Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
These cute little toys serve as 3D printer torture tests:
Surprise Eggs
Obviously, each egg can hold only one of those toys, but I had to run them off in both retina-burn orange PETG and black PETG-CF for comparison.
These Surprise Egg models came from Thingiverse, but they’re also available on Printables. You’ll find many more, of course, at a variety of scales, with these on the small end.
The white eggs print with no difficulty at all, as does most of the equipment contained within:
Surprise Eggs – contents – orange PETG
Most moving parts require careful back-and-forth movement to break them free, but they’re surprisingly functional. The PETG-CF, printed with an Extrusion Multiplier = 0.8, looks better, although the moving parts were more firmly stuck together.
Not all of the equipment came out perfectly:
Surprise Eggs – contents on platform
Even without any special preparation, the MK4 didn’t have much trouble. If you were doing those for real, you could add stickum to the sheet or switch to a sheet with absurdly high PETG griptivity.
Although I devoted considerable attention to leveling & shimming the table under Mary’s HQ Sixteen, the machine rolls on ball bearing wheels atop (relatively) smooth plastic tracks. Parked at a few spots along the dozen feet of table, the machine will slowly and quietly roll away. This calls for some sort of parking brake, but until inspiration strikes, a simple anchor will suffice:
HQ Sixteen – anchor
It’s a cocoa container chosen from (one of) my Boxes o’ Containers, with a husky chunk of steel atop some very sticky double-sided foam tape inside the red lid.
You can see one of the ball bearing wheel just above the strap applying tension to the practice quilt out of view on the left. The thing that looks like a wheel just under the strap is an encoder for the stitch regulator that we haven’t connected yet.
To prevent the machine from simply bulldozing the container along with it, the lid sits on a sheet of EVA craft foam stuck to a sheet of rigid foam board (with adhesive on both sides).
Scan the lid:
Container lid scan
Select all the red pixels, do a little cleanup, turn it into a binary mask:
Container lid mask
Import it into LightBurn, trace the perimeter, do some curve optimization / smoothing, duplicate the outline, set one to cut EVA foam and the other to cut adhesive board, and Fire The Laser.
Elapsed time: about fifteen minutes from realizing what was needed to plunking the anchor in place.
I briefly considered a full-frontal laser-cut finger-jointed box for the weight, but … Mary’s not a big fan of that campfire smell, particularly in a room dedicated to the Fiber Arts.
One string of three white LEDs in the left handlebar of Mary’s Handi-Quilter HQ Sixteen died over the past two decades:
HQ Sixteen – left LED deaders
A view minus the glare:
HQ Sixteen – left LED PCB
I replaced all 15 LEDs with new-old-stock white LEDs from my stash, while neglecting to pay close attention to the silkscreened orientation marks.
I used up a lot of solder wick while re-extracting seven of the LEDs :
HQ Sixteen – left LED PCB – orientation
The LED in the front-right corner is in the string with the two LEDs just above it, while pointing in the opposite direction. This definitely violates the Principle of Least Surprise.
Being of sound mind, I tested all the replacement LEDs before installing them:
HQ Sixteen – LED testing
Which tedious process weeded out a couple of deaders, one with its case on backwards, and a handful of completely different white LEDs evidently from a different manufacturing batch. Buying low-budget LEDs directly from a sketchy source halfway around the planet does have its downsides.
Being that type of guy, I also tested the removed LEDs. Weirdly, one of the strings had two dead LEDs, which suggests one failed short and the increased current took another LED down with it.
Two of the three strings in the central PCB had died and were replaced without incident: they all pointed in the same direction and I can deal with consistency.
So as to not bury the lede, I remounted the front handlebar unit of Mary’s Handi-Quilter HQ Sixteen long-arm sewing machine so she can see the control panel with its small LCD:
HQ Sixteen – remounted handlebars in use
The new and old white LEDs produce distinctly different colors and intensities on the practice quilt fabric.
The original HQ Sixteen design bolted squarely atop the arm:
HQ Sixteen – original front handlebar mount
The control surface is, admittedly, angled slightly forward, but Mary was unable to see the lower few lines of the LCD without standing on tiptoe.
Begin with a crude tracing of the mating surfaces:
Front handlebar base tracings
Import the image into Inkscape and lay some shapes on it:
Front handlebar base layout – Inkscape
Import the SVG into LightBurn and cut templates to verify the hole positions:
HQ Sixteen – handlebar bolt templates
Obviously that took more than one try.
Rationalize the outlines, clean things up, and organize the shapes into useful named layers:
Front handlebar base layout – Inkscape layers
Save as an Inkscape SVG, import into OpenSCAD, and extrude the layers defining all those shapes into a solid model:
Handlebar Base Mount – solid model
That’s the most recent iteration; earlier ones appear in various pix.
I had intended to use either square nuts or heat-set inserts, but it turned out to be easier to just slam BOSL2 threaded nuts into the front plate and be done with it:
Handlebar Base Mount – solid model – hex nuts
The trick is to sink the nuts around a hole sized slightly larger than the screw’s nominal diameter, letting the threads fill empty space.
The handlebar base is mounted symmetrically along the machine arm centerline aligned with the two screws on the right. The rear block is offset to the left to clear the machine cover on the right, so the hull() wrapped around the two looks weird.
The front plate stands proud of the rest by dint of incorporating only a small slice of its back face into the hull() filling the gaps between the two. It’s not particularly stylin’, but it’s pretty close.
Finding the correct angle for the front plate required a couple of iterations, but they all built successfully:
HQ Sixteen – handlebar mount – on platform
Putting the threaded holes vertical created nicely formed threads that accepted the screws without hassle.
The block screws firmly to the arm and the handlebar unit screws to the block:
HQ Sixteen – remounted handlebars – side
The display now faces front:
HQ Sixteen – remounted handlebars – front
I eventually replaced those black oxide screws with shiny stainless ones, just for pretty.
The nine LEDs under the display now do a great job of lighting up the front of the machine’s arm, rather than the fabric at the needle, but fixing that will be a whole ‘nother project.
The handlebar grips with their control buttons now tilt at a somewhat inconvenient angle, which is also a whole ‘nother project.
Early reports from the user community are overwhelmingly positive.
The OpenSCAD source code and the SVG layout as a GitHub Gist:
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Loading the STL into PrusaSlicer, adding a text label to remind me which way it printed, then slicing with my PETG-CF profile shows the “Actual Speed”, which seems to take acceleration into consideration:
PrusaSlicer preview – actual speed
The colors in the legend don’t quite match the colors on the model, but the greenish layers with the jolts trundle along in the mid-20 mm/s range and the blue-ish straight-through layers at 30-ish mm/s.
Eryone PETG-CF has a somewhat fuzzy appearance that seems not characteristic of other brands, so I’ll try something else when these spools run out:
MK4 Resonance Test Box – overview
The right side of the box (as oriented on the platform) got all the layer retractions and came out festooned with PETG hairs:
MK4 Resonance Test Box – right side
You can check my labels by tracking the small retraction zit sticking up from the top layer; I got it wrong the first time. Open the images in a new tab to see more pixels.
The front:
MK4 Resonance Test Box – front side
The left:
MK4 Resonance Test Box – left side
And the rear:
MK4 Resonance Test Box – rear side
You can barely see the shadow of the “Rear” text on the surface, even though the wall is two threads thick and the text is indented by 0.2 mm, about half the thread width.
As far as I can tell, the MK4 Input Shaper compensation does a great job of suppressing resonance or wobble in all directions.
Judging from the dates codes on the ICs inside, Mary’s HandiQuilter Sixteen long-arm machine is about two decades old and many of the white LEDs in the front handlebars have gone dark:
HQ Sixteen – dead handlebar LEDs
The vertiginous view looks upward into the handlebar at the top of the machine (more on this later). The PCBs run strings of three series LEDs from a 16 VDC supply with a 390 Ω ballast resistor (oddly enough, on the ground end of the string), so one failed LED takes down all three.
I decided to replace all the LEDs, on the principle they’re surely dimmer than they used to beand to take advantage of a decade or so of improvement in white LEDs (yes, I have old stock).
After discovering that the HandiQuilter engineers violated the Principle of Least Surprise by orienting adjacent LED strings in opposite directions, I found one of the strings still didn’t light up.
Pop quiz: which one of these LEDs caused the problem?
5 mm LEDs – swapped polarity
To the best of my knowledge, all 5 mm round LED packages mark the cathode lead with a flat edge. It’s easy to remember, as the cathode side of the schematic symbol has a bar: straight bar = straight edge.
Inside, the LED chip’s cathode lead is bonded to the reflective cup, with the anode lead wire-bonded to the top.
Took me a while to see what was wrong, too.
For whatever it’s worth, the backward LED works fine.
Mary is at least the third owner of a steel rack, originally intended to hold packages of retail stuff, which now holds (much of) her collection of quilting rulers:
Quilting Ruler Rack Base – overview
Obviously, it was never intended to hold heavy acrylic sheets, but it worked surprisingly well, right up to the point where too many of the rulers collected on two adjacent columns of pegs and overbalanced the whole affair atop her while she attempted to remove a ruler.
Subsequent accident recreation showed the rack toppled when the weight of the rulers on the two adjacent columns of hooks moved the center of mass outward, just inside the line between those feet, whereupon the slightest tug on a ruler pulled it over.
Measurements revealed the four legs do not sit on a square contact patch, are not parallel to the radii from the center point, and are not uniformly distant from the center. Rather than committing to a finished product, I made a cardboard prototype to verify a bigger base would solve the problem and I could capture all those feet.
You don’t have such a rack, so the exact dimensions don’t matter, but the LightBurn layout looks like this:
Quilting Ruler Rack Base
The disk is two cross-laid sheets for stiffness, with marks burned on the top to help align the feet more-or-less around the center point.
The oblong rings fit around the feet to capture them, so cut eight or twelve to make four stacks a bit taller than the wire diameter.
The H shape then glues atop the rings to hold the feet in place. They’re not removable, but a razor knife will eventually solve that problem.
I slobbered hot melt glue across the cardboard disks to hold them together, glued and aligned the rings where the feet dented the disks, stood the rack in the rings, and glued the H plates.
About an hour elapsed from the sound of the crash to the rack once again standing quietly beside the fabric cabinets.
We’ll run this for a while and eventually replace it with a plywood disk and screwed-in-place clamps for the feet, which will surely call for wood surface preparation / stain / seal treatment.
The Smell of Molten Projects in the Morning 
