The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Author: Ed

  • Xubuntu 8.10: Xrandr For Dual Rotated Displays

    Up to this point I’ve been using a hardcoded

    Option "Rotate" "CCW"

    in my /etc/X11/xorg.conf file to get a portrait-mode display on my right-hand monitor, as described in grisly detail there.

    That kills xrandr, which prevented any further display configuration and seemed to sometimes kill off the screensaver. Maybe the screens would blank and then power down, maybe they’d just power down, maybe they’d be on all the time.

    However, simply eliminating the hardcoded Rotate didn’t solve the problem, as xrandr refused to do anything. The appropriate command-line syntax isn’t obvious to the casual observer, but this was alleged to work: xrandr -o left.

    Come to find out, after considerable digging, that one must add this secret incantation to each Display stanza in /etc/X11/xorg.conf:

    Option  "RandRRotation" "on"

    And, perforce, remove the Rotate option.

    That’s evidently due to the fact I’m using the proprietary nVidia driver, which I think everybody does.

    Log out, Ctrl-Alt-Backspace to restart the X server, log back in again, and shazam the cute little Display applet in the Settings Manager actually works. Not only that, but you can specify Left rotation for Display 1 and that actually works, too.

    Update: but, alas, it seems to not be sticky between sessions. Worse, there seems to be no combination of xrandr parameters that can rotate the right-hand screen from a console on the other or, presumably, from a startup script. It is not obvious what this means, either:

    This option selects the X display to use. Note this refers to the X screen abstraction, not the monitor (or output).

    I can’t find anything that works.

    And, FWIW, there’s no Screensaver config applet in the Settings Manager (at least not that I can find), so you fire it up from the command line:

    gnome-screensaver-preferences

    Yes, you use the Gnome screensaver preferences in Xubuntu.

  • How to Plumb a Hot-water Heating System

    My buddy Eks just replaced his host-water furnce with a high-efficiency unit.

    Can you tell that Eks is an engineer?

    The plumber used one of those fancy pipe-compression tools that mashes the mating parts together with an O-ring for sealing. Faster and safer than sweating the joints together, but I want to fast-forward two or three decades to check out the durability.

    As he put it, “You may be able to get a better furnace installation, but you probably can’t pay any more for it…”

  • My Eyeglass Sizes: A Summary

    Having decided to try getting sunglasses from one of those “our lab is in Hong Kong” places, the question arises: what lens & frame size do I need?

    Rummaging through the heap produces this assortment:

    Frame label Lens size Frame width Earpiece Commentary
    53-19 53×40 141 145 Current glasses
    55-16 55×45 142 140 Current sunglasses
    54-16 54×45 133 135 Old sunglasses
    56-16 56×45 137 133 Wire rims, aviators
    52-19 52×39 140 140 Clear, previous daily
    56-16 58×50 135 130 Aviators, too big

    The obvious conclusion is that any lens in the low 50s x 40-ish range will suffice. Pity that the LPS (low-price supplier) doesn’t have anything non-aviator-ish or un-dorky (even by my slack standards) in the 40-ish range, but maybe it’ll work out OK.

    Some general observations.

    I used to wear relatively large aviator-style lenses, as I worked on little parts that occasionally went sproing. Not enough energy to merit safety glasses, but annoying enough to want good eye coverage. These days, alas, I tend to wear a headband magnifier.

    Progressive bifocals require a relatively tall (and, it seems, currently unstylish) lens. Aviators solve that problem, but really are too large for my face. No matter that I wore them for years.

    Anti-reflection coating is wonderful. Pity that the LPS can’t put it on tinted lenses; I’ll see how that works out.

    I wear one pair of glasses all day, every day, and take fanatic care of them; we have an ultrasonic cleaner pretty much dedicated to eyewear. By and large, my lenses last forever. The frames, as you’ve seen there, tend to fail first.

    [Update: It turns out 53×35 lenses really aren’t tall enough for gray 20% transmission sunglasses: the progressive transition is a bit cramped and there’s too much daylight around the top & bottom. I think they’ll be OK for biking, as I wear hideous goggles to keep the dust out of my eyes. A pupillary distance of 62 seems OK. About $63 delivered.]

  • Infra-red Photography: Roosting Turkeys

    The turkeys were discussing their activities yesterday evening while getting ready for bed in the trees out back. This isn’t unusual, but they seemed rather louder than usual.

    We walked out the driveway, me with the Sony DSC-F717 in IR Night Shot mode, and eavesdropped for a while. The two early birds in the trees may have been air bosses for the rest of the flock, as nobody else arrived while we were there.

    So I didn’t get any pictures, but it reminded me of some I took a few years ago when a hen with a gaggle of chicks roosted in a maple directly in front of the house.

    Three peeps are easy to see, but she had at least two others snuggled up on her left side!

  • Shutdown Problems with Xubuntu 8.10 on a Dell 531s

    As described there, I set up a cron job to back up our low-budget file server to an external USB drive and turn it off for the night.

    After a while, it became painfully obvious that

    shutdown -P now

    was, at best, intermittently successful at turning off the power. The shutdown sequence would sometimes hang near the end, with a blank screen, after unmounting all the drives (so there are no logs), with the power on. Keyboard & mouse were dead, tapping the power button produced a display about acpid being unhappy, but nothing I could follow up.

    Oddly, that same command issued from a terminal window would work perfectly for as long as I was willing to restart the machine.

    Even more oddly, the box would shut off properly from the GUI or the GDM login scren.

    A puzzlement…

    After several days of tedious “try this” experimentation and rummaging through the scripts in /etc/init.d/, it seems this command works in the cron job the way it’s supposed to

    halt -p -f

    The -p calls for a power-down and -f says to force the halt (rather than calling shutdown, which we know won’t work).

    So, finally, I can hack 25% off the power bill for that thing.

    Memo to self: some day, figure out exactly how the whole shutdown sequence works.

  • Laser Pointer Annoyances

    Laser pointer battery contact
    Laser pointer battery contact

    Maybe it’s just me, but all of the laser pointers I’ve bought, even the relatively spendy ones, have crappy switches and unstable battery contacts.

    For example, this is the business end of a $12 (!) pen-style pointer. The battery contact was off-center and poorly secured; I pried the white plastic retainer out, bashed the spring into submission, and replaced the retainer with a length of heat-shrink tubing. It wasn’t pretty.

    This pointer has an actual mechanical switch module inside, with a clicky mechanism actuated by the external button. Cheaper pointers seem to rely on bare PCB contacts bridged by the button’s base. Ugh.

    Laser pointer battery orientation: positive DOWN
    Laser pointer battery orientation: positive DOWN

    Memo to Self: The AAA cells fit into the housing with the positive terminal away from the laser head. The white plastic plug has a molded cross that could be mistaken for a + symbol, but it’s not.

  • Mandatory Setup Slide for All Presentations

    Presentation Setup Slide
    Presentation Setup Slide

    When you put together a presentation, add this slide at the very end.

    Display it while you’re setting up the projector so you can make sure all the corners are on-screen, all the colors work, and that the circles are actually circular. Your audience will appreciate your consideration.

    The text font should be whatever you’re using for the main body text in the presentation. If you think the text I’ve used is too large, then you’ve never sat in the back of your own presentation…

    When you’re ready to start, whack the Home key and your regular title slide will appear.

    Here it is as a single-slide PowerPoint presentation, because WordPress doesn’t allow uploading OpenOffice ODP presentations. Copy the slide into your own file and let your audience move around accordingly.