Category: Software

General-purpose computers doing something specific

HQ Sixteen: Improved Anchor

The original anchor / weight keeping the HQ Sixteen from rolling away suffered a disastrous fall, so I conjured a much better-looking replacement from the vasty digital deep:

The handle and fancy nut came from the deceased pepper mill, sitting on laser-cut acrylic in a 3D printed base, with a drawer liner disk peeking out from underneath.

The orange disk in the solid model represents the steel slug harvested from the old anchor:

HQ Sixteen Anchor - solid model - Show view — HQ Sixteen Anchor – solid model – Show view

A ring of hot-melt glue under the weight keeps it from rattling around in there, with the snug-fitting central post encouraging good positioning. I made the acrylic lid sit flush with the top of the base by the simple expedient of running another ring of glue around it, plunking the base + weight atop it on a flat surface, then taking a deep breath while the glue solidified. The nut & screw thus compress a solid stack of acrylic + glue + steel + glue + PETG-CF, rather than just parts flying in formation.

The OpenSCAD source code also produces a pair of outlines for laser-cutting the adhesive sheet and acrylic, suitable for export to an SVG file:

HQ Sixteen Anchor - solid model - cuts — HQ Sixteen Anchor – solid model – cuts

They’re offset inward by amounts appropriate for my CO₂ laser:

if (Layout == "Cuts") {
  left(BaseOD/2 + Gap)
    offset(r=-1.0)
      circle(d=BaseOD);
  right(Cap[OD]/2 + Gap)
    offset(r=-0.2/2)
      projection()
        tube(1.0,id=Cap[ID],od=Cap[OD],anchor=BOTTOM);
}

It might be prudent to apply those offsets to the original outlines in LightBurn or whatever you use for lasering.

The OpenSCAD source code as a GitHub Gist:

	// Anchor block for HQ Sixteen
	// Ed Nisley – KE4ZNU
	// 2026-09-29

	include <BOSL2/std.scad>

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

	/* [Hidden] */

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

	Gap = 10.0/2; // build platform minimum spacing
	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 832*4;

	$fn=NumSides;

	// Sizes

	Screw = [5.5,25.5,5.0]; // 10-24 screw + washer holding it together

	Weight = [11.0,80.0,11.5]; // stamped steel slug

	Cap = [26.0,Weight[OD],5.5]; // acrylic disk with handle hole

	BaseFloor = 10.0;
	BaseOD = 90.0; // printed anchor

	Spacing = 25.0; // Show view separation

	//———-
	// Model things

	module Housing() {

	tube(Screw[LENGTH],id=Screw[OD],od=BaseOD,anchor=BOTTOM) position(TOP) {
	tube(Weight[LENGTH],id=Screw[ID],od=Weight[ID],anchor=BOTTOM); // weight bushing
	tube(BaseFloor – Screw[LENGTH],id=Screw[ID],od=BaseOD,anchor=BOTTOM) position(TOP)
	tube(Cap[LENGTH] + Weight[LENGTH],id=Cap[OD],od=BaseOD,anchor=BOTTOM);
	}

	}


	//———-
	// Build things

	if (Layout == "Show") {
	Housing();
	color("Orange",0.7)
	up(BaseFloor + Spacing)
	tube(Weight[LENGTH],id=Weight[ID],od=Weight[OD],anchor=BOTTOM);
	color("Gray",0.8)
	up(BaseFloor + 2*Weight[LENGTH] + Spacing)
	tube(Cap[LENGTH],id=Cap[ID],od=Cap[OD],anchor=BOTTOM);
	}

	if (Layout == "Cuts") {
	left(BaseOD/2 + Gap)
	offset(r=-1.0)
	circle(d=BaseOD);
	right(Cap[OD]/2 + Gap)
	offset(r=0.2/2)
	projection()
	tube(1.0,id=Cap[ID],od=Cap[OD],anchor=BOTTOM);
	}

	if (Layout == "Build") {
	Housing();
	}

view raw HQ Sixteen Anchor.scad hosted with ❤ by GitHub

2026-10-01

HQ Sixteen: Improved Fabric Rod Bushings

Descending from the previous bearings / sleeves / bushings, I added a rib to hold them in place as the rod slides back and forth while fiddling with fabric:

HQ Sixteen - Rod Bushing - rib retainer - solid model - build view — HQ Sixteen – Rod Bushing – rib retainer – solid model – build view

An idealized serving suggestion:

HQ Sixteen - Rod Bushing - rib retainer - solid model - show view — HQ Sixteen – Rod Bushing – rib retainer – solid model – show view

Which might count as the “better design” I expected it would need.

They’re still almost invisible in use:

HQ Sixteen - Rod Bushing - rib retainer — HQ Sixteen – Rod Bushing – rib retainer

Which is as it should be: inconspicuous, no more black dust, and E-Z rotation.

The modified OpenSCAD source code is added to the original GitHub Gist:

	// Bushing for HQ Sixteen table rods
	// Ed Nisley – KE4ZNU
	// 2026-02-20
	// 2026-09-29 add retaining rib

	include <BOSL2/std.scad>

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

	/* [Hidden] */

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

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 832*4;

	$fn=NumSides;

	Rod = [25.0,28.7,100.0]; // very short rod

	Sleeve = [Rod[OD] + 0.3,31.2 – 0.2,9.0]; // LENGTH = overall
	Rim = [Sleeve[ID],Sleeve[OD] + 6.0,0.6];

	LockRing = [Sleeve[ID],Sleeve[OD] + 2*(1.0),4.0]; // locks sleeve on plate

	IdlerLength = 15.0; // far right end of rods

	NumSlots = 2*4;
	Kerf = 1.0;

	Gap = 5.0;

	module Bushing(oal,lk=false) {

	difference() {
	union() {
	tube(oal,id=Sleeve[ID],od=Sleeve[OD],anchor=BOTTOM);
	tube(Rim[LENGTH],id=Rim[ID],od=Rim[OD],anchor=BOTTOM);
	if (lk)
	up(oal)
	tube(LockRing[LENGTH],id=LockRing[ID],od=LockRing[OD],chamfer=LockRing[LENGTH]/3,anchor=TOP);
	}
	for (a=[0:NumSlots-1])
	zrot(a*360/NumSlots)
	up(oal/4 + Rim[LENGTH])
	right(Sleeve[ID]/2)
	cuboid([Sleeve[OD],Kerf,oal],anchor=BOTTOM);
	}

	}


	//—–
	// Build things

	if (Layout == "Show") {
	color("Gray",0.5)
	xcyl(Rod[LENGTH],d=Rod[OD]);
	right(Rod[LENGTH]/3)
	zrot(180) yrot(90)
	Bushing(Sleeve[LENGTH]);
	left(Rod[LENGTH]/3)
	yrot(90)
	Bushing(IdlerLength,lk=true);
	}

	if (Layout == "Build") {
	right(Rim[OD]/2 + Gap/2)
	Bushing(Sleeve[LENGTH]);
	left(Rim[OD]/2 + Gap/2)
	Bushing(IdlerLength,lk=true);


	}

view raw HQ Sixteen – Rod Bushing.scad hosted with ❤ by GitHub

	// Bearing sleeve for HQ Sixteen table rods
	// Ed Nisley – KE4ZNU
	// 2026-02-20

	include <BOSL2/std.scad>

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

	/* [Hidden] */

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

	HoleWindage = 0.2;
	Protrusion = 0.1;
	NumSides = 832*4;

	$fn=NumSides;

	Rod = [25.0,28.7,100.0]; // very short rod

	Sleeve = [Rod[OD] + 0.3,31.2 – 0.2,9.0]; // LENGTH = overall
	Rim = [Sleeve[ID],Sleeve[OD] + 6.0,0.6];

	IdlerLength = 15.0;

	NumSlots = 2*4;
	Kerf = 1.0;

	Gap = 5.0;

	module Bearing(oal) {

	difference() {
	union() {
	tube(oal,id=Sleeve[ID],od=Sleeve[OD],anchor=BOTTOM);
	tube(Rim[LENGTH],id=Rim[ID],od=Rim[OD],anchor=BOTTOM);
	}
	for (a=[0:NumSlots-1])
	zrot(a*360/NumSlots)
	up(oal/4 + Rim[LENGTH])
	right(Sleeve[ID]/2)
	cuboid([Sleeve[OD],Kerf,oal],anchor=BOTTOM);
	}

	}


	//—–
	// Build things

	if (Layout == "Show") {
	color("Gray",0.5)
	xcyl(Rod[LENGTH],d=Rod[OD]);
	right(Rod[LENGTH]/3)
	yrot(90)
	Bearing(Sleeve[LENGTH]);
	left(Rod[LENGTH]/3)
	yrot(90)
	Bearing(IdlerLength);
	}

	if (Layout == "Build") {
	right(Rim[OD]/2 + Gap/2)
	Bearing(Sleeve[LENGTH]);
	left(Rim[OD]/2 + Gap/2)
	Bearing(IdlerLength);


	}

view raw Rod Bearing Sleeve.scad hosted with ❤ by GitHub

2026-09-30

Knitted Spider: Eyemaxxing
A 3D printed spider with a knitted texture seemed a sufficient oxymoron to justify its existence:

Knitted Spider – black eyes

But all-black looked rather somber, even for an All Hallow’s Eve decoration, so I used PrusaSlicer’s Multi-Material Painting to print the eyes in retina-burn orange:

Knitted Spider – orange eyes – wipe tower

The chunky wipe tower shows the cost of switching filaments for a quartet of little eyes. The new Prusa INDX extruder design reduces that waste, but I’m not going there.

You can see the block of painted-on support under the palps, which worked better than overenthusiastic automatic support generation.

The consensus suggested the spider suffered from insufficient eye, so I upleveled it to maximum spider spec:

Knitted Spider – 8 eyes – on platform

Which looks like evolution in action:

Knitted Spider – iteration

The additional eyes came from a trivial OpenSCAD / BOSL2 sphere:
```
include <BOSL2/std.scad>
spheroid(d=5.0,style="icosa");
```
Which is both small and large enough to have a useful number of facets:

Knitted Spider – 5mm icosa sphere eye model

Those facets will come in handy for Multi-Material Painting.

Adding the sphere to the spider model turned out to be trickier than I imagined, because PrusaSlicer requires object to sit flat on the platform, but merging the sphere and spider models got it done:

Knitted Spider – merged models

Then you can use the Move tool to haul the sphere into place:

Knitted Spider – eye positioning

Use the Scale tool to reduce it to a suitable size.

With the eye in place, copy-n-paste creates a duplicate Merged sphere at the same coordinates, which you chivvy into its proper spot. Repeat as needed for more eyes!

The sphere facets are far below the 0.4 mm nozzle’s resolution, but they simplify painting the eye with “Smart Fill” angle settings:

Knitted Spider – 8 eyes – slicer material painting

I had initially thought to just drop separate spheres in place and assign them to the orange extruder, but the slicer (quite properly) treats them as separate objects and creates balls sitting in sockets.

Instead, the eyes must become part of the spider’s shape, have their exterior surfaces painted, then get sliced. In order to do that, I exported the 8-eyed spider as a new STL file and imported it back for painting & slicing:

Knitted Spider – 8 eyes – slicer model

The original single-color spider prints in an hour and adding any number of eyes doubles the time, so those MMU3 tool changes are expensive. Although the printer is reliable, the auto-retract spools I set up sometimes retract the filament beyond the feed gear inside the MMU3, which the firmware detects and calls for manual intervention. It’s best to be puttering in the basement while the printer buzzes away.
2026-09-23
Dog Paw Coaster
Start with a picture of a dog paw:

Dog Paw Coaster – starting picture

Rescale the paw to about 100 mm vertically to properly fit a normal-size glass / tumbler / mug. This may be considerably larger than life, but dog owners always want more dog, so it’ll work.

Generate an outline mask in GIMP:

Dog Paw Coaster – paw mask

Generate another mask for the pads & toenails:

Dog Paw Coaster – pad mask

Convert those into paths, save them as SVG files, and hand them to OpenSCAD:
```
include <BOSL2/std.scad>

/* [Hidden] */

PadThick = 1.2;
BaseThick = 2.0;

RimHeight = 0.4;
RimWidth = 0.8;
RimOffset = 1.0;

Clearance = 0.1;    // embiggen pad recesses

OutlineFN = "Dog Paw - Outline.svg";
PadFN = "Dog Paw - Pads.svg";

union() {


  linear_extrude(h=BaseThick)
    import(OutlineFN);

  color("Green")
    up(BaseThick)
      linear_extrude(h=PadThick)
        difference() {
          import(OutlineFN);
          offset(r=Clearance)
            import(PadFN);
        }

  
}
```
Which will get you a solid model like this:

Dog Paw Coaster – OpenSCAD model

Should you want decorative raised rims around the perimeter and pads:

Dog Paw Coaster – raised rim – OpenSCAD model

Then turn this on:
```
if (false)
  color("Red")
    up(BaseThick + PadThick)
      linear_extrude(h=RimHeight) {
        difference() {
          offset(r=RimOffset + RimWidth)
            import(PadFN);
          offset(r=RimWidth)
            import(PadFN);
        }
        difference() {
          offset(r=-RimOffset)
            import(OutlineFN);
          offset(r=-(RimOffset + RimWidth))
            import(OutlineFN);
        }
      }
```
Run the solid model through PrusaSlicer, send it to the MK4, and, while the printer is buzzing away, run the pads through an online nesting program to see how well that works:

Dog Paw Coaster – Pads nesting – LightBurn layout

While nesting didn’t save much material, it might come in handy for something more intricate and now I’ll be able to find it again.

Then get busy:
- Stick adhesive sheet to the chipboard
- Mirror the pads to cut adhesive side up
- Cut the pads, rescue a toenail from the chip tray
- Import the paw outline SVG
- Offset 0.75 mm inward
- Stick adhesive sheet on the cork
- Cut paw outline (adhesive up, but not mirrored!)
- Peel & stick
Which turned out pretty good:

Dog Paw Coaster – assembled

I used Concentric infill on the top to resemble the fur pattern, but it came out way too subtle.

The owner liked it, though, which made it all worthwhile.
2026-09-17
CUPS 2.4.19 vs. Printing
After a rather tedious morning devoted to figuring out why printing had suddenly stopped working, it seems there’s something badly wrong with the most recent CUPS update.

The symptoms included:
- Wrong sheet orientation for multi-page output regardless of the Landscape or Portrait setting
- No output at all, generally with a CUPS error message
The error messages were utterly inscrutable:
- “missing required flags”
- “cfFilterChain: pdftopdf (PID 8189) stopped with status 1”
- “temp file (object 3 0, offset 11462): dictionary has duplicated key /x12; last occurrence overrides earlier ones”
Downgrading two packages restored the status quo ante:
- libcupsfilters 2.2.1-2 → 2.1.1-4
- cups 2.4.19-1 → 2.4.16-2
Perhaps cups need not be reverted, but I’m loathe to fiddle around with it now that printing works again.

Those are now frozen in /etc/pacman.conf:
```
IgnorePkg = cups libcupsfilters
```
The least-awful way to downgrade / revert packages seems to be with manjaro-downgrade. You can, of course, do it on hard mode with pacman or pamac, but perusing a list of what’s in the update cache helped figure out what just changed.

And there they will sit until the next update rolls through.
2026-09-14
Huion H610Pro Tablet vs. Digimend vs. DKMS

A month or two ago the Huion H610Pro tablet’s buttons stopped working with the input-remapper macros I set up to do useful things. Considerable searching showed that the Digimend kernel driver project previously handling the buttons went inertial two years ago and, apparently, no longer worked with contemporary kernels. Further searching suggested old Huion tablets, which mine certainly is, should be handled by the native kernel / X drivers, so I uninstalled Digimend.

Which produced a persistent error message from the DKMS machinery telling me something awful was happening with the now-missing Digimend.

An Arch Linux BBS thread suggested manually removing various detritus left behind during successive kernel updates in places like /usr/lib/modules and /var/lib/dkms. Given that my desktop box runs the 6.18 kernel, I felt reasonably confident in removing the 5* kernel directories and anything mentioning digimend from those locations.

After the box started up the next morning, all the tablet buttons once again worked the way they use to.

The nice thing about Free Software is having access to all the pieces when something breaks …

2026-09-01
Smashed Glass Coasters: Chipboard Variation
The summer season brings iced drinks with condensation trickling down the mug and, alas, running off the smashed glass coasters:

Printed Coaster – Set C – oblique

The hard parts of making those coasters involved converting the glass fragment outlines into vectors and arranging them in interesting patterns. However, with those files already in hand, making a similar coaster with chipboard “fragments” was straightforward:

Chipboard Fragment Coaster – detail

Slightly modify the OpenSCAD code to suit thinner chipboard:
```
include <BOSL2/std.scad>

fn = "Printed Fragment Coaster - 5 in Set B - Inkscape paths.svg";

FragmentThick = 0.8;

BaseThick = 2.0;
RimHeight = 0.4;

union() {


  linear_extrude(h=BaseThick)
    import(fn,id="Perimeter");

  color("Green")
    up(BaseThick)
      linear_extrude(h=FragmentThick)
        difference() {
          import(fn,id="Perimeter");
          import(fn,id="Recesses");
        }

  color("Red")
    up(BaseThick + FragmentThick)
    linear_extrude(h=RimHeight)
      difference() {
        import(fn,id="LipOut");
        import(fn,id="LipIn");
        import(fn,id="Island");
      }

}
```
Run the solid model through PrusaSlicer:

Chipboard Fragment Coaster B – slicer preview

And have a baseplate an hour later:

Coaster Printing – in progress

While that’s buzzing away, tell LightBurn to cut chipboard instead of metallized paper, stick some craft adhesive sheet on the chipboard, and Fire The Laser:

Chipboard Fragment Coaster – chipboard cutting

Remember to mirror the fragments, because you’re cutting them bottom-up.

Do the same for the cork sheet going on the bottom, which does not require mirroring.

I tossed the cardboard alignment fixtures I used to stick the cork onto the 3D printed baseplate, so make another one for each coaster.

The top layer holds the baseplate:

Chipboard Fragment Coaster – cork fixture – top

The cork + adhesive sheet is inset 0.5 mm from the edge of the baseplate, so the outline cut in the bottom layer of cardboard is just that much smaller:

Chipboard Fragment Coaster – cork fixture – bottom

Although the time used to make a fixture isn’t deducted from your allotment, I’m not sure about making two identical fixtures, so I’m saving these for the next time.

Then peel-n-stick the chipboard fragments in their recesses:

Chipboard Fragment Coaster – variety

The first baseplate didn’t have raised rims around the fragments (because there’s no need to retain any epoxy), but the result looked kinda … flat:

Chipboard Fragment Coaster – flat top

Fixing that was a matter of not setting the rim height to zero in the OpenSCAD code.

It’s perfectly functional even without a rim:

Printed Coaster – chipboard inserts – sweaty mug

Protip: White chipboard is a Terrible Idea™ in a quick-n-easy laser cuttery project. All the rest have only red or blue fragments for a good reason.

Conversely, white PETG makes a nice contrast to the deep red and blue.

Prosit!
2026-08-28