Software – Page 83 – The Smell of Molten Projects in the Morning

Lenovo Q150: Setup for HP 7475A Plotter Demo

Starting with a blank 120 GB SSD, I had to disable the “Plug-n-Play OS” BIOS option to get the Lenovo Q150 to boot from a System Rescue CD USB stick. While the hood was up, I told the BIOS to ignore keyboard errors so it can boot headless.

Partitioning:

50 GB ext4 partition for Mint
8 GB swap
The remainder unallocated

Booting & installing Mint Linux 17.2 XFCE from another USB stick went smoothly, after which it inhaled the usual gazillion updates. Rather than wait for the auto-updater to wake up and smell the repositories, I generally get it done thusly:

sudo apt-get update
sudo apt-get upgrade
apt-get dist-upgrade
apt-get autoremove

Add my user to the dialout group, so I have access to the USB serial converter on /dev/ttyUSB0 that will drive the plotter.

Configure a static IP address that appears in the appropriate /etc/hosts files.

Install some useful packages:

nfs-common
openssh-server
htop and iotop

Set up ssh for public key authentication, rather than passwords, on an unusual port, so everything else can happen from the Comfy Chair upstairs.

Install packages that Chiplotle will need:

build-essential
python-setuptools
python-dev
python-numpy
python-serial
hp2xx

I think some of those would be auto-installed as dependencies by the next step, but now I can remember what they are for the next time around this action loop:

sudo easy_install -U chiplotle
... blank line to show underscore above ...

Plug the old hard drive into a USB-SATA adapter to copy:

~/.bashrc — my familiar colorful prompt
baseplotter.py — works properly with hardwired handshaking
~/.chiplotle/config.py — set up to use rtscts handshaking
PlotterShapes.py — the demo program

Then chuck up some paper and pens to let it grind out art:

HP 7475A - demo plot — HP 7475A – demo plot

It’s good clean fun…

2016-01-08

Chip-on-board LED Desk Lamp Retrofit

After the 5 mm white LEDs failed on the original desk lamp rebuild, I picked up some chip-on-board LED lamps from the usual eBay supplier:

COB LED Desk Lamp - bottom — COB LED Desk Lamp – bottom

The LED’s aluminum baseplate (perhaps there’s an actual “board” inside the yellow silicone fill) is firmly epoxied to a small heatsink from the Big Box o’ Heatsinks, chosen on the basis of being the right size and not being too battered.

The rather limited specs say the LED supply voltage can range from 9 to 12 V, suggesting a bit of slack, with a maximum dissipation of 3 W, which definitely requires a heatsink.

The First Light test looked promising:

COB LED Desk Lamp - first light — COB LED Desk Lamp – first light

That’s driven from the same 12 VDC 200 mA wall wart that I used for the failed ring light version. Measuring the results shows that the supply now runs at the ragged edge of its current rating, with the output voltage around 10.5 V with plenty of ripple:

The 260 mA current (bottom, trace 1 at 100 mA/div) varies from 200 to 300 mA as the voltage (top, trace 2 at 2 V/div) varies between 10 V and a bit under 11 V. If you believe the RMS values, it’s dissipating 2.7 W and the heatsink runs at a pleasant 105 °F in an ordinary room. The wall wart gets about as warm as you’d expect; it contains an old heavy-iron transformer and rectifier, not a trendy switcher.

The heatsink mount looks nice, in a geeky way:

COB LED Desk Lamp - side detail — COB LED Desk Lamp – side detail

The left side must be that long to anchor the gooseneck; I thought about tapering the slab a bit, but, really, it’s OK the way it is. Dabs of epoxy hold the gooseneck and heatsink in place.

The heatsink rests on a small ledge at the bottom of the slab that’s as tall as the COB LED is thick, with a wire channel from the gooseneck socket:

COB LED Heatsink mount - Slic3r — COB LED Heatsink mount – Slic3r

The Hilbert Curve infill on the top produces a textured finish; I’m a sucker for that pattern.

The old lamp base isn’t particularly stylin’, but the new head lights up my desk below the big monitors without any glare:

COB LED Desk Lamp - overview — COB LED Desk Lamp – overview

Now, let’s see how long this one lasts…

The OpenSCAD source code as a Github gist:

	// Chip-on-board LED light heatsink mount for desk lamp
	// Ed Nisley KE4ZNU December 2015

	Layout = "Show"; // Show Build

	//- Extrusion parameters must match reality!

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

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

	//———————-
	// Dimensions

	ID = 0; // for round things
	OD = 1;
	LENGTH = 2;

	Gooseneck = [3.0,5.0,15.0]; // anchor for end of gooseneck

	COB = [25.0,23.0,2.5]; // Chip-on-board LED module

	Heatsink = [35.5,31.5,4.0]; // height is solid base bottom
	HSWire = [23.0,28.0,53.3]; // anchor width OC, width OAL, length OC
	HSWireDia = 1.4;

	HSLip = 1.0; // width of lip under heatsink

	BaseMargin = 22ThreadWidth;
	BaseRadius = Gooseneck[OD]; // 2 x gooseneck = enough anchor, sets slab thickness
	BaseSides = 2*4;
	Base = [(Gooseneck[LENGTH] + Gooseneck[OD] + Heatsink[0] + 2*BaseRadius + BaseMargin),
	(Heatsink[1] + 2BaseRadius + 2BaseMargin),
	2*BaseRadius];


	//———————-
	// 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);
	}

	//– Lamp heatsink mount

	module Lamp() {

	difference() {
	translate([(Base[0]/2 – BaseRadius – Gooseneck[LENGTH]),0,0])
	hull()
	for (i=[-1,1], j=[-1,1])
	translate([i(Base[0]/2 – BaseRadius),j(Base[1]/2 – BaseRadius),Base[2]/2])
	sphere(r=BaseRadius/cos(180/BaseSides),$fn=BaseSides);

	translate([(Heatsink[0]/2 + Gooseneck[OD]),0,Heatsink[2] + COB[2]]) // main heatsink recess
	scale([1,1,2])
	cube((Heatsink + [HoleWindage,HoleWindage,0.0]),center=true);

	translate([(Heatsink[0]/2 + Gooseneck[OD]),0,Heatsink[2] – Protrusion]) // lower lip to shade lamp module
	scale([1,1,2])
	cube(Heatsink – [2HSLip,2HSLip,0],center=true);

	translate([0,0,Base[2]/2]) // goooseneck insertion
	rotate([0,-90,0]) rotate(180/8)
	PolyCyl(Gooseneck[OD],Base[0],8);

	translate([0,0,Base[2]/2 + Gooseneck[ID]/2]) // wire exit
	rotate([180,0,0])
	PolyCyl(Gooseneck[ID],Base[2],6);

	translate([Gooseneck[OD],0,(COB[2] – Protrusion)/2]) // wire slot
	rotate([180,0,0])
	cube([2*Gooseneck[OD],Gooseneck[ID],(COB[2] + Protrusion)],center=true);

	}

	}

	//———————-
	// Build it

	if (Layout == "Show") {
	Lamp();
	}

	if (Layout == "Build") {

	}

view raw Chip On Board Heatsink Mount.scad hosted with ❤ by GitHub

2016-01-06

Web Security Warning: Say What?

Having turned on my old Kindle Fire’s “security warnings” just to see what happens, I’m confronted by pop-ups like this on a regular basis:

People who know what they’re talking about tell me there’s no way for ordinary civilians, such as I, to evaluate the validity of the “credentials” described by that pop-up. In this case, the credential apparently comes from DigiCert, which ought to be trust-able, and was issued to cmcore.com, an actual IBM subsidiary that apparently does Web analytics.

It works fine through my desktop browsers. The Kindle, however, can’t even find digicert.com, so the problem must be an Amazon thing.

The only response that makes sense is to continue loading: gizmodo.com might have cat pictures!

I should just turn off the warnings and be done with it…

2016-01-02

Command-line CD Ripping & Encoding

A recent and rather battered book-on-CD posed more than the usual problems for Asunder, so I finally broke down and fiddled around with cdparanoia and lame. This has obviously been done many times before, but breaking it into two simple steps per CD makes the inevitable errors easier to find and work around.

Invoke cdparanoia thusly to rip an entire CD into separate tracks:

cdparanoia -B -v

The files pop out sporting names like track01.cdda.wav, but they won’t be around long enough for you to develop a deep emotional attachment.

Throw a handful of parameters at lame to convert the WAV files into tagged MP3 files:

d=7
for t in {01..18} ; do lame --preset tape --tt "D${d}:T${t}" --ta "Author Name" --tl "Book title" --tn "${t}/18" --tg "Audio Book" --add-id3v2 track${t}.cdda.wav D${d}-${t}.mp3 ; done
rm track*

There’s surely a way to make a double substitution work in the track sequence, but the syntax, ah, escapes me at the moment.

You might want to not delete the WAV files until you’re happy with the MP3 results.

In any event, that produces a sequence of MP3 files imaginatively named along the lines of D1-01.mp3, which fits neatly into the cramped LCD space available on an MP3 player.

Your quality preferences may differ…

2015-12-29

Blue Gauntlet Fencing Helmet Ear Grommet

Our Larval Engineer practiced fencing for several years, learning the fundamental truth that you should always bring a gun to a knife fight:

Fencing - taking a hit — Fencing – taking a hit

It’s time to pass the gear along to someone who can use it, but we discovered one of the ear grommets inside the helmet had broken:

Blue Gauntlet M003-BG Helmet - broken ear grommet — Blue Gauntlet M003-BG Helmet – broken ear grommet

The cylinder in the middle should be attached to the washer on the left, which goes inside the helmet padding. It’s a tight push fit inside the washer on the right, which goes on the outside of the padding. Ridges along the cylinder hold it in place.

Being an injection-molded polyethylene part, no earthly adhesive or solvent will bother it, soooo… the solid model pretty much reproduces the original design:

Fencing Helmet Ear Grommet - show — Fencing Helmet Ear Grommet – show

The top washer goes inside the padding against your (well, her) ear, so I chamfered the edges sorta-kinda like the original.

There are no deliberate ridges on the central cylinder, but printing the parts in the obvious orientation with no additional clearance makes them a very snug push fit and the usual 3D printing ridges work perfectly; you could apply adhesive if you like. The outside washer has a slight chamfer to orient the post and get it moving along.

The posts keep the whole affair from rotating, but I’m not sure they’re really necessary.

Printing a pair doesn’t take much longer than just one:

Fencing Helmet Ear Grommet - build — Fencing Helmet Ear Grommet – build

It doesn’t look like much inside the helmet:

Blue Gauntlet M003-BG - replacement ear grommet - installed — Blue Gauntlet M003-BG – replacement ear grommet – installed

The OpenSCAD source code as a gist from Github:

	// Fencing Helmet Ear Grommet
	// Ed Nisley KE4ZNU December 2015

	// Layout options

	Layout = "Show"; // Base Cap Build Show

	//- Extrusion parameters must match reality!
	// Print with +1 shells and 3 solid layers

	ThreadThick = 0.20;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	//———————-
	// Dimensions

	NumSides = 12*4;
	$fn = NumSides;

	//———————-
	// 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);
	}


	//——————-
	// Parts

	// Base on outside of liner

	PostOD = 15.5;
	PostLength = 8.0;

	BaseOD = 26.0;
	BaseLength = 3.4;

	module Base() {
	difference() {
	union() {
	cylinder(d=BaseOD,h=2.0);
	cylinder(d=20.0,h=BaseLength);
	for (i=[0:5])
	rotate(i*360/6)
	translate([11.5,0,0])
	rotate(180/6)
	cylinder(d1=2.5,d2=3*ThreadWidth,h=4.0,$fn=6);
	}
	translate([0,0,-Protrusion])
	// PolyCyl(PostOD,4.0,NumSides/4);
	cylinder(d=PostOD,h=PostLength,$fn=NumSides/4);
	translate([0,0,(BaseLength – 4*ThreadThick)])
	cylinder(d1=PostOD,d2=(PostOD + 2ThreadWidth),h=(4ThreadThick + Protrusion),$fn=NumSides/4);
	}
	}

	// Cap inside liner

	CapID = 12.0;
	CapOD = 28.0;
	CapThick = 3.0;

	module Cap() {
	difference() {
	union() {
	rotate_extrude(convexity=2)
	polygon(points=[
	[CapID/2 + CapThick/3,0.0],
	[CapOD/2 – CapThick/3,0.0],
	[CapOD/2,CapThick/2],
	[CapOD/2,CapThick],
	[CapID/2,CapThick],
	[CapID/2,CapThick – CapThick/3]
	]);
	translate([0,0,CapThick – Protrusion])
	cylinder(d=PostOD,h=(PostLength – (CapThick – Protrusion)),$fn=NumSides/4);
	}
	translate([0,0,-Protrusion])
	PolyCyl(CapID,10.0,$fn);
	}
	}

	//———————-
	// Build it!

	if (Layout == "Base")
	Base();

	if (Layout == "Cap")
	Cap();

	BuildSpace = 30/2;
	if (Layout == "Build") {
	for (j=[-1,1])
	translate([j*BuildSpace,0,0]) {
	translate([0,-BuildSpace,0])
	Base();
	translate([0,BuildSpace,0])
	Cap();
	}
	}

	if (Layout == "Show") {
	color("LightGreen") Base();
	translate([0,0,12])
	rotate([180,0,0])
	color("LightBlue") Cap();
	}

view raw Fencing Helmet Ear Grommet.scad hosted with ❤ by GitHub

2015-12-24

Kenmore Progressive Vacuum Cleaner vs. Classic Electrolux Dust Brush

Vacuum cleaner dust brushes, separated by millimeters and decades:

Kenmore vs adapted Electrolux dust brushes

The bulky one on the left came with our new Kenmore Progressive vacuum cleaner. It’s fine for dust on a flat horizontal or vertical surface and totally useless for dust on actual objects. It’s supposed to snap around the handle at the end of the cleaner’s flexy hose, where it helps make the entire assembly too large and too clumsy, or on the end of the “wand”, where it’s at the wrong angle. The bonus outer shell slides around the stubby bristles in the unlikely event they’re too long for the flat surface at hand.

The brush on the right emerged from the Box o’ Electrolux Parts that Came With The House™, must be half a century old, and consists of a cast aluminum lump with various holes milled into it, adorned with luxuriously long and flexible horsehair. Suffice it to say they don’t make ’em like that any more. Heck, they probably don’t make horses with hair like that any more, either.

The blue plastic adapter atop the aluminum ball looks like you’d expect by now:

The short snout fits neatly into the space available inside the ball. The abrupt ledge at the top of the snout, of course, didn’t work well; I rushed the design for a show-n-tell.

The OpenSCAD source code (as a Github gist) bevels that ledge and tweaks the interior air channel a bit:

	// Kenmore vacuum cleaner nozzle adapters
	// Ed Nisley KE4ZNU December 2015

	// Layout options

	Layout = "LuxBrush"; // MaleFitting CoilWand FloorBrush CreviceTool ScrubbyTool LuxBrush

	//- Extrusion parameters must match reality!
	// Print with +1 shells and 3 solid layers

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	//———————-
	// Dimensions

	ID1 = 0; // for tapered tubes
	ID2 = 1;
	OD1 = 2;
	OD2 = 3;
	LENGTH = 4;

	OEMTube = [35.0,35.0,41.7,40.5,30.0]; // main fitting tube
	EndStop = [OEMTube[ID1],OEMTube[ID2],47.5,47.5,6.5]; // flange at end of main tube

	FittingOAL = OEMTube[LENGTH] + EndStop[LENGTH];

	$fn = 12*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);
	}


	//——————-
	// Male fitting on end of Kenmore tools
	// This slides into the end of the handle or wand and latches firmly in place

	module MaleFitting() {

	Latch = [40,11.5,5.0]; // rectangle latch opening
	EntryAngle = 45; // latch entry ramp
	EntrySides = 16;
	EntryHeight = 15.0; // lower edge on inside of fitting

	KeyRadius = 1.0;

	translate([0,0,6.5])
	difference() {
	union() {
	cylinder(d1=OEMTube[OD1],d2=OEMTube[OD2],h=OEMTube[LENGTH]); // main tube

	hull() // insertion guide
	for (i=[-(6.0/2 – KeyRadius),(6.0/2 – KeyRadius)],
	j=[-(28.0/2 – KeyRadius),(28.0/2 – KeyRadius)],
	k=[-(26.0/2 – KeyRadius),(26.0/2 – KeyRadius)])
	translate([(i – (OEMTube[ID1]/2 + OEMTube[OD1]/2)/2 + 6.0/2),j,(k + 26.0/2 – 1.0)])
	sphere(r=KeyRadius,$fn=8);

	translate([0,0,-EndStop[LENGTH]]) // wand tube butts against this
	cylinder(d=EndStop[OD1],h=EndStop[LENGTH] + Protrusion);
	}

	translate([0,0,-OEMTube[LENGTH]]) // main bore
	cylinder(d=OEMTube[ID1],h=2OEMTube[LENGTH] + 2Protrusion);

	translate([0,-11.5/2,23.0 – 5.0]) // latch opening
	cube(Latch);

	translate([OEMTube[ID1]/2 + EntryHeight/tan(90-EntryAngle),0,0]) // latch ramp
	translate([(Latch[1]/cos(180/EntrySides))cos(EntryAngle)/2,0,(Latch[1]/cos(180/EntrySides))sin(EntryAngle)/2])
	rotate([0,-EntryAngle,0])
	intersection() {
	rotate(180/EntrySides)
	PolyCyl(Latch[1],Latch[0],EntrySides);
	translate([-(2*Latch[0])/2,0,-Protrusion])
	cube(2*Latch[0],center=true);
	}
	}
	}

	//——————-
	// Refrigerator evaporator coil wand

	module CoilWand() {

	union() {
	translate([0,0,50.0])
	rotate([180,0,0])
	difference() {
	cylinder(d1=EndStop[OD1],d2=42.0,h=50.0);
	translate([0,0,-Protrusion])
	cylinder(d1=35.0,d2=35.8,h=100);
	}
	translate([0,0,50.0 – Protrusion])
	MaleFitting();
	}
	}


	//——————-
	// Refrigerator evaporator coil wand

	module FloorBrush() {

	union() {
	translate([0,0,60.0])
	rotate([180,0,0])
	difference() {
	union() {
	cylinder(d1=EndStop[OD1],d2=32.4,h=10.0);
	translate([0,0,10.0 – Protrusion])
	cylinder(d1=32.4,d2=30.7,h=50.0 + Protrusion);
	}
	translate([0,0,-Protrusion])
	cylinder(d1=28.0,d2=24.0,h=100);
	}
	translate([0,0,60.0 – Protrusion])
	MaleFitting();
	}
	}


	//——————-
	// Crevice tool

	module CreviceTool() {

	union() {
	translate([0,0,60.0])
	rotate([180,0,0])
	difference() {
	union() {
	cylinder(d1=EndStop[OD1],d2=32.0,h=10.0);
	translate([0,0,10.0 – Protrusion])
	cylinder(d1=32.0,d2=30.4,h=50.0 + Protrusion);
	}
	translate([0,0,-Protrusion])
	cylinder(d1=28.0,d2=24.0,h=100);
	}
	translate([0,0,60.0 – Protrusion])
	MaleFitting();
	}
	}

	//——————-
	// Mystery brush

	module ScrubbyTool() {

	union() {
	translate([0,0,60.0])
	rotate([180,0,0])
	difference() {
	union() {
	cylinder(d1=EndStop[OD1],d2=31.8,h=10.0);
	translate([0,0,10.0 – Protrusion])
	cylinder(d1=31.8,d2=31.0,h=50.0 + Protrusion);
	}
	translate([0,0,-Protrusion])
	cylinder(d1=26.0,d2=24.0,h=100);
	}
	translate([0,0,60.0 – Protrusion])
	MaleFitting();
	}
	}


	//——————-
	// Electrolux brush ball

	module LuxBrush() {

	union() {
	translate([0,0,30.0])
	rotate([180,0,0])
	difference() {
	union() {
	cylinder(d1=EndStop[OD1],d2=30.8,h=10.0);
	translate([0,0,10.0 – Protrusion])
	cylinder(d1=30.8,d2=30.0,h=20.0 + Protrusion);
	}
	translate([0,0,-Protrusion])
	cylinder(d1=25.0,d2=23.0,h=30 + 2*Protrusion);
	}
	translate([0,0,30.0 – Protrusion])
	MaleFitting();
	}
	}



	//———————-
	// Build it!

	if (Layout == "MaleFitting")
	MaleFitting();

	if (Layout == "CoilWand")
	CoilWand();

	if (Layout == "FloorBrush")
	FloorBrush();

	if (Layout == "CreviceTool")
	CreviceTool();

	if (Layout == "ScrubbyTool")
	ScrubbyTool();

	if (Layout == "LuxBrush")
	LuxBrush();

view raw Kenmore Wand Bushings.scad hosted with ❤ by GitHub

That’s supposed to prevent the WordPress post editors from destroying the formatting…

2015-12-23

Chiplotle: Better RTS-CTS Handshake Hackage

With hardware handshaking in full effect, the Chiplotle routine that sends data to the HP 7475A plotter doesn’t need to sleep, because the Linux serial handlers take care of that under the hood. Rather than simply comment that statement out, as I did before, it’s better to test the configuration and only sleep when needed:

The routine that extracts values from ~/.chiplotle/config.py is already included (well, imported) in the distribution’s baseplotter.py file, so all we need is a test for (the lack of) hardware handshaking:

   def _write_string_to_port(self, data):
      ''' Write data to serial port. data is expected to be a string.'''
      #assert type(data) is str
      if not isinstance(data, basestring):
         raise TypeError('string expected.')
      data = self._filter_unrecognized_commands(data)
      data = self._slice_string_to_buffer_size(data)
      for chunk in data:
         if not get_config_value('rtscts'):
             self._sleep_while_buffer_full( )
         self._serial_port.write(chunk)

The wisdom of reading a file inside the innermost loop of the serial data output routine may be debatable, but:

The output is 9600 b/s serial data
The expected result is that we’re about to wait
Plenty of smart folks have improved file I/O, so the read is probably a cache hit

For all I know, it doesn’t actually read a file, but consults an in-memory data structure. Works well enough for me, anyhow.

The configuration file I’ve been using all along looks like this (minus most of the comments):

# -*- coding: utf-8 -*-
serial_port_to_plotter_map = {'/dev/ttyUSB0' : 'HP7475A'}

## Serial connection parameters.
## Set your plotter to match these values, or vice versa..
baudrate = 9600
bytesize = 8
parity = 'N'
stopbits = 1
timeout = 1
xonxoff = 0
rtscts = 1


## Maximum wait time for response from plotter.
## Every time the plotter is queried, Chiplotle will wait for
## a maximum of `maximum_response_wait_time` seconds.
maximum_response_wait_time = 4


## Set to True if you want information (such as warnings)
## displayed on the console. Set to False if you don't.
verbose = True

That’s much prettier…

2015-12-21