Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
My Shop Assistant (who now merits a Proper Name) returned a fairly new measuring tape to the Basement Laboratory, reporting that the retracting crank handle fell off in “normal use”.
Stripped handle threads
Admittedly, this was a surplus find, but you’d think the build quality would be a bit higher. I’m sure I paid a minute fraction of list price: you could have bought it for much more in a reputable store.
Maybe this is why the whole lot got scrapped out:
Handle detail
I applied a bit of JB Industro Weld to the plastic (?) threads on the spool, twisted the handle in place, squared it up, then eased more epoxy around the top of the threads and let it cure flat on the bench.
Remounted handle
I’d say the original design wasn’t particularly good and the implementation left a lot to be desired. If the interior fittings have similar flaws, I’ll eventually regret applying JB Weld in such a cavalier manner…
So I finally noticed that the water wasn’t nearly as soft as it used to be, which usually means I forgot to dump a bag of salt in the tank. This time, the water was halfway up the tank, which usually means something’s broken.
The usual cause: crud clogging the filter screen upstream of the venturi that sucks brine out of the tank. The usual fix: rinse the screen.
This time, however, the screen was clean. Pulling the gasket off the nozzle assembly revealed a collection of particles and chunks inside the fluidic channels; this is what the gasket looked like after I sorted everything out.
Original gasket and venturi
The gasket has at least three layers: a stiff red backing, a compliant green middle layer, and a white surface layer with molded channels matching the red nozzle. The two black cylinders are metering plugs with precisely shaped orifices that control the 0.1 and 0.3 gallon/minute brine and rinse flows.
The green and white layers evidently disintegrated into chunks that blocked the nozzle. With no flow through the venturi, the tank could fill until the float valve limited the flow, but the brining step had a very, very low flow and the resin bed eventually ran out of capacity.
I ordered a replacement nozzle and gasket assembly, figuring that Sears (actually, its OEM supplier) might have changed things in a non-compatible way. The old part numbers, which will get you the new equivalents:
Gasket: 7163663
Nozzle + gasket: 7187772
The new parts looked like this:
Replacement venturi and gasket
Surprise! The fancy molded gasket is no more; the replacement is a flat rubber sheet with the appropriate alignment notches and holes. The nozzle assembly might have come out of the same molding machine on the same shift.
I reassembled all the fiddly parts, manually set the softener to its Brine stage, let it suck a few inches of salt water out of the tank, and then returned it to automatic operation. At this point, the water heater is full of hard water and it’ll take a few repetitions of that cycle to get back to normal.
Given the limits of the gasket’s resolution, I’m sure the Batman icon is completely coincidental and sincerely regretted…
After I failed to fix that old USB memory, my friend suggested a brain transplant: swap the Flash chip from the dead stick into a new one. That has a low chance of success because the innards will be different for every manufacturer and, even for USB sticks of the same vintage, nothing remains the same from lot to lot.
Anyhow, I removed the fancy end caps from the donor stick, which looks to be swag from a medical conference:
Case caps removed
The key step is to crack the case open without damaging anything inside. This technique works wonderfully well:
Cracking the case
Grab diagonally opposing corners in a bench vise and slowly increase the clamping force until the case snaps apart. Poke a screwdriver in the gap, remove the case from the vise, and pry the thing open.
As it turned out, the innards were completely different: different Flash controllers and different Flash memory chips. So it goes.
Not surprisingly, you can find the data sheets / manuals / configuration utilities for the Flash controller chips by searching for the obvious keywords. Machine translation is your friend…
I decided to replace the sawed-off flanges on that salvaged heatsink to make all three use the same mounting arrangement, whatever that might turn out to be.
Nothing particularly fancy about it: two random chunks of aluminum sheet and two thinner strips, sanded to roughen their surfaces, and epoxied into place.
The repaired heatsink is marginally taller than its siblings, but not so anybody will ever notice, and it’s no more off-kilter than they are, either.
A quartet of 5/16-inch lathe bits provided the right spacing to hold the heatsink over its new flanges while the epoxy filled in all the gaps and irregularities. I probably should have paid a bit more attention to squaring things up, but it’s good enough for what it’ll need to do.
Found this inside a friend’s dead USB memory stick:
Cold solder joint in USB memory
The leads come from a teeny 12 MHz crystal. The solder blob on the other side looked just fine, but you simply can’t tell by looking.
As it turned out, the stick was dead for some other reason: the Flash memory controller chip got hot when the stick was drawing power. Resoldering all the joints had no effect, which wasn’t surprising.
I suspect a killer static discharge or some such calamity.
I had to drive the old brakes off the mounting studs with a drift punch; the studs were pretty well rusted after a decade of continuous use under the hostile conditions that pass for normal around here. Shined them up, applied a generous layer of Never-Seez, and bolted the new brakes in place.
Turns out that the rear brakes on a Tour Easy are backwards from their orientation on an upright bike: the studs point spinward, so the cable exits on the right side of the frame. Doesn’t make any difference, as that’s how the front brake studs work, but if you’re thinking of buying some fancy brake with odd mounting requirements, you probably shouldn’t.
The installation specs require “more than 39 mm” of cable between the clamp bolt and the bracket on the other arm. The Tour Easy frame tubes are closer together than that, allowing a bare 25 mm of cable.
Rear brake cable and boot
I trimmed the boot to fit, but the real problem is that the arms aren’t at quite the right angle with respect to the braking surface on the rim and provide a bit less leverage than you’d like; the pad alignment is also trickier. I tried adding spacers to the brake pads, but the mounting studs aren’t quite long enough for that.
The first road test indicates the new brakes work much better than the old ones…
Of course, it broke at the first pedal stroke while pushing off across an intersection, which is why I never try to ace out oncoming cars.
This was, mercifully, on the left side of the bike, so I could replace it without removing the rear wheel. Being that sort of bear, I now carry spare screws and we were back on the road in about ten minutes.
A closer look at the head end of the screw shows some interesting details:
Fractured screw – head
The tail end has matching cracks:
Fractured screw – tail
Notice how the cracks are all oriented in the same direction. The screw fractured at the edge of the brazed-on frame fitting, so I suspect the seat stay clamp must be moving just enough to flex the screw across that plane.
I mooched a pair of hardened socket head cap screws from Eks, ground down the head of the right-side screw for better chain clearance around the sprockets, buttered ’em up with Never-Seez, and we’ll see how long Real Steel lasts.
Right-side screw with ground-down head
I really should conjure up a clamp that mounts to the frame tubing, rather than depend on that puny brazed-on fitting, shouldn’t I?
It appears that new Tour Easy ‘bents come with more brazed-on fittings and a more secure seat stay mounting bracket. A photo was there when I looked.
The Smell of Molten Projects in the Morning 