Backlighting the overhead, first pass

Mon, 02 Nov 2026 12:00:00 +0000

Panel backlighting is the moment a pile of printed parts starts to look like a cockpit. It’s also where light leaks show up.

The plan

One 5 V bus runs the length of the overhead, with a single PWM dimmer so the whole panel can be turned down for night flying. Each section gets its own short LED strip behind the legend plate.

Light bleed

Bare PETG glows like a lampshade. Two fixes made the difference:

A coat of black primer on the back of every legend plate.
A 1 mm printed baffle around each LED so light only reaches the legend above it.

Wiring notes and the pinout are in the library.

First knobs off the printer

Wed, 14 Oct 2026 12:00:00 +0000

The first thing I printed for the cockpit was the humble autopilot knob. It looks simple, and the outside is. The bore is where it gets interesting.

The problem with D-shafts

A 6 mm D-shaft drawn at 6.0 mm in CAD prints too tight on most machines, and a loose bore spins on the flat. After a few tries, this is what worked on my printer with PETG:

Test	Bore	Flat	Result
1	6.00 mm	4.50 mm	Would not fit
2	6.20 mm	4.60 mm	Fit, but spun
3	6.15 mm	4.45 mm	Press fit, holds

What I’d tell my past self

Print the bore as a small test coupon first. It takes ten minutes and saves an hour of reprinting full knobs.