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.

Month: December 2008

  • Ya Gotta Have Tools, Mobile Division

    Once upon a time we delivered a van full of composted leaves to Mary’s Vassar Farms garden plot in the evening.

    There’s a gate at the entrance that was half-closed, but Mary’s never seen it closed & locked, so we drove in and parked by the plot to toss bags. We were done in about 15 minutes, drove back to the gate, and found the Vassar security folks had locked it… with the van in plain sight.

    My guess is that they were busting our chops, but one should never ascribe to malice what can be explained by stupidity.

    We had a phone, but none of the bystanders knew what number to call. The ladies reported that the other gate was also locked. A chain-link fence surrounds the plots.

    What to do?

    The gate hinges were plain old 1″ bolts and nuts, so I figured I could just dismount a gate, drive out, then put the gate back in place. Non-destructive and easy to explain if The Man arrives while I’m at work. Plan B was to just cut the padlocked chain holding the gates together.

    The back of the van has a small “tool” compartment for the jack and suchlike. I long ago added a multi-bit screwdriver set, a medium adjustable wrench (not quite big enough for a 1″ bolt, alas), a Vise-Grip, and similar odds & ends.

    Fortunately, it turned out that the chain around the middle of the gates had two links held together with a 1/4-20 bolt and two nuts. I suspect this sort of thing has happened before, perhaps to someone else with a Vise-Grip.

    Five minutes later, we were outside, the gate was closed & locked, and the tools were back in place.

    Memo to self: add a bigger wrench.

  • Spots on the Windshield

    So a while ago we stayed at Mary’s folks’ apartment in Saratoga Springs.

    We parked in the Visitors section of the lot in front of the rental office and, the next morning, the windshield had a bunch of whitish water-droplet-sized spatters. The previous day had been a bit rainy and we drove home over some wet roads, so I thought nothing of it; that’s what windshield washer juice is for.

    But the spots didn’t quite wash off: most of the white center went away, leaving an oval outline with a line across the middle. The spots now looked like a Greek capital Theta, as though each droplet had landed on the window, slumped to the bottom of the wet area, then evaporated.

    I discovered that diligent rubbing with windshield washer juice and a soft rag didn’t remove the Thetas. They looked, alarmingly, as though they’d etched their way into the glass: thin lines emerged from the rounded outline, with a sort of crinkly surface finish.

    Running up the hazmat scale, I applied homebrew glass cleaner to no avail. Then I deployed denatured alcohol. Ditto.

    Finally, I had a bright idea: glugged some vinegar on a rag and wiped those suckers right off, leaving the windshield sparkly clean!

    As nearly as I can tell, the apartment watered their fancy new sod overnight with genuine Saratoga municipal water through below-ground sprinklers. Yup, water straight from the same aquifers supplying the local mineral baths. Maybe cleaned up a bit, but certainly not softened.

    Hard water spots on the windshield, indeed!

    And, yup, soap doesn’t lather worth a darn in their shower…

  • Steel Preservation, The Good Old Days of

    Cadmium plated hangers
    Cadmium plated hangers

    Last year I geared up for scraping the soffits and figured I should put a piece of plywood across the windows so I couldn’t possibly have the ladder fall into a window. The storm windows are big, awkward inserts that hang from hooks atop the frames, so I planned to cut a plywood blank to match the opening.

    Gene left us a cigar box of “Storm Window Hdwr” containing this card of hooks-and-eyes that looked just like the ones on the windows. Alas, they’re not quite the same and don’t quite fit, a fact I discovered after mounting them and manhandling the sheet out the window. So much for “standard size”.

    But I’m sure the hardware on the side of the house looks as good as it does because it’s cadmium-plated, too! None of the hooks & eyes have a hint of rust, other than where the edges scrape together, after half a century.

    I heroically refrained from sucking my thumb afterward…

  • Rehabilitating an Old Variac

    Variac Rotor Before Fixup
    Variac Rotor Before Fixup
    Variac Brush Holder and Staking
    Variac Brush Holder and Staking
    Variac Rotor After Fixup
    Variac Rotor After Fixup

    So I’ve had this ancient 5 A Variac on the heap for far too long, finally came up with an actual application, and discovered that not only was the line cord shot, it basically didn’t work.

    Of course, I had to replace the cord & outlet before I discovered that it didn’t work…

    The classic Variac failure happens when the carbon brush wears down to nothing, at which point the holder scrapes on the windings and the whole thing burns out. In this case, the brush still had 3/16″ left, but the sliding holder was firmly corroded in place.

    I soaked it in PB’laster, rapped it all over with a small drift punch, and managed to drive the holder out. In the process, the brass sleeve around the brush holder came out, putting the entire problem on the bench.

    The rotor had two brass rivets securing the brush contact bar (the part that’s connected to the actual brush holder by a length of copper braid) that would not come out, nohow. After I broke one off (the first picture), I found that they were swaged over on the bottom, so I broke the other one off and punched both stubs out.

    I spent a few hours wearing a headband magnifier and gently filing everything to a pair of slip fits: brush holder into sleeve, sleeve into rotor. The rotor is aluminum, so I applied a liberal dose of oxidation inhibitor, slipped the sleeve in place, and staked that sucker down.

    Which meant I spent another half hour filing the brush holder to restore the slip fit…

    Turned out that the rivets were 40 mils, the holes were 43, and 00-90 machine screws are 43.5. I don’t have a 00-90 tap (mostly because I know I’d break it by looking hard at it), so I just ran a screw into the hole and formed the threads. They must have 10% engagement, tops, but this isn’t a high-stress application.

    This is, I think, the first time I’ve ever used those 00-90 screws and nuts. The washers are 0-80 so they reach over the brush contact bar far enough to hold it in place. Dang, those things are small!

    The main conduction path seems to be through a brass slip contact, into the aluminum rotor, through the brass sleeve, and into the carbon brush. I’m not convinced the rivets / screws conduct any appreciable amount of current to the contact bar and through the braid, but I shined up the contact patches anyway.

    Put it all back together, fired it up, and it worked!

    Ought to be good for the next half-century, at least…

  • License to Laugh?

    Washington DC License Plate
    Washington DC License Plate

    Found this one in a Hershey motel parking lot.

    It turns out that these are official DC tags, not some weird protest movement’s idea of a good time!

    http://dmv.dc.gov/serv/plates/tax.shtm

  • Counterfeit Memory Stick from eBay

    Bogus Memory Stick - Front
    Bogus Memory Stick – Front

    Last year I bought a “generic” Sony Memory Stick using eBay’s Bidding Assistant to get one of a whole bunch of similar items. Got it for a reasonable price, opened it up, and it turned out to be “too good to be true”: it looked to be a genuine Sony stick in sealed Sony packaging.

    I checked the “how to identify a counterfeit Memory Stick” sites and concluded that it really was genuine, what with good printing and laser engraving. Sometimes these things happen; maybe the seller got a pallet of leftovers?

    Bogus Memory Stick - Rear
    Bogus Memory Stick – Rear

    It failed a few months later, I mailed it to Sony for a warranty replacement, they concluded it was a fake, and sent it back. Huh. Those cunning Chinese are getting really good at making fakes; maybe this was a “fourth-shift” product from the real Sony factory.

    I contacted the seller, who said he sells “generic” products. I pointed out that “generic” means a second-tier manufacturer’s correctly labeled product, but that he sold a falsely labeled item. He offered a refund, I asked for money to cover my shipping, and he agreed. Knock me over with a feather.

    So I sent it back and he actually refunded my money, plus shipping both ways. More feather toppling.

    Sony Warranty Rejection
    Sony Warranty Rejection

    The term “fraud” did not enter the conversation, but I think he knew he was on thin ice and was willing to do whatever it took to make me Go Away.

    From what I can tell, reporting this to eBay has no effect, because they already know and simply do not care.

  • Database Follies

    My “biz” (I use the term loosely) credit card statement had a $7.25 mystery charge from “NEWARK US CHICAGO IL”. I have done biz with Newark Electronics (and their HQ is in the Windy City), but not recently. Soooo, I gives ’em a call to ask WTF. Got passed from ear to ear, eventually reaching Jolanta in Credit Card Billing.

    I described what I knew, she tapped in my credit card number, paused for a moment, then said “Oooooh, I know what happened!”

    Turns out that they use “general account numbers” (or order numbers, or some such) for low-budget customers like me and that they recycle those numbers. A while ago it seems “the computer” started

    1. Assigning some no-doubt-carefully-chosen general account number to the new transaction
    2. Reaching into the database for, um, data
    3. Sending the bill to the old account holder

    Oops.

    She says “the programmers are working on it right now” and she’ll refund the money muy pronto.

    Wanna bet that a few somebodys got mystery charges for a few kilobucks apiece?

    Uh-huh…