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.

Tag: Repairs

If it used to work, it can work again

  • Upstart vs. NFS Mounts vs. Display Manager: Resolved!

    Quick summary: the current Linux startup machinery Runs All The Things! in parallel, leaving you to figure out all the interdependencies and update all the script files to match your requirements. Mostly, the distro maintainers figure all that, but if you have essential files mounted as NFS shares, then you can will reach a login screen before the mount process completes.

    Having wrestled with this problem for a while, I think I’ve doped out the right way to coerce the Upstart Pachinko Machine to converge on a workable login.

    The solution is to fire off a unique signal after the NFS mount command, then force the display manager to wait until it receives that signal, rather than depend on happenstance as I did before. The mounts occur in /etc/init/local.conf, which now looks like this:

    description "Stuff that should be in /etc/rc.local"
author "Ed Nisley - KE4ZNU"

start on (local-filesystems and net-device-up IFACE=em1)
stop on shutdown

emits nfs-mounted

script

logger Starting local init...

logger Mounting NFS filesystems
mount /mnt/bulkdata
mount /mnt/userfiles
mount /mnt/diskimages
mount /mnt/music
initctl emit nfs-mounted
logger Ending local init

end script

    The start condition ensures that this code won’t run until the wired LAN is up; note that what was once eth0 is now em1. Then, after the mounts happen, initctl fires the nfs-mounted signal.

    The modification to /etc/init/lightdm.conf script consists of one additional line to wait for that signal:

    start on ((filesystem
           and runlevel [!06]
           and started dbus
           and plymouth-ready
           and nfs-mounted)
          or runlevel PREVLEVEL=S)

stop on runlevel [016]

emits login-session-start
emits desktop-session-start
emits desktop-shutdown

    I’m not convinced lightdm.conf is the right spot to jam a stick in the gears, but it seems to be the least-awful alternative. The login-session-start signal doesn’t appear in any file in that subdirectory and I have no idea where else to look.

    Anyhow, the greeter screen now shows a desktop background from the NFS mount, which I regard as A Good Sign:

    Xubuntu greeter - after NFS fix
    Xubuntu greeter – after NFS fix

    Until the next startup revision, anyway…

  • Microsoft Comfort Curve Keyboard Cleaning Redux

    Part of the routine cleaning around here involves running the vacuum cleaner nozzle over the keyboard to suck up random debris, but that doesn’t extract crud from under the keycaps. Almost exactly three years after the previous cleaning, I finally decided the keys had lost enough of their normal feel to justify the hassle of taking the thing apart.

    Bolstered by that experience, however, I just yanked the keycaps off with a removal tool from my old bag of tricks, revealing the horror that lies beneath the surface:

    Microsoft Comfort Curve Keyboard - crud buildup
    Microsoft Comfort Curve Keyboard – crud buildup

    Obviously, I got nasty habits…

    Microsoft Comfort Curve Keyboard - crud detail
    Microsoft Comfort Curve Keyboard – crud detail

    The keycaps took a swim in a dishpan full of hot soapy water, endured some scrubbing, and emerged looking like new. Thwacking them on a towel ejected the remaining water from the posts.

    With the electronics still in place, I vacuumed the larger chunks out of the tray, scrubbed the aforementioned hot soapy water around the bushings with an acid brush, then cleaned up the residue with cotton swabs. There’s a paper towel under the drain gutters to catch the runoff, which worked surprisingly well.

    The keycap legends have been eroding, as they’re basically a decal stuck on the surface. Eventually I’ll have a crappy non-clicky Das Keyboard Model S Ultimate.

    [Update: a spammer’s script has been attempting to create hundreds of junk comments per day, so I’ve temporarily disabled comments for this post. Drop me a direct note using the About / Copyright / Contact link on the right if it’s critical. I expect this to pass in a few days, but I may be underestimating the stupidity out there. ]

    A note from regular commenter Frans:

    Don’t get a Das Keyboard if you want a keyboard without a keypad. Look into e.g. a Leopold Tenkeyless Otaku. The one to which I include a link comes with the same Cherry MX Brown switches as the Das Keyboard Silent.

    Elite Keyboards

    I want one too.

    They look good to me, too, although I hope the weird Esc key is optional…

  • Water Heater Anode Rod – One Year Check

    A one-year-old magnesium rod looks pretty good, all things considered:

    Water Heater Anode Rod - one year
    Water Heater Anode Rod – one year

    The previous one was still working after seven years, although I had to wreck it to get it out…

  • Sony NP-FS11 Battery Status & Rebuild

    The trio of batteries I built for the Sony DSC-F505V two years ago faded away; that camera seems particularly hard on the batteries, perhaps because they’re two cells in parallel that don’t share well. Two of the three seem pretty well gone:

    Sony NP-FS11 2011 Packs - 2013-11 tests
    Sony NP-FS11 2011 Packs – 2013-11 tests

    Back then, I bought 12 cells, built six into those batteries, and left six charged cells sitting in a bag. After rebuilding the two worst batteries with those new-old-stock cells, it seems they maintained a substantial fraction of their charge while resting in the cool and the dark:

    Sony NP-FS11 2011 Cells - 2013 packs - 2013-11-24
    Sony NP-FS11 2011 Cells – 2013 packs – 2013-11-24

    However, the camera would regard them as discharged, because it infers charge state from voltage. Squinting at the curves, their condition after a few minutes is roughly equal to a new & freshly charged battery produces over on the right when it’s nearly discharged.

    The other curves show the result after their first charge in two years: basically, full capacity. The fact that both pairs of curves come pretty close to overlaying means they’re still well matched.

    Sony NP-FS11 batteries - rebuilt
    Sony NP-FS11 batteries – rebuilt

    The third cell isn’t up to their spec, but it’s close enough to not bother rebuilding right now: 1.2 vs 1.4 A·h.

    The Kapton tape pull tabs work wonderfully well, as the rebuilt batteries fit the compartment rather more snugly than the un-hacked cases.

  • Samsung Quiet Jet Vacuum: Improved Floor Brush Strips

    Those simple floor brush strips for the Samsung vacuum cleaner worked moderately well, but the urethane adhesive didn’t have enough grip on the plastic strips. Having just run out of that batch, I made up another set with slightly undercut holes:

    Bushing Solid Model - better holes - bottom
    Bushing Solid Model – better holes – bottom

    That’s half a thread width on each side, just enough to give the adhesive something to grab. Such is the plan, anyway.

    I taped the strips to a pair of credit cards (actually, flat cards without embossed characters), slathered a thin layer of urethane atop them, and laid on squares of the same wool fabric I used the last time:

    Samsung vacuum floor strips - gluing
    Samsung vacuum floor strips – gluing

    Then I piled a steel block atop an aluminum slab on both arrays, fast forwarded a day, peeled and flexed and cut the strips apart:

    Samsung floor brushes - glued
    Samsung floor brushes – glued

    The urethane foamed through the holes as I hoped and (seems to have) locked the fabric in place, at least well enough to withstand some experimental bending on the workbench.

    Now, to see how they stand up to actual use…

    The OpenSCAD source code:

    // Samsung Vacuum cleaner nozzle floor strips
// Ed Nisley KE4ZNU January 2013
//  November 2013 - adapt to M2, enlarge holes

Layout = "Build";			// Show, Build

//- Extrusion parameters must match reality!
//  Print with +0 shells and 3 solid layers

ThreadThick = 0.25;
ThreadWidth = 0.4;

HoleWindage = 0.75;

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

Protrusion = 0.1;           // make holes end cleanly

//----------------------
// Dimensions

Body = [6.0,59.0,3*ThreadThick];	// width, length, thick

Tab1 = [4.5,5.0,0.0];				// width, length, offset from centerline
Tab2 = [3.5,5.0,0.5];

HoleOC = 8.0;						// adhesive anchoring holes
HoleDia = 2.0;
HoleSides = 4;
HoleMax = floor(Body[1]/(2*HoleOC));

echo("HoleMax: ",HoleMax);

//----------------------
// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {           // based on nophead's polyholes

Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

FixDia = Dia / cos(180/Sides);

cylinder(r=(FixDia + HoleWindage)/2,
         h=Height,
         $fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

    Range = floor(50 / Space);

    for (x=[-Range:Range])
        for (y=[-Range:Range])
            translate([x*Space,y*Space,Size/2])
            %cube(Size,center=true);

}

module BackingStrip() {

	difference() {
		union() {
			translate([0,0,Body[2]/2])
			cube(Body,center=true);
			translate([Tab1[2],-1*Body[1]/2,Body[2]/2])
			cube([Tab1[0],2*Tab1[1],Body[2]],center=true);
			translate([Tab2[2],+1*Body[1]/2,Body[2]/2])
			cube([Tab2[0],2*Tab2[1],Body[2]],center=true);
		}
		for (i = [-HoleMax:HoleMax])
			translate([0,i*HoleOC,-Protrusion])
			rotate(45) {
				PolyCyl(HoleDia,(Body[2] + 2*Protrusion),HoleSides);
				PolyCyl((HoleDia + ThreadWidth),(ThreadThick + Protrusion),HoleSides);
			}
	}
}

//----------------------
// Build it!

ShowPegGrid();

if (Layout == "Show")
	BackingStrip();

if (Layout == "Build")
	rotate(90) BackingStrip();

  • Toyota Sienna Hood Rod Pivot

    We don’t drive the van nearly often enough (*) to keep the battery charged in cold weather, so I use a trickle charger to keep it alive between jaunts. While opening the hood one evening, I managed to twist the plastic fitting that anchors the hood prop rod beyond its limits and snapped the poor thing off, which left me holding the hood in one hand and the rod in the other.

    After extricating most of the fragments from under the van, I found that the OEM part had a hollow post that snapped into a square hole in the front bulkhead under the hood. The post had two keys and a pair of snap latches that held it in place, a design that seemed optimized for rapid assembly with no fiddly parts, but which depended on a few millimeters of plastic to restrain a meter of steel rod.

    I made up a simple replacement with a solid square post and a square cap to clamp it against the bulkhead:

    Toyota Sienna hood rod pivot - first version
    Toyota Sienna hood rod pivot – first version

    The general idea is that the screw puts the entire post under compression, giving it less temptation to shear at the deck line when I twist the rod a bit too far out of line. That 8-32 screw seemed entirely adequate to the task; a 10-32 screw would take up too much of the post for my liking.

    Alas, it turns out that underneath the bulkhead’s top flange lies a metal plate surrounding the headlight that’s so close to the hole that the big blocky cap wouldn’t fit. So I slimmed the cap down to three thread widths and tried again, only to discover that the plate came that close to the edge of square hole.

    However, there was a gap between the bottom of the bulkhead and the top of the plate, so I introduced pivot and cap to Mr Belt Sander, removed enough plastic to let the cap slide into the gap, then discovered the 8-32 screw head was just slightly too large to let the screw align with the post.

    Another tweak to the model, based on actual measurements on the abused parts, produced the final version:

    Toyota Sienna Hood Rod Pivot - solid model
    Toyota Sienna Hood Rod Pivot – solid model

    The rod hole has a nice bevel, there’s no fragile neck between the rod hole and the base flange, the solid post lies flat on the platform for EZ building, and there’s a slight offset between the post and the flange that eliminates the need for support material. Printing it lying down orients the filament paths around the hole and base, making the part stronger in the direction it needs the most strength.

    I think the cap walls could be slightly thicker, but we’ll see how long the thing lasts…

    A group photo of all the versions, lined up from left to right, shows the broken OEM part, the first blocky attempt, the slimmed-down and too-long version to the rear, the shorter version that actually fit, and a backup part for when that one breaks:

    Toyota Sienna hood rod pivot versions
    Toyota Sienna hood rod pivot versions

    The sanded-down part held the hood open while I took that group picture. Here’s what it looks like under load:

    Toyota Sienna hood rod pivot - in place
    Toyota Sienna hood rod pivot – in place

    The scrawls on the bulkhead just in front of the pivot remind me of fluid levels, torques, and suchlike. The stud sticking out to the rear is a headlight aiming screw mounted in the plate that caused so much hassle; you’d think I’d have noticed it before starting this adventure, but noooo…

    For what it’s worth, that’s rapid prototyping in action: three (and a half) iterations in quick succession, each getting closer to a goal that you (well, I) can’t quite define, but will recognize when it appears. Took about three hours over the course of two days.

    I loves me my M2 3D printer…

    (*) Indeed, the tires often take three miles to warm up their flat spots due to sitting in the garage for a week…

  • HP Scope Probe Flange Repair: Improved Spares

    While reducing the clutter atop the Electronics Workbench, I ran off four more probe flange reinforcements, just so I’m ready for the next crunch:

    HP scope probe flange disks
    HP scope probe flange disks

    They’re almost identical to the previous version, although I tweaked the taper to end slightly inside the cylindrical cup, thereby eliminating the coincident faces and leaving a minute rim that doesn’t matter:

    HP Scope Probe Flange Repair - bottom
    HP Scope Probe Flange Repair – bottom

    Given that I’ve had the ‘scope for nigh onto two decades and have only broken one probe flange, I think four reinforcements will be a lifetime supply: with any luck, the scope will blow a capacitor before I do.

    The OpenSCAD source code:

    // Tek Scope Probe Flange
// Ed Nisley KE4ZNU November 2013

//- Extrusion parameters must match reality!
//  Print with 2 shells and 3 solid layers

ThreadThick = 0.20;
ThreadWidth = 0.40;

HoleWindage = 0.2;

Protrusion = 0.1;            // make holes end cleanly

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

//----------------------
// Dimensions

FlangeOD = 16.0;
FlangeID = 8.75;
FlangeThick = IntegerMultiple(1.25,ThreadThick);

DiskOD = FlangeOD + 4*ThreadWidth;
DiskThick = FlangeThick + 4*ThreadThick;

NumSides = 8*4;

//----------------------
// Useful routines

module PolyCyl(Dia,Height,ForceSides=0) {            // based on nophead's polyholes

Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2);

FixDia = Dia / cos(180/Sides);

cylinder(r=(FixDia + HoleWindage)/2,
h=Height,
$fn=Sides);
}

module ShowPegGrid(Space = 10.0,Size = 1.0) {

Range = floor(50 / Space);

for (x=[-Range:Range])
for (y=[-Range:Range])
translate([x*Space,y*Space,Size/2])
%cube(Size,center=true);

}

//----------------------
// Build it

ShowPegGrid();

difference() {
union() {
translate([0,0,2*ThreadThick])
cylinder(r=DiskOD/2,h=DiskThick,$fn=NumSides);    // cylinder around flange

cylinder(r1=(DiskOD - 2*ThreadWidth)/2,                // flange reinforcing plate
r2=DiskOD/2,
h=(2*ThreadThick + Protrusion),
$fn=NumSides);
}
translate([0,0,(DiskThick - FlangeThick)])                // flange clearance
PolyCyl(FlangeOD,2*FlangeThick,NumSides);

translate([0,0,-DiskThick/2])                            // probe nose clearance
PolyCyl(FlangeID,2*DiskThick,NumSides);
}