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.

Category: Oddities

Who’d’a thunk it?

  • Erosion at Work

    Exposed cable anchor
    Exposed cable anchor

    Many years ago, I suppose Central Hudson (the local power utility) drilled a hole into this shale bank, poured in some concrete, and planted an anchor for a pole guy rope.

    Time passes…

    Perhaps this is the result of putting a parking lot behind what’s now the Adriance Library’s Arlington Branch; the asphalt level is two feet below the base of that exposed concrete slug and extends rather close to it. I wonder if the excavators took away too much shale and erosion has continued the process.

    The anchor looks bent, doesn’t it? The pole certainly carries more wires and cables than it did earlier in its career; that lower wire may be exerting more force than is strictly desirable.

    It’ll take a lot more time before this becomes a real problem…

  • Experimental Determination of Squirrel Sprint Speed

    So there we were, biking along the northern segment of the Dutchess Rail Trail, when a squirrel scampered up a fencepost a few hundred feet ahead of us and struck a classic tree-rat pose: standing up atop the post, tail arched behind, front paws together.

    As we rolled closer, the squirrel noticed us and, as squirrels are wont to do, panicked.

    *Must* *run* *away*

    Squirrels tend to escape up the nearest tree, which works perfectly with most predators. In this case, though, the squirrel was already as high as it could get on the post and there were no trees within jumping distance.

    Decision time: can’t run up, can’t escape to the side, must not run toward the threat.

    *Must* *run* *away*

    So the critter lit off along the top rail, hurdling over the protruding fenceposts in a dead run, as fast as its little legs could carry it.

    Which, as it turned out, was just over 15 mph. We stopped pedaling and coasted, but this section is slightly down-grade and we didn’t slow very much.

    The thing was running at my eye level, about five feet to my left, and kept pace with us for maybe a dozen fenceposts. Finally it decided this tactic wasn’t working and dove off the fence into the bushes beside the trail.

    Squirrels must produce adrenaline like I produce saliva.

    And I really, really need a helmet camera…

  • Slide-out Ads: FAIL!

    You know those slide-out ads, the ones that emerge from the lower-right corner of your screen, demanding your attention? The ones that aren’t pop-ups, so pop-up blockers don’t work on them?

    Just had this one appear.

    Focus Your Attention Online
    Focus Your Attention Online

    Words fail me.

    BTW, if you figure out how to block those mumble things, let me know!

  • Dry Ice Sublimation Rate

    For reasons I’m not at liberty to discuss, we had a cooler of dry ice pellets in the freezer for a few days. I used about a pound of it a time to mumble.

    I started with “10 pounds” of dry ice in a half-pound Styrofoam container with 1.5-inch thick walls; the total weights include the container. For what it’s worth, dry ice costs $3.50/pound under 10 pounds, then $2.75/pound over that. It used to be plenty cheaper in the old days, evidently, but everything else was, too.

    In between withdrawals, the cooler sat in the freezer and and the dry ice quietly sublimated; here’s how the weight varied between uses.

    Starting weight: 9.2 lb gross, so I lost quite a bit in transit. Which, as it happened, was about half an hour in a bike trailer during a rather hot afternoon.

    A) 7.2 to 6.7 lb -> 0.5 lb / 15 hr = 0.033 lb/hr

    B) 3.8 to 3.0 lb -> 0.8 lb / 11 hr = 0.072 lb/hr

    C) 2.7 lb to 2.0 lb -> 0.7 lb / 11 hr = 0.064 lb/hr

    I’m suspicious of that low number for the first stay, too. Maybe a side effect of having the cooler’s cavity nearly full of dry ice? Or the freezer ran defrost cycles for the other two?

    Anyhow, to a back-of-the-envelope resolution the cooler loses a bit over 0.05 lb/hour of dry ice. Call it 15 hr/lb.

    The temperature of sublimation is, according to Wikipedia, -109°F. The freezer is around 0°F: a differential of 109°F across 1.5 inches of Styrofoam. Assuming the cooler foam has R=4 with units of (ft^2·hr·°F) / (BTU·in ) and an internal surface area of 304 in^2, the cooler leaks heat at 38 BTU/hr. Call it 11 W.

    Cross check: Wikipedia says the enthalpy of sublimation at STP is 571 kJ/kg. Sublimating 0.07 lb = 0.031 kg requires 18 kJ (18 kW·s) and doing that over the course of an hour requires 5 W.

    Well, considering the rough-and-ready measurements and the fact that the freezer isn’t at STP and that I’m ignoring gas leakage and a bunch of other stuff, a factor of two error is spot on.

    If I were you, though, I’d double-check those calculations before leaping to any particular conclusions. Fair enough?

    When all was said and done, I found this thing in the bottom of the cooler. It wasn’t there when we started, soooo…

    Dry Ice Thing
    Dry Ice Thing

  • Chipmunks Discover Agriculture

    Chipmunk atop sunflower
    Chipmunk atop sunflower

    One of the sunflowers in the garden started swaying wildly, despite having no breeze at all. I though it was a goldfinch plucking seeds, but a quick look through the binoculars showed a brown furry tail hanging below the topmost seed head, about five feet off the ground.

    Mary reports that this is one of five sunflower plants growing in a tight group near the garden fence; she thinks a chipmunk’s seed stash sprouted. This could be the start of something big: next thing you know, they’ll be planting seeds and harvesting crops!

    As we watched, the critter’s cheeks became more and more distended.

    Chipmunk stuffing cheek pouches
    Chipmunk stuffing cheek pouches

    Eventually, however, gluttony overcame common sense.

    Getting the last seed
    Getting the last seed

    Seconds after the shutter clicked, the sunflower head disintegrated, depositing the chipmunk on the ground with a rustle and a soft plop.

    No damage done, we’re sure, and that critter’s pantry should be stuffed full in short order. Next year Mary will probably do some extensive sunflower culling to get room for the rest of her crops!

    And, yes, the title is a riff on Bears Discover Fire…

  • How to Impress a Contest Judge

    Every now and again, I’m asked to judge a technical contest of one sort or another. Let us assume, for the purposes of this discussion, that you are participating in such a contest and I’ve just begun to look at your entry…

    Rule 0: Send a PDF

    The contest rules will tell you what document files they expect; typically, it’ll involve some version of Microsoft Word. Why they do that, I cannot say, but Word documents aren’t really suited to read-only document distribution. Not to mention, some of us don’t have MS Word installed…

    In addition to those files, also include a PDF of your final document file so that when I open it, it’ll look exactly the way you intended. MS Word documents tend to look weird on any PC other than yours, particularly if you have any odd fonts or formatting options turned on. If you can’t figure out how to produce a PDF, install OpenOffice and use the direct PDF export; that’ll also show you how weird MS Word can appear in a different word processor.

    Don’t waste time on a fancy layout, but do pay attention to the basics:

    • Images must fit inside the margins of a single page
    • Use simple fonts that are large enough to read
    • Avoid complex tables and drawings: use PNG images instead

    Hint: ask a friend to review your submission, ideally a few days before you plan to submit it. Take any comments you get very seriously.

    Rule 1: Tell Me What You Did

    The first two paragraphs of your documentation must tell me:

    • What your project does
    • Why that’s a great idea

    That should take, at most, half of the first page.

    You have two paragraphs to catch my attention; sweat bullets over those words!

    Hint: If you can’t summarize what your project does in one sentence, maybe you don’t have a good project.

    Rule 2: Let Me Judge How Easy (or Hard) It Was

    Going on at length about how easy the project was produces the impression that maybe there’s not enough effort in there to justify a few kilobucks of prize money. Conversely, kvetching about how hard you worked indicates that you bit off more than you can chew.

    Let the project tell the story. A good project requires more than a few evenings of effort and, believe it or not, the amount of effort will show up in your description, even if you don’t mention it at all.

    Hint: If you’re trying to be funny, it probably won’t work.

    Rule 3: Use Good Pictures

    Examine all the pictures with a hyper-critical eye.

    • If they’re blurry, delete them and take them again.
    • If you think a picture might be out of focus, it is.
    • If there is the slightest trace of doubt in your mind about the quality of a picture, delete it and try again until you get it right.

    When you get the focus right, ruthlessly crop your pictures. Hint: I don’t need to see the crap on your workbench or the dirty laundry in the corner of your room. Devote all the pixels to your project!

    When you don’t care enough to invest a few minutes getting a good picture, the rest of your project is probably sub-optimal, too. Don’t bother to submit it, OK?

    Crisp pictures can’t sell a weak project. Blurry images rarely accompany a good project.

    Hint: That big LCD on the back of your camera is there for a reason. Use it!

    Rule 4: Support Your Claims

    If you claim to have built a multi-node, RF-networked, high-bandwidth, vibration sensor measurement system, then you must include data supporting your claims. Otherwise, I’ll assume you don’t know what you’re talking about or haven’t actually gotten it working, should my back-of-the-envelope calculations indicate there’s not enough RF bandwidth / range / compute power to pull it off.

    You must convince me that your project does what you claim!

    Hint: Should you claim to have built a snake-armed robot that balances atop a ball while serving drinks from a refrigerator, a video demonstrating it in action is worth a thousand words.

    Rule 5: Don’t Hide a Skeleton

    You may encounter a serious problem that simply can’t be fixed before the contest deadline. When that happens, explain what you intended to have happen, what the problem is, and what you propose as a solution. As long as the problem is secondary to the project’s intent, that’ll be fine.

    For example, if your project involves half a dozen different sensors and you just can’t get the humidity sensor working, explain your debugging efforts and the results.

    Conversely, if it’s a networking project and you can’t get the Ethernet code working, then your entire project just went down the drain and you shouldn’t submit it. I can generally tell when a project simply isn’t going to work, so your efforts to hide the corpse won’t gain you any points.

    Hint: Start your project early enough so that when something goes wrong, you have time to fix it.

    Rule 6: Use the Specified Hardware and Use It Hard!

    The contest is generally about using some particular microcontroller or chunk of hardware. Your project should fully utilize that chip: make sure you read the manual and exploit a whole bunch of its unique features.

    Hint: a project where all the action takes place in a Javascript routine or another, entirely different microcontroller probably isn’t making good use of the specified chip.

    The Bottom Line

    If you’ve got a good project and describe it well, you’re probably in the money. Plenty of other entrants will ignore these suggestions and wind up on the bottom of the pile.

    Fair enough?

  • Railway Infrastructure: The Rot

    Saw this while riding along a rail-trail route west of Philadelphia. Evidently they left the catenary support structures standing over the trail to carry the (still energized!) power lines, but the I-beams webs across the trail have rusted completely through.

    Rusted railway catenary support
    Rusted railway catenary support

    Verily, rust never sleeps… I wonder if they ran diesel locomotives along this part of the line?

    The beams across the active railway seem to be in fine shape.