The Smell of Molten Projects in the Morning
Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Mary’s relatives encountered this repair in a rental flat during Thanksgiving week:
Don’t have a hex bolt with the right thread? No problem: just use a sheet-metal screw, perhaps with a self-drilling point:
Those hex heads let you apply more torque with less risk of stabbing yourself in the palm, which strikes me as an all-around Good Thing. I prefer socket-head cap screws, myself, but I’ll admit they’re an acquired taste.
I’d like to think I wouldn’t do that …
The inside of the replacement J5 V2 Tactical Flashlight doesn’t have quite as much dirt on the LED emitter, but it’s still pretty bad:
The small white dingus at about 10 o’clock seems to be a plastic shred stuck on end to the emitter lens. Here’s a better look, rotated a quarter-turn counterclockwise:
There’s also an alien egg glued to the heatsink beside the LED:
I’m hoping it’s another random plastic blob.
There’s no point in returning this one; it’ll suffice for my purposes. However, given two random samples, I’d say the J5 Tactical Flashlight factory, wherever it may be in China, is really filthy.
I’d hoped that paying a bit more for a “tactical” flashlight, instead of going bottom dollar, would yield a better product. Maybe it did?
These emerged from a hidden corner of a basement shelf, where they’ve been sitting undisturbed for far too long:
I’ve known for a while that the PETE plastic used for nearly all bottles isn’t completely waterproof, but never had occasion to measure the results.
The laser-etched date code on the bottles says they “expired” in late August 2012, so, assuming one year of shelf life, they’ve been quietly evaporating for five years.
Sampling a few bottles shows a nearly uniform weight of 459 g. A drained bottles weighs 13 g, so let’s say the bottles now contain 445 g of water. They should start out with 500 g, although I’d be mildly surprised if it wasn’t a bit over that to prevent some dork from complaining about getting only 498 g.
Rounding in all the right directions, losing 60 g during five years works out to a tidy 1 g/month in a basement room at 60% RH.
The surface area of those wonderfully convoluted bottles might be 300 cm², so they lose 3 mg/cm²·month.
They’re near enough to 0.10 mm thick, which I’m sure is a compromise between reducing weight (and, thus, plastic cost) and incurring messy failures during normal handling. The evaporation rate surely varies as an inverse exponential of thickness, but I’m not going there.
I’m certain water bottlers know those numbers to several decimal places and can plot them versus all the interesting variables.
Memo to Self: don’t lose track of the water bottles!
Fortunately, it’s hard to damage an aluminum-body “tactical” flashlight:
A keyboard and cylindrical cell charger arrived intact, with absolutely no credit due to Amazon’s careful packaging:
Sometimes, a box does arrive with a token scrap of padding dropped inside, but, as nearly as I can tell, it’s cheaper for Amazon to replace the occasional damaged item than to waste time and material stuffing the boxes with air pillows, eco-foam peanuts, or, heaven forfend, space-filling foam.
Pretty much as expected, the dust brush nozzle failed again, adjacent to the epoxy repair:
A bit of rummaging turned up some ¾ inch Schedule 40 PVC pipe which, despite the fact that no plumbing measurement corresponds to any physical attribute, had about the right OD to fit inside the adapter’s ID:
The enlarged bore leaves just barely enough space for a few threads around the circumference. Fortunately, the pipe OD is a controlled dimension, because it must fit inside all the molded PVC elbows / tees / caps / whatever.
The pipe ID isn’t a controlled dimension and, given that the walls seemed far too thick for this purpose, I deployed the boring bar:
That’s probably too much sticking out of the chuck, but sissy cuts saved the day. The carriage stop keeps the boring bar 1 mm away from the whirling chuck.
Bandsaw it to length and face the ends:
The PVC tube extends from about halfway along the steep taper from the handle fitting out to the end, with the section closest to the handle making the most difference.
Ram it flush with the end:
I thought about gluing it in place, but it’s a sufficiently snug press fit that I’m sure it won’t go anywhere.
Natural PETG probably isn’t the right color:
Now, let’s see how long that repair lasts …
The OpenSCAD source code as a GitHub Gist:
| //——————- | |
| // eBay horsehair dusting brush | |
| // Hacked for 3/4" Schedule 40 PVC stiffening tube | |
| module DustBrush() { | |
| union() { | |
| translate([0,0,40.0]) | |
| rotate([180,0,0]) | |
| difference() { | |
| union() { | |
| cylinder(d1=EndStop[OD1],d2=31.8,h=10.0); | |
| translate([0,0,10.0 – Protrusion]) | |
| cylinder(d1=32.0,d2=30.0,h=30.0 + Protrusion); | |
| } | |
| translate([0,0,-Protrusion]) | |
| cylinder(d1=26.0,d2=24.0,h=100); | |
| translate([0,0,-Protrusion]) // 3/4 inch Sch 40 PVC | |
| PolyCyl(27.0,100); | |
| } | |
| translate([0,0,40.0 – Protrusion]) | |
| MaleFitting(); | |
| } | |
| } |
So I picked up a J5-V2 Tactical Flashlight as a possible bike headlight, on the basis of a 750 (“max output”) lumen LED, zoomable beam, and use of standard 18650 lithium cells (rather than USB charging). The geometry required to stick it on the Tour Easy remains a puzzle, but an az-el dingus replacing an upper fairing mount may work well enough.
Anyhow, it seems the LED in this flashlight fell on the floor during assembly, where the (silicone?) LED emitter lens picked up a remarkable amount of dirt:
The inside of the front focusing lens carries an array of scratches or, perhaps, a greasy fingerprint that serves the same purpose:
All vendors tell you to contact them before posting a critical review, although they often don’t provide much in the way of contact information. I sent a note with photos to J5 through their website’s contact info; having not heard anything after three days, I’ll fire up the Amazon return process …
After two weeks of more-or-less daily use, without any further seasoning:
The seasoning in between the scuffs & scrapes remains in fine shape. Running the Scotchbrite pad around the perimeter obviously wears the coating, but, on the whole, nothing sticks anywhere.
I’ve started re-seasoning it after each use, which isn’t a big deal, and we’ll see how the scratches level out.
The lovely gray-black patina on the nubbly outside surface from the original moderate-woo oven seasoning requires no further attention.
The Smell of Molten Projects in the Morning 