Archive for January, 2019
The LED parts box disgorged some single-color Pirhana-style LEDs:
Didn’t quite catch the blink, but the
Ping-Pong ball radome lights up just as you’d expect.
The radome sits on a stripped-down RGB LED spider:
The circuitry is the same as the First Light version, with a 1 MΩ resistor stabilizing the LED ballast resistor:
Those are 1 µF ceramic caps in the astable section, so I’m no longer abusing electrolytics, and a stylin’ 100 nF film cap metering out the LED pulse up above.
Just for pretty, I’ve been using yellow / black wires for the battery connections and matching the LED color with its cathode lead.
The OpenSCAD source code as a GitHub Gist:
I’ve used the LMS set of inch-size MT3 spindle collets on occasion, but releasing them required an unseemly amount of drawbar battering. It recently occurred to me to check their fit in the spindle taper:
The only place they touch the spindle is right around the base, so it’s no wonder they clamp poorly and release grudgingly. I tried several others with the same result.
Cross-checking shows a much closer fit along the entire length of the dead center, so it’s not the spindle’s fault:
Stipulated: we’re not talking toolroom precision here
I set the collets on centers:
And proceeded to file away the offending section to move the clamping force closer to the business end of the collet:
I did the small collets, the ones I’m most likely to need, and left the big ones for another rainy day.
They don’t have much clamping range and seem good only for exact-inch-size rods.
I should lay in a stock of ER16 and maybe ER32 collets for small stuff.
Some of our regular walks take us over the Rt 376 bridge downstream of the Red Oaks Mill dam and I try to take a picture whenever we cross.
For reference, two years ago in December 2016:
The dam breast seem from the north (left in above pictures) in December 2018:
Searching for the obvious keywords will produce far more pictures than the subject may deserve.
Getting hydropower from the rubble would require considerable capital investment …
[Update: It seems I interchanged “em” and “de” throughout this post. ]
Up to this point, I’ve been labeling printed parts with
emdebossed legends that look OK on the solid model:
Alas, the recessed letters become lost in their perimeter threads:
Raising the legend above the surface (“
deembossing”) works reasonably well, but raised letters would interfere with sliding the battery into the holder and tend to get lost amid the surface infill pattern.
The blindingly obvious solution, after far too long, raises the letters above a frame embossed into the surface:
Which looks OK in the real world, too:
The frame is one thread deep and the legend is one thread tall, putting the letters flush with the surrounding surface and allowing the battery to slide smoothly.
The legend on the bottom surface shows even more improvement:
An OpenSCAD program can’t get the size of a rendered text string, so the fixed-size frame must surround the largest possible text, which isn’t much of a problem for my simple needs.
Spotted this in a mall built just before the 2008 financial implosion:
Maybe the original catalog items went obsolete by the time they signed up enough tenants in that section to justify any lighting at all?
In related news, a facelift some years ago at the motel next to the decaying Red Oaks Mill dam installed square lamp posts on the existing square concrete pedestals, but replaced the original metal conduit with a plastic sheath:
The cable may sit low enough in the recess to survive, but I wouldn’t bet my life on it.
A Red Fox came trotting around the garden on the day before Christmas, then nosed up to the back of the house:
Presumably, it was in search of a snack. We wish it good hunting.
A few hours later, the fox walked quickly across the back yard with half a dozen turkey toms close behind, perhaps urging it away from their hens. Everybody remained calm and collected, knowing their roles in this particular play.
A bag of 100 nF ceramic caps arrived from across the continent (“US Stock”) and failed incoming inspection:
The capacitor mark says 104, which is what you’d expect on a 100 nF cap, but the first half-dozen out of the bag measured around 55 nF, far outside even the loosest -20%/+50% tolerance.
Stipulated: the factory can ship every capacitor it makes with a proper mark.
Given their (lack of) provenance, they could be mis-marked 47 nF caps.
Somewhat to my surprise, a refund occurred instantly after I reported the problem.
Trust, but verify.