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.
Mechanical widgetry
Mary counts birds for Project Feederwatch and the feeder goes up at Halloween, whereupon birds begin smashing against the windows. Having bought a lifetime supply of paracord for this purpose on our previous house, I made a DIY Birdsaver for the rear windows:
This project was tremendously simplified by discovering the soffits consist of molded PVC sheets having exactly the proper 4 inch spacing and a convenient lip perfectly suited to capture the knot:
So far, no thuds …
A knife found in Mary’s Bucket o’ Gardening Gear was in need of a sheath:
Unlike the time before or the time before that, a few minutes with LightBurn laid out the overall pattern:
The knife’s silhouette came from a few minutes with GIMP, because cleaning up the edges on a graphics tablet is easier than fiddling with precise spline curves. Export the selection as an SVG, import into LightBurn, set to Fill, and Fire The Laser:
The upper block in the LightBurn layout is an oversized rectangle so I could cut that out first, stick craft adhesive on both sides, trim the edges, drop it back into the hole, then cut the middle part of the sheath.
It’s made of recycled through-dyed chipboard and it won’t last forever, but that’s not a problem because these things tend to wander off before they disintegrate.
I must do a few more for the other garden bucket, but those should be straightforward.
Part of the Autumn festivities around here involves blowing leaves into piles, then shredding them into garden mulch. Given that I have a plug-in electric leaf blower / wind stick, I use this as an excuse to exercise the emergency generator (similar to that one) with a (relatively) short extension cord.
As with all small gasoline engines, I fire a shot of starting fluid into the air cleaner to reduce the number of engine-start yanks, which means I must remove the generator’s side panel and unscrew the filter cover. For years I have sworn mighty oaths on the bones of my ancestors to knobify that screw, thus eliminating fiddling with a screwdriver.
Finally:
A dozen minutes of printing and a snippet of good double-sided tape later:
The knob sticks out far enough to push into the foam “sound deadening” liner on the cover, so it won’t vibrate loose.
The OpenSCAD source code:
include <BOSL2/std.scad>
/* [Hidden] */
HoleWindage = 0.2;
Protrusion = 0.1;
// Screw head dome
HeadHeight = 2.0;
HeadOD = 14.75;
DomeRadius = (HeadHeight^2 + (HeadOD^2)/4) / (2*HeadHeight);
echo(DomeRadius=DomeRadius);
KnobOD = HeadOD;
KnobLength = 15.0;
RimFudge = 0.3; // ensures a printable edge
// Build it
difference() {
cyl(h=KnobLength, r=KnobOD/2,anchor=BOTTOM,texture="trunc_pyramids",tex_size=[2.0,KnobLength/4]);
# up(KnobLength - HeadHeight + RimFudge)
spheroid(r=DomeRadius,circum=true,style="icosa",anchor=BOTTOM);
}
The cover has robust plastic latches, so I haven’t ever bothered to tighten those screws.
The common fate of all “soft touch” silicone handles is to become sticky and gooey. While some goo may be removable, I’ve found that wrapping self-bonding silicone tape around the mess both encapsulates it and maintains the grippiness of the original silicone.
The most recent casualty is the decade-old ceramic crysknife I returned to service while the rest of the knives were being sharpened:
While I was at it, I added griptivity to the leaf blower handle:
Long years ago, before getting transparent silicone tape, I’d wrapped a kitchen slotted spoon:
Stipulated: Butt-ugly and built to stay that way.
Oddly, the handle on the matching spatula / scraper remains non-gooey to this day.
Should you care more about form than function, this repair is not the one you seek …
Because nobody will ever see the Radiator Sleds, I started a batch with the tail end of the white PETG spool and set up the Spool Join function to switch to the retina-burn orange PETG when the white filament ran out.
The two colors combined nicely on that layer:
Unfortunately, the Spool Join didn’t work out quite right and I had to extricate the white filament from the MMU3, then coerce the orange filament into position.
The key section of the MMU3 looks like this:
The Selector assembly rides on the smooth rods, driven by the stepper motor on the far end of the leadscrew. It stops at one of the five filament tubes (visible to the left of the upper smooth rod, with filament tips showing), whereupon a drive gear pushes the filament into the Selector, under the FINDA sensor (the threaded fitting sticking out of the top), into the PTFE tube, down to the Nextruder, through the idler to trip the Filament Sensor, then into the extruder’s planetary drive gear.
I think this happened:
Fortunately, I was watching the whole operation and could intervene.
The MMU3 works well when the filament behaves properly, but it’s very sensitive to bends in the filament and misshapen ends. In this case, the white filament had the usual tight curve due to being would around the spool hub, which was enough to mis-align its end with the MMU3 tube while backing out.
Trust, but verify.
Mary’s zero-mph crash loosened the starboard handlebar plug enough to let it eventually decamp for parts unknown. Its replacement, a somewhat fancier aluminum plug with an expanding cone retainer using an actual M3 nut, worked fine for the last year, but Mary recently noticed the socket head screw had worked loose.
In the interim, I’d moved the Bafang thumb control from its original position on the crossbar to just above the rear shifter:
Which moved the clamp on the shortened grip off the end of the handlebar tube, so I flipped the grip around, tightened the clamp, and installed the plug.
Unfortunately, the grip ID is 4 mm larger than the tube ID, which meant the plug’s cone retainer was struggling to hold on in there. Perhaps the plastic cone has relaxed bit, but I figured giving it more traction would be a Good Idea™ before I declared victory:
It’s a little plastic sleeve with slots to let it expand against the inside of the grip:
Yes, it’s sticking out slightly; you can see the corresponding gap up inside next to the tube.
A wrap of double-sided sticky tape glues it in place as the retainer presses it against the grip ID and a dot of low-strength Loctite should keep the screw from loosening again.
The OpenSCAD source code:
// Handlebar grip sleeve
// Ed Nisley - KE4ZNU
// 2025-10-25
include <BOSL2/std.scad>
/* [Hidden] */
ID = 0;
OD = 1;
LENGTH = 2;
HoleWindage = 0.2;
Protrusion = 0.1;
NumSides = 3*2*4;
$fn=NumSides;
Sleeve = [18.5,22.0,14.0];
Kerf = 1.0;
difference() {
tube(Sleeve[LENGTH],id=Sleeve[ID],od=Sleeve[OD],anchor=BOTTOM);
for (a=[0,90])
zrot(a)
up(Sleeve[LENGTH]/4)
cuboid([2*Sleeve[OD],Kerf,Sleeve[LENGTH]],anchor=BOTTOM);
}
That was easy …
This being the season of monsters, I rebuilt and deployed a few from last year:
Real spiders have better camouflage, but cardboard works pretty well:
I must move them to the driveway on Friday:
This one stands out in any situation:
Tiny T-Rexes are just cute:
They need support, because their heavy head bends the spine just above the hips, so they’re snuggled up against pillar lamps or each other:
The cardboard Mantis turned out entirely too fragile:
Reassembling the poor thing with a blob of hot-melt glue on each joint held it together.
If I used something other than corrugated cardboard, they’d likely survive longer out there.
A handful of RGBW tea lights provide just enough illumination to make them visible.
The Smell of Molten Projects in the Morning 