips
	Strips = 2;

	/* [Hidden] */

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 334;

	$fn=NumSides;

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

	Gap = 5.0;

	WallThick = 5.0; // default thickness for things

	NoseRadius = 6.0; // corner roundoff

	NoseOA = [44.0,36.5]; // overall nose size
	NoseAngles = [87,87]; // front & rear inward angles wrt left side

	NoseCenters = [ // centers of circles defining the nose corners
	[NoseRadius, NoseOA.y/2 – NoseRadius],
	[NoseRadius,-(NoseOA.y/2 – NoseRadius)],
	[NoseOA.x – NoseRadius, NoseOA.y/2 – NoseRadius – (NoseOA.x – 2NoseRadius)tan(90 – NoseAngles[0])],
	[NoseOA.x – NoseRadius,-(NoseOA.y/2 – NoseRadius – (NoseOA.x – 2NoseRadius)tan(90 – NoseAngles[1]))],
	];

	LEDMargin = 1.0;
	LEDStrip = [41.5 + LEDMargin,8.0 + LEDMargin,1.8 + 0.2]; // 24 V COB LED strip unit + windage
	LEDBaseOA = [LEDStrip.x + StripsLEDStrip.y,NoseOA.y + 2Strips*LEDStrip.y,WallThick]; // LED mount

	DraftAngle = 3.0; // angle of frame wrt horizontal at right end of nose
	DraftWedge = [NoseOA.x,NoseOA.y + 2LEDStrip.y,NoseOA.xtan(DraftAngle)];

	HoleOffset = [-10.0,5.5,DraftWedge.z + 10.0]; // from left front corner of nose
	HolePosition = HoleOffset + [0,-NoseOA.y/2,WallThick]; // absolute coordinates from origin

	Screw = [4.0 + HoleWindage,9.0,2.0]; // LENGTH=button head

	Bracket = [WallThick,Screw[OD] + 4.0,HoleOffset.z + Screw[OD/2] + 2.0 + WallThick];

	Supply = [46.0,30.0,21.0]; // 24 VDC power supply
	SupplyScrewOffset = 5.0; // … M4 screw hole from end of supply case

	CapWall = 3.0;
	CapRadius = CapWall – 1.0;
	CapInset = 1.0;
	CapOA = [20.0,Supply.y + 2*CapWall,Supply.z + CapWall]; // x & y to cover existing holes

	//———-
	// Define Shapes

	//—– 2D outline of nose piece just under frame casting

	module NosePlan() {
	hull()
	for (p = NoseCenters)
	translate(p) circle(r=NoseRadius);
	}

	//—– LED mounting plate

	module Mount() {

	union() {
	difference() {
	union() {
	right(LEDBaseOA.x/2 – Strips*LEDStrip.y)
	cuboid(LEDBaseOA,rounding=WallThick/2,except=BOTTOM,anchor=BOTTOM);
	up(LEDBaseOA.z) left(-HoleOffset.x/2)
	yrot(DraftAngle)
	cuboid(DraftWedge,rounding=WallThick/2,edges="Z",anchor=LEFT+BOTTOM);
	}
	down(Protrusion)
	linear_extrude(LEDBaseOA.z + DraftWedge.z + Protrusion)
	NosePlan();
	if (Strips > 1)
	translate([HolePosition.x – Bracket.x/2,HolePosition.y – Bracket.y,-Protrusion])
	cyl(LEDBaseOA.z + 2*Protrusion,d=4.0,anchor=BOTTOM);
	}
	difference() {
	union() {
	translate([HolePosition.x,HolePosition.y,(Bracket.x/2)*sin(DraftAngle)])
	left(Bracket.x)
	cuboid(Bracket,rounding=WallThick/2,edges=LEFT,anchor=BOTTOM+LEFT);
	translate([HolePosition.x – Bracket.x/2,HolePosition.y,0]) // rounding filler
	cuboid([LEDStrip.y,Bracket.y,WallThick],anchor=BOTTOM+LEFT);
	}
	translate(HolePosition)
	xrot(180/6) xcyl(l=NoseOA.x,d=Screw[ID],$fn=6);
	}
	}
	}

	//—– Endcap for power supply

	module EndCap() {

	difference() {
	cuboid(CapOA,rounding=CapRadius,except=BOTTOM,anchor=LEFT+BOTTOM);
	right(CapOA.x – CapWall) down(Protrusion)
	cuboid(Supply + [0,0,Protrusion],anchor=RIGHT+BOTTOM);
	right(CapInset + SupplyScrewOffset)
	zcyl(l=2*CapOA.z,d=Screw[ID],$fn=6,anchor=BOTTOM);
	}

	}


	//———-
	// Build things

	if (Layout == "NosePlan") {
	NosePlan();
	}

	if (Layout == "PowerCap") {
	EndCap();
	}

	if (Layout == "Show") {
	Mount();

	ctr = 80;
	ofs = Supply.x/2 – CapInset;
	left(ctr – ofs)
	EndCap();
	left(ctr + ofs)
	xflip()
	EndCap();
	color("Silver",0.6)
	left (ctr)
	cuboid(Supply,anchor=BOTTOM);
	}

	if (Layout == "Build") {
	Mount();
	back((LEDBaseOA.y + CapOA.y)/2 + Gap) right(Gap) up(CapOA.z) zflip()
	EndCap();
	back((LEDBaseOA.y + CapOA.y)/2 + Gap) left(Gap) zrot(180) up(CapOA.z) zflip()
	EndCap();
	}

view raw HQ Sixteen Nose Ring Lights.scad hosted with ❤ by GitHub

2025-05-30

Sears Humidifier: Lid Hinge Re-repair

The longsuffering Sears Humidifier that Came With The House once again has functioning hinges:

Sears Humidifier - lid hinge gluing setup — Sears Humidifier – lid hinge gluing setup

That’s the gluing “fixture” with enough steel piled on the lid to keep it from moving and machinist vises pushing / holding the hinge fragments in place.

I used the same technique as before, with duct tape aligning the loose pieces and JB Plastic Bonder sticking them together:

Sears Humidifier - right hinge outboard — Sears Humidifier – right hinge outboard

The other side of that hinge shows the broken section at the end of the molded void:

Sears Humidifier - right hinge inboard — Sears Humidifier – right hinge inboard

The other hinge has a 3D printed replacement end:

Sears Humidifier - left hinge inboard — Sears Humidifier – left hinge inboard

The other side shows there’s not much of the original hinge left:

Sears Humidifier - left hinge outboard — Sears Humidifier – left hinge outboard

I very carefully installed the lid on the newly cleaned humidifier in the Basement Shop, where it flips up and down like anything.

At the start of this year’s humidification season, I will very carefully carry the lid up the basement stairs to the Sewing Room and we’ll see how long it survives in actual use.

2025-05-28

3D Printer Filament Spool Washers

The auto-rewind spindles for PolyDryer boxes fit a variety of spools, but recessed hubs like this require a pair of washers to center the spindles:

Filament spool washers - recessed hub — Filament spool washers – recessed hub

They’re laser-cut, although you could print them easily enough:

Filament spool washers - recessed hub - installed — Filament spool washers – recessed hub – installed

The size for that particular spool:

OD = 80 mm
Flange side ID = 51 mm
Nut side ID = 43
Thickness = ¼ inch, near enough

Other spools required a 3 mm shim on the flange side to sit centered in the PolyDryer boxes. Those are basically identical what you see above, with a 72 mm OD matching the flange.

The PETG-CF filament arrived on cardboard spools, which are apparently the new hotness:

Filament spool washers - printed — Filament spool washers – printed

The 56 mm spool ID requires adapters on both sides, with the flange side getting a 4 mm shim:

Filament spool washers - printed shim - flange side — Filament spool washers – printed shim – flange side

That skootches the spool over against the 1 mm shim on the nut side:

Filament spool washers - printed - nut side — Filament spool washers – printed – nut side

It would be possible to modify the auto-rewind spindle diameters to suit, if you were a dab hand with Fusion360, but the variety of hubs around here tells me a set of cheap adapters & shims makes more sense.

You should not assume anything will fit the spools you have, no matter how much they resemble what you see above.

The OpenSCAD source code as a GitHub Gist:

	// Polymaker PolyDryer auto-rewind spool washers
	// Ed Nisley – KE4ZNU
	// 2025-05-20

	include <BOSL2/std.scad>

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


	/* [Hidden] */

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 334;

	$fn=NumSides;

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

	Gap = 5.0; // Build separation
	SpoolWidth = 20.0; // Show separation

	FlangeOD = 72.0; // auto-rewind spindle
	FlangeHubOD = 50.5 + 1.0;
	NutOD = 77.0;
	NutHubOD = 42.0 + 1.0;


	//———-
	// Define Shapes

	module EryOneCF(Side = "Flange") {

	SpoolID = 56.0 – 1.0;
	SpoolSideThick = 3.0;

	if (Side == "Flange")
	tube(4.0,od=FlangeOD,id=FlangeHubOD,anchor=BOTTOM) // flange side
	position(TOP)
	tube(SpoolSideThick,od=SpoolID,id=FlangeHubOD,anchor=BOTTOM);

	if (Side == "Nut")
	tube(1.0,od=NutOD,id=43.0,anchor=BOTTOM) // nut side
	position(TOP)
	tube(SpoolSideThick,od=SpoolID,id=NutHubOD,anchor=BOTTOM);

	}



	//———-
	// Build things

	if (Layout == "Show") {
	left(SpoolWidth/2) yrot(90) EryOneCF("Flange");
	right(SpoolWidth/2) yrot(-90) EryOneCF("Nut");
	}

	if (Layout == "Build") {
	left((FlangeOD + Gap)/2) EryOneCF("Flange");
	right((NutOD + Gap)/2) EryOneCF("Nut");
	}

view raw PolyDryer spool washers.scad hosted with ❤ by GitHub

2025-05-21

3D Printed 20×102mm Cartridge

Having accumulated a box of empty 12 gram CO₂ capsules and having already done Too Many bomb fins:

The capsule is obviously the wrong shape, too short, and only 19 mm diameter, but it’s the thought that counts.

Apply the contour gauge to a genuine slightly battered 20×102mm cartridge:

Scan the sketch, import into Inkscape, rotate the image to correct the case taper angle vs. the page, lay lines & curves around the perimeter, align half of it at the page origin to work with OpenSCAD, export as SVG:

Cartridge - 20x102mm outline - Inkscape layout — Cartridge – 20x102mm outline – Inkscape layout

Import into OpenSCAD, let rotate_extrude do the heavy lifting, and remove some pieces:

Cartridge Case - build view solid model — Cartridge Case – build view solid model

The little disk represents a fired primer you’d print separately in a different color and glue into the pocket shown in this cutaway view:

Cartridge Case - cutaway solid model — Cartridge Case – cutaway solid model

The interior void could hold sand for additional heft, as the whole thing is obviously nose-heavy; that’s certainly in the nature of fine tuning. Obviously, we are not dealing with anything that could go bang.

It builds just like you’d expect:

20x102mm cartridge - printing — 20x102mm cartridge – printing

Dab some adhesive on the capsule tip, ditto for the primer, stick them in place, and it’s all good.

I like the gray PETG-CF version:

20x102mm cartridges - blue gray PETG-CF — 20x102mm cartridges – blue gray PETG-CF

Maybe not such a good idea in this day & age. Print responsibly, as they say.

Update

Print a sabot to fit a CO₂ capsule into a genuine steel cartridge.

The solid model:

Cartridge Case - sabot solid model — Cartridge Case – sabot solid model

The OpenSCAD making it happen:

module Sabot() {
tube(SabotOA[LENGTH],id=SabotOA[ID],od=SabotOA[OD],anchor=BOTTOM)
    position(BOTTOM)
      tube(SabotOA[LENGTH]/2,id=SabotOA[ID],od=CartridgeOA[ID],anchor=BOTTOM);
}

The result:

The OpenSCAD source code (minus the sabot) and outline as a GitHub Gist:

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view raw Cartridge – 20x102mm outline.svg hosted with ❤ by GitHub

	// 20x102mm cartridge
	// Ed Nisley – KE4ZNU
	// 2025-05-18

	include <BOSL2/std.scad>

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

	Powder = true; // build internal void

	/* [Hidden] */

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

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 334;

	$fn = NumSides;

	CartridgeOA = [21.0,29.5,101.4]; // must match SVG pretty closely

	PrimerOA = [2.0,8.0,2.0];

	CapsuleTip = [7.5,7.5,5.0];
	Capsule = [7.5,18.8 + HoleWindage,83];
	SeatingDepth = 25.0;

	Void = [CartridgeOA[ID]- 4.0,CartridgeOA[OD]- 4.0,CartridgeOA[LENGTH] – SeatingDepth – 4*PrimerOA[LENGTH]];

	//———-
	// Define shapes

	module Cartridge() {

	difference() {
	rotate_extrude()
	import("Cartridge – 20x102mm outline.svg",layer="Cartridge Aligned Half");
	up(PrimerOA[LENGTH])
	cyl(PrimerOA[LENGTH] + Protrusion,d=PrimerOA[OD],anchor=TOP);
	up(CartridgeOA[LENGTH] + CapsuleTip[LENGTH])
	cyl(SeatingDepth,d=Capsule[OD],anchor=TOP);
	up(CartridgeOA[LENGTH] – SeatingDepth)
	cyl(Void[LENGTH],d=CapsuleTip[OD],anchor=BOTTOM);
	if (Powder) {
	up(Void[LENGTH]/2)
	cyl(Void[LENGTH],d=CapsuleTip[OD],anchor=BOTTOM);
	up(2*PrimerOA[LENGTH])
	cyl(Void[LENGTH],d=Void[OD],rounding=Void[OD]/2,anchor=BOTTOM);
	down(Protrusion)
	cyl(Void[LENGTH],d=PrimerOA[ID],anchor=BOTTOM);
	}
	}

	}

	module Primer() {
	difference() {
	cyl(PrimerOA[LENGTH] – Protrusion,d=PrimerOA[OD] – HoleWindage,anchor=BOTTOM);
	up(PrimerOA[LENGTH])
	spheroid(d=PrimerOA[ID]);
	}
	}


	//———-
	// Build things

	if (Layout == "Show")
	//render()
	difference() {
	Cartridge();
	cuboid(3*CartridgeOA[LENGTH],anchor=LEFT+BACK);
	}

	if (Layout == "Build") {
	Cartridge();
	right(CartridgeOA[OD])
	Primer();
	}

view raw Cartridge 20x102mm.scad hosted with ❤ by GitHub

2025-05-20

Cusinart Smart Stick Blender Motor Coupler

When our stick blender (Cusinart CSB-77, with an instruction manual dated 2011) failed, I dropped fifteen bucks on the shortest one we could find, which turned out to be inconveniently long for the shorter member of the user community. The old one recently emerged from the depths of the bench for triage; the failure was in the coupler between the motor and the blade shaft, but required complete disassembly before trying to repair it.

Pry out two obvious plastic plugs, remove two screws holding the top of the handle together, pull the handle apart, and reveal a PCB with a discrete diode bridge and an open-frame switch:

Stick blender coupler - PCB — Stick blender coupler – PCB

Fortunately, the wire colors matched my preconception. Unsolder the wires to get that side of the handle off.

Un-bend the tab holding the metal shell to the plastic frame and pull it off, whereupon the frame halves unsnap to release the motor:

Stick blender coupler - shell removed — Stick blender coupler – shell removed

The white nylon (?) coupler on the motor shaft pries off the splined motor shaft:

Stick blender coupler - motor shaft splines — Stick blender coupler – motor shaft splines

That black ring inside the coupler should be on the blade shaft:

Stick blender coupler - blade shaft — Stick blender coupler – blade shaft

It apparently got jammed in the coupler when the shaft’s drive dogs / splines (barely visible down inside) ripped up the coupler. I don’t know if that was a sudden failure or the end result of gradually accumulating damage, but the inside of the coupler was badly chewed up.

Dismantling the blade unit requires prying three plastic clips back, one at a time, while pushing upward on the intricate black plastic fitting around the shaft:

Stick blender coupler - blade housing clips — Stick blender coupler – blade housing clips

That let me ease a drop of oil down the shaft to what looks and feels like a plastic sleeve bearing near the blade end of the housing; oil should not be needed on a plastic bearing, but it definitely improved the bearing’s attitude. The snap ring securing the shaft is far enough away to prevent me from even trying to remove it, because I know there is no way I can reinstall it:

Stick blender coupler - blade shaft snap ring — Stick blender coupler – blade shaft snap ring

Some Xacto knife action removed the shredded plastic to reveal the remains of four slots for the blade shaft’s two drive dogs / splines:

Stick blender coupler - OEM coupler end view — Stick blender coupler – OEM coupler end view

Measuring All. The. Things. produced a reasonable solid model of the slots:

Stick Blender drive coupler - splines - solid model — Stick Blender drive coupler – splines – solid model

Removing those from a model of the coupler defined the shape:

Stick Blender drive coupler - PrusaSlicer — Stick Blender drive coupler – PrusaSlicer

As usual, having one in hand let me check the fit and, after a few tweaks, the next one was Just Right™.

The other end of the coupler is a simple cylinder sized for a firm press fit on the motor shaft splines:

Stick blender coupler - new coupler detail — Stick blender coupler – new coupler detail

My coupler is chunkier than the OEM coupler, because there was enough room in there and PETG-CF, being weaker than nylon, needs all the help it can get:

Stick blender coupler - new coupler installed — Stick blender coupler – new coupler installed

It’s one of the few things I’ve printed with 100% infill. If when that plastic fails, I’ll try something else.

Put the little rubber ring on the blade shaft and reassemble everything in reverse order:

Stick blender coupler - mating ends — Stick blender coupler – mating ends

The blender works as well as it ever did, while the halves couple and uncouple the way they should, so we’ll declare victory and keep the new blender as a backup.

The OpenSCAD source code as a GitHub Gist:

	// Stick Blender drive coupler
	// Ed Nisley – KE4ZNU
	// 2025-05-16

	include <BOSL2/std.scad>

	Layout = "Show"; // [Show,Build,Splines]

	/* [Hidden] */

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 334;

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

	ShellOA = [5.0,14.0,28.0]; // ID=motor shaft

	MixerSocket = [6.6,0,17.2]; // passes rubber retainer

	Retainer = [3.0,6.5,5.5]; // ID=mixer shaft,OD=rubber ring
	RetainerRebate = [Retainer[ID],3.9,1.5]; // … fits under shaft lip

	DriveSocket = [6.7,8.8,12.0]; // OD=notch OD
	DriveNotch = [(DriveSocket[OD] – DriveSocket[ID])/2,1.5,DriveSocket[LENGTH]]; // … drive notch shape on +X
	DriveChamfer = -DriveNotch.y;

	$fn = NumSides;

	//———-
	// Define Shapes

	module Splines() {
	render()
	for (a = [0:90:270])
	zrot(a)
	right(DriveSocket[ID]/2 – Protrusion)
	cuboid(DriveNotch + [Protrusion,0,0],chamfer=DriveChamfer,edges=[TOP+FWD,TOP+BACK],anchor=LEFT+BOTTOM);

	}

	module Coupler() {

	difference() {
	tube(ShellOA[LENGTH],id=ShellOA[ID],od=ShellOA[OD],anchor=BOTTOM);
	up(ShellOA[LENGTH] – MixerSocket[LENGTH])
	cyl(Retainer[LENGTH],d=Retainer[OD],anchor=BOTTOM);
	up(ShellOA[LENGTH] + Protrusion)
	cyl(DriveSocket[LENGTH] + Protrusion,d=DriveSocket[ID],anchor=TOP);
	up(ShellOA[LENGTH] – DriveNotch[LENGTH] + Protrusion)
	Splines();
	}
	}

	//———-
	// Build things

	if (Layout == "Splines")
	Splines();

	if (Layout == "Show")
	Coupler();

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

view raw Stick Blender drive coupler.scad hosted with ❤ by GitHub

2025-05-19

Humidifier Float Clip Replacement

This being the end of the humidifcation season, I tried to set the longsuffering Sears Humidifier’s water level float to dry the thing out. After a few days, it became obvious that wasn’t working and I eventually found the clip intended to hold the float at the top of its travel had broken:

Humidifier float clips - on float — Humidifier float clips – on float

Building the retina-burn orange replacement started with a scan of the original:

The black segment at the bottom is a shadow due to the scanner’s light bar being offset from the imaging sensor.

Using GIMP, duplicate the remaining part of the latch, flip it left-to-right, then align it at the proper position:

Humidifier float clip - repaired — Humidifier float clip – repaired

The latch is the only tricky part and the ID of the ring is easy to locate, so (still in GIMP):

Trace the edge of the whole shape
Using Quick Mask mode, remove all but the latch
Convert the selection to a path
Export it as an SVG file

Then import it into OpenSCAD and eyeballometrically translate the shape to put the ring ID at the origin:

  color("Red")
    translate([-23.6,-42.6])
      import("Humidifier float clip - cabinet latch.svg");

Which looks like this:

Float clip - 2D latch — Float clip – 2D latch

Then glom a perfect ring onto it:

Float clip - 2D model parts — Float clip – 2D model parts

Extrude half an inch upward:

Float clip - extruded model — Float clip – extruded model

And It Just Works™:

Humidifier float clip - installed — Humidifier float clip – installed

There being no obvious affordance to get the ring over the two bumps in the float, I applied Channellock pliers to the float while easing the ring into place.

Re-rebuilding the hinges sits behind a few other things going on around here …

2025-05-15

Tag: MK4

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