Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Tag: Improvements
Making the world a better place, one piece at a time
Removing a water heater element is no big deal: apply the appropriate socket (1-1/2 inch for this heater) to the hex head and turn it out. The trouble comes during installation, when you must hold that long rod exactly horizontal inside the tank, gripping the electrical fittings inside a narrow access port amid all the insulation.
My fingers can’t hold the element horizontal and twist it at the same time, so I made a tool: cross-threading the heating element and goobering the threads in the tank port is not an option!
Improvised heating element installation tool
A 32 mm socket just cleared the square blue electrical insulation block and butted against the 1-1/2 inch hex head. Because the block is square and the socket is hex, it was a pretty loose fit, but this was the right general idea.
I put a layer of masking tape on the inside of the socket and covered the electrical connections on the element.
Then I mixed up a batch of Bondo auto-body repair epoxy, buttered up the end of the heating element, and gooshed it into the socket. The Bondo filled in the gaps between hex and square, turning the wrench into a custom-fit tool that firmly gripped the heating element.
Reinstalled heating element
A brief pause for Bondo curing, pop an extension into the socket to use as a handle, return to the water heater, and screw that sucker right in place. Worked like a charm!
There’s a flexible gasket sealing the element to the tank port and I gave the element a few degrees more twist when I tightened it up, so the insulation block isn’t neatly aligned.
Getting the socket off wasn’t too difficult: twist to the side, pull, and the Bondo pops off the masking tape. Peel the tape off the element and it looks pretty much like it did before. The Bondo fell out of the socket when the element came out, so that was easy enough.
I was busy getting the water heat back in action and didn’t take any detailed pix, but I think you get the idea…
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
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:
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
After dumping last month’s data, I conjured up a piece of double-sided circuit board and soldered a turret terminal to each side. It’s thin enough to fit between the cell’s positive cap and the holder’s contact without distorting things too much.
The lowest range on most of my digital meters is 200 mA, which is far too high. I tried an ancient analog meter with a 50 µA range, but the meter’s resistance was too high to keep the Hobo’s PC program happy: it claimed there was no logger out there. Finally I found a digital meter with a 4 mA range and 1 µA resolution, which was just right.
Turns out that the logger draws 8 or 9 µA between readings, which is pretty much what it should be. At that rate, a CR2032 lithium coin cell with a capacity of 230 mA should have a lifetime of 23 k hours: call it three years. Obviously, it’ll be less than that, what with periodic loggings and dumpings and suchlike.
The current’s the same with the external temperature probe plugged in and doesn’t change when I poke the capacitors. So the logger seems to be working perfectly.
Which means I got a bad batch of Renata CR2032s two years ago. I just pulled one from another logger that I installed 5 Feb 09: all of six months ago. If I installed a series of really feeble cells in this logger, well, that would explain what I experienced.
I’m currently using Energizers in the other loggers, so we’ll see what happens a year from now.
But I’ll keep the alkalines on the back of this logger, as they should last basically forever at this rate.
Bezel bottom 3.3 mm thick, excluding depression on bottom surface
Screw head sticks out of depression 0.9 mm
Some deft work on the bezel installed in the camera, using the blunt end of a transfer punch, a pin vise, and a calculator reveals these protrusions:
1.4 mm does not trigger anything
2.1 mm triggers the half-pushed focus action
2.4 mm reliably triggers the shutter
So the new stem can stick out about 1.4 mm when the button is released and must not stick out more than 2.4 mm with the button fully depressed: a whopping 1 mm of travel!
Eyeballing the shutter release on my DSC-H5, that seems to be about right. I think it has more travel between “released” and “half pressed” than those measurements indicate, but it’s close. And sloppy, too: the H5’s button has a lot of side-to-side wobble, indicating that the stem is not a close fit in the bezel hole.
The screw head is 3 mm dia after being turned down and that’s about the right size for the nut that will adjust the travel distance, as it must fit into the recess in the bezel. The nut sets the protrusion when the shutter button is released: 1.4 mm.
The distance from the shutter button’s bottom to the bezel sets the travel from “released” to “click”: 1 mm, more or less. They’re held apart by the spring, so that’s the default state.
Circular Milling the Nut
I re-centered the 3-jaw chuck under the spindle, put a 1-72 nut on the turned-down screw, and applied some gentle manual CNC to convert the nut from a hex to a disk. The trick is to approach the nut from the right side (the +X side) and go clockwise around it (climb milling), so that the cutting force tends to jam the nut against the screw head. Do it the other way and the nut will zip downward away from the cutter
Surprisingly, I got that right the first time.
Using a 2 mm end mill and figuring a 2.9 mm final diameter, the radius of the circle to move the end mill around the nut is: R = (2.9 + 2.0) / 2
So the G-code for one pass looks like:
#<R>=[[2.9+2.0]/2]
G1 X#<R> F150
G2 I[0-#<R>]
Shutter Button Parts
Now, given the fragility of that setup, you don’t cut it all at once. You start from a diameter of maybe 4 mm and go down by 0.2 mm until you hit 3.0, then make a final pass at 2.9 mm. EMC2’s AXIS MDI mode makes this easy enough: type in the commands for a pass at 4.0 mm, then click on the previous command, change 4.0 to 3.8, and then just clickety-click.
Spindle far too slow at 3000 RPM, feed at 150 mm/min seemed fine. Sissy cuts worked out OK.
After the first few passes, my dim consciousness became aware of the fact that this is how I should have turned down the screw head…
Button Assembly – Top
I cleaned up the bezel by putting it in an ultrasonic cleaner to shake the crud off, put it on a warm firewall router overnight to dry it out, then slobbered some Plastruct solvent adhesive into the cracks and clamped it for another night. The bezel was slightly out-of-round from the damage, so I hand-trimmed the bent plastic using a “high speed cutter” (#193, basically an end mill) in a Dremel flexible shaft at about 1/3 max speed until the shutter button bottomed out smoothly within the inner recess. Not a bit of CNC to be seen: hand held all the way.
Button Assembly – Bottom
Then loosen the nut a bit, poke the screw through the bezel, put the spring on, and screw the shutter button in place. Adjust the nut so the screw head is 1.4 – 1.5 mm from the bottom of the bezel with the nut resting in the recess.
Button Assembly – Pressed
Twiddle the shutter button until the screw head protrudes 2.4 mm from the bezel with the button pressed down.
That’s measured with the hole-depth tang of a caliper, sitting atop the screw head. I don’t believe there’s 0.1 mm accuracy in the measurements, but they’re close enough. I did file off a few mold flash bumps from the shutter button & bezel during this adventure.
Mark the screw threads above the button, unscrew it, chop the screw off with a stout diagonal cutter (it’s brass and not very thick, it’s OK), file the end flat, clean up the threads.
The trick seems to be that the button must rest just below the inner ring of the bezel, so that it bottoms out smoothly when pressed. If it’s above the ring, then one side will hang up. The ring depth thus seems to limit the maximum travel, although I can’t say whether this is the way it’s supposed to work or not.
I iterated & filed until the screw was flush with the top of the button with it screwed down to the proper position. It helped to figure out that one turn of the shutter button on the screw changed the “pressed” protrusion by 1/72″ = 0.35 mm.
Urge some low-strength Loctite under the nut and into the shutter button’s hole, reassemble everything, and you’re done.
Urethane Adhesive on Body Socket
The fall bent the bezel tabs so they no longer latch firmly in the camera body. I put two dabs of urethane adhesive on the socket in the body. The adhesive expands (foams!) as it cures; I hope it will lock the bezel in place while still allowing it to be removed if needed.
I dabbed off most of the adhesive you see in the picture before installing the bezel; it’s not as awful as it looks!
The final result has slightly less travel than the (undamaged, original) shutter button in my DSC-H5, but it works perfectly: half-press to focus, full press to trigger the shutter.
Having figured out what to do, I started with the button, which is chromed plastic, nothing too fancy, and not at all hard to machine.
Laser Aligning to the Button Stem
A small post turned from an acrylic rod (the gray cylinder) supports the button in the Sherline 3-jaw chuck attached to the mill table; that was the only way to keep it reasonably level. Laser alignment got eyeballometrically close to the middle; it looks a bit off to the right, but the end result was OK.
Removing the Broken Stem
A 2 mm end-cutting bit chewed off the stem in short order; I set the jog speed to about 100 mm/min and just jogged down until the cutter was flush with the button. Spindle at 4000 rpm, for lack of anything smarter.
I decided to go with a 1-72 brass machine screw, which is slightly larger (1.75 mm) than the original 1.5 mm button stem. That means I must drill out the bezel hole, as well, but the 1.5 mm diameter of the next-smaller 0-80 screws in my assortment was a sloppy fit.
A touch of manual CNC for the drilling, #53 with the spindle at 3000 rpm, Z touched off at the button’s surface:
G81 Z-4 R3 F150
The spindle was slow enough and the feed fast enough to keep from melting the button without applying any coolant.
I tapped the hole 1-72 by simply screwing the tap in with my fingers…
Chuck-in-chuck For Head Shaping
The 3-jaw lathe chuck doesn’t grip a 1-72 screw (no surprise there), so I grabbed the screw in the Sherline’s smallest drill chuck and poked that in the lathe. This doesn’t make for great concentricity, but it was close enough. The right way, as my buddy Eks reminds me, is to slit a nested bunch of brass tubing and use them as collets, but … next time, fer shure.
Button With Reshaped Screw Head
Anyhow, here’s what the button & screw look like so far. The backside of the screw head looks like it needs some cleanup; there’s nothing like taking a picture to reveal that sort of thing.
The pencil lead is 0.5 mm and the grid in the background has 1 mm squares, just to give you an idea of the scale.
My brother-in-law Tee dropped his Sony DSC-H1 camera, which landed atop its shutter button on the pavement.
Bad news…
the shutter button broke off
the bezel popped out
the teeny little snap ring that held the shutter button stem in the bezel vanished, because…
the stem broke and the end vanished, too
Good news…
apart from some scuffs, the camera still works
he managed to find the shutter button
and the button bezel
and the spring!
Shutter Button – Spring – Bezel
A bit of browsing reveals that many, many Sony DSC-Hx (where x is an integer from 1 through 9, inclusive) owners have the same problem, minus the inconvenience & embarrassment of first dropping the camera. Turns out that the shutter button stem breaks at that notch in normal use.
It seems the stem snaps while you’re taking pix, whereupon the spring launches itself and the button cap into the nearest river / drain grate / weedy area, never to be seen again. Tee is exceedingly fortunate to have found all the major pieces!
Shutter Button Stem – End View.
Here’s the broken end of the stem, with the button cap out of focus in the background. The stem is 1.5 mm in diameter, so the snap ring was surrounding, what, 0.75 mm of plastic? In what alternate universe did this design decision make sense?
I think the snap ring contributed to the problem by eroding the stem in the notch; that little white stub isn’t half of the stem diameter; it may have stretched under impact, but surely not all that much.
Yes, you can buy a replacement button for about 30 bucks direct from Sony, but it seems the new stem is subject to the same failure after a short while. They’re standing by the original design, marginal though it may be.
Now, obviously, this stem failed from abuse, no argument there. Everybody else had their stem fail without provocation, though, so it really isn’t adequate to the task at hand.
Bezel Socket View
Anyhow, there’s also some damage at the bezel socket on the camera body, but nothing major. The dented silver areas on either side of the switch membrane are ESD shields, so that any static discharge from your finger will (most likely) dissipate on the external frame of the camera, rather than burrow into its guts via the switch.
The bezel twist-locks into the camera body, which means that you can remove the bezel if you can get a good grip on it. It turns clockwise to remove.
Shutter Switch Closeup
Peering closer at the membrane switch, it looks as though the button stem did some damage on its way out, although Tee admits to using various pointy objects to trigger the shutter while figuring out what to do with the camera.
More good news: the switch still works correctly, including the focus function with the button half-pressed, That means the switch membrane and contacts are in good shape.
Bezel – Top View
The bezel itself is pretty well graunched, with a nest of cracks underneath that damaged arc to the left of the pictures. I think it’s in good enough condition that I can remove the bent plastic, ooze some solvent adhesive into the damage, and compress it enough to make everything stick together.
Bezel – Side View
Obviously, this calls for some Quality Shop Time!
The overall plan is to remove the remaining stem from the button, drill-and-tap the button head for a miniature brass screw (1-72, I think), reshape the screw head into a membrane-friendly plunger (about 3 mm diameter and flat), then put it all back together with a nut in place of the snap ring.
I should be able to install the bezel (without the button), then insert some drill rod through the hole to figure out how far the screw must protrude to trigger the focus & shutter switches. Perhaps a pin vise will grip the drill rod and bottom out on the bezel’s central ring, so I can do a trial-and-error fitting?
Then I can adjust the screw to that overall length below the bezel with the button pressed, whack off anything that sticks out above the button, adjust the nut to limit the button’s outward travel, slobber Loctite over everything, and put it all together for the last time.
That’s the plan, anyway. As the Yiddish proverb has it, “If you wish to hear G*d laugh, tell him your plans.”
The Smell of Molten Projects in the Morning 