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.
Who’d’a thunk it?
My buddy dBm took pity on my plight:
The far end has a 2.5 mm hex driver, although I’ve never encountered a nut for an M1×0.25 screw in the wild. It doesn’t fit an 0-80 nut and gulps 00-90 nuts, so it’s definitely hard metric.
My collection of glasses required an aggregate two turns of tightening, which prompted dBm to remind me of threadlock.
Done!
Thank you, dBm!
Mary made a batch of veggies in tomato sauce and froze meal-size portions as winter treats. The moist air inside the containers froze into delicate ice blades on the zucchini slices:
A closer look:
The blade cross-sections might be oblong hexagons, but it’s hard to tell with crystals melting almost instantly after the lid comes off. Some of the smaller hair-like blades reminded me of tin whiskers.
Yummy!
Spotted in a museum:
It’s been quite a while since BIOS boot sequences started with the floppy drive. Combined with a CMOS backup battery failure, I’d say this poor PC has been chugging along for two decades.
On another floor:
Isolating a Windows kiosk from the Interwebs is an excellent design principle, but Windows Update really wants to phone home. The kiosk’s presentation ran Adobe Flash 10, so it’s been confined for maybe a decade.
Looks like it’s time for another fundraising drive to replace the PCs with Raspberry Pi controllers. The real expense, of course, goes into rebuilding the presentations using whatever tech stack is trendy these days.
Following a linkie I can no longer find led me to retrieve the Tektronix Circuit Computer in my Box o’ Slide Rules:
I’m pretty sure it came from Mad Phil’s collection. One can line up the discolored parts of the decks under their cutout windows to restore it to its previous alignment; most likely it sat at the end of a row of books (remember books?) on his reference shelf.
The reverse side lists the equations it can solve, plus pictorial help for the puzzled:
Some searching reveals the original version had three aluminum disks, shaped and milled and photo-printed, with a honkin’ hex nut holding the cursor in place. The one I have seems like laser-printed card stock between plastic laminating film; they don’t make ’em like that any more, either.
TEK PN 003-023 (the paper edition) runs about thirty bucks (modulo the occasional outlier) on eBay, so we’re not dealing in priceless antiquity here. The manual is readily available as a PDF, with photos in the back.
Some doodling produced key measurements:
All the dimensions are hard inches, of course.
Each log decade spans 18°, with the Inductive Frequency scale at 36° for the square root required to calculate circuit resonance.
Generating the log scales requires handling all possible combinations of:
I used the 1×100 tick on the outer scale of each deck as the 0° reference for the other scales on that deck. The 0° tick appears at the far right of plots & engravings & suchlike.
The L/R Time Constant (tau = τ) pointer on the top deck and the corresponding τL scale on the bottom deck has (what seems like) an arbitrary -150° offset from the 0° reference.
The Inductive Frequency scale has an offset of 2π, the log of which is 0.79818 = 14.37°.
The risetime calculations have a factor of 2.197, offsetting those pointers from their corresponding τ pointer by 0.342 = log(2.197) = 6.15°.
A fair bit of effort produced a GCMC program creating a full-size check plot of the bottom deck on the MPCNC:
By the conservation of perversity, the image is rotated 90° to put the 1 H tick straight up.
The 3018 can’t handle a 7.75 inch = 196 mm disk, but a CD-size (120 mm OD) engraving came out OK on white plastic filled with black crayon:
The millimeter scale over on the right shows the letters stand a bit under 1 mm tall. And, yes, the middle scale should read upside-down.
Properly filling the engraved lines remains an ongoing experiment. More downforce on the diamond or more passes through the G-Code should produce deeper trenches, perhaps with correspondingly higher ridges along the sides. Sanding & polishing the plastic without removing the ink seems tedious.
The Great Dragorn of Kismet observes I have a gift for picking projects at the cutting edge of consumer demand.
More doodles while figuring the GCMC code produced a summary of the scale offsets:
Musings on the parameters of each scale:
How to draw decades of tick marks:
It turned out easier to build vectors of tick mark values and their corresponding lengths, with another list of ticks to be labeled, than to figure out how to automate those values.
More on all this to come …
Spotted in an arboretum:
How about good old “Keep Out”?
I’m not sure what the “do not touch” icon is supposed to mean, other than a lack of “no entry” icons.
We rented a van to haul our bikes on a vacation trip, but the tire pressure warning alarm sounded when I turned into the driveway. Measuring the tire pressures showed the left rear tire was at 51 psi, far below the 72 psi shown on the doorframe sticker, and a quick check showed a possible problem:
The small circle in the tread to the left of that mark turned out to be a metal tube:
Their tire contractor determined the tire wasn’t leaking, the metal tube hadn’t punctured the carcass, and all was right with the world. After, of course, two hours when we expected to be loading the van.
The rental company was good about it, perhaps because I reported they sent the van out with the other rear tire grossly overinflated to 86 psi (!); obviously, their prep didn’t include checking the tires. Somewhat to my surprise, the space under the passenger seat for a jack was empty.
During the trip, the van laid an egg:
A good time was had by all, but our next bicycling vacation will definitely have much more bicycling and much less driving!
This chipmunk didn’t die in bed, either:
Similar to the previous example, one of the hawks surely dismantled the tail to get at the good parts, although we haven’t seen any gibbage.
Looking into the end, you can see where the next segment would attach:
Somewhere nearby, there’s a recently vacated nest with a pantry full of carefully chosen seeds and nuts, just waiting for another critter to move in …
The Smell of Molten Projects in the Morning 