The Smell of Molten Projects in the Morning
Ed Nisley's Blog: shop notes, electronics, firmware, machinery, 3D printing, and curiosities
If you measure something often enough, it becomes science
Having grossly exceeded the Gentec ED-200 maximum power spec, I wasn’t surprised to see this when I finally tucked it back in the drawer:
The 0.5 mm scale suggests the damage came from a defocused 2 mm beam or the hot central part of a larger beam, but I obviously wasn’t paying enough attention at the time.
The rest of the surface seems undamaged, so this may have been one of those inadvertent long-duration pulses or several shorter shots in one spot.
Two years ago, a quartet of new BatMax NP-BX1 batteries performed about as well as could be expected and, by last fall, had deteriorated about as much as expected:
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:
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.
Just a few more batteries for the blinkies.
So I bought a trio of NP-BX1 batteries from Newmowa, an Amazon supplier with a few more vowels than usual, and repeated the exercise:
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:
The color code:
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.”
It seems two months of sunlight will fade laser charred MDF down to its original state:
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:
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:
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:
Of course, if those two tape strips don’t exactly abut, the paint produces a nasty line:
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:
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:
Perhaps these will outlast the garden season …
A rare trip to the Poughkeepsie Railroad Station provided an opportunity to check out the LED bulbs in the chandeliers:
The 108 bulbs had only one deader (lower left in chandelier C).
I have no way of knowing if they’re the same bulbs from six years ago, but the accumulation of bugs / dust / crud inside the (what I would expect to be) sealed envelopes suggests they’ve been hanging there for quite a while:
The dark cruciform patches might come from failed LED chip strings, although the bulbs all had the same eyeballometric brightness. The patches all seem to have a hard lower edge, so we may be seeing shadows from dust accumulating atop the chips on the PCB.
They’re a definite step up from CFL bulbs, although still not as pleasant as OG incandescent filaments.
Cleanup after painting the hairlines involved opening the cap of the rarely used can of methyl ethyl ketone:
It seems white-tinted polyethylene deteriorates after a dozen years of exposure to concentrated MEK fumes, suggesting I don’t use nearly enough enamel paint.
The Container Stockpile disgorged a pair of pure polyethylene jars that should last another decade.
We deployed six sticky traps in the onion patch immediately after planting in late April and replaced the cards in mid-June. The first set of cards collected a considerable number of what resemble, to my untrained eye, onion maggot flies and the onion plants remain healthy:
Each image shows both sides of a single card.
The cards sit a foot above the shredded leaf mulch and I managed to drop at least one of the cards while extracting it from the cage, but they all have plenty of onion maggot flies in addition to the random debris.
The cards inside their cages have not accumulated larger insects like honeybees / moths / butterflies, although the tiniest specks are definitely mini-critters along the beetle / gnat / aphid / mosquito axis.
Unlike last year, the second set of cards will remain in place until harvest to maintain continuous pressure on the fly population.
If you’re really interested, the dozen original camera images have more detail.
Just to see how the OMTech 60 W laser cuts wood:
From left to right:
I thought a pine plank would cut faster than oak, but they’re equally stubborn.
Maple requires slightly more power, with the glued butt joints between the slabs putting up a stiff resistance.
A sheet of 3 mm MDF cuts well at 20 mm/s 60% and I expect 3 mm plywood might need similar numbers.
A pervasive odor of burned wood seems to be the only downside; if you think a wood stove is a good idea, you’ll love laser cutting the stuff. Sanding the blackened perimeter and sealing the surface surely helps, but it’s feasible only for the kind of simple convex shapes you don’t really need a laser to cut.
The Smell of Molten Projects in the Morning 