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: Machine Shop

Mechanical widgetry

  • Water Heater Drain & Flush

    Flushing with Y hose connector
    Flushing with Y hose connector

    For reasons that aren’t germane here, I’m responsible for two water heaters. Having just replaced one of them, I figured I should do a preemptive drain-and-flush on the other and check its anode rod.

    In principle, you just hitch a garden hose to the drain valve, turn it on, and flush the sediment right out of the bottom. In practice, it doesn’t work that smoothly, as the valve has a teeny little opening that instantly clogs with grit.

    The first step is to shut off the water, open the drain valve, and disconnect both flexible couplings at the top of the heater. You will move the heater a little bit during this operation and that will cause the flexy connectors to leak, maybe just a little bit, but enough to cause Bad Things to occur.

    In the past I’ve used a Y hose connector with a homebrew double-female adapter to blow water into the bottom of the heater; the hose runs to a nearby sink with a male hose thread on the cold-water faucet. The two teardrop-shaped black handles on the Y adapter are ball valve handles (crappy valves, but good enough).

    It goes like this:

    • Close the Y hose valve
    • Turn on the water at the sink
    • Open the water heater drain valve
    • Open the Y drain valve
    • Watch a brief piddle of water hit the bucket
    • Close the Y drain valve
    • Open the Y hose valve to blast water into the tank
    • Close it again
    • Open the drain
    • Repeat as needed

    With any luck, you won’t have that much sediment and the drainage will clear after only a few iterations. That didn’t happen here…

    Water heater drain valve parts
    Water heater drain valve parts

    The next step is to apply a strap wrench to the drain valve, remove the cover and core, and see if the larger opening will produce more flow.

    Note that the drain valve, at least on this Whirlpool heater, is basically a coarse-thread plug that depends on a rubber disk to seal against the valve body. I’d really rather have a full-flow ball valve down there instead of this piddly little thing.

    it is possible to replace the drain valve entirely, but the last time around I applied far more force than I thought prudent to the plastic valve body and got exactly bupkis in the way of rotation. Not wanting to break the damn thing off, I gave up.

    Valve cleanout with copper wire
    Valve cleanout with copper wire

    Anyhow, with the guts of the valve out of the way, the flow was still fairly weak. I rammed a copper wire up its snout and dislodged a truly disheartening amount of crud. The opening kept jamming shut, which meant there was a great pile of sediment atop the opening, so I spent quite  while wiggling the wire to keep the water flowing and the grit emerging. The pic at at the bottom shows some of the pile; there’s a heaping double handful of sediment on that shovel.

    The bottom of the tank is flat, with the valve pretty much flush with the bottom. That means you’ll leave a huge pile of sediment inside unless you swish some water around. That, of course, will clog the valve. Repeat until tired.

    When you go to put the valve back together, don’t be surprised if it doesn’t seal. Tighten the cap, put a hose plug on the outlet, and move on.

    You can tell by the color of the water that Something Is Not Right inside the tank… more on that tomorrow.

    Some of the water heater sediment
    Some of the water heater sediment
  • Audio Headset Hanger

    Headsets Off the Desk
    Headsets Off the Desk

    For obscure reasons, I have a pair of headsets attached to the PC: one USB that’s used for phone calls and one plugged into a sound card for everything else.

    They’ve been cluttering up the corner of the desk for far too long, so I bent up a rack from a surplus coat hanger. Nothing critical, as long as it’s tall enough to hold the mics off the desk and wide enough they don’t clunk together.

    The trick is to just drill a hole in the top of the desk and poke the end of the rod into it. That works because my desk has a notch along the edge just exactly the right width to hide the hole!

    Hanger Mounted Under Desk
    Hanger Mounted Under Desk

    Maybe you don’t want to do this to the top of your desk, in which case maybe you can bend the hanger around the edge and put a screw in the bottom or the desktop. If you don’t look under there very often, the spiders will take over; this one is from the basement desk that I haven’t used for far too long.

    Details of the hanger, not that you can’t figure it out on your own:

    Headset Hanger
    Headset Hanger

    I suppose you could actually buy these things…

  • Digital Caliper Disassembly

    Caliper Back Side - Label Removed
    Caliper Back Side – Label Removed

    Just in case I spill a sticky liquid on the caliper and must disassemble it again…

    This was a relatively inexpenive, but not dirt cheap, caliper that has worked fine all along, apart from the issue with the thumb roller frame.

    After removing all the obvious screws, taking off all the various doodads, and extracting the sliding jaw, it still doesn’t come apart. The trick, as always, is to peel the label off the back side to reveal the five crucial screws that secure the electronics package to the metal scale.

    These screws don’t have the best heads in the world, but a #2 Phillips driver, solid pressure, and steady torque gets them out. All but one of the screws are pointed; the one in the lower-left corner (as above) is a machine screw that, I think, ensures a good electrical connection between the metal frame and the electronics package.

    Caliper Disassembled
    Caliper Disassembled

    With those screws removed, the electronics package pulls off to expose the innards. Note the cough delicate hand-forging that secures the tang to the back plate.

    The schmutz on the far right matched up with a similar patch of rust on the sliding scale. Some TopSaver rust treatment applied with a scrubbing pad reduced the problem to mere discoloration; the rust wasn’t all that deep.

    Reassemble in reverse order, with dabs of lubricant on the obvious wear points along the way. The thumb roller must go on after securing the electronics package, not before.

  • Water Heater: Flexible Tube Heat Trap

    Flexible tube heat trap loop
    Flexible tube heat trap loop

    The insulation on water heaters is pretty good these days: the exterior shell stays within a few degrees of ambient temperature. However, hot water rises, which shouldn’t come as any surprise, and convection currents can drain a surprising amount of heat out of both the hot & cold water lines on the top of the heater.

    So I added heat trap loops to the inlet & outlet plumbing using flexible tubing. These are 18″ long and I might replace them with 24″ lines to reduce the angle at the water heater. Surprisingly, there’s not much strain in the tubing: it’s happy with that bend.

    The guidelines say you need a foot or so of vertical loop, but even this piddly loop keeps the upper fitting at ambient temperature after a night without drawing any hot water.

    In theory, you can screw heat-trap nipples into the water heater, but this heater came with something that looks like heat traps and heat most certainly still traveled up the cold water pipe. I think that had something to do with conduction from the tank to the metallic shell of the nipples.

    I’ll add all the usual insulation when I’m sure everything is tight.

    As always:

    • This may or may not satisfy your local plumbing code
    • If it leaks, it’s not my problem
    • If it breaks, you get to keep all the pieces
    • Etc, etc, etc.
  • Slow Leak Detector: Tissue Paper

    Tissue-paper leak detector
    Tissue-paper leak detector

    When you make a plumbing joint with screwed compression fittings, there’s always a question of whether you’ve tightened the nut enough to make a good seal. The fittings come with copious warnings to not overtighten the nuts, which means I tend to undertighten them.

    It’s easy to spot a major leak or a trickle, but what about a very slow ooze on a hot water line where the drip will evaporate before you notice?

    Fold up a piece of tissue paper and secure it around the joint with a wire tie. Come back a few minutes / hours / days later: it’s easy to tell if the tissue has ever been wet, because its texture will be dramatically different.

    Having just replaced a water heater, the subject of leakage is a hot topic around here…

  • Blender Bearing Repair: Round Two

    Blender impeller and bearings
    Blender impeller and bearings

    It seems the bearings in our cheap blender last about a year, even if we don’t put the impeller in the dishwasher.

    The top bearing, the one nearest the impeller (on the left in the pic), developed detents, which says at least one of the balls has failed.

    Both bearing housings are rusty; water has no trouble getting past the flexible seals at each end. As they’re not immersion-proof, I assume the water has little trouble getting past the shield rings on either side of the balls.

    I replaced both of them, squeezed some silicone stopcock grease above the top bearing in the vain hope of excluding liquids, and we’ll see what transpires.

  • Recumbent Bicycle Amateur Radio Antenna Self-disassembly

    Auto-unscrewed Antenna Mast
    Auto-unscrewed Antenna Mast

    Vibration is a real killer for bike-mounted hardware. The antenna mast on my bike has been unscrewing itself, despite my repeated attempts to tighten it. Fortunately, I’ve managed to notice the rattle before the mast falls off into traffic.

    We’ll see if a dab of medium strength (blue) Loctite will do the job.

    One thing to worry about: this is an electrical as well as a mechanical joint. I hope there’s still enough metal-to-metal contact to get RF energy to the radiating part of the whip!

    [Update: Yup, works just like you’d expect. Problem solved.]

    The antennas on the other two bikes have remained tight, so maybe it’s just that my riding style generates more vibration? Hard to imagine; it’s not like I venture off-road.

    More details on the homebrew mount are there and how commercial mounts fail are there.

    The unsightly masking tape wrap is where I attached a reflector for a (rare) after-dark ride a while ago. Making a set of bushings for the reflector clamps is a low-priority job in the queue right now.

    [Update: Done!]