The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Software

General-purpose computers doing something specific

Handi-Quilter HQ Sixteen: Front Handlebar Angled Mount

So as to not bury the lede, I remounted the front handlebar unit of Mary’s Handi-Quilter HQ Sixteen long-arm sewing machine so she can see the control panel with its small LCD:

HQ Sixteen - remounted handlebars in use — HQ Sixteen – remounted handlebars in use

The new and old white LEDs produce distinctly different colors and intensities on the practice quilt fabric.

The original HQ Sixteen design bolted squarely atop the arm:

HQ Sixteen - original front handlebar mount — HQ Sixteen – original front handlebar mount

The control surface is, admittedly, angled slightly forward, but Mary was unable to see the lower few lines of the LCD without standing on tiptoe.

Begin with a crude tracing of the mating surfaces:

Import the image into Inkscape and lay some shapes on it:

Front handlebar base layout - Inkscape — Front handlebar base layout – Inkscape

Import the SVG into LightBurn and cut templates to verify the hole positions:

HQ Sixteen - handlebar bolt templates — HQ Sixteen – handlebar bolt templates

Obviously that took more than one try.

Rationalize the outlines, clean things up, and organize the shapes into useful named layers:

Front handlebar base layout - Inkscape layers — Front handlebar base layout – Inkscape layers

Save as an Inkscape SVG, import into OpenSCAD, and extrude the layers defining all those shapes into a solid model:

Handlebar Base Mount - solid model — Handlebar Base Mount – solid model

That’s the most recent iteration; earlier ones appear in various pix.

I had intended to use either square nuts or heat-set inserts, but it turned out to be easier to just slam BOSL2 threaded nuts into the front plate and be done with it:

Handlebar Base Mount - solid model - hex nuts — Handlebar Base Mount – solid model – hex nuts

The trick is to sink the nuts around a hole sized slightly larger than the screw’s nominal diameter, letting the threads fill empty space.

The handlebar base is mounted symmetrically along the machine arm centerline aligned with the two screws on the right. The rear block is offset to the left to clear the machine cover on the right, so the hull() wrapped around the two looks weird.

The front plate stands proud of the rest by dint of incorporating only a small slice of its back face into the hull() filling the gaps between the two. It’s not particularly stylin’, but it’s pretty close.

Finding the correct angle for the front plate required a couple of iterations, but they all built successfully:

HQ Sixteen - handlebar mount - on platform — HQ Sixteen – handlebar mount – on platform

Putting the threaded holes vertical created nicely formed threads that accepted the screws without hassle.

The block screws firmly to the arm and the handlebar unit screws to the block:

HQ Sixteen - remounted handlebars - side — HQ Sixteen – remounted handlebars – side

The display now faces front:

HQ Sixteen - remounted handlebars - front — HQ Sixteen – remounted handlebars – front

I eventually replaced those black oxide screws with shiny stainless ones, just for pretty.

The nine LEDs under the display now do a great job of lighting up the front of the machine’s arm, rather than the fabric at the needle, but fixing that will be a whole ‘nother project.

The handlebar grips with their control buttons now tilt at a somewhat inconvenient angle, which is also a whole ‘nother project.

Early reports from the user community are overwhelmingly positive.

The OpenSCAD source code and the SVG layout as a GitHub Gist:

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view raw Front Handlebar Layout.svg hosted with ❤ by GitHub

	// Handiquilter HQ Sixteen front handlebar base mount
	// Ed Nisley – KE4ZNU
	// 2024-11-22

	include <BOSL2/std.scad>
	include <BOSL2/threading.scad>

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

	HandlebarOffset = [0,-30.0,14.0]; // pure empirical values
	HandlebarAngle = [60,0,0];

	FrameBlockThick = 35.0; // how much meat they need
	HandlebarThick = 12.0;

	/* [Hidden] */

	Holes = [[-19.0,0,0],[0,0,0],[0,12.5,0]]; // Must match SVG hole coordinates

	FrameCenter = [-45,-65]; // coordinates of corner hole center
	HoleCenter = [-40,-20];


	Protrusion = 0.1;

	module AdapterBlock() {

	union() {
	hull() {
	linear_extrude(height=FrameBlockThick,convexity=10)
	translate(FrameCenter)
	import("Front Handlebar Layout.svg",layer="Machine Frame");

	translate(HandlebarOffset)
	rotate(HandlebarAngle)
	linear_extrude(height=0.05*HandlebarThick,convexity=10)
	translate(HoleCenter)
	import("Front Handlebar Layout.svg",layer="Handlebar Base");
	}

	translate(HandlebarOffset)
	rotate(HandlebarAngle)
	linear_extrude(height=HandlebarThick,convexity=10)
	translate(HoleCenter)
	import("Front Handlebar Layout.svg",layer="Handlebar Base");
	}
	}

	module AdapterHoles() {

	linear_extrude(height=FrameBlockThick,convexity=10)
	translate(FrameCenter)
	import("Front Handlebar Layout.svg",layer="Machine Holes",convexity=2);

	translate([0,0,FrameBlockThick – 7.0])
	linear_extrude(height=7.0 + Protrusion,convexity=10)
	translate(FrameCenter)
	import("Front Handlebar Layout.svg",layer="Machine Counterbore",convexity=2);

	translate(HandlebarOffset) // cut clearance for nut threads
	rotate(HandlebarAngle)
	linear_extrude(height=HandlebarThick + Protrusion,convexity=10)
	translate(HoleCenter)
	import("Front Handlebar Layout.svg",layer="Handlebar Holes",convexity=2);

	}

	module Adapter() {

	union() {
	difference() {
	AdapterBlock();
	AdapterHoles();
	}

	# translate(HandlebarOffset) // add threads inside holes
	for (c = Holes)
	rotate(HandlebarAngle)
	translate(c)
	threaded_nut(10.0,6.2,HandlebarThick,1.0, // flat size, root dia, height, pitch
	bevel=false,ibevel=false,anchor=BOTTOM);
	}
	}

	// Build things

	if (Layout == "Block")
	AdapterBlock();

	if (Layout == "Holes")
	# AdapterHoles();

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

	if (Layout == "Build")
	rotate([180,0,0] – HandlebarAngle)
	Adapter();

view raw Handlebar Base Mount.scad hosted with ❤ by GitHub

2024-12-02

Doorbell Button Skulls
With only days to spare, I decorated the doorbell button:

Doorbell button skulls – installed

Yeah, I jammed Sharpies in the eye sockets, but they look exactly the way they should. The middle skull is in the middle of the actuator in the hope that’s where it’ll get pushed.

The solid model comes directly from the seasonally appropriate teapot lid handle with a rectangle to suit the doorbell button actuator:

Doorbell Button Skulls – solid model

Perforce, the OpenSCAD code has eyeballometric magic numbers:
```
// Doorbell Button Enhancement
// Ed Nisley - KE4ZNU
// 2024-10-28

Button = [5.0,13.0,40.0];    // button width, boss depth, button height

union() {
    rotate([0,0,65])
    translate([-121,-105])      // totally eyeballometric
        import("stackofskulls - 50mm.obj",convexity=10);

        translate([0,Button.y/2,Button.z/2])
            cube(Button,center=true);
}
```
The rectangular slab goes all the way down to the platform because I couldn’t be bothered with support or a little wedge.

I’m sure it will survive exactly as long as it must.

Dunno how many little ones will venture up the driveway, though:

Halloween mailbox decorations
2024-10-31
Gizo Spider Footpads
Given a 3% failure rate for the tiny footprint of Gizo spider legs, I added 5 mm pads to each foot:

Gizo Spider – footpads

A few rounds of successive approximation and one copypasta hit the right spots:
```
// Gizo spider footpads
// Ed Nisley - KE4ZNU
// 2024-10-26

pts = [
[24,-23],[28.5,-7],[29.5,14.5],[20,28],
[-24,-23],[-28.5,-7],[-29.5,14.5],[-20,28]
];

translate([14,0,2.8])
  import("/mnt/bulkdata/Project Files/Prusa Mk4/Models/Gizo Spider/GizoSpider.stl");

linear_extrude(height=0.2)
  for (pt = pts)
    translate(pt)
      circle(d=5,$fn=2*3*4);
```
Which was enough to stick the legs firmly to the build platform:

Gizo spider – white leg towers

Talk about blank looks:

Gizo spider – black on platform

White filament is particularly susceptible to charred globbing:

Gizo spider – white char inclusion

Which was, fortunately, completely hidden inside the shell.

Extensive testing showed the pads pushed the error rate below 1.5%:

Gizo spider pile

As before, dots of hot melt glue hold the eyes in place.

All’s well that ends well: just in time, too.
2024-10-30
Humidifier Lid Hinges
The humidifier that Came With The House™ had a lid with two broken plastic hinges that I figured I could never replace, but while cleaning out the fuzz for the upcoming season I found one missing piece stuck inside the lid. Given a hint, I glued it back in place:

Humidifier Hinge – outlined

There’s a strip of duct tape around the outside holding the fragment in place while the adhesive cured.

A manual curve fit to the image in Inkscape produced the red outline, which gets saved as a plain SVG and fed into OpenSCAD to create a solid model:

Humidifier Hinge – solid model

The cylinder doesn’t exactly fit the end of the hinge, but it’s close enough. The straightforward OpenSCAD code making that happen:
```
// Humidfier Hinge Replacement
// Ed Nisley KE4ZNU
// 2024-10-20

HingeThick = 10.0;
PinLength = 10.0;

ScrewOD = 2.0;

NumSides = 2*3*4;
Protrusion = 0.1;

difference() {
    union() {
        translate([0,0,HingeThick])
            cylinder(d=6.0,h=PinLength,$fn=NumSides);

        linear_extrude(height=10.0,convexity=5)
            translate([-3.1,-8.0])
                import("Humidifier Hinge - ouline.svg");
    }

    cylinder(d=ScrewOD,h=4*(HingeThick + PinLength),center=true,$fn=8);
}
```
The pin has a hole for a M2 screw, but contemplation of the broken pieces suggested the pin wasn’t the weakest link, which later experience confirmed.

Figuring I’d need only one hinge, I made a spare for fitting:

Humidifier hinge – on platform

The unmodified part fit just about perfectly, whereupon a completely ad-hoc fixture involving a pair of laser-cut MDF slabs, a craft stick epoxy mixer, and more duct tape held it in place while the adhesive cured:

Humidifier hinge – fixturing

The hinge pin turned out to be half a millimeter too long, which is easily fixed, and it worked fine:

Humidifier hinge – installed

That’s more duct tape wrapped around the perimeter to hold the pieces in place, should it break again.

Which, I regret to report, occurred on the way up the stairs from the Basement Shop™ when the lid slipped from my grasp, fell away from the rest of the humidifer’s top panel, and jammed open:

Humidifier hinge – break

The PETG-CF part held together, the adhesive remained bonded to both pieces, but the original plastic fractured just below the joint. A closer look from the other side shows the break:

Humidifier hinge – break detail

The other hinge broke about where it did before.

So the humidifier remains in service with the lid in status quo ante and a small bag inside holding the fragments for the next return to the shop.

Drat!
2024-10-28
Laser Cutter: Focus Ramp Tests
A few ramp tests with various Focus Distance + Home Offset settings as noted:

Ramp Test Targets – 14-17 mm

The bottom test was at 15 mm, which (contrary to previous estimates) seems to center the narrow band round 0.0 mm. Given the depth of field, a millimeter one way or the other likely doesn’t matter, particularly given the mmm lack of flatness in many materials.

The controller settings making it happen:

KT332N Autofocus settings

What they mean:
- Home Offset = distance to retract after the autofocus “pen” = switch activates so the tip of the pen clears the material
- Focus Distance = distance beyond Home Offset to put the focal point at the surface of the material (or wherever you want)
- Enable Homing = makes autofocus work at the push of a button
- Homing Speed = how fast the platform moves while focusing
Getting the focus right really makes the laser cut like it should!
2024-10-24

Laser Cutter: Focus Ramp Fixture

After figuring out the Ruida focus settings, a focus ramp fixture seemed like a good thing to have around:

Ramp Test Fixture - setup — Ramp Test Fixture – setup

The solid model shows a bit more detail:

Laser Focus Ramp Fixture - solid model — Laser Focus Ramp Fixture – solid model

Centering the autofocus “pen” = switch on the peg in the back puts the beam dead-center in the fixture, with the notches as comfort marks. The top of the peg is flush with the center notch, so the machine should be properly focused at that level after a focus operation.

Obviously, your laser has a different pen location, as will this one the next time I fiddle with anything around the nozzle.

The general idea is to tape a target to the ramp, with some attention to flattening the paper (tape the edges in critical spots as needed) & putting its zero at the center marks, align the fixture to the laser path along the X axis & secure it with a few magnets, then burn a single line at low power along the length of the scale:

Ramp Test Fixture - laser line — Ramp Test Fixture – laser line

The mark will be thinnest in the region with the best focus, which should be centered around the 0.0 mark in the middle. In that photo, the thinnest section runs from about -2.0 to +1.0, although (at least for me) it does take some squinting to be sure.

The ramp has a 1:10 = 5.71° slope to spread 1 mm of vertical focus across 10 mm of horizontal distance. If you’re being finicky, you should rescale the targets to correct the 0.5% cosine error, but IMO it’s irrelevant for this purpose.

A few more tests varying the focus distance by a millimeter:

Ramp Test Targets - 15 16 mm — Ramp Test Targets – 15 16 mm

AFAICT, setting the controller’s Focus Distance to 16 mm is about right. That puts the focal point 18 mm below the nozzle, as shown in the earlier post, and is pretty much what I’ve been using all along.

The OpenSCAD code as a GitHub Gist, along with a simplified target layout in SVG format:

	// Laser Cutter Focus Ramp Fixture
	// Ed Nisley KE4ZNU
	// 2024-10-10

	FocusPenOffset = [-19,23,0];
	FocusPenOD = 10.0;

	RampHeight = 16.0;
	RampScale = 10;
	RampLength = RampScale * RampHeight;

	Magnet = [5.0,60.0,10.0];

	NumSides = 3*4;

	Protrusion = 0.1;

	RampAngle = atan(RampHeight/RampLength);
	echo(RampAngle=RampAngle);

	Slot = [(RampLength + 25.0),10.0,8RampHeight]; // very tall to cut through everything

	Body = [(Slot.x + 210.0),30.0,3RampHeight]; // extend Z to reach baseplate

	FocusPillarHeight = (RampHeight/2) + Body.z/3; // match Z at center of body

	BasePlate = [(Body.x + 2Magnet.x + 25.0),max(Magnet.y,FocusPenOffset.y + 2*5.0),3.0];
	BaseRound = 5.0;

	//—– Build it

	difference() {
	union() {
	translate(FocusPenOffset)
	cylinder(d=FocusPenOD,h=FocusPillarHeight,$fn=NumSides);

	difference() {
	union() {
	rotate([0,RampAngle,0])
	cube(Body,center=true);

	linear_extrude(height=BasePlate.z)
	hull()
	for (i=[-1,1], j=[-1,1])
	translate([i(BasePlate.x/2 – BaseRound),j(BasePlate.y/2 – BaseRound)])
	circle(r=BaseRound,$fn=NumSides);
	}

	cube(Slot,center=true);

	translate([0,0,FocusPillarHeight]) {
	cube([0.5,2*Body.y,1.0],center=true);

	rotate([0,RampAngle,0])
	cube([2*Slot.x,0.5,1.0],center=true);
	}

	}
	}

	translate([0,0,-Body.z])
	cube(2*[BasePlate.x,BasePlate.y,Body.z],center=true);
	}

view raw Laser Focus Ramp Fixture.scad hosted with ❤ by GitHub

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view raw Target Layout – LightBurn.svg hosted with ❤ by GitHub

Contrary to what you might think, the targets are not laser cut, although you could use the crosshairs for LightBurn’s Print and Cut alignment.

2024-10-18

Seasonally Appropriate Teapot Knob
Long years ago, the Bakelite (or some such) lid on our rarely used teapot disintegrated, whereupon I replaced it with an aluminum sheet and metal knob. Admittedly, a metal knob was not the brightest idea I ever had, but it sufficed for a few uses over the intervening decades.

Mary hosted this month’s quilting bee and, after having someone else bring a larger teapot for the occasion, suggested I Make. A. Better. Knob. After a bit of searching, this statue seemed appropriate for the season:

Skull teapot knob

It’s printed with PETG filament that should easily withstand the no-more-than-boiling-water temperatures found atop a teapot.

I imported the original model into PrusaSlicer, shrank it to 50 mm tall and simplified the mesh, exported it as an OBJ file, imported it into OpenSCAD, mashed it together with a 1/4-20 threaded_nut from BOSL2, added the finger protector, and got a suitable model:

Teapot Knob – solid model bottom view

The as-printed threads were a bit snug with $slop=0, but running the screw in with a dot of silicone grease to ease the way worked fine.

I should rebuild the whole lid in PETG-CF sometime.

The OpenSCAD code stitches the parts together:
```
// Teapot Knob
// Ed Nisley - KE4ZNU
// 2024-10-11

include <BOSL2/std.scad>
include <BOSL2/threading.scad>

StackHeight = 50.0;
ThreadLength = 25.0;
HeatbreakOD = 40.0;
HeatbreakThick = 3.0;

    intersection() {
        union() {
            cylinder(d=HeatbreakOD,h=HeatbreakThick,$fn=2*4*9);
            up(HeatbreakThick)
                translate([-121,-105])      // totally eyeballometric
                    import("stackofskulls - 50mm.obj",convexity=10);
        }

        union() {
            threaded_nut(100,INCH/4,ThreadLength,INCH/20,        // flat size, root dia, height, pitch
                                     bevel=false,ibevel=false,anchor=BOTTOM);
            up(ThreadLength)
                cylinder(d=100,h=StackHeight);
        }
    }
```
2024-10-16