The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Tag: Repairs

If it used to work, it can work again

Tour Easy: ERRC Easy Reacher Pack Repairs

Grocery Hauling Setup

I have a pair of underseat packs on my Tour Easy that have sagged rather badly over the years. That might have something to do with the fact that my toolkit and other odds & ends weighs more than some bike frames; while I don’t need that stuff very often, it’s good to have around.

Tools & suchlike live in the left-side pack, the near one in the photo, and you can see the problem. The right-side pack holds HT batteries, my belt pack, and other relatively lightweight stuff; I’ll fix that one when I see whether this works. The panniers at the rear wheel are for groceries and other bulky items. The trailer, well, that’s how we do groceries…

Broken Pack Backplate

Anyway, the underseat packs have a black plastic (styrene?) backing that cracked under the stress of the stuff inside, allowing the top corners to cave in and the bottom to droop.

The hooks holding the pack to the underseat rack were riveted through the backing sheet and the hardware, but a couple of good shots with a punch broke them free.

Some rummaging in the Parts Heap turned up a big acrylic sheet (“100 times stronger than glass!”) that’s absolutely the wrong material for the job: it’s too brittle. However, I’d like to see whether a stiff backplate will solve the problem or if I’m going to have to get ambitious and build an internal pack frame.

Acrylic Plate and Aluminum Stiffener

It’s essentially impossible to get a picture of a project built largely from acrylic sheet, but here goes.

I traced the outline of the old backplate onto the new sheet’s protective paper, introduced it to Mr Belt Sander to get those nice round corners, then drilled the holes. It turns out to not be quite symmetric, so there’s a right way and a wrong way to insert it into the pack.

All the hardware is stainless steel. They used aluminum rivets, which is the only reason I could punch them out without too much difficulty, that I’m replacing with SS 10-32 machine screws & nuts.

The aluminum stiffener is a random chunk of ribbed extrusion from the Heap; the original was almost exactly twice as long as one backplate, so the two halves (one for the other pack) are precisely right. I milled out the center rib around the nuts to get enough clearance for a nut driver.

Stiffener Hardware Detail

Herewith, a closeup of the hardware. There’s an acrylic sheet in there, honest, it’s under the aluminum extrusion and fender washer. Really!

I put an automobile license plate in the bottom of each underseat pack to act as a floor for all the crap inside; it’s an almost perfect fit and should give you an idea of the pack’s size. It also maintains the bottom’s rectangular shape and keeps heavy stuff from sagging; there’s a hole scuffed in the bottom from the intersection of a high curb and just such an oversight.

Tour Easy Underseat Pack Detail

Having washed the pack while it was apart (there’s a first time for everything), it looks a lot better than it did before. The yellow block in the front pocket is the kickstand plate mentioned there. It used to have a mesh pocket along the side, too, but that snagged on something and got pretty well ripped, so Mary trimmed it off when she sewed a patch over the aforementioned hole.

It’s still saggy, but the top corners of the plate are holding it up a lot better now. If they crack again, I might just have to go with some aluminum sheet.

These packs seem to be obsolete. The ERRC Lloonngg panniers (search for them) seem to be, well, too long for most purposes; they look as though they would interfere with ordinary rack packs. If I were doing it over, I’d look into hacking a pair of smallish duffel bags.

2009-08-19
Kensington Expert Mouse Trackball: Scroll Ring Troubles
Trackball Scroll Ring

The oddly named Kensington “Expert Mouse” (it’s a trackball) sits to the left of my keyboard, where it serves as my main pointer controller; I’m right-handed, but have used a left-hand mouse / trackball for years.

[Edit: a comment from the future compares it with a different trackball that may work on the right.

Also, search for Kensington scroll to find other posts. There may be no good fix for scroll ring problems.]

Recently the scroll ring has become balky, stuttering upward & downward rather than actually scrolling. It’s an optical device, so I suspected it had ingested a wad of fuzz that blocked the beam path.

The top photo shows the infra-red emitter adjacent to the scroll ring’s slotted rim. The silver bar to the right of the emitter is the magnet that provides those soft detents. There’s no obvious fuzz.

Disassembly is straightforward.
- Tip the ball out into your hand and put it where it can’t possibly roll off the desk.
- Peel the four rubber feet off the bottom, remove four screws, and the top half of the body pops off.
- Remove three screws from each of the two button cap assemblies and pry the button caps off the case bottom.
- Remove two screws from the ball socket, pull it off, and clean any fuzz from the openings.
Surprisingly, I didn’t find much crud at all.

Scroll Ring Emitter and Detector

This photo shows the IR emitter and detector, peering at each other across the electrical isolation gap in the circuit board. Nothing obviously wrong here, either…

They both seem to be dual elements, which makes sense for a quadrature position encoder. Unfortunately, replacing them seems to be really difficult; they don’t look like stock items.

So I put it back together, plugged the USB cable in, restarted the X server (this being Xubuntu 8.10), and it pretty much works again.

Kensington replaced a previous Expert Mouse under warranty when one of the three minuscule red bearing balls that support the trackball went walkaround, but that gadget had been getting erratic, too.

I’m not sure what’s going on, but I have a bad feeling about this.

[Update: More troubles lead to some interesting pix and an insight. Maybe even a fix!]

Further Update: Ten years in the future, a real fix appears!
2009-08-09
Hobo Data Logger: AA Battery Pack Hack

Hobo Battery Mod – Outside View

We have a bunch of Hobo Data Loggers recording various & sundry temperatures, humidities, and light levels around the house; as the saying goes, “If you observe something long enough, it turns into science.”

Normally the things run on single CR2032 lithium cells, which last for a good long time. However, Something Happened to the one that’s collecting groundwater temperatures at the water inlet pipe from the town supply: it started eating lithium cells like potato chips.

Hobo Battery Mod – Inside View

It was still producing good data, so I was loathe to toss it out. Instead, I figured all it needed was more battery, as a high current for a lithium cell doesn’t amount to much for an AA cell. A pair of alkaline AA cells produces just about exactly 3 V and the data logger can’t tell the difference.

So I opened the logger one last time, soldered the wires from a dual AA cell holder to the appropriate points on the circuit board, affixed the holder to the back with one of the case screws, and it’s been working fine ever since.

However, this seems like one more application where whatever plastic they thought would last doesn’t: the AA holders routinely split at the ends. Maybe the joint should be thicker, maybe it’s the wrong plastic for the job, but without the cable tie acting as a belly band one end of the holder splits off in a year or so. Bah!

Update: Maybe I got a batch of bad CR2032 cells, as the logger’s current seems to be just about right. Read the comments and then check the followup there.

2009-08-08
Tektronix 492 Spectrum Analyzer ROM and EPROM HEX Files
Tek 492 Memory Board

Having gotten my buddy Eks back on the air with new EPROMs for his Tek 492 spectrum analyzer, here are the Tek 492 ROM Images (← that’s the link to the file!) you’ll need to fix yours.

[Update: the comments for that post have pointers to other images and a clever hack to use a standard EPROM. If you’re not a stickler for perfection, that’s the way to go.]

They’re taken from a “known good” Tek 492, so they should work fine: the firmware verifies the checksum in each chip as part of the startup tests; if it’s happy, we’re happy.

Because WordPress doesn’t allow ZIP files, I tucked the HEX files into an OpenDocument file that also contains the pinouts and some interposer wiring hints & tips.

If you’re using the OpenOffice.org word processor, you’re good to go. Open the document and get all the instructions you need to extract the files and put them to good use.

If you’re not using OOo, then choose one of:
- Install OpenOffice.org (it’s free software, so kwitcher bitchin’)
- Futz with whatever Microsoft claims will import ODT files (if it doesn’t work, don’t blame me)
- Just extract the HEX files and do whatever you want (if you know what you want)
The trick, explained in the document itself, is that ODT files are just ZIP files with a different file extension, so any unzip program will unpack them. You won’t see the HEX files in the document, you must apply unzip to the ODT file itself.

After unzipping, you’ll find three HEX files in the directory that originally held the ODT file, along with the collection of files that make up the OpenDocument document.

The only files you care about:
```
U1012 – 160-0886-04.hex
U2023 – 160-0838-00.hex
U2028 – 160-0839-00.hex
```
Use ’em in good health…

Oh, if you haven’t already figured it out, the DIP switch on your board is also bad. Saw the damn thing apart with a Dremel tool, pry off the debris, unsolder the pins, and install a new one. Just Do It.
2009-08-04
Bicycle Water Bottle Cap: Relaxed

Water bottle cap

Being cyclists, we were doing the resuable-water-bottle thing long before it became trendy, but now that we use hydration packs, we just tote bottles along when we’re driving or on some other sort of outing. Eventually the bottles wear out / get lost and we page a new one in from the essentially infinite stash in the bottle cupboard.

This one had a cap that simply couldn’t be pried open with bare hands, no how, no way. I eventually got it open by main force and the threat of high temperatures.

Turns out there were two problems: the aperture in the pull-up ring is a wee bit small on the sealing nub and the ridge on the screw cap is about two wee bits large for the recess in the ring.

The former succumbed to an O (letter Oh) drill, which I pulled & pushed through the hole by hand to enlarge the aperture from 0.320 to 0.332. It still seals reasonably well, although it’ll pee a thin stream under more pressure than you should apply to such a bottle, which means I put a slight scratch on the aperture.

The latter required gently shaving the ridge with a box cutter (gasp). It’s still rather stiff, but entirely workable. That doesn’t affect the seal, because the ring’s skirt is a snug fit against the screw cap.

Why not just throw the fool thing out? After all, it’s just a freebie water bottle…

We run on the “Use it up, wear it out, fix it once, wear it out again, then put it on the shelf because maybe you can use the parts for something” principle.

Now, that’s not the way things are done these days, but it works for us…

2009-07-28
Bike Helmet Mirror Re-Repair

Socket with brass reinforcement

The front ball joint on the mirror on Mary’s helmet loosened enough that the mirror blew out of position every time we got up to a decent traveling speed. I’ve repaired these mirrors several times before; they’re plastic and tend to fracture / wear out / break at inconvenient moments.

The first pic shows the mirror (the black surface is reflecting the dark floor joists overhead) with an old blob of epoxy that repaired a break in the outer socket. The socket originally had stylin’ curves joining it to the mirror, which proved to be weak spots that required epoxy fortification.

This time the socket split axially on the side away from the mirror, which released the pressure on the ball socket that seats into it. I found a chunk of brass tube that fit snugly over the socket, then carved some clearance for the existing epoxy blob. The key feature is that the tube remains a ring, rather than a C-shaped sheet. to maintain pressure around the socket.

Clamping the reinforcement ring

Here are the various bits, with the reinforcing ring clamped in place. I coated the socket exterior with JB Weld epoxy, slipped the ring in place, and tapped it down with a brass hammer to seat flush with the front face of the socket. That left gaps between the socket opening and the tube that I eased more epoxy into with an awl. A bit more epoxy around the exterior smoothed over that ragged edge.

The strut at the bottom of the picture ends in a ball joint held by a socket that slips into the mirror socket. The loose brass ring above the mirror is some shim stock that I added some years ago to take up slop between the ball socket and the mirror socket and tighten the ball joint. I suppose that pressure eventually split the outer socket, but so it goes.

Repaired mirror joint

The clamp squished the outer socket enough to snug it around the ball socket, so when I reassembled the mirror it was fine. To be sure, I dunked the ball in my lifetime supply of Brownell’s Powdered Rosin for a bit more non-slip stickiness.

I have a box full of defunct bike helmet mirrors, dating back to those old wire-frame square mirrors that clamped onto the original Bell helmets. The newer plastic ones just don’t last; we ride our bikes a lot and even fancy engineering plastic isn’t nearly durable enough. A few bits of metal here and there would dramatically improve the results!

I’m going to build some durable wire-frame mirrors, but … this will keep us on the road for a while. I suppose I should make a preemptive repair on my helmet mirror while I’m thinking of it…

2009-07-27
Why We Use Bicycle Tire Liners

Bike tire puncture

A glass chip gashed the front tire of my bike a while ago, but the slit didn’t cut the Kevlar belt underneath and I let it slide. The pre-ride check before our 50-mile day trip to Old Rhinebeck Aerodrome showed that things had gotten worse (the tire liner was peeking out through the belt), so I replaced the tire before we set out.

Tire liner abrasion

This pic shows that the tire liner was doing its job, although it was slightly abraded and had picked up some road grit. The tube had a barely visible mark.

I generally use fluorescent green Slime tire liners, but this one is a competing brand I picked up a while ago. Not much to choose between the two, although I think Slime liners have a better edge taper and tend to be more flexible.

Notice the other nicks and gashes in the tire tread? We run Schwalbe Marathons on the rear and Primo Comets on the front, both have Kevlar belts. Flats are not a problem any more, even with plenty of sharp road debris; I replace the tires every two years or so when the tread wears smooth or a major gash worries even me. My rule of thumb: when I can see the liner, it’s time to replace the tire.

Tread gash – Schwalbe Marathon

There are riders who argue for very lightweight tires on the basis of performance: better acceleration and lower rolling resistance. I’m willing to trade all that off against not having to dismount a tire by the side of the road…

[Update: Plenty more posts on this general subject, with graphic illustrations of tire damage. Search for liner and you’ll find ’em.]

2009-07-26