I wanted a slightly larger “plate cap” to fit a big incandescent bulb and it seemed a fake heatsink might add gravitas to the proceedings:
Yeah, that antique ceramic socket holds the bulb at a rakish angle. Worse, even though I painstakingly laid out the position of the heatsink atop the bulb, it’s visibly off-center. Which wouldn’t be so bad, had I not epoxied the damn thing in place.
After reaming out the M2’s filament drive, the entire blue base printed without incident.
A closer look at the cap:
Memo to Self: Next time, line it up with the vertical glass support inside the bulb and ignore the external evidence.
The boss has a hole for the braid-enclosed cable to the knockoff Neopixel:
The cupped surface perfectly fits the bulb’s 3.75 inch diameter. While you wouldn’t mill out a real heatsink, it definitely looks better this way and (alas) gives the epoxy more footprint for a better grip.
I built the fins with a 1/8 inch cutter in mind, so the fin root radius allows for a
G3 arc without gouging. I doubt machining a fake heatsink from aluminum makes any sense, but the cheap extruded heatsinks on eBay don’t look very good. Plus, they sport completely unnecessary tapped holes for LED mounts and suchlike.
A cross-section shows the wiring channel and cable entry:
I epoxied the Neopixel in place, applied double-sided carpet tape to the whole thing, then painstakingly trimmed around the fins with an Xacto knife:
That looked better from the top side (where it was completely hidden) and came heartbreakingly close to working, but after about a day the cable + braid put enough torque on the cap to peel it off the bulb. Obviously, the tape holds much less enthusiastically after that.
Part of the problem came from the cable’s rather sharp angle just outside the cap:
Rakish angle, indeed. Two of ’em, in fact.
Unlike the smaller cap on the halogen bulb, this time I didn’t bother with a brass tube ferrule, mostly to see how it looks. I think it came out OK and the black braid looks striking in person. Conversely, a touch of brass never detracts from the appearance.
Obviously, the cable wasn’t long enough, either. Part of that problem came from underestimating the braid length: it shortens dramatically when slipped over the cable, even when you expect shortening. Somehow I managed to overlook that, despite cutting the cable quite long enough, thankyouverymuch. There’s a tradeoff between gentle angles and having the cable stick out too far for comfort.
Memo to Self: Use a cable at least four inches longer than necessary, measure the combined cable + braid assembly after screwing the bulb in the socket, and don’t epoxy anything before all the parts are ready for assembly.
That’s why it’s a prototype made out of blue PETG…
Protip: running old ceramic sockets through the dishwasher greatly simplifies their subsequent cleanup.
All in all, I like it.
The OpenSCAD source code as a GitHub gist: