Category: Machine Shop

Mechanical widgetry

Layered Paper: Random Blocks

I wanted to see / feel what 18 paper layers would look & feel like:

Random Blocks – framed

That’s a black mask layer atop 16 cut layers of cheerful colored paper in rainbow order and a solid purple sheet at the bottom:

Random Blocks – framed detail

The layer runs at 100 mm/s with 20% of a 60 W laser. The relatively low speed, combined with right-angle corners, produces very crisp results unlike the rounded-corner Subpixel holes.

The holes form a 16×16 grid and cutting the first few layers with 250-ish holes takes a bit under three minutes apiece:

Random Blocks – cutting red layer

The sheets sit in the Letter sheet fixture and get four round holes in the corners for the assembly fixture, plus a binary sheet ID helping me with the stacking order:

Random Blocks – assembly process

The hole patterns come from Inkscape through LightBurn, in a grindingly intricate manual process crying out for automation. This is a feasibility study to see if the result is worthwhile and, yeah, it looks promising. More about all that later.

If someone had asked Young Me what I’d be doing in half a century, dabbing colored paper with a glue stick would not have been one of my choices and not just because glue sticks hadn’t been invented back then.

Another couple of years and I’ll be ready for the Activity Room at the Olde Folkes Home.

2025-07-21
CNC-3018XL: Reversing the Axes
The CNC-3018XL fit into its new home with the Run/Hold buttons toward the front:

3018CNC – new orientation

Which is rotated 180° from its previous orientation, putting Quadrant I and the most-positive coordinates in the left-front corner. Rather than stand on my head while trying to use the jog keypad upside-down, I reversed the axis directions by changing the GRBL Direction port invert mask value from its previous 4:

$3=7

Because the home switch positions haven’t changed, reverse the Homing dir invert mask from 0:

$23=3

The XY origin remains in the center of the platform, so the G54 XY offset didn’t change. The Z offset puts the Pilot pen tip 10 mm above the platform, which will change as you (well, I) touch it off on the paper:

G10 L2 P1 X-169.0 Y-149.5 Z-44.0

Jog to the left rear corner (with Z at the home position) and set the G28 park position:

G28.1

Jog to the right front corner (also Z homed) where (manual) tool changes take place:

G30.1

Configure bCNC for manual tool changes without probing at the G30 position:

bCNC probe config

The machine will move to the tool change position at each Tn M6, the operator (that would be me) inserts ~~tool~~ pen n as needed, pokes the Run button, and watches it draw pretty pictures in a resolutely techie manner:

3018CNC – Spirograph test pattern

For completeness, the current GRBL settings:
```
$$
$0=10
$1=100
$2=0
$3=7
$4=0
$5=0
$6=0
$10=1
$11=0.010
$12=0.020
$13=0
$20=1
$21=0
$22=1
$23=3
$24=100.000
$25=2000.000
$26=25
$27=1.250
$30=1000
$31=0
$32=0
$100=401.284
$101=400.000
$102=400.000
$110=3000.000
$111=3000.000
$112=3000.000
$120=1000.000
$121=1000.000
$122=1000.000
$130=338.000
$131=299.000
$132=44.000
$#
[G54:-169.000,-149.500,-34.450]
[G55:0.000,0.000,0.000]
[G56:0.000,0.000,0.000]
[G57:0.000,0.000,0.000]
[G58:0.000,0.000,0.000]
[G59:0.000,0.000,0.000]
[G28:-335.000,-3.310,-3.450]
[G30:-1.000,-297.000,-1.000]
[G92:0.000,0.000,0.000]
[TLO:0.000]
[PRB:0.000,0.000,0.000:0]
```
The weird $100 X axis step/mm value is correct, because QC escapes are a thing.
2025-07-18
Kenmore 158 Sewing Machine: COB LEDs Redux

Having harvested the COB LED lighting from the Kenmore 158 Mary gave to a friend, I took advantage of a sewing pause to install the hardware on the 158 she now uses:

Kenmore 158 – needle light detail

That’s the sandblasted presser foot atop the original glare-y metal plates.

For the record, this is inside the machine’s power connector:

Kenmore 158 – power connector wiring

Power for the original glowworm incandescent light comes from the two rightmost terminals: 120 VAC switched by the machine’s power button. Those terminals now go to a new, much more flexy, cable for the 12 VDC power supply, with a step-up supply for the needle LEDs.

An overview of the wire routing:

Kenmore 158 – COB LED wire routing

There’s now a 9-pin JST SM connector between the repurposed serial cable and the LEDs, mostly so I can add another light bar to the front in the unlikely event it becomes necessary.

The rear light bar wire once again burrows into the machine above the presser foot lever:

Kenmore 158 – COB LED bar wire routing

All the LED wiring fans out through the endcap:

Kenmore 158 – COB LED needle heatsink

You can just barely see the edge of the strip of LEDs epoxied to the bottom of the machine nose, on the right of the needle.

If I were inclined to rebuild the needle LEDs, I’d use flexy silicone wiring instead of the Teflon insulated coax. The black insulation wouldn’t be nearly as pretty, but it’d be *way* easier to cut to length and solder.

The patient survived the operation and sewing should resume shortly …

2025-07-17
CNC-3018XL: Foam Feet

The 3018XL plotter now lives on a different bench than it grew up on and the stepper motors resonate the plywood benchtop wonderfully well. After finding the machine weighs enough to flatten small foam blocks under the Official Feet, I cut out four 60×80 mm foot pad brackets:

3018XL – foam foot pad bracket

They’re attached to the 2040 frame extrusions with M4 screws into tee nuts; the third hole is there just in case it became necessary. I’m not sure whether MDF will bend under that offset load, but having all four brackets perfectly fit into two pieces of MDF left over from previous projects was a compelling justification.

Some utility knife work produced the foam pads from a big sheet of polyethylene packing material:

3018XL – foam foot pad – installed

A piece of double-sided duct tape with amazingly gooey adhesive joins foam and bracket.

If the resonance was annoying to my deflicted hearing, it must have been pretty bad. Now, even Mary thinks it sounds OK.

Now, to discover whether the machine’s weight squashes those big foam blocks.

2025-07-15
Snowflake Coaster: One Year Later

After more-or-less constant use under a cup in the bathroom, a Snowflake Coaster has reached the end of its life:

Snowflake coaster – 1 yr use

The acrylic flake is fine, but the wood has mildewed:

Snowflake coaster – 1 yr use – detail

It’s second from the left in the bottom row:

Snowflake Coaster – assortment

All except the pair in the left column had a coat or two of rattlecan clear, which suggests wood-ish coasters need something much more durable, along the lines of clearcoat epoxy. No surprise there!

2025-07-14
Dutchess Rail Trail: Brush Trimming & Pruner Repair
The bushes & trees along the Dutchess Rail Trail were reaching out to touch us again, so I took some slow rides with many stops.

~~Maple~~ Oak trees along Page Park Drive:

DCRT Brush Trimming – oak – 2025-07

Blackthorn encroaching through the fence at Overocker:

DCRT Brush Trimming – blackthorn – 2025-07

A tree somebody tossed down the trail bank near Morgan Lake:

DCRT Brush Trimming – discarded tree – 2025-07

The slide lock on my trusty rehabilitated Fiskars bypass pruner worked loose and began sliding into the LOCK position when held overhead, then fell apart during disassembly:

Fiskars pruner – lock rebuild

The lock now consists of:
- An M4 × 12 mm nut from a Chicago Screw that exactly matched the 5 mm OD cylinder passing through the pruner body
- A laser-cut fluorescent acrylic disk for thumb grippiness
- A washer just because
- An M4 hex-head screw
- A dab of Loctite bonding screw to nut
Clean the blades with alcohol and it’s ready for the rest of the season.

I should have put a wave washer in the stack for some springiness, but it works surprisingly well for what it is.

Now: discover how long acrylic lasts out there in the wild.

Update: Yeah, the lock needed a wave washer for more friction, which became apparent after the first overhead branch.
2025-07-10

CNC-3018XL Setup: Table Riser Blocks

After fixing the X axis drive, the CNC-3018XL table moved properly again, so I measured its overall alignment:

3018CNC - table height measurement — 3018CNC – table height measurement

The +Y side (on the left in the photo, keeping in mind I’ve rotated the axes) turned out to be 0.7 mm too low, so I made a set of riser blocks to level the tabletop:

Table Riser - solid model — Table Riser – solid model

The 10 mm height would ram the tip of a Pilot pen about 10 mm below the tabletop surface, were it not for the spring-loaded pen holder:

Pilot V5RT holder - installed — Pilot V5RT holder – installed

The 0.7 mm difference in height levels the tabletop:

CNC3018XL - table riser positions — CNC3018XL – table riser positions

The OpenSCAD code produces an SVG outline I intended to use for a foam pad, but then I found a quartet of springs that worked even better:

CNC3018XL - table spring mount — CNC3018XL – table spring mount

So it’s now aligned within ±0.3-ish mm across the surface, with the unflatness of a slab cut from a 1955-era Formica kitchen countertop accounting for most of the difference in a swale from Quadrant III across the origin to Quadrant I.

Which a check plot using an old file shows will be Flat Enough for my simple needs:

CNC3018XL - test plot — CNC3018XL – test plot

Having the camera alignment remain exactly spot on came as a pleasant surprise:

The faded cross to the left came from the table’s previous position; there’s no positive index between the countertop slab and the underlying T-slots.

Part of the motivation for these blocks was to verify PrusaSlicer automagically handles filament / color changes between two objects, as long as OpenSCAD hasn’t unioned them as part of a common transformation. Not having to cut out the socket around the text simplifies the code from what I’d been doing with previous objects.

The OpenSCAD source code as a GitHub Gist:

	// CNC 3018 table riser blocks
	// Ed Nisley – KE4ZNU
	// 2025-06-29

	include <BOSL2/std.scad>

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

	/* [Hidden] */

	HoleWindage = 0.2;
	Protrusion = 0.1;

	BlockOA = [40.0,30.0,10.0]; // riser block size

	SlotBlock = [8.0,BlockOA.y,3.0]; // alignment in slot

	BoltOD = 6.0 + HoleWindage; // central bolt

	LogoFont = "Fira Sans Condensed:style=SemiBold";
	LogoSize = 7.5;
	LogoColor = "Red";
	LogoThick = 0.4;

	//———-
	// Define Shapes

	module Riser(thick=1,matl="Block") {

	LogoText = format_fixed(thick,1);

	if (matl == "Text" \|\| matl == "All")
	right(BlockOA.x/4) zrot(90)
	color(LogoColor)
	up(thick + SlotBlock.z + ((matl == "All") ? 0.01 : 0))
	text3d(LogoText,LogoThick + ((matl == "All") ? 0.01 : 0),LogoSize,LogoFont,
	anchor=TOP,atype="ycenter");

	if (matl == "Block" \|\| matl == "All")
	difference() {
	cuboid(SlotBlock,$fn=8*3,anchor=BOTTOM,rounding=2.0,except=[BOTTOM,TOP]) position(TOP)
	cuboid(BlockOA,$fn=8*3,anchor=BOTTOM,rounding=2.0,except=[BOTTOM,TOP]);
	down(Protrusion)
	zrot(180/6)
	cyl(2*BlockOA.z,d=BoltOD,$fn=6,anchor=BOTTOM,circum=true);
	}

	}




	//———-
	// Build things

	if (Layout == "Show")
	down(SlotBlock.z)
	Riser(BlockOA.z,matl="All");

	if (Layout == "Outlines") {
	projection(cut=false)
	Riser(BlockOA.z,matl="Block");
	}

	if (Layout == "Build") {
	up(BlockOA.z + SlotBlock.z) xrot(180)
	Riser(BlockOA.z,matl="Block");
	up(BlockOA.z + SlotBlock.z) xrot(180)
	Riser(BlockOA.z,matl="Text");

	}

view raw 3018XL Table Risers.scad hosted with ❤ by GitHub

2025-07-09

Category: Machine Shop

Layered Paper: Random Blocks

CNC-3018XL: Reversing the Axes

Kenmore 158 Sewing Machine: COB LEDs Redux

CNC-3018XL: Foam Feet

Snowflake Coaster: One Year Later

Dutchess Rail Trail: Brush Trimming & Pruner Repair

CNC-3018XL Setup: Table Riser Blocks