Posts Tagged Repairs

Forester: TPMS FTW, Redux

Now I know the Forester’s TPMS icon blinks on 1000 feet from a cold start with 12 psi in the offending tire. I returned home and pulled this from a sipe in the left rear tire:

Road debris - blade fragment

Road debris – blade fragment

It’s atop a 0.1 inch grid.

The flat side on the right rode tangent to the tire surface, recessed slightly below the tread, and pretty much invisible inside the sipe. Of course, the point punched through the tire’s steel belt and let the wind out, ever so slowly.

I initially thought it was a utility knife blade fragment, but under the microscope it looks more like a saw blade tooth. It’s obviously been kicking around on the road for quite a while; back in the day, they occasionally swept the roads, but that was then and this is now.

Makes me glad I didn’t buy four new tires after the last flat. I suppose installing two plugs in the same tire counts as a net loss, but they’re small, widely separated injuries and that’s how it’ll roll.

For the record: with 14 k miles on the tires, tread wear = 2/32 inch of the original 6/32 inch depth.

Those tires should last another 30 k miles at our current pace, although I expect more random debris will kill one stone cold dead before that.

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X10 TM751 RF Transciever: End of Life

X10 control from the two HR12A remotes got much worse over the last few months and eventually failed completely, which meant I had to actually walk over to the lights and click the switches. Not to be tolerated, sez I, so I would walk to the bedroom and poke the appropriate buttons on the wired controller (long since obsolete) by the bed. That worked perfectly, which eventually convinced me to dismantle the TM 751 transceiver.

It’s not good when soot plates the case:

X10 TM751 - Smoked case

X10 TM751 – Smoked case

I like how they capacitively coupled RF from the antenna for complete line-voltage isolation.

The PCB looked like it got rather hot over there on the left side:

X10 TM751 - Overheated PCB

X10 TM751 – Overheated PCB

A Zener diode on the component side of the PCB looked a bit toasty, so I decided this gadget had passed its best-used-by-date and dropped it in the electronics recycling box (after harvesting the antenna, just in case).

A new-in-box TM 751 from eBay arrived a few days ago and works just fine.

Done!

 

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Truth In Labeling: Bike Tube Division

The lumpy surface of the Michelin Pro-Tek Max tubes now in the back tire of our bikes can’t be patched, which means (being that type of guy) I must carry along a spare tube in addition to a handful of CO2 cartridges. So, having cleaned out my tube stash, I ordered a pair from an Amazon supplier, not my usual bottom-dollar eBay suppliers, clearly described as fitting the Schwalbe Marathon Plus 700x35C tires.

The Amazon listing and the box label agreed, but (being that type of guy) I just had to extract the tube to see what I got:

Meetlocks tube size mismatch

Meetlocks tube size mismatch

Huh.

According to the seller, who speaks and writes English far better than I can handle Mandarin (or whatever):

Yes, you are right, you also didn’t bought wrong items for your tire. we marked the 700×28-32, just for our manufacture to difference from another big size from 700/35-45C, because if we marked the size 700×28-35C, sometimes , the worker will packing 700×35-45c into the packing, and let the tube can not used for the 700x35c customer..

Huh.

It turns out the tube has 35-38 embossed into the rubber, so it’s not obvious the tube would fit into the smaller  28-32 size tires as labeled. It all depends on what you trust: the mold, the tube’s stamp, the box label, or the advertising.

Next time around, an event I hope (but do not expect) lies far in the future, I’ll spend a bit more for what will undoubtedly be the same tube from the same factory, but from a vendor buying enough QC to ensure the workers know what they’re packing. Having all the labels match would be a definite bonus.

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Schwalbe Marathon vs. Glass Chips, Yet Again

We biked to some errands on an unseasonably warm 4 January and, a few days later, I noticed the rear tire on Mary’s bike was flat. A bit of Quality Shop Time later:

Brown Glass Chip

Brown Glass Chip

On the upside, I found it in the garage and fixed it in the basement.

The chip emerged from one of two adjacent gashes in the middle of the tread, but hadn’t quite cut through the tire. A somewhat larger chip (that’s a 0.1 inch grid) in the other gash cut through the Schwalbe Marathon’s protective belt to puncture the tube, then fell out.

The rear wheel of her bike now sports a Michelin Pro-Tek Max tube inside a Schwalbe Marathon Plus tire, as does mine. The wheel + tube + tire probably weighs as much as some entire carbon-fiber bikes, but it doesn’t matter.

Searching for the obvious keywords will produce many other instances…

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Unicode Keyboard Flameout and Workaround

For unknown reasons, probably having to do with the unmitigated disaster of trying to get an SDRPlay radio working with GNU Radio (about which, more later), Unicode keyboard input stopped working. This is not to be tolerated, because engineering notation requires a lot of Greek letters.

Unicode support seems to be baked into the lowest levels of the Linux operating system, although it’s not clear to me whether it’s in X, QT, GTK, or somewhere else. Googling the obvious keywords was unavailing; evidently this feature never ever fails or, more likely, very few people use it to any extent.

Note that I already have the Compose key set up, but Compose sequences don’t include Greek letters.

After considerable flailing, I added the Simple Greek keyboard layout and defined the (otherwised unused) Menu key as the keyboard layout switcher. That’s a pretty big hammer for a rather small problem; I devoutly hope Unicode mysteriously starts working again.

For reference, the Greek keyboard layout looks like this:

Greek keyboard layout

Greek keyboard layout

I’d have put Ω on the W key, rather than V, but that’s just because so many fonts do exactly that.

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Pot Lid Repair

For reasons not relevant here, we (temporarily) have a set of pots with glass lids. One of lids had a remarkable amount of crud between the glass and the trim ring under the knob, which turned out to be corrosion falling off the screw. Trying to remove the screw produced the expected result:

CKC Pot Lid - broken screw in handle

CKC Pot Lid – broken screw in handle

For whatever reason, they used an ordinary, not stainless, steel screw:

CKC Pot Lid - corroded screw

CKC Pot Lid – corroded screw

I figured I could mill the stub flat, drill out the remainder, install a new insert, and be done with it. The knob has a convex surface and, even though this looked stupid, I tried clamping it atop a wood pad:

CKC Pot Lid - precarious clamping

CKC Pot Lid – precarious clamping

Two gentle cutter passes convinced me it was, in fact, a lethally stupid setup.

Soooo, I poured some ShapeLock pellets into a defunct (and very small) loaf pan, melted them in near-boiling water, and pressed the knob into the middle, atop some stretchy film to prevent gluing the knob in place:

CKC Pot Lid - ShapeLock bedding

CKC Pot Lid – ShapeLock bedding

That’s eyeballometrically level, which is good enough, and the knob sits mechanically locked into the room-temperature plastic slab. Clamping everything down again makes for a much more secure operation:

CKC Pot Lid - clamped ShapeLock fixture

CKC Pot Lid – clamped ShapeLock fixture

A few minutes of manual milling exposes the original brass insert molded into the knob, with the steel screw firmly corroded in the middle:

CKC Pot Lid - screw stub milled flat

CKC Pot Lid – screw stub milled flat

Center-drill, drill small-medium-large, and eventually the entire insert vanishes in  a maelstrom of chips and dust:

CKC Pot Lid - OEM insert removed

CKC Pot Lid – OEM insert removed

Run a 10-32 stud into an insert, grab in drill chuck, dab JB Kwik around the knurls, press in place while everything’s still aligned in the Sherline, pause for curing, re-melt the ShapeLock, and the insert looks like it grew there:

CKC Pot Lid - new insert installed

CKC Pot Lid – new insert installed

Wonder to tell, a 1 inch 10-32 screw fit perfectly through the pot lid into the knob, with a dab of low-strength Loctite securing it. Reassemble everything in reverse order, and it’s all good:

CKC Pot Lid - repaired knob

CKC Pot Lid – repaired knob

Well, apart from those cracks. I decided I will not borrow trouble from the future: we’ll let those problems surface on their own and, if I’m still in the loop, I can fix them.

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Kenmore 158 Sewing Machine: Another Foot Pedal Rebuild

The pedal on Mary’s most recent Kenmore 158 lost its low-speed control, which meant I must add a few more graphite / carbon disks to the stacks:

Kenmore 158 - carbon disks

Kenmore 158 – carbon disks

The contacts needed a bit of attention, too:

Kenmore 158 - carbon contact plates - detail

Kenmore 158 – carbon contact plates – detail

Contrary to what I found in the previous rheostats, these stacks end with a double-thick graphite disk backed up by a disk of brass shimstock, all of which needed cleaning, too. No broken disks, none severely eroded, no debris, just a general shortening of the stacks; I think the disks gradually turn into carbon dioxide.

Each stack has 42 graphite disks that average 0.79 mm thick, the double-thick disks measure 1.5 mm, and the brass shims are 0.30 mm = 12 mil. The punched contacts on those brass plates stand 0.95 mm proud of the surface.

With the big graphite plugs in place, the ceramic housing had 37 mm deep holes for the disk stacks. Subtracting the 0.95 mm contact leaves about 36 mm and, seeing as how the stacks add up to just under 36 mm overall, there’s barely room for one additional disk. I added one to each stack, buttoned the pedal up, and it works perfectly again.

Good thing I have a bag of those disks from the crash test dummy machine!

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