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):
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:
Make a very shallow cut to verify the alignment:
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:
Pick a nice Bakelite ring out of the drill:
And eventually you can see all the way to the glass envelope:
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:
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?
One of the octal tubes in my collection has a broken spigot / key post that lets some light in through the bottom of the normally opaque Bakelite base:
Perhaps drilling out the base would let more light pass around the evacuation tip, but that requires a shell drill to clear the tip. Some doodling suggested a drill with 12 mm OD and 8 mm ID, which was close enough to one of the smaller homebrew drills in my collection that I decided to see how it worked:
You (well, I) can’t freehand such a hole, particularly with a glass tip in the middle, so I needed a way to clamp the tube in either the drill press or the Sherline. A pad for the clamp screw in a V-block seemed appropriate:
The screw hole sits at the 1/3 point to put more pressure near the pin end of the base. Maybe that matters.
The setup looks like this, with a small red laser dot near the front of the base:
The tube rests on a random scrap of plastic, with the hope that the drill won’t apply enough pressure to break the glass envelope.
In normal use, the V-block would be oriented the other way to let you cross-drill the cylinder. In this end-on orientation, drilling torque can rotate the tube; compliant padding for more traction may be in order.
The OpenSCAD source code as a GitHub Gist now includes a module that spits out the clamp:
NYSDOT seems oddly reluctant to perform routine brush clearing along Rt 376 from Red Oaks Mill to the Hamlet of New Hackensack, despite the obvious hazard presented by the bushes:
If it were a pleasant back-country lane, rather than our main route to the Dutchess Rail Trail, perhaps having the greenery take over the shoulder wouldn’t matter quite so much:
Turns out the shoulder just north of Maloney has developed lethal cracks as the pavement subsides into the adjoining section of the Mighty Wappinger Creek. A bit more clearance would still be nice.
We were sitting in the Credit Union and, as usual, I scouted out the WiFi situation:
Huh. Not what you’d expect to find in a bank lobby.
In case you haven’t seen what can happen with a thermostat, you can pwn a Nest.
Searching with the obvious keywords should provide plenty of reasons why the Internet of Things isn’t ready for prime time, not that that will slow it down in the least.
A few days after installing the replacement cord caps, I bumped the bottom rail of the miniblind while opening the window and had one endcap disintegrate; apparently window hardware isn’t hardened against prolonged UV exposure. Who knew?
Fortunately, I can fix that:
Making the walls three threads wide provides enough room for a single solid infill thread:
The exterior shape comes from a hull wrapped around six circles: four to define the corner radius and a pair that bump the center out by the calculated chord height. The interior shape comes from a pair of chord-radius polygonal circles (they only have three facets across the length of the inside wall) that fit the bottom rail almost perfectly.
As always, natural PETG has a crystalline, slightly transparent, appearance:
I should spring for some opaque white filament, but that way lies madness; I might start caring what these things look like.
You can buy entire miniblinds for a few bucks a pop, but the last time we did that, they were different than the ones we had before. That wouldn’t matter if the standard miniblind mounting brackets fit our 1955 Anderson windows, but noooo they don’t: the custom adapters I machined for the first miniblind brackets, of course, didn’t fit the new miniblinds.
Now I can just snap the replacement endcaps (and cord pulls) in place, declare victory, and move on.
The OpenSCAD source code as a GitHub Gist:
The original doodle with some dimensions that didn’t withstand careful measurements:
Apart from the Bakelite bases on octal tubes, I figured there should be no problem shining a light up through the glass envelope. Come to find out that some of the tubes with Miniature 7 bases have an electrostatic shield (?) across the bottom that pretty well blocks the light.
This 6BJ6 has a neatly trimmed octagon:
The shield plate, if that’s what it is, doesn’t have a standardized shape. This 6CB6 sports a simple square:
The Box o’ Hollow State Electronics contains one 6BE6 tube (a heptode with five grids connected to four pins) without a shield:
Yeah, those pins are rather grotendous.
And another 6BE6 with a semitransparent smudge not connected to anything else; it would look accidental if it weren’t inside the tube:
All the shielded tubes are pentodes, for whatever difference that makes.
The APRX iGate program I’m using produces a hardware & software event log file:
2016-09-03 11:24:40.368 TTY /dev/serial0 read timeout. Closing TTY for later re-open. 2016-09-03 11:25:10.373 TTY /dev/serial0 Opened. 2016-09-03 11:32:05.485 CLOSE APRSIS noam.aprs2.net:14580 heartbeat timeout 2016-09-03 11:32:15.495 CLOSE APRSIS noam.aprs2.net:14580 reconnect 2016-09-03 11:32:15.776 CONNECT APRSIS noam.aprs2.net:14580 2016-09-03 12:25:11.154 TTY /dev/serial0 read timeout. Closing TTY for later re-open. 2016-09-03 12:25:46.154 TTY /dev/serial0 Opened. 2016-09-03 15:50:14.905 TTY /dev/serial0 read timeout. Closing TTY for later re-open. 2016-09-03 15:50:46.155 TTY /dev/serial0 Opened. 2016-09-03 16:50:51.155 TTY /dev/serial0 read timeout. Closing TTY for later re-open. 2016-09-03 16:51:26.155 TTY /dev/serial0 Opened.
I have no idea what’s going on with the “read timeout” messages. They seem to occur almost exactly a hour apart, except when they’re a few hours apart. The TNC-Pi2 board includes a PIC processor; maybe it loses track of something every now & again, but APRX only notices if it happens in the middle of a read operation.
The APRSIS server connection drops every few days and APRX seems well-equipped to tolerate that.
All in all, it’s working fine…