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.

Category: Recumbent Bicycling

Cruisin’ the streets

Terracycle Chain Idler Tires: TPU Tweakage

Although the 3D printed tires for our Terracycle chain idlers fit nicely, adjacent TPU threads didn’t bond well:

Terracycle Chain Idler Tire – delamination

Based on some earlier items, I’d been printing TPU at 220 °C, but 230 °C fuses the threads together:

Terracycle Chain Idler Tire – correct settings

The filament turned out to be 1.79 mm diameter, rather than the nominal 1.75 mm, and a few iterations showed a 0.95 Extrusion Multiplier worked much better.

Those were printed at 30 mm/s with 0.25 mm layer height.

I now have a good stock of spare tires, each slightly different than all the others:

Terracycle Chain Idler Tire – spares

The first two slightly delaminated printed tires will remain in service until they show signs of falling apart, because I’d rather ride the bike than fiddle with it.

2025-08-29
Terracycle Chain Idler: 3D Printed Tire
The Terracycle (now T-cycle, for reasons presumably involving the transfer of money) chain return idlers on our Tour Easy bikes developed hardening of their urethane tires:

Terracycle Idler tire – printed vs OEM

Urethane shouldn’t crack like that, but after more than fifteen years, stuff wears out.

The white ring is 95A TPU printed on the Makergear M2, which is definitely more flexy than the original tire, but has the redeeming feature of being both Good Enough and trivially easy to model:
```
include <BOSL2/std.scad>

NumSides = 4*3*2*4;
$fn=NumSides;

Thick = 3.5;
ID = 46.4;
OD = ID + 2*Thick;
Length = 11.2;

tube(Length,id=ID,od=OD,anchor=BOTTOM);
```
It printed with 5 mm brims on both the ID and OD, because TPU has the barest adhesion to the M2’s glass plate + hair glue. There’s a long-unopened box now on the bench with a BuildTak PEI surface (thank you: you know who you are!) that should improve the situation.

In any event, the tires fit well:

Terracycle Idler tire – installed

The layer-to-layer adhesion isn’t as good as I think it should be, so I’ll likely use those tires as testcases for tweaking the new build plate & settings.
2025-08-25
Lovely Weather

The forecast of several pleasant days will have me in the garage wrenching on bikes, doing car maintenance, and finishing home chores.

Back next week …

Obligatory cat(erpillar) picture:

Milkweed Tussock Caterpillar

2025-08-20
Bicycle Mobile Rebuild

A long-lost repair finally made it to the top of the list:

Bicycle Mobile – bottom view

The original string had long since rotted out, but everything else was in a plastic bag just waiting for this occasion.

The colorful cylinders are stacks of laser-cut 6 mm disks with a 2 mm hole, held to the wire & string with a tiny dot of high-viscosity cyanoacrylate glue at each end:

Bicycle Mobile – detail

The disks came from acrylic leftovers:

Bicycle Mobile – laser-cut acrylic

The motion you can’t see makes the shiny bikes much more visible out there:

Bicycle Mobile – side view

The string came from dismantled badge reels providing spiral springs for the auto-retracting spools in the PolyDryer boxes.

The weight ball had a 2 mm hole filled by a wood plug which I cleaned out piecemeal with a 1.5 mm drill bit in a pin vise; a short length of wood skewer holds the new string in place.

Because the upper arms support more weight, their disk stacks need fewer disks for the same leverage. The original mobile had (at most) four 6 mm chromed plastic balls at each level, so I started with eight 3 mm disks, adjusted the stack length as needed, glued them in place, then removed the surplus disks by crushing them with a Vise-Grip.

I should rip off the design (“© otagiri 1979”) to build another with recumbent bikes.

2025-07-29
Dutchess Rail Trail: Brush Trimming & Pruner Repair
The bushes & trees along the Dutchess Rail Trail were reaching out to touch us again, so I took some slow rides with many stops.

~~Maple~~ Oak trees along Page Park Drive:

DCRT Brush Trimming – oak – 2025-07

Blackthorn encroaching through the fence at Overocker:

DCRT Brush Trimming – blackthorn – 2025-07

A tree somebody tossed down the trail bank near Morgan Lake:

DCRT Brush Trimming – discarded tree – 2025-07

The slide lock on my trusty rehabilitated Fiskars bypass pruner worked loose and began sliding into the LOCK position when held overhead, then fell apart during disassembly:

Fiskars pruner – lock rebuild

The lock now consists of:
- An M4 × 12 mm nut from a Chicago Screw that exactly matched the 5 mm OD cylinder passing through the pruner body
- A laser-cut fluorescent acrylic disk for thumb grippiness
- A washer just because
- An M4 hex-head screw
- A dab of Loctite bonding screw to nut
Clean the blades with alcohol and it’s ready for the rest of the season.

I should have put a wave washer in the stack for some springiness, but it works surprisingly well for what it is.

Now: discover how long acrylic lasts out there in the wild.

Update: Yeah, the lock needed a wave washer for more friction, which became apparent after the first overhead branch.
2025-07-10
Newmowa NP-BX1: 2025 Batteries
A new sextet of NP-BX1 batteries for the Sony AS-30V helmet camera arrived:

Newmowa NP-BX1 – 2022 vs 2025

The traces:
- Blue = 2025 batteries
- Red = 2022 batteries when new
I don’t know what the bump in the middle of the new battery discharge curve means. Something weird in the chemistry, I suppose. Getting good batteries from Amazon surely remains a crapshoot and I now have four chargers.

Recharging all six batteries required 5488 mA·hr, just over 900 mA·hr apiece. Running the camera on a one-hour bike ride burns 600-ish mA·hr, so that’s comforting.

Comparing the new results with the 2022 batteries tested last month:

NP-BX1 – Newmowa 2022 in 2025-06

The upper traces appear in red in the first plot, the lower curves come from three years of use.

I’ll deploy the two best 2022 batteries (D and F) in the SJCAM M20 keeping watch from the Forester’s dashboard.
2025-07-08
Newmowa NP-BX1: Three Years Later

A pair of the 2022 batch of Newmowa NP-BX1 lithium batteries for the Sony AS-30V helmet camera no longer survive a typical hour-long bike ride:

NP-BX1 – Newmowa 2022 in 2025-06

The best four have a capacity down 14% from the good old days and the weakest pair are down 29%.

The camera uses 1.9 W, so a battery with 2.5 W·hr capacity should last 78 minutes, but about 400 mV of voltage depression causes the camera to give up before using its full capacity.

So they have a useful lifetime of maybe two years in our regular bike riding schedule and I should have bought replacements last year. I hope the next batch isn’t New Old Stock or recycled cells.

2025-06-26