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.

Author: Ed

  • Getting More Clearance While Bicycling

    Some cyclists complain that motorists don’t give them enough room while passing. That’s less of a problem for recumbent bikes, but this gets me a lot more clearance:

    Bike trailer with propane tank
    Bike trailer with propane tank

    There’s one section of very nice and totally gratuitous 6-lane highway (NY Route 55 near the NYS DOT Region 8 HQ; I think they’re just showing off) where drivers normally edge over to the left side of the right-hand lane where I’m riding. With a 20-lb propane tank lashed to my bike trailer, most folks have no trouble whatsoever with a double lane change into the far left lane…

  • 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?

  • APRS Beaconing: On Being Relatively Prime

    I ran into an amusing situation on a recent family bike ride with our GPS-to-APRS trackers running: my ladies were transmitting a few seconds apart. As a result, I had to listen to a pair of very short data bursts in quick succession throughout the whole ride.

    Under normal circumstances that doesn’t happen, because I set the TinyTrak3+ trackers to delay during and wait a second after a voice PTT that collides with an automatic beacon. Somehow they never managed to delay an APRS beacon to knock the synchronization off kilter.

    So I tweaked the automatic transmission intervals to make us relatively prime: 179, 181, and 191 seconds. That’s close enough to the original 180 seconds as to make no difference, while now ensuring that we won’t collide with each other for very long even if we should get aligned.

    An alternative is SmartBeaconing, which I’ll turn on in a while after I collect a bit more data.

    A useful table of primes is there.

    If you have some spare CPU and power, you can join the Great Internet Mersenne Prime Search and help find new primes, albeit ones much larger than I need…

  • Yaesu FT-857 Front Panel: Up-Armored Plug

    The  remote cable for the Yaesu FT-857 I have in the car terminates in an 8-pin modular plug. The connector body has a cutout for the round rubber (?) insulation around the cable; it’s not set up for a standard flat 8-wire network cable. However, the cable makes a right-angle bend immediately outside the Front Panel to fit inside the confines of the remote mounting case, which pulled the insulation out of the connector.

    Connector with displaced insulation
    Connector with displaced insulation

    The electrical connections are fine, but that can’t last. I finally got around to armoring that bend to (I hope!) prevent any problems. Contrary to what you might expect from my proclivity to blob epoxy on everything, I blobbed on hot-melt glue to hold the wires in place, as well as turn a bit of the cable into a rigid body. Even in a hot car, this ought to work fine…

    Connector with hot-melt glue
    Connector with hot-melt glue

    I put some ordinary adhesive tape on the back of the Panel, butted up against the connector body, to keep the glue out of the socket and off the (back of the) Front Panel. That prevents the connector from becoming one with the Panel.

    Pause while the glue solidifies, release the latch and pry the connector+glue off the tape with a small screwdriver, trim the excess glue, then peel the tape off the Panel. The connector snaps into place just like it should and the wires no longer have any freedom of motion.

    Here’s what the modified connector looks like in all its glory. The cable really does bend downward slightly beyond a right angle in order to fit into a recess in the Front Panel.

    Finished connector kludge
    Finished connector kludge

    This isn’t suitable for a connector getting a lot of the old in-out in-out, but the Front Panel remains in place for months at a time and this should delay the inevitable failure.

  • 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.

  • Emergency Spoke Repair: FiberFix FTW!

    The rear wheel of my bike popped a spoke while I was riding along a section of unimproved trail trail. Actually, it’d be more accurate to say “as-abandoned” railway line; they ripped out the ties and graded the baby-head ballast more-or-less level. It wasn’t really suitable for a long-wheelbase recumbent bike, but I really hate white-water rafting, which was the other choice.

    Anyhow.

    Of course, the broken spoke was on the sprocket side of the rear wheel. I discovered this when we were out of the most rugged section, so I have no idea how long I’d actually been abusing the wheel.

    I released the rear brake, gingerly rode to the campsite, then installed the FiberFix emergency spoke I’ve been carrying around for a few years. After snugging the cord and tightening the nipple, I added a turn to each of the two adjacent spokes, making the wheel true enough to continue the mission.

    FiberFix spoke in action
    FiberFix spoke in action

    The other end simply passes through the spoke hole in the hub. It doesn’t mind the deformation pressed into the hub.

    Hub end of FIberFix spoke
    Hub end of FIberFix spoke

    Much easier than removing the sprocket cassette under field conditions, that’s for sure!

    Back home in the shop, I installed a new spoke, tightened it up to match the others, backed out the extra turn in the adjacent spokes, and the wheel trued right up.

    I originally built the wheel using a Park Spoke Tension Meter, which is a wonderful tool. If you build wheels, even occasionally, you really, really need one. Lace ’em up, tighten uniformly, then tweak just a little bit for a perfectly true wheel.

    And, yeah, Phil hubs on all three bikes. I hate adjusting bearings. The man is gone; may his legacy live forever.

    Memo to Self: Tension = 23±1 on the drive side.

  • SPD Cleat Backing Plate: Filling the Gap

    SPD cleat backing plate gap filler
    SPD cleat backing plate gap filler

    Mary’s feet are exquisitely sensitive to irregularities in the insoles of her shoes, which poses a real problem with her bike shoes: those SPD cleat recesses are no good at all.

    This is a view down into one shoe, with the SPD cleats adjusted all the way to the rear. That leaves a large recess in the front, which was painfully obvious to her sole. The white shape is the gap filler…

    I pressed a sheet of paper across the gap to get the general shape, traced it twice onto a slab of 0.060-inch aluminum with a nice pebbly paint job, and cut the two pieces out. A few conversations with Mr Belt Sander, a few licks with a rat-tail file, and they dropped right onto place. The recess is slightly curved, but I didn’t have to bend the pieces to fit.

    I laid duct tape across the whole affair, put the insoles back in place, and it was all good.

    The backing plate is 0.072 inch thick and she was content with the difference.

    In previous shoes, with the cleat near the middle of the adjustment range, I’ve stuffed epoxy putty into the gaps. That works, but it doesn’t bond to the (miracle engineering plastic) soles and tends to crumble. This is Not A Good Thing…