A notebook of investigations. Each post starts from a thread sticking out, and follows it to the end.
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A broken spoke on my hub motor, and the tension meter I ended up welding
Second 2,000 W hub-motor wheel to lose a spoke. Instead of retensioning by ear, I designed and then welded a tension meter: three-point bending over almost the whole spoke, the force set by the click of a torque wrench, the reading taken with a caliper. The reasoning, the dead ends, the tool, the first numbers, and what remains to be measured.
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A family trailer designed before the first weld: kitchen, gear box, three bikes
Designing a home-built trailer towed by a long-wheelbase VW T5: drawer kitchen, fridge and gas, a large box for climbing, surfing and hiking gear, three bikes on the roof. Why the classic Mini axle was undersized, why a Seat Cordoba 1.9D axle replaced it, where to put the axle for 7% nose weight, how long a drawbar makes reversing easy, and why the real motorway risk is crosswind, not snaking.
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The bug I set out to fix was already fixed — and the fix was wrong
How do you pick what to contribute to when you're starting out? I followed the usual advice — find a well-scoped task in an active project — and ran into three things nobody had reported: a wrong table entry in code merged two months ago and reviewed by four people, a missing sensor, and a performance defect the package maintainer had instrumented himself without anyone reporting it. The story of one evening on a Pixel 3a, with the dead ends, the prediction I got wrong, and what to write when you failed to prove something.
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Vibe design: getting an AI to model a part it will never see
How to model a TPU suction cup from a paper sketch, in dialogue with an AI that has neither the part nor the calipers. Why open questions go in circles, why a wrong render moves faster than a good question, why dimensions that add up prove nothing, and what 95A TPU forces onto the drawing when you print through a Bowden tube.
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A European Pixel 3a running Linux: what Google abandoned in 2022 now runs a 2026 kernel
A European Pixel 3a (G020F), last updated by Google in May 2022, factory-reset and cracked. In one evening: postmarketOS with a mainline Linux 7.1.3 kernel, Phosh, SSH over the USB cable. The full story — why the mainline kernel rather than Ubuntu Touch, unlocking the bootloader, and the hour spent blaming the cable when the real culprit was kernel USB autosuspend relayed by TLP. And why this isn't just a hobby: Chat Control, age verification, and the government ID Google will soon require from developers before you can install their apps.
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Six years of disappointing prints: what my FLSun QQ-S delta really had, and how we calibrated it for good
A 2020 FLSun QQ-S delta printer, 'always a bit disappointing' next to a Bambu Lab. Switch to Klipper, then an investigation: an extruder under-extruding by 11.5% since day one, tower angles never calibrated, a motor current the official Klipper config doesn't set, a levelling method that lied. The story, the numbers, the tools and the full procedure to reproduce it — no probe, just a sheet of paper.
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Neato error 4202 “battery discharged”: the day my vacuum decided it was dead
Error 4202 on a Neato D8, D9, D10 or D800: the battery isn’t necessarily dead. How I got the pack’s bq40z50 chip to talk using a two-euro ESP32, what it said, the twist that came the next day, and the new attempt.
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The Fire, the Model, and What a Different Policy Would Have Changed
Six days of megafire in Gironde and the Landes, a model that learns to represent firefighting, and a stinging question: what would another policy have changed?
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My model was setting the Atlantic on fire
A wildfire in the Landes — what if it heads for the Blayais nuclear plant? Two days to cobble together a tool that answers, and all it got wrong.
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The night works for us
37.7 °C outside, 30 °C in the bathroom, and the extractor fan hasn’t run all week. How an instrumented house learns to shed its heat at night.
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Reverse-engineering a 1970 sofa bed, with an AI at Blender's controls
A Czechoslovak sofa bed spotted online, an AI driving Blender, and three wrong theories before the right one. A parametric reverse-design, missteps included.
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My son, brainrot and me: a father's investigation inside the dopamine machine
My son was getting irritable after his Roblox videos. Instead of speculating, I analyzed the transcripts of his 10 favorite videos. Here is what the data said.