Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
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:
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
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.
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
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…
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.
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.
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.
The Smell of Molten Projects in the Morning 