Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
A long-lost repair finally made it to the top of the list:
Bicycle Mobile – bottom view
The original string had long since rotted out, but everything else was in a plastic bag just waiting for this occasion.
The colorful cylinders are stacks of laser-cut 6 mm disks with a 2 mm hole, held to the wire & string with a tiny dot of high-viscosity cyanoacrylate glue at each end:
Bicycle Mobile – detail
The disks came from acrylic leftovers:
Bicycle Mobile – laser-cut acrylic
The motion you can’t see makes the shiny bikes much more visible out there:
The weight ball had a 2 mm hole filled by a wood plug which I cleaned out piecemeal with a 1.5 mm drill bit in a pin vise; a short length of wood skewer holds the new string in place.
Because the upper arms support more weight, their disk stacks need fewer disks for the same leverage. The original mobile had (at most) four 6 mm chromed plastic balls at each level, so I started with eight 3 mm disks, adjusted the stack length as needed, glued them in place, then removed the surplus disks by crushing them with a Vise-Grip.
A small sewing notions cabinet, once my mother’s, now holds some of Mary’s supplies and, a few days ago, had one of its drawer pulls fall off. While preemptively tightening all the screws, I found one no longer held onto its pull:
Notions drawer pull – parts
They don’t make drawer pulls like that any more!
As I see things, it can be forgiven for losing its grip after nearly a century.
Thread the screw in as far as it will go and lay the pull flat on the bench vise anvil:
Notions drawer pull – hammering setup
A few gentle whacks with a pin punch on top and bottom, plus a tap on each side, compressed the pull’s remaining threads around & into the screw:
Notions drawer pull – reshaped
Put it back in its drawer, snug the screw, and it’s all good.
That should suffice for at least the remainder of its first century …
The next step involves creating a corresponding set of LightBurn layouts to burn those holes out of colored paper sheets to produce layered paper art:
Random Blocks – framed
I know it’s art, because that’s what I was thinking when I made it.
Setting up the LightBurn layouts requires enough manual effort to make the whole thing impractical except as a testcase to see how it all worked out. An overview of the LightBurn workspace:
Random Blocks – 16×16 – LightBurn layout overview
The little bitty grid in the upper left quadrant represents the 700×500 platform of my laser and each of the blue squares is 159 mm on a side. I tend to not delete the intermediate steps, because they serve as some sort of documentation the next time I wonder how I did that thing.
So, we begin.
Import the Inkscape SVG file:
Random Blocks – 16×16 – LightBurn SVG import
The blue outer square and the blue text identifying it are on LightBurn’s T2 tool layer, with the black squares on the C00 layer. All of that happens automagically, because I used colors from the LightBurn palette in Inkscape.
The lonely square in the upper right is the template from which the other 256 squares were cloned, but it has no further purpose in life.
The 16×16 grid consists of sixteen overlaid groups, which need sorting out for ease of access, so drag each one off into a more useful arrangement:
Random Blocks – 16×16 – LightBurn sheet separation
Note that each of the 256 possible positions has a square in only one of those groups.
Each of the 16 groups corresponds to a sheet of paper, with the squares indicating holes exposing the sheet below it. The color of each square, as seen from the top of the stack, comes from the first sheet in the stack without a hole. Perforce, every sheet above the one without a hole must have a hole, which means you must merge all those sheets.
Line up (duplicates of) those 16 groups in the vertical line forming the left column in this arrangement:
Random Blocks – 16×16 – LightBurn array duplication
The top group is the layer I named H000 in Inkscape, with the others in order down to H337 on the bottom. You can see why labeling them is pretty much required.
I should have equalized the vertical spaces between the groups in the left column, but it doesn’t really matter.
The rest of the triangle comes from duplicating each group using LightBurn’s Grid Array tool with a convenient space between each copy. Make 15 copies of the top group for a total of 16 H000 and no copies of the bottom H337.
Hit Delete Duplicates to get rid of all the overlaid outer squares
If you’re fussy, Duplicate the line of blocks and move it up
Group each block individually to keep all the little squares together with the outline
Thusly:
Random Blocks – 16×16 – LightBurn combined layers
Combine each of those blocks with the sheet cutting template, tweak the binary sheet identification holes, and group the result:
Random Blocks – 16×16 – LightBurn cutting layouts
The leftmost block has All The Holes, the next one is missing a few, and so on across the line:
Random Blocks – 16×16 – LightBurn cutting layouts – detail
So the leftmost block corresponds to the black mask atop all the layers. Because it doesn’t have alignment holes in the corners or a binary sheet number, you get to align it by eyeball after gluing up the rest of the stack.
The rightmost block has no cutout squares at all and goes on the bottom of the stack. It also lacks a sheet number, but it’s easy to identify.
Set the LightBurn speed / power values for the layers to cut your stock of colored art paper.
Position the Letter Page Holder template to put the center of the sheet cutout at the center of the platform:
Random Blocks – 16×16 – LightBurn fixture template
Drop the fixture on the platform, use magnets to hold it down, then do a Print and Cut alignment on the corner targets so the template matches the fixture.
Then:
Click to select one of the blocks
Hit Ctrl-D to duplicate it
Hit P to slam it to the middle of the template
Hit Alt-S to Fire The Laser
Hit Del to delete the block
Iterate until done
I used a stack of paper in rainbow order roughly corresponding to the Inkscape layer colors, but you could stack them backwards or even use random colors and nobody would ever know:
Random Blocks – framed detail
I kinda like it, but wow that took a lot of prep work …
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.
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:
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 …
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:
The Smell of Molten Projects in the Morning 
