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

OMTech Laser Cutter: Custom Air Fitting Wrench

Changing the lens on the laser requires unscrewing the nozzle after removing the assist air fitting that collides with the focus pen holder:

Laser head – assist air vs focus pen

All the 12 mm open-end wrenches in my Drawer o’ Spare Wrenches being much too large, I finally got around to making a custom wrench:

Air fitting wrenches

The plywood wrench came from a traced scan of a similar wrench, then adjusting the jaw opening to 12 mm. It served to verify the overall shape & size, then became a template for the real wrench atop a scrap of 1/8 inch aluminum sheet with flaking paint.

Some bandsawing and filing later:

Air fitting wrench – at nozzle

A little wrench makes swapping the lens somewhat less tedious, which is a Good Thing™.

Protip: Remember to adjust the Focus Distance by the difference between the two lenses.

2026-01-30
Plywood Coaster Warpage

This is what happens to an uncoated plywood coaster with fairly deep laser engraving after about half a year of use:

Warped plywood coaster – front

The poor thing went all potato chip:

Warped plywood coaster – side

I swapped it for one with polyurethane sealant, much like those fancier coasters with the same layout, and we’ll see if it survives longer …

2026-01-27
Snow Day

Today looks like a good day to fire up the snowblower and clear the driveway:

Snow – 2025-01-26

One of the bolts holding the muffler on the engine worked its way past its rebuilt locking plate and will require attention before getting out there.

Fortunately, it looks like a good day for shop projects …

2026-01-26
Silica Gel Beads: Indicator vs. Water

Just to see what happened, I dumped a few of those beads:

Silica gel beads – 36pctRH ambient

Into a few drops of water in a bottle cap:

Indicating silica gel beads – saturated

After a few days, it was obvious only the larger beads changed color and, no matter what the description said, they were not going to become any color I would recognize as green.

While the larger ones did get darker, the smaller ones must have already been at their limit of adsorption and remained at the same shade.

For humidity levels under about 20%, I think changing the desiccant every month or so is the only way to be sure.

2026-01-23
Ortur YRC-1 Chuck: Tube Reinforcement

Tuck a neatly laser-cut disk into a flimsy cardboard tube:

Ortur YRC-1 – cardboard tube reinforcement

Put a big conical center in the tailstock:

Ortur Chuck Rotary conical center – front

Whereupon the tube remains nicely tubular on both ends and aligned along the chuck axis:

Ortur YRC-1 – chucked cardboard tube

Which is why you save all that scrap material …

Yes, it’s the core from a toilet paper roll, which is way cheaper than burning through tumblers / mugs / shot glasses / whatever while figuring this stuff out.

2026-01-22
Prusa MK4 Nozzle Tool Mod

Contemplating a 0.8 mm nozzle to print more-transparent things, I ran off an Official MK4 Nozzle Replacement Tool to stabilize the heater block while applying a wrench to the nozzle:

Prusa MK4 Nextruder Tool – without inlet scoop

For obvious reasons, it doesn’t fit with the inlet scoop I installed as part of blinging the MK4:

Prusa MK4 Nextruder Tool – inlet scoop installed

Removing the scoop is a matter of removing those two cap screws, which is no big deal, but a little flush-cutter action made that problem Go Away forever:

Prusa MK4 Nextruder Tool – inlet scoop mod

Yeah, I should have modified the solid model. Maybe next time.

A version of the tool fits extruders covered with an Official Prusa Silicone Sock thermal insulator, but they were out of stock when I was in the mood. My heater wears a knockoff sock:

Prusa MK4 Nextruder Tool – silicone sock vs nozzle

Unlike the Official Sock, there’s no way to get a wrench on the nozzle with that one installed, but removing the sock is no big deal.

I apparently installed the nozzle / heater block slightly higher than specified, so the tool didn’t quite fit. Loosening those two thumbscrews and lowering the nozzle to fit the tool solved that problem. Fortunately, the automatic bed leveling routine corrects for nozzle height differences on the fly.

The scoop is back on the fan, the sock once again surrounds the heater, and I can easily swap in the 0.8 mm nozzle when the time comes.

2026-01-21
Olive Oil Bottle Cap Covers
We buy olive oil in large bottles, then fill smaller bottles for easier handling. The caps on those bottles were never meant to last as long as we keep them and the thin, deeply drawn aluminum tends to crack after a while.

So I conjured a cap cover from the vasty digital deep:

Olive Oil Cap – solid model

Which looks exactly like you’d expect when printed in black PETG:

Olive oil bottle cap – details

You can see the raggedy edge of the original cap just inside the cover’s rim. A snippet of double-sided tape holds the cover in place, after de-oiling the cap with alcohol.

Having gotten one to fit, I made enough for All The Bottles:

Olive oil bottle cap – installed

Only two of those see regular service: one in use and another filled when the first is nearly empty. The remaining pair huddle in the back of the shelf against future need.

The OpenSCAD source code produces those fancy knurls with BOSL2’s textured cyl() :
```
// Shower soap dish
// Ed Nisley - KE4ZNU
// 2026-01-17

include <BOSL2/std.scad>

/* [Hidden] */

HoleWindage = 0.2;
Protrusion = 0.1;
NumSides = 5*3*4;

$fn=NumSides;

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

WallThick = 1.0;
BaseThick = 2.0;

CapOD = 36.0;

CoverOA = [CapOD,CapOD + 2*WallThick,20.0 + BaseThick];

//----------
// Build it

  render()
    difference() {
      cyl(BaseThick,d=CoverOA[OD],chamfer1=1.0,anchor=BOTTOM) position(TOP)
        cyl(CoverOA[LENGTH] - BaseThick,d=CoverOA[OD],
            texture="trunc_pyramids",tex_size=[2,6], style="convex",
            anchor=BOTTOM);
      up(BaseThick)
        cyl(CoverOA[LENGTH],d=CoverOA[ID],anchor=BOTTOM);
    }
```
2026-01-20