Tag: Repairs

If it used to work, it can work again

Bike Helmet Earbud Iteration

Based on having to seal the rear vent hole of the previous earbud, I did the same for the new one:

Earbud – blocked vent

The audio quality was terrible, so I tried another bud with a foam windscreen over the hole and a hole punched in the middle of the double-sided white foam tape:

Earbud – foam over vent

The audio remained unintelligible, so I tried an upscale (but still cheap, because surplus) Koss earbud, first without blocking the vents and then with snippets of Kapton tape:

Koss earbud – tape over vent

The earphone has three slits on each side, but only the middle slit has a hole penetrating the case; it must be a stylin’ thing.

That sounded better, so I’ll roll with it. There’s supposed to be a foam cover over the housing, but those things always get grody and fall off; there’s not much point.

As nearly as I can tell, contemporary earbud designs optimize for volume (dBm/mV) and thumpin’ bass, all to the detriment of actual audio quality. Based on numerous samples over the years, there is zero correlation between price (admittedly, on the low end) and audio quality (admittedly, with my crappy hearing).

I own a pair of very nice (and thoroughly obsolete) Shure E2c sound-isolating ear beetles that sound great (even with my crappy hearing), but I’m unwilling to chop them up for the bike headset …

2014-08-18
Easy Reacher Pack: New Elastic Cord

The elastic cord behind the left-side under-seat Easy Reacher pack on my Tour Easy snapped some time ago, probably due to wear against the brace I installed to keep it from flopping around. Quite contrary to what I expected, the repair turned out to be almost trivially easy.

The cord terminates in a pair of plastic lugs, each with a ferrule that slipped off under moderate persuasion to reveal a pair of wedges that engaged the cord:

Easy Reacher pack – elastic cord clamp

I expected the ferrule to have a positive lock engaging those wedges, but, nope, there’s (at most) a small ridge. Pry the wedges out and the cord slides out of the lug without a protest; the wedges don’t quite meet in the middle with the ferrule in place and there’s plenty of retention force on that flexy cord.

One of the shorter bungie cords in my collection turned out to be exactly the right diameter and length, with ends secured in its hooks using a simple crimped wire. Bending the ends of the wire at right angles freed the cord from its embrace:

Easy Reacher pack – unclamping new elastic cord

The original stainless steel hook lies by the edge of the road along my usual bicycling route, but a slightly reshaped S hook (made, alas, of ordinary steel) fits around the cord well enough. When this one rusts away, I have plenty more.

Insert cord into lugs, push ferrules over locking wedges, remove one ferrule and lug, install reshaped S hook, reinstall lug and ferrule, install new cord on pack:

Easy Reacher pack – new elastic cord

Install pack on bike: done!

I have no explanation for how well this worked out; I fear the Universe is saving up spit for something truly awful.

2014-08-07

Image File Recovery Redux

Took a picture of the sewing machine setup with the Sony DSC-F717, transferred it into DigiKam, got the “done transferring, you can disconnect the camera” message, believed it, disconnected the camera, deleted the image file, and then discovered that DigiKam mislaid the image file.

Rather than re-set-up and re-take the shot, I followed my own directions and recovered the image from the Memory Stick:

dmesg | tail
[43176.079853] usb 2-1.6.3: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[43176.079855] usb 2-1.6.3: Product: Sony PTP
[43176.079856] usb 2-1.6.3: Manufacturer: Sony
[43198.073652] usb 2-1.6.3: USB disconnect, device number 22
[43333.788533] sd 9:0:0:0: [sdc] 1947648 512-byte logical blocks: (997 MB/951 MiB)
[43333.803292] sd 9:0:0:0: [sdc] No Caching mode page found
[43333.803299] sd 9:0:0:0: [sdc] Assuming drive cache: write through
[43333.824681] sd 9:0:0:0: [sdc] No Caching mode page found
[43333.824688] sd 9:0:0:0: [sdc] Assuming drive cache: write through
[43333.825491]  sdc: sdc1
sudo dd if=/dev/sdc of=/tmp/pix.bin bs=1M
^C615+0 records in
614+0 records out
643825664 bytes (644 MB) copied, 38.5841 s, 16.7 MB/s
strings -t x pix.bin | grep Exif | head
  68006 Exif
 208006 Exif
 3f8005 _Exif
 7b8006 Exif
13d8006 Exif
15b0005 wExif
1798005 CExif
19c0006 Exif
1b90006 Exif
1f98005 %Exif
dd if=pix.bin of=image03.jpg bs=$((16#1000)) count=1K skip=$((16#3f8))
1024+0 records in
1024+0 records out
4194304 bytes (4.2 MB) copied, 0.0121431 s, 345 MB/s
display image03.jpg
convert image03.jpg dsc00656.jpg

Obviously, there was a bit more flailing around than you see here, but that’s the gist of the adventure. For what it’s worth, image01 was a random blurred shot and image02 is the ID picture I keep on all my cameras.

The convert step discards all the junk after the end of the image, so the dsc00656.jpg file doesn’t include anything unexpected.

The picture isn’t all that much to look at, even after cropping out the background, but …

Kenmore 158 - stepper drive test — Kenmore 158 – stepper drive test

The advantage of the manual method: renewing one’s acquaintance with tools that come in handy for other tasks.

2014-08-04

Flashlight Switch: Poor Solder Joints
My desk flashlight has three “functions”:
- 5 UV LEDs
- 10 white LEDs
- laser pointer
A four-click rotary pushbutton switch actuates the three functions (plus “off”) in sequence:

Flashlight switch – internal wiring

All three lights became intermittent, which suggested a poor return connection at the far end of the battery. The case is, of course, aluminum, with coarse-cut threads that grate as you tighten the parts. I cleaned the crud out of the threads, anointed them with Ox-Gard compound, and discovered that the laser and UV LEDs were still flaky.

Taking the thing apart and unsoldering the switch connections revealed the problem:

Flashlight switch – bad solder joints

Yup, two lousy solder joints. They’re not exactly cold solder joints, because there’s not really a joint there to begin with; the switch tabs never got hot enough to bond with the molten solder before it cooled.

A dab of flux and touch from a hot soldering iron solved that problem.

Assemble in reverse order and it works better than it ever did before!
2014-08-03
Interplak Water Jet: End of the Line

The brittle tubing on Mary’s Interplak water jet continued to disintegrate, so I replaced the entire tube with Tygon:

Interplak water jet – interior

Nisley’s First Rule of Plumbing: Never, ever look inside the pipes delivering water to your faucet.

Interplak handle – interior view

That’s not quite inside the pipes, but it’s pretty grotendous, isn’t it?

As expected, flexible tubing doesn’t transmit the pressure pulses nearly as well as the OEM rigid tubing, so we finally bought a new Waterpik. At least you can get replacement tubing for Waterpiks, but I’ll wait until it fails before stocking up.

Contrary to what you might expect, I cut the Interplak’s cord, harvested the motor windings, and dumped the carcass in the trash.

2014-07-27
Shimano SPD Pedals: Creaking Resolved

Both Shimano SPD pedals on my Tour Easy have been creaking while climbing hills and I’ve gradually eliminated all the usual mechanical suspects: loose bottom bracket bearings (it’s a cartridge), loose cranks (they’re the old-school tapered squares), loose pedal spindles, and so forth. Of course, it’s impossible to produce the creak with the bike clamped in the work stand, which make debugging particularly frustrating.

After all that, I noticed the shoe soles were wearing the pedal frames just outside the cleat clamps:

Shimano SPD pedal – shoe sole abrasion

So I went so far as to carve away a bit of the sole:

Shimano SPD cleat – trimmed shoe sole

Turns out none of that solved the problem.

What did solve the problem: a drop of oil on the rear of the cleat. You can see a smear of oil on the sole; it doesn’t take quite so much.

As nearly as I can tell, the rear of the cleat drags on the slightly irregular surface of the clamp and, both surfaces being hardened steel, they stick-and-slip just slightly.

A dab of grease may provide longer-lasting relief …

2014-07-24
M2 Platform Leveling
This doesn’t happen very often, but, after a few road trips and some jostling around, the M2’s platform was definitely out of alignment: the first layer came out generally too thin, with the X-Y+ quadrant very much too thin.

I tried a quick and dirty adjustment that didn’t produce meaningful results, then broke out the Starrett Taper Gauge and did it right.

The relocated platform height switch is about 4.5 mm higher than the nozzle, so:
- Jog the nozzle off the platform to the right
- Home the Z axis
- Define that position as Z=-6: G92 Z-6
- Move to Z=0: G0 Z0
- Jog around measuring the height of the nozzle above the platform
- Adjust screws to reduce variation
- Change Z offset in startup G-Code
- Run off a few test patterns to get the platform heated
- Measure actual thickness
- Change Z offset to get the right answer
- Done!
This progression of cold measurements, read top-to-bottom, left column first, shows the observed nozzle height above the platform around the edges and at the center:

M2 Platform Leveling Progression – 2014-06-30

The final measurements seem to indicate the glass plate is 0.2 mm convex in the center, but I wouldn’t trust the measurements to that level of accuracy. It’s probably bowed upward, but it’s certainly close enough.

The cold measurements suggest that the Z offset should be -4.80 mm, but the measurements on the hot platform with actual extrusion threads showed that -4.50 mm produced the correct thicknesses.

It’s not clear automating the movements would produce better or faster results than just manually jogging the nozzle around the platform, particularly since it happens only every few months.

This would be easier with the Z offset stored in the EEPROM and some modified startup G-Code to retrieve it.
2014-07-16