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: Machine Shop

Mechanical widgetry

Handlebar Grip Sleeve
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);
  }
```
That was easy …
2025-10-31
Monster Restocking

This being the season of monsters, I rebuilt and deployed a few from last year:

Alligator – installed

Real spiders have better camouflage, but cardboard works pretty well:

Spider 1 – camouflaged

I must move them to the driveway on Friday:

Spider 2 – camouflaged

This one stands out in any situation:

Green spider

Tiny T-Rexes are just cute:

Tiny T-Rex with pillar lamp

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:

Mantis and Tiny T-Rexes

The cardboard Mantis turned out entirely too fragile:

Mantis – dismantled

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.

2025-10-30
Mantis Durability

A Praying Mantis appeared on the house wall:

Mantis – alert

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:

Mantis – dismantled

I doubt a predator was involved …

A site search will reveal previous encounters with their kind.

2025-10-29
Work Sharp Precision Adjust Sharpener: Button Improvement

A recent professional knife / lopper sharpening convinced me to up my sharpening game, so I figured a Work Sharp Elite sharpener would improve our backup blades:

Work Sharp Knife Sharpener – overview

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 …

2025-10-24
Fiskars Lopper Jaw Repair

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.

2025-10-23
3D Printed Smashed Glass Coasters: Being Epoxy-Tight

Each of the glass fragments in a 3D printed coaster sits atop a metallized paper reflector in its own recess and gets covered with epoxy:

Printed Coasters – epoxy fill

That’s an early printed coaster with the epoxy pool covering the entire surface. Putting a rim around each fragment to form separate pools works better.

Assuming I do a tidy job of filling the recesses, this process worked exactly as you’d expect until I printed a coaster with blue PETG-CF filament:

Printed Coaster – Set C – oblique

Other than a slightly ragged cork layer motivating me to make the cork slightly smaller and use a fixture to align it properly, the coaster looks reasonably good. However, a close inspection shows all the epoxy pools are slightly recessed below their rims.

It turns out printing PETG-CF with an extrusion multiplier of 0.8, which I figured based on fitting threaded parts together, doesn’t fuse the threads into an epoxy-tight surface:

Printed Coasters – PETG-CF leakage – footprint

Fortunately, I’d been working on a silicone mat that could take a joke. I managed to move the coaster to a plastic sheet and refill the drained pools, although they continued to drain while curing.

After the epoxy cured to a rubbery texture, I scraped off the meniscus around the perimeter of the coaster, but the bottom shows it cured in a pool of its own making:

Printed Coasters – PETG-CF leakage

The cork conceals the evidence and the result looks good enough for my simple needs:

Smashed Glass 3D Printed Coaster – Set C – in use

Memo to self: Use the correct filament preset for the job!

2025-10-22
3D Printed Smashed Glass Coasters: Cork Alignment Fixture

The printed coaster frame sits on a cork base:

Printed Coaster – inset cork

A sheet of craft adhesive holds them together; stick a generous rectangle of adhesive on the cork, then cut them at the same time. However, given the irregular perimeter, it’s basically impossible (for me, anyway) to align the cork + adhesive with the printed frame.

A single-use fixture made from corrugated cardboard make that task trivially easy:

Printed Coaster – cork alignment fixture – detail

The LightBurn layout shows the cork layer and the two fixture pieces:

The cork shape is offset 0.5 mm inward from the Perimeter shape, but I found offsetting the cardboard cut by only 0.3 mm inward produced a snug fit around the cork. The other piece of cardboard gets cut with the exact Perimeter shape and no offset, with the laser kerf providing just enough clearance for a very snug fit on the printed shape.

Align the two pieces of cardboard by eye to match their inner shapes as shown in the picture, tape them together, and the fixture is ready. In principle, the outer edges should exactly coincide: Trust, but verify.

Peel off the craft adhesive paper and put the cork in the bottom of the fixture. The cork comes off a roll and really wants to roll up again, making the masking tape holding it flat mandatory:

Printed Coasters – cork alignment template

Yes, that’s a different coaster.

Flip the fixture over, drop the coaster in place, press firmly together, peel the tape, and pull out the finished coaster:

Printed Coasters – white PETG finished

The fixture goes in the recycling bin, as those fragments will never pass this way again.

2025-10-21