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.
If it used to work, it can work again
I picked up a pair of Raspberry Pi V1 cameras, both of which arrived unstuck to their breakout board:
Requiring the customer to peel off the white layer and stick the camera to the PCB helps keep costs low. They’re $4 if you’re willing to wait two months or $7 from a “USA Seller”.
Apparently, “porcelain chip fix” epoxy survives about a year in a bathroom sink:
It came loose from the drain rim while I was cleaning the sink; I wasn’t doing anything particularly vigorous.
The stain in the lower right goes all the way around the epoxy:
For what should be obvious reasons, I was loathe to scuff up the sink surface to give the epoxy a better grip, so it couldn’t make a watertight seal all the way around.
A closer look at the stain:
I’m reasonably sure that’s iron bacteria colony, rather than actual rust, as there’s no iron to be found anywhere nearby.
For lack of anything smarter, I’ll apply another dose of the same epoxy, although this time I won’t be expecting a long-term fix.
Riding south on Rt 376 takes us across the Mighty Wappinger Creek on a four-lane concrete bridge built about 1995. This Dutchess County Aerial Access photo shows it in 2016:
A pothole opened up on the south end of the span last year:
NYS DOT patched it a while ago:
This year, we’ve been avoiding a new pothole opening on the north end:
It’s difficult to ride between the right side of the hole and the weeds growing from the curb joint under the guide rail, so we take the lane whenever we can. The extensive vegetation growing in the bridge structure can’t possibly be a good thing.
The bridge deck rests on steel beams across the creek, with plenty of corroded concrete along the edge:
The concrete seems to be failing by tension overload as the beams flex downward under traffic loading and pull the top surface apart. The surface has irregular transverse cracks across the deck width, not all of which look like control joints.
With potholes and surrounding cracks allowing brine into the deck, we expect much worse deterioration during the next few years.
My Professional Engineer license has long lapsed, not that I ever knew anything about bridge design, so this is mostly observational.
The 4 inch column on the rear patio holds a bracket, probably intended for a welcoming sign or some such, which keeps the suet feeder mostly out of reach. It desperately wanted a coat of black paint to match the railing, so I stripped the old paint and applied Evapo-Rust:
The dark areas are iron oxide being converted to loose iron sulfide, which is what Evapo-Rust does for a living.
One could, of course, simply buy new eye screws & nuts, but we’re deep into historical preservation around here.
An hour of soaking and a few minutes of wire-wheeling got everything down to bare metal, ready for some rattle-can primer and black paint action:
It’s a version of what Eks calls a “used car finish”: high shine over deep pits.
Discussion of why one should not paint threaded parts will be unavailing; in this case, paint serves as permanent threadlock. I re-spritzed the eyescrews & nuts after getting everything aligned, so as to produce a lovely two-coat over-all finish.
The birds won’t care one way or the other and, as long as the paint lasts, neither will we.
The display on Mary’s Cateye Astrale “Cyclocomputer” had once again faded to gray, so it’s time for a new CR2032 lithium cell:
The old cell read 2.5 V, well below what it should be.
The notes scrawled on the cell become readable under better light:
Seven years (at 1942 mile/yr) ain’t bad at all!
To replace the cell fast enough to maintain the odometer reading, just unscrew & remove the battery cover, slam the back of the Astrale on the bench, and pop in the new cell.
Maybe I should replace the cell twice a decade, regardless of how feeble it might be?
Back in the early 90s, I bought a Branson Ultrasonic Cleaner for small parts. It turned out to be ideal for eyeglasses, migrated to the bathroom, and has been used at least daily ever since. After nigh onto three decades, this happened:
We tend to push the ON button and let it turn off by itself after a little over four minutes (exactly 255 seconds!), so the gray plastic sheet over the ON switch failed first. You can barely see the outline of the transparent film previously covering both switches, which probably helped waterproof the switches.
The gray plastic disk sits atop the switch actuator, so I punched a slightly larger polypropylene disk (from my stash of clamshell packages), stuck it to the disk with double-sided tape, lined it up over the hole, and covered the mess with Kapton tape:
This is in the nature of an expedient fix, as I’m not sure the polypro disk is flexible enough. The next iteration will cover the entire gray area and I’ll see about a transparent tape covering.
Maybe in another decade?
The flanges around the door of our giant mailbox rusted through, leaving the door to bend along the embossed (debossed? Whatever) lines across the front. Eventually, the bend got bad enough to keep the door from latching closed, but reviews of the current crop of mailboxes suggest they’re even more prone to rusting after even fewer years.
Well, I can fix that:
Because the bottom third of the door, basically everything around and below that horizontal ridge, had corroded, the general idea was to stiffen it with an internal plate:
The array of small holes suggest the plate’s rich lived experience. Some are even tapped!
External angle brackets stiffen the sides along the corroded flanges and surround the equally corroded pivot holes:
The term “brick shithouse” springs unbidden to mind, doesn’t it? Those spare holes come from previous uses; I decided this application didn’t demand cosmetic perfection and, as a result, the remaining angle stock has no holes at all.
Also, the angle brackets are as long as they are because that’s the maximum throat depth for Tiny Bandsaw™. I splurged on a Proxxon 10-14 TPI blade (for future reference: PN 28172) that cuts aluminum like butter, much better than the stock 14 TPI blade.
The hinge pins used to be rivets. After careful consideration, I replaced them with 1/4-20 button-head cap screws:
Yes, the sheet metal now pivots on screw threads, rather than a nice smooth cylinder. The nyloc nut maintains the proper amount of looseness around the battered sheet metal.
While I had the door open, I slobbered hot melt glue over the flag anchor, which should keep it from spitting the ratchet pin into the roadside debris ever again:
A pleasant evening of Quality Shop Time, indeed!
The alert reader will note I’m securing aluminum plates with stainless steel hardware on a (nominally) galvanized steel box, thereby forming several batteries with a brine electrolyte from wintertime road salt. My engineering judgement determined this repair will last Long Enough™ and, most likely, succumb to somebody not quite making the curve while accelerating from the traffic signal.
Aaaaand those painted numbers still look pretty good after four years.
The Smell of Molten Projects in the Morning 