Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Blow out the contrast, flip right-to-left, then mask them en masse:
Small fragments – masked
Delete the images (inside their selection masks) to create a binary mask:
Small fragments – masks
Have LightBurn trace the binary images, wrap a rounded rectangle around the lot of them, duplicate the rectangle as a base plate, then fire the laser:
Smashed glass palette – fresh cut
They’re not secured in their sockets, but they won’t fall out unless I fat-finger the whole affair:
Smashed glass palette – loaded
The thing that takes getting used to: the whole process was about two hours of wall clock time from start to finish, with a leisurely breakfast and KP in the middle.
In round numbers, the total capacity declined from 3.25 W·hr to 2.5 W·hr, which means a single battery can’t quite power the camera for the duration of our normal hour-long rides. I do not know what voltage trips the camera’s decision, but the batteries definitely shut down sooner.
So, based on their previous track record, I bought another quartet of Batmax batteries. Being that type of guy, I tested both the old (2020) and new (2022) sets:
NP-BX1 – BatMax 2022 vs 2020 – used-new
The blue traces are the C/D batteries from the as-new tests back in early 2020, the green traces are C/D after two years of use, and the red traces are the “new” quartet after their first charge in the Official BatMax Charger.
It looks very much like BatMax is selling used batteries repackaged as new items, because they are indistinguishable from my used ones. They definitely are not the “Premium Grade A cells” touted in the description.
I returned them for a refund and sent the test results to BatMax; they sent “new replacements” even though I said I would not pay for any future shipments. The batteries had a slightly different wrapper, but the test results were still indistinguishable from used batteries. I offered to return the package and was told that would not be needed.
It seems three good batteries now cost about as much as four crap batteries, under the reasonable assumption chargers are essentially free.
Three batteries isn’t quite enough for my usual rotation and, for unknown reasons, one cannot buy only batteries, so in short order I will have two chargers and six batteries.
The consolidated test results:
NP-BX1 – Newmowa Batmax 2022 comparison
The color code:
Newmowa: red
BatMax 2020 new: blue
BatMax 2020 used: orange
BatMax 2022 new: green + lime
I stopped writing Amazon reviews after having a few detailed-writeups-with-graphs rejected for the usual unspecified reasons. As the Finn put it, “You wanna download, you know the access code already.”
Lay some pieces atop an acetate sheet (to prevent scratching) on the scanner, grab the whole thing, then isolate an interesting chunk:
Smashed Glass – dark – piece 1
Next time: flip the image left-to-right to match the glass piece as seen from the top, because the scanner was looking at the bottom.
The weird purple background started as black, but blowing out the contrast while ignoring the color mis-correction makes the next step easier.
Trace around the perimeter with Scissors Select, clean up the result in Quick Mask mode, expand the selection by a few pixels to improve clearance, then turn it into a two-color image mask:
Smashed Glass – piece 1 – outline
Import the mask into Lightburn, trace it into vector paths (which is trivially easy and accurate given such a high-contrast image), then cut a chipboard prototype to make sure it fits:
Smashed Glass – piece 1 – acrylic mount
Clean up any misfits, test as needed, cut the inner shape and outer perimeter from 1.5 mm black acrylic, cut just the outer perimeter from 3 mm clear acrylic. Put the piece of black acrylic matching the glass shape into the scrap box.
Mix up a few milliliters of clear pourable epoxy, butter up the clear acrylic, lay the black acrylic on top, line up the edges, then gently place the shattered glass into the cutout:
Smashed Glass – piece 1 – acrylic top
Next time: apply gentle pressure, perhaps through a flexy sheet, to ensure the entire glass surface contacts the epoxy layer while squeezing out the bubbles. This will surely skate the glass across the acrylic, so don’t leave it unsupervised.
The relatively clear areas show where epoxy eased its way into the cracks between the granules; there is no correlation between the air bubbles and unfilled cracks. The epoxy had the viscosity of warm honey and I didn’t expect it to flow so easily, but it doesn’t affect the outcome.
Wait for a day, no matter how hard that may seem, for the epoxy to cure. Leave the small cup holding the remnants of the mixed epoxy nearby so you can test the cure without disturbing the Main Event.
The bottom looks pretty much like the top:
Smashed Glass – piece 1 – acrylic bottom
The shattered edge reflects off the bottom of the clear acrylic, as seen through the side:
At first we thought a mighty crunch in the morning meant the trash collection truck had dropped a garbage bin from a great height, but the sound of sirens and a myriad flashing lights revealed the true cause in our neighbor’s front yard:
NHR Crash – frontal view
The extent of the damage was more apparent from the road side:
The driver was walking around uninjured and the ambulance left quietly.
A day later, the trajectory became apparent:
NHR Crash – trajectory
The right side barely kissed the tree on the right, but the front wheel hooked the utility pole (that’s the new pole in the picture), snapped it off at ground level in addition to the usual break maybe ten feet up, and bounced a piece off the other tree:
NHR Crash – utility pole
I didn’t know you could shatter a cast aluminum alloy wheel, but the missing half of the outer face was lying amid the rather scrambled stone wall along driveway.
We’re reasonably sure we know the cause. Feel free to draw your own conclusions.
After the flatbed hauled away the car and everybody left, I harvested a few pounds of interesting debris from the lawn:
NHR Crash – tempered glass
It’s tempered glass from the driver-side windows, shattered into small chunks and barely hanging together in those sheets. Laminated windshield glass is entirely different stuff.
The smaller chunks glitter like jewels:
NHR Crash – tempered glass fragments
Obviously, the window had a bit of tint.
The smallest chunk, seen from its flat surface, shows the cuboid fragments:
NHR Crash – tempered glass fragment – front
A side view shows more complexity:
NHR Crash – tempered glass fragment – side
Tempering prevents a glass sheet from shattering into long knife-blade shards. Although the edges of the fragments are not keen, we are dealing with broken glass: they are sharp.
Broken tempered glass also sheds razor-edged flakes perfectly shaped to penetrate bike tires, although most roadside glass comes from ordinary beverage bottles. The tiniest flakes can make a mess of your eyes, so exercise at least some rudimentary shop safety practices.
Those slabs ought to be good for something, even if they fall apart at the slightest touch …
It seems two months of sunlight will fade laser charred MDF down to its original state:
Please Close The Gate – unpainted faded
That’s through a thick layer of indoor urethane sealant slathered over MDF without any surface prep. Obviously, not removing the char had no effect on the outcome. On the upside, the urethane did a great job of protecting the MDF from rainfall.
So. Back to the shop.
Lacking wider masking tape, two strips of tape laid along a cut-to-suit slab of fresh MDF will serve as a paint mask:
Please Close The Gate – masked engraving
Belatedly I Learned: cut the tape close to the edge, then fold it under so the autofocus pen can’t possibly snag it en passant.
Shoot the entire surface with a couple of black enamel rattlecan coats:
Please Close The Gate – masked paint
Yes, the engraved areas look reddish, most likely due to another complete lack of surface prep. Perhaps brushing / vacuuming / washing would remove some of the char, but let’s see how it behaves with no further attention.
Peel the tape, weed the letters / antlers, slather on a coat of urethane, and it looks downright bold:
Please Close The Gate – sealed
Of course, if those two tape strips don’t exactly abut, the paint produces a nasty line:
Please Close The Gate – mask gap
Should you overlap the strips a wee bit to ensure cleanliness, the engraved surface will then have a noticeable (in person, anyhow) discontinuity due to the laser losing energy in two tape layers, which wouldn’t matter in this application. We defined the few paint lines as Good Enough™ for the purpose; a strip of absurdly wide masking tape is now on hand in anticipation of future need.
Burnishing the tape might have prevented paint bleed around the engraved areas:
Please Close The Gate – paint creep
But, given that I was painting raw / unfinished MDF with an unsmooth surface, burnishing probably wouldn’t produce a significantly better outcome.
By popular request, the new signs sit a few grids lower on the gates:
The air assist pump sits in the right rear of the OMTech laser’s main compartment:
OMTech 60W laser – Z motor – air pump
Where it is, of course, exposed to all the usual dust / fragments / fumes / smoke generated by laser cutting & engraving, enhanced by my attention to getting good air flow over the platform. The picture shows the base plate in as-delivered condition, which it will never resemble ever again.
The problem: any crud in the air can clog the pump or contaminate the laser focus lens.
Four screws into threaded holes hold the pump to the base plate, secured with jam nuts on the outside.
The air inlet is a round fitting centered on the bottom of the pump housing:
OMTech 60 W Laser Air Assist – pump inlet
You’ll note the out-of-focus crud scattered on the base plate.
The general idea is to drill a hole through the base plate, put a snorkel on the inlet, and have it inhale fresh, relatively clean, basement air from outside the cabinet. The trick will be not touching the base plate with anything solid, because the pump vibrates like crazy; its four squishy standoffs do a great job of isolating the tremors from the base screwed to the laser cabinet.
Having a few other things going on at the moment, I just laid two generous wads of cheesecloth where they can filter the bigger chunks out of the air stream:
OMTech 60 W Laser Air Assist – cheesecloth filter installed
The air flow meter says the pump still delivers 12 l/m to the nozzle, so the cheesecloth has no effect compared to four or five feet of 4 mm ID tubing.
A doodle summarizes the inlet fitting dimensions:
OMTech 60 W Laser Air Assist – pump inlet fitting measurements
That looks like a 3D printed disk with a snout for a short air hose should do the trick, with a thin gasket sealing the disk to the fitting.
TIL: Muntin, which I’d always known was called a Mullion.
With that as preface, one of Mary’s quilting cronies lives in a very old house updated with vinyl windows sporting wood muntins arranged in a grille. The wood strips forming the grille end in plastic clips that snap into the sash, thereby holding the grill in place to make the window look more-or-less historically correct, while not being a dead loss as far as winter heating goes.
Time passed, sun-drenched plastic became brittle, and eventually enough clips broke that the grilles fell out. An afternoon quilting bee produced a question about the possibility of making a 3D printed clip, as the original manufacturer is either defunct or no longer offers that particular style of clip as a replacement part.
Well, I can do that:
Window Muntin Clips
The original is (obviously) the transparent injection-molded part in the upper left. The other two come hot off the M2’s platform, with the one on the right showing the support material under the sash pin.
The solid model looks about like you’d expect:
Window Muntin Clip – solid model
There is obviously no way to build it without support material, so I painted the bottom facet of the sash pin with a PrusaSlicer support enforcer:
Window Muntin Clip – PrusaSlicer
The pin comes out slightly elongated top-to-bottom, but it’s still within the tolerances of the original part and ought to pop right into the sash. We’ll know how well it works shortly after the next quilting bee.
The doodle with useful measurements amid some ideas that did not work out:
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The Smell of Molten Projects in the Morning 