Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
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.
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:
Prusa MK4 MMU filament joining
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 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:
The rear end of the white filament passed through the FINDA sensor
The MK4 reversed the Nextruder to drive the filament back into the MMU3
The rear end of the filament didn’t reenter its filament tube and escaped out to the side
The MMU3 drive gear couldn’t pull the filament backward, because the back end was misplaced
The Extruder planetary drive gear couldn’t pull the filament forward, because the front end was now above the gear
Both the FINDA and the Filament Sensor showed the filament was present, so the MK4 knew something was wrong
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.
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:
Tour Easy – right handlebar control stack
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:
Handlebar Grip Sleeve – PrusaSlicer
It’s a little plastic sleeve with slots to let it expand against the inside of the grip:
Handlebar grip sleeve – installed
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);
}
The next morning found it huddled against the cold:
Mantis – chilled
It had reached operating temperature and gone about its business a few hours later.
I deployed a cardboard Mantis in its honor as a seasonally appropriate yard decoration, but mine didn’t survive the night nearly as well as the real one:
Protip: Wear gloves, because you’re working in front of an unprotected and eventually very sharp blade.
The blade-holding clamp snaps magnetically into a rotating chuck so you can flip the knife over, at least if it’s not quite as long as that one. The chuck index has a spring-loaded release button:
Work Sharp Knife Sharpener – rear view
The spring is powerful and the button arrived with a recess around the screw holding the chuck together:
Work Sharp Knife Sharpener clamp button – as received
Pressing the button hard enough to release the chuck hurt my index finger, but their Tech Support said it’s like that and that’s the way it is. Turning the screw adjusts the spring compression, but I think this situation calls for “more secure” rather than “easy to push”.
Fortunately, I have a laser cutter and know how to use it:
Work Sharp Knife Sharpener clamp button – filled
Despite appearances, it’s a 10 mm disk of 4.3 mm clear acrylic stuck to the screw head with a snippet of white double-sided tape and flush with the surrounding plastic surface.
A smooth button makes my index finger much happier …
The Fiskars PowerGear lopper Mary uses in the garden had occasionally encountered a tomato cage wire and the blade had a few dents. We recently had a bunch of knives / blades / tools sharpened by somebody who knows what he’s doing and, while the lopper blade is now deadly sharp, grinding the dents out changed its shape enough that it no longer met the opposing plastic (probably glass-filled nylon) anvil.
For lack of anything smarter, I cleaned the anvil, spread a layer of hot-melt glue over the surface, squished it flat with a snippet of PTFE fabric, and closed the jaws:
Fiskars lopper jaw repair – silicone cloth indent
Which left a blobular layer on both sides of the now perfectly matched blade channel:
Fiskars lopper jaw repair – blade indent
Trimming off the blobs made it slightly more presentable:
Fiskars lopper jaw repair – trimmed edges
The textured surface definitely looks great, even if the rest looks like the hack job it is.
I’m hoping the glue layer has enough traction on the anvil to survive the duty it gets in the garden, where Mary uses it to harvest cabbages & suchlike. I’m sure the occasional cage wire will test its resolve, but we’ll know more next summer.
The Smell of Molten Projects in the Morning 