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.

Tag: Repairs

If it used to work, it can work again

  • Raspberry Pi “Moster” Heatsink Retaping

    A pair of colorful laser-cut stacked acrylic Raspberry Pi cases with “Moster” (*) heatsinks arrived, with the intent of dressing up the HP 7475A plotters for their next Show-n-Tell:

    Moster RPi Heatsink - assembled case
    Moster RPi Heatsink – assembled case

    Unfortunately, the thermal tape on one of the CPU heatsinks was sufficiently wrinkled to prevent good contact with the CPU:

    RPi taped heatsinks - as received
    RPi taped heatsinks – as received

    The seller sent a replacement copper slug with tape on one side. Presumably, they glue it to the heatsink with thermal silicone:

    Moster RPi Heatsink - silicone adhesive
    Moster RPi Heatsink – silicone adhesive

    Of which, I have none on hand.

    So I did what I should have done originally, which was to drop a few bucks on a lifetime supply of thermally conductive heatsink tape, apply it to the bare side of the slug and stick the slug to the heatsink with their tape:

    Moster RPi Heatsink - replacement adhesive tape
    Moster RPi Heatsink – replacement adhesive tape

    The blue stuff is the separation film, with the tape being white. It doesn’t match the black tape on the other side, but seems gooey enough to work.

    Done!

    Despite the heatsink hype, ball grid array chips dissipate most of their heat through their pads (and perhaps a central thermal pad) into the PCB, so sticking a heatsink atop the package is largely decorative, along the lines of hotrod ornamentation.

    The epoxy packages used in previous Raspberry Pi iterations had better thermal conductivity to their top surface:

    RPi 3 B - epoxy CPU
    RPi 3 B – epoxy CPU

    Than the more recent metal-top packages, which surely have inert-gas fill under the lid:

    RPi 3 B - metal CPU
    RPi 3 B – metal CPU

    Pix cropped after being pilfered from the Official Raspberry Pi site.

    Yes, the heatsink does conduct some heat into the air, even if not nearly as much as you might want.

    (*) I’m pretty sure “Moster” was a typo in the original eBay listing which took on a life of its own to become something of an unofficial trademark. All of the search results ship from Duluth, Georgia (USA), regardless of the nominal seller; feel free to draw your own conclusions.

  • New Utility Pole

    After about a month, a replacement for the fallen utility pole arrived:

    New Utility Pole Arrives
    New Utility Pole Arrives

    This is much easier than digging a hole by hand:

    New Utility Pole - auger clearing
    New Utility Pole – auger clearing

    Verily, given the right tools, any job becomes do-able:

    New Utility Pole - installing
    New Utility Pole – installing

    It was fascinating for me and just another day at the office for everybody else:

    New Utility Pole - wiring
    New Utility Pole – wiring

    They nailed the original pole tag to the new pole, complete with the original 1940 nail:

    New Utility Pole - pole tag 144701
    New Utility Pole – pole tag 144701

    I expect this pole will outlive me, just as the original pole outlived the folks who built our house.

    The most memorable comment came from the person doing the CHG&E damage assessment, who really really wanted this to not be their problem: “Anybody could steal a pole tag and nail it on that pole.” I asked what location their records showed for the pole tag, whereupon the conversation moved on.

    Second-place award: no, we were not interested in trenching underground lines 300 feet along the property line, at our expense, to avoid an “unsightly” pole.

    For unknown reasons, I was supposed to figure out which telecom utilities had wired the pole, notify them, and wait for them to tack their cables to the new pole. I called both Verizon and Altice / Optimum, got service tickets, and watched them close the tickets without further action. I tried re-opening the Verizon ticket and was told somebody would be there within 48 hours. An Optimum guy showed up, promised a quick return visit from a team with proper equipment, but nothing happened.

    I suppose having no customer at the end of the cable removed any motivation to clear their hardware off our lawn, so, after two weeks, I deployed the bolt cutter, rolled up the cables, and scrapped ’em out.

    Done!

  • Michelin Protek Tube: Another Slow Leak

    After a few days of topping off the rear tire on Mary’s bike, with no gashes or debris in the tire, I finally replaced the Michelin Protek tube and autopsied it:

    Michelin Protek tube autopsy
    Michelin Protek tube autopsy

    While it’s possible to extract the valve and perhaps even clean / replace it, I think that’s just delaying the inevitable. The rubber shreds may be necessary to fill large punctures, but they seem to wreck the valve seal.

    Her bike now has an ordinary (pronounced “cheap”) tube inside the Schwalbe Marathon Plus armored tire. We’ll see how long this lasts.

  • Raspberry Pi vs. MicroSD: Another One Bites the Dust

    The Raspberry Pi running the MPCNC recently seized up with baffling symptoms, which generally indicates the poor little MicroSD card serving as a “hard disk” has failed:

    Defunct Sandisk Ultra 32 GB MicroSD
    Defunct Sandisk Ultra 32 GB MicroSD

    I managed to open a terminal emulator, whereupon all of the non-built-in shell commands couldn’t be found.

    Proceed as before: binary-copy the entire MicroSD card to another one, pop it in the RPi, and it’s all good again.

    For the record, the new card is an unused Samsung Evo Plus. I do not understand the difference between the “Evo Plus” and “Evo+” branding, other than to suspect one of being a very good fake.

    In round numbers, MicroSD cards seem to last a year under what seems like not-too-demanding service; I’m not running the MPCNC all day, every day.

  • Alligator Clip Lead Refurbishing

    So this happened when I grabbed an alligator clip lead:

    Dual Alligator Clip Collection
    Dual Alligator Clip Collection

    My coax cable and clip lead collection includes everything from “I’ve had it forever” to “Recent cheap crap”, including much of Mad Phil’s collection. Some of the recent crap included Chinese clip leads with what can charitably be described as marginal connections:

    Alligator clips - bent wire
    Alligator clips – bent wire

    The insulation may provide some compliance in the crimp, but the alligator clip itself consists of cheap steel which won’t hold a crimp, even if it was crimped firmly to start with.

    As a rule, the crimps aren’t particularly good:

    Black Dual Alligator - as manufactured
    Black Dual Alligator – as manufactured

    The most obvious effect is high end-to-end resistance:

    Black Dual Alligator - before - A
    Black Dual Alligator – before – A

    Yes, yes, 122 Ω in an alligator clip lead is high.

    The test setup isn’t particularly intricate:

    Black Dual Alligator - test setup
    Black Dual Alligator – test setup

    The lackadaisical crimps also have unstable resistances:

    Black Dual Alligator - before - B
    Black Dual Alligator – before – B

    So I figured I may as well repair the lot of ’em.

    I stripped the lead back to expose fresh copper, soldered it to the clip, then re-crimped the clip around the insulation for some token strain relief:

    Black Dual Alligator - soldered
    Black Dual Alligator – soldered

    I won’t win any soldering awards, but the resistance is way better than before:

    Black Dual Alligator - after
    Black Dual Alligator – after

    If more than half an ohm seems a tad high for a foot of copper wire, you’re right. My slightly magnetized bench screwdriver shows it’s not copper wire:

    Copper-plated steel wire
    Copper-plated steel wire

    I’d say it’s copper-plated steel, wouldn’t you?

    Those of long memory will recall the non-standard ribbon cable I used as a 60 kHz loop antenna. In this case, the Chinese manufacturer figured nobody would notice or, likely, care. Given the crappy overall quality of the end product, it’s a fair assumption.

    I was mildly tempted to replace the wire with good silicone-insulated copper, but came to my senses; those “high voltage” silicone test leads will be Good Enough for higher-current connections.

    While I was at it, I pulled apart my entire collection just to see what was inside and fix the ailing ones. These clips date back to the dawn of time, with what started as excellent crimps:

    Crimped Alligator Clips - as manufactured
    Crimped Alligator Clips – as manufactured

    Alas, after I-don’t-know-how-many decades, they’re not longer gas-tight, so I soaked a dollop of solder into each one:

    Crimped Alligator Clips - soldered - Made In Japan
    Crimped Alligator Clips – soldered – Made In Japan

    Chekkitout: “Made In Japan”.

    Someone, perhaps me wearing a younger man’s clothes or, less likely, Mad Phil in a hurry, solved a similar problem with bigger blobs and no strain relief:

    Crimped Alligator Clips - cut and soldered
    Crimped Alligator Clips – cut and soldered

    So, now I have a slightly better collection of crappy alligator clip leads. The copper-plated steel wires will eventually fail, but it should become obvious when they do.

    Test your clip leads today!

  • Bathroom Drain Rod Status

    The bathroom drain rod slipped out of the pop-up stopper, giving me the opportunity to see how well it’s surviving:

    Bathroom drain lever - 2019-08-03
    Bathroom drain lever – 2019-08-03

    After not quite two years, it’s not obviously rotting away.

    Life is good …

  • CNC 3018-Pro: Assembly Tweaks

    If you regard your new CNC 3018-Pro Router kit as a box of parts which could, with some adjustments and additional parts, become a small CNC router, you’re on the right track.

    In my case, the aluminum extrusions arrived somewhat squashed inside their well-padded foam shipping carton, which leads me to believe the factory responsible for tapping the bolt holes in the ends must be a fairly nasty place. In any event, the hammerhead T-nuts for the gantry struts simply didn’t fit into some sections of the slots, although they worked fine elsewhere.

    So, file a smidge off the rounded sides of a few nuts:

    3018CNC - 2020 T-nuts - filed
    3018CNC – 2020 T-nuts – filed

    Which let them slide into place and rotate properly despite the bent channel:

    3018CNC - 2020 T-nuts - trial fit
    3018CNC – 2020 T-nuts – trial fit

    The assembly instructions used a word I’d never encountered before:

    3018CNC - Gantry plate position
    3018CNC – Gantry plate position

    Turns out ubiety is exactly correct, but … raise your hand if you’ve ever heard it in polite conversation. Thought so.

    I’ve not noticed any harm from rounding off the position to 46 mm; just position both struts the same distance from the rear crossbar and it’s all good.

    The struts behind the CAMTool CNC-V3.3 electronics board were also squashed, prompting a bit more filing:

    3018CNC - CAMTool v3.3 board - trial fit
    3018CNC – CAMTool v3.3 board – trial fit

    The CAMTool board is basically an Arduino-class microcontroller preloaded with GRBL 1.1f and surrounded with spindle / stepper driver circuits.

    As with the MPCNC, I’ll dribble G-Code into it from a Raspberry Pi. Alas, the struts behind the CAMTool board are on 75 mm centers, but the Pi cases on hand have feet on 72-ish mm centers. Pay no attention to the surroundings, just drill the holes in the right spots:

    3018CNC - RPi case - drilling
    3018CNC – RPi case – drilling

    Add more T-nuts and short button head screws, with rubber pads between the case and the struts:

    3018CNC - RPi case - mounted
    3018CNC – RPi case – mounted

    It’s coming together!