Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
Just for curiosity’s sake, I applied a slitting saw to the oldest defunct generic NP-FS11 battery pack, cutting carefully along the bonded joint between the two parts.
No coolant, 1000 rpm, 200 mm/min, the saw is 22 mm diameter. Much slower than you’d use if you were in production, but I’m not.
First cut all the way around at 0.5 mm inside the case, then another pass at 1.0 mm. The second cut went ting as it passed the tabs at the base of the cells, so I knew the halves were released.
Inside we find a pair of 14430 Li-Ion cells, wired in parallel, with a little protection circuit board just jam-packed with teeny parts. One may reasonably assume the circuit controls over-charge and over-discharge, as well as current limiting.
Pack opened
So a reasonable (or, perhaps, amusing) thing to do would be to buy raw cells from a nominally reputable supplier, do a heart transplant, and see if that improves the situation.
Protection Circuit – Outboard
Photos of the protection PCB, showing the cell connections. Positive end of the cells is toward the PCB. I think there’s enough clearance in the camera’s battery compartment to allow a wrap of tape around the case in lieu of re-bonding the plastic together.
Straight up: this is about a stainless steel socket head cap screw I installed eight years ago, not the original Easy Racers screw, so this is not their problem.
I rode out for milk-and-eggs at the corner store, a flat one-mile ride, and stopped at the traffic signal. Light goes green, line of cars accelerates, so do I… and there’s a snap and the left side of the seat sags backwards. I am not a powerhouse rider and it’s March, so I’m not doing leg presses while getting up to cruising speed.
I continued the mission by sitting slightly to the right on the seat and pedaling gingerly, then diagnosed the problem in the corner store’s parking lot. If I’d been further away, I’d have done the repair right there, but I figured it’d hold together until I got home. It did.
The problem turned out to be a broken screw holding the left-side seat strut to the threaded eyelet on the rear dropout. The top picture shows the way I have it set up: seat strut clamp outboard, rack strut inboard, with a socket head cap screw extending all the way through, and secured with a pair of stainless nuts that went missing along with the broken screw end.
Screw fracture closeup
Here’s the fracture across the end of the screw, which shows no evidence of foul play. As nearly as I can tell, the whole thing snapped off in one event, with none of the crud that would indicate a progressive crack. Compared with that wheel stud, this is in pristine condition.
So it’s time to replace the right-side screw, as well, which means a trip to the Bike Repair Wing of the Basement Laboratory. While I had the bike up in the repair stand, I decided to reshape the head on the right-side screw for better chain clearance.
As nearly as I can tell, the usual practice puts both the seat strut and the rack strut outboard of the threaded eyelet on the dropout, but that seems wrong to me. The seat strut puts a tremendous amount of stress on the screw, so you really want that lever arm as short as possible: put the clamp against the eyelet. While the rack isn’t as heavily loaded, cantilevering it outboard of the clamp just doesn’t look right.
But putting the rack strut inboard of the eyelet means the screw head sticks out rather more than I’d like. Very rarely, the chain will snick against the head and even more rarely it jams between the head and the freewheel. Nothing much happens (it’s a freewheel, after all), but I think reducing the head thickness ought to help.
Reshaped socket head cap screw
So I chucked the screw in the lathe, shortened the socket by about half, and put a taper on the head. If I had a stock of round-head cap screws, one of those would be even better.
The shortened socket makes it a bit tricky to get enough bite with the hex key, but this isn’t something that requires much attention after it’s installed… and I get to do all that in the shop.
Dabs of Loctite in the eyelet and nuts, for sure!
By a truly rare coincidence, a standard 1-1/2 inch cap screw is exactly the right length.
Right-side mount
Here’s a view of the installed right-side screw, looking rearward along the upper rear triangle tube. Seat strut to the outside, rack strut to the inside, and reshaped head above the cluster.
Took the bike out for a 16 mile spin today and it’s all good.
A note for the weight weenies in the crowd: a rack on the back of the seat adds a redundant support structure. Without that, a failed seat strut can be a real showstopper. Even if you don’t use your bike as a pack mule, maybe you should add a rack.
After 30-some-odd years, the X10 controller we’ve been using to turn off all the lights at bedtime finally stopped working. For the last few months it had been occasionally jamming ON, even when nobody pushed any keys, and the only way to reset it was pulling the plug.
The big silver can on the white cable is an ultrasonic mic, so perhaps the circuitry around that was getting cranky: the ultrasonic cleaner in the bathroom (which we use for eyeglasses) would reliably jam it. I think the controller was responding to the third harmonic of the 40-ish kHz cleaner power, delivered through the power line.
As you’d expect, all the electrolytic caps were shot; ESR for the big one was “open”, the smaller ones around 5 Ω. The capacitance values were entirely within spec, of course. I replaced all three.
X10 Controller keyboard
While I had the hood up, I cleaned the switch contacts, even though that probably had nothing to do with the problem. Back in the day, they used actual metal deformable domes, stuck under an adhesive layer that did a fine job of keeping the crud and dust out.
Put everything back together, fired it up, and it misbehaved the same way. I’d say we got our money’s worth out of it, though.
A replacement is on the order of $15 from the usual eBay suppliers, so it’s not the end of the world.
The new one probably doesn’t have the ultrasonic receiver, so it shouldn’t respond to the ultrasonic cleaner with the same enthusiasm.
I attempted to assemble the Totally Featureless Clock’s case using Liquid Nails Clear Seal, figuring that it’d be easier to fixture than runny epoxy. I hoped that the joints would have enough surface area to allow curing, but was dead wrong.
Hope is not a strategy and proper fixturing is your friend.
Anyhow, I was left with eight surfaces on four dislocated panels covered with more-or-less cured sealant. I left ’em sit for a few days, then had to choose between:
Remove enough of the sealant to make the joints fit or
Machine new panels
Turns out that xylene (from my can of Goof-Off) removes cured Liquid Nails Clear Seal just fine, without affecting the surface of the acrylic panel. Soak the corner of a rag, rub vigorously, and the gunk comes right off.
Note, however, that Goof-Off comes in many different formulations. The one I have is mostly xylene, but the California “VOC Compliant” version is mostly acetone… which, I think, eats acrylic plastic for lunch.
All of that stuff eats your liver for lunch, too.
Don’t do like I did and use your bare finger in the rag. Alas, any solvent that actually works also eats any protective glove in my inventory for lunch.
Discovered that one of my toolmaker’s vises had a defunct screw securing the jaw to the body: one side of the head simply vanished over the years. Hadn’t mattered up until now, but I really wanted the jaw to not ride up when clamping the workpiece and the screw was rather loose.
It’s difficult to tighten a screw with half a slot…
Eventually I figured out that the screw has a 6-40 thread. My Brownells Gunsmith screw assortment (which they no longer offer) has, among others, 6-48 and 8-40 screws in flat, fillister, socket, and round head, but nothing in 6-40.
After exhausting all other possibilities, I looked in the assortment box again and found four round-head crosspoint screws with captive lockwashers that I must have salvaged from some dead piece of gear.
Of course, they turned out to be 6-40. Whew!
Chopped off the lockwasher, added a dab of Loctite, and it fit perfectly. I flipped the sliding plate over, as it appeared somewhat worn, but I’m certain that didn’t make any difference.
The screw must have a flat head (and you can’t flip the plate over) if you mount the vise on a machined V-way, but that’s not anything I’m likely to do. In that event, maybe I’ll just file the top off the screw and be done with it.
The drain in our black bathroom(*) stopped working: the pop-up drain seal didn’t pop up.
I finally wedged myself under the sink, with my feet in the shower stall, and removed the operating rod. Turns out that we replaced the countertop and sink (nine years ago; nothing lasts) and the drain used plastic pipe.
Except, of course, for the operating rod that sticks out into the drain. That’s chrome-plated steel, evidently with a few plating imperfections, and the end had simply rotted away. I suppose there’s a small chunk of steel decomposing in the trap.
How much would it have cost to use stainless steel in this corrosion-prone application? Or good old brass (“contains an ingredient known to the State of California to cause cancer or birth defects”)?
After a brief moment of consideration, with my feet still in the shower, I pushed the rod through the bearing ball so the other end stuck out by about the right amount and replaced it in the drain.
Swapped Rod
Yeah, there’s an icky rusted end hanging out there in mid-air, but the next person under that sink will understand exactly what’s going on…
(*) It’s the size of a large closet with wraparound black ceramic tile, a white tile shower stall, and a wall-sized mirror over the sink. We painted the walls and ceiling white, installed an ersatz gray granite counter top (it’s laminate, not anything spendy) with a shiny white sink, and it’s all good. The original half-century-old grout is in fine shape: some things really do last!
After putting Mary’s newly covered seat on her Tour Easy, I replaced the tire liner in the front wheel; the previous tube had gone flat, as mentioned there, due to erosion from the end of the liner.
Here’s what the taped liner looked like: smashed as flat as you’d expect from 100 psi applied evenly over the surface. The tube had a rectangular imprint on it, with what looked like minute abrasions, around the outline of the tape. Nothing major, but it shouldn’t ought to look that way.
Taped tire liner
I rolled that liner up, popped it in the Bike Tire Stuff drawer and replaced it with a Slime liner. This picture shows the ends of the two liners: the brown one (bottom) is about 90 mils thick in the center, the Slime liner (top, fluorescent green) is 60-ish.
Tire liner comparison
As nearly as I can tell, I’ve never had an abrasion flat with a Slime liner, while various other brands have caused troubles.
I broke the edges of the Slime liner with a bit of sandpaper, just to see what that’ll do. Most likely, bad things, seeing as how I’ve never done that before…
The Smell of Molten Projects in the Morning 