Advertisements

Vacuum Tube LEDs: Octal Tube Base Drilling

Clamping the octal tube into the Sherline let me set the XY=0 origin to the center of the base with the laser dot (visible near the front):

Octal tube clamped on Sherline mill

Octal tube clamped on Sherline mill

Find the edges, touch off the half the 32.2 mm diameter, then align the drill at XY=0 directly over the exposed evacuation tip:

Octal Tube - drill alignment

Octal Tube – drill alignment

Make a very shallow cut to verify the alignment:

Octal Tube - drill first touch

Octal Tube – drill first touch

Just inside the scuffed ring from the drill, you can see the fractured ring where the original one-piece Bakelite spigot / key / post broke off.

Then extract the drill from the chuck, file more relief behind the cutting edges so they actually cut, re-chuck, and continue the mission:

Octal Tube - drilling

Octal Tube – drilling

Pick a nice Bakelite ring out of the drill:

Octal Tube - drilled ring

Octal Tube – drilled ring

And eventually you can see all the way to the glass envelope:

Octal Tube - base opening

Octal Tube – base opening

The (knockoff) Neopixel LED sits directly below the evacuation tip and is about the same diameter, so much of that enlarged opening will be in shadow. Despite that, the tube does seem noticeably brighter:

Octal Tube - drilled base opening

Octal Tube – drilled base opening

Drilling that tube was so harrowing that I can’t imagine similar surgery on an intact octal base.

Perhaps just slicing off the tip of the Bakelite spigot and gluing a single very bright red/orange LED in place, rather using than a (knockoff) Neopixel a few millimeters away, will suffice.

Or just give up, top-light these tubes, and move on?

Advertisements