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

Monthly Image: Wall Painting

One day, long ago, this tree grew in a certain bedroom:

Outlet tree

And then a flower appeared in the laundry room:

Outlet flower

Much to our delight, she asked for forgiveness, not permission … which was, of course, granted immediately.

2018-12-15
Astable Multivibrator: SMT LED Ballast Resistor

The original astable multivibrator ran from a dead CR123 primary lithium cell:

CR123A Astable – front

With a terminal voltage falling from barely 3 V, the LED drew about 3 mA (1 mA/div), tops, without a ballast resistor:

Astable – CR123A 2.8 V – 1 mA -green

Hacking in a charged NP-BX1 secondary lithium cell boosted the supply to 4 V:

NP-BX1 Holder – SMT pogo pins

Which, diodes being the way they are, raised the LED current to nearly 400 mA (100 mA/div):

Astable – NP-BX1 4V – base V – 100mA-div

Somewhat to my surprise, a few weeks of abuse didn’t do any obvious damage to the LED, but I added a resistor while I was soldering up another holder:

Astable – 51 ohm SMD ballast

There’s not quite enough room for a 1/8 W axial resistor, so why not blob in a surface-mount resistor?

Which cuts the current down to a mere 15 mA (10 mA/div) from a lithium battery at 4 V:

Astable – NP-BX1 – 51 ohm ballast – 10ma-div

It’s still blindingly bright, but now I don’t feel bad about it.

2018-12-14
Desk Drawer Stops

The stops aligning the top two drawers of an old desk vanished, so I got the job of replacing them. They’re hammered into the wood frame:

Drawer Stops – width measurement

And stand up just enough to engage the back of the drawer face:

Drawer Stops – height measurement

Back in the Basement Laboratory Shop Wing, I harvested steel strips from a defunct PC case, rubber-hammered them flat, sharpened a cold chisel (un-hardened, so it always needs sharpening), and got to work:

Drawer Stops – chiseled blanks

The pointy sides should have sharp edges, which you get for free with a chisel. You also get a bench full of little steel slivers perfectly suited for embedding in human flesh. Wearing eye protection is more than just a good idea, too.

Introducing what will become the visible edges to Mr Disk Sander makes them marginally less hazardous:

Drawer Stops – in progress

A slightly fuzzy picture of a test fit shows the stops should suffice:

Drawer Stops – trial fit

Which they did:

Drawer Stops – installed

Nobody will ever notice the blob of hot melt glue behind each one:

Drawer Stops – glue blob

Done!

2018-12-13

Astable Multivibrator: NP-BX1 Base

Adapting the NP-BX1 battery holder to use SMT pogo pins worked well:

NP-BX1 Holder - SMT pogo pins — NP-BX1 Holder – SMT pogo pins

The next step is to add sockets for those 14 AWG wires:

NP-BX1 Battery Holder - Wire Posts - solid model — NP-BX1 Battery Holder – Wire Posts – solid model

Start by reaming / hand-drilling all the holes to their nominal size and cleaning out the pogo pin pocket.

Solder wires to the pogo pins and thread them through the holder and lid:

Astable - NP-BX1 holder - pogo pin soldering — Astable – NP-BX1 holder – pogo pin soldering

That’s nice, floppy silicone-insulated 24 AWG wire, which may be a bit too thick for this purpose.

The pogo pins will, ideally, seat with the end of the body flush at the holder wall. Make it so:

Astable - NP-BX1 holder - pogo pin protrusion — Astable – NP-BX1 holder – pogo pin protrusion

Dress the wires neatly into their pocket:

Astable - NP-BX1 holder - pogo pin wiring — Astable – NP-BX1 holder – pogo pin wiring

Butter the bottom of the lid with epoxy, clamp in place, set it up for curing, then fill the recess:

Astable - NP-BX1 base - curing — Astable – NP-BX1 base – curing

While it’s curing, make a soldering fixture for the 14 AWG wires:

Astable - drilling strut soldering fixture — Astable – drilling strut soldering fixture

The holes are on 5 mm centers, in the expectation other battery holders will need different spacing.

Solder it up and stick the wires into the base:

Astable - NP-BX1 base - detail — Astable – NP-BX1 base – detail

Jam a battery in and It Just Works™:

Astable - NP-BX1 3.8V - 20ma-div - cap V — Astable – NP-BX1 3.8V – 20ma-div – cap V

The traces:

Green = supply current at 20 mA/div
Yellow = LED driver transistor base voltage
Purple = other transistor collector voltage
White = base – collector voltage = capacitor voltage

The measurement setup was a bit of a hairball:

Astable - NP-BX1 base - current probe — Astable – NP-BX1 base – current probe

For completeness, here’s the schematic-and-layout diagram behind the circuitry:

Astable - NP-BX1 base - schematic — Astable – NP-BX1 base – schematic

I love it when a plan comes together!

The OpenSCAD source code as a GitHub Gist:

	// Holder for Sony NP-BX1 Li-Ion battery
	// Ed Nisley KE4ZNU January 2013
	// 2018-11-15 Adapted for wire leads from 1.5 mm test pins, added upright wire bases

	// Layout options

	Layout = "Fit"; // Show Build Fit Case Lid Pins

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

	ThreadThick = 0.25;
	ThreadWidth = 0.35;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	inch = 25.4;

	BuildOffset = 3.0; // clearance for build layout

	Gap = 2.0; // separation for Fit parts

	//- Basic dimensions

	WallThick = 4*ThreadWidth; // holder sidewalls

	BaseThick = 6*ThreadThick; // bottom of holder to bottom of battery
	TopThick = 6*ThreadThick; // top of battery to top of holder


	//- Battery dimensions – rationalized from several samples
	// Coordinate origin at battery contact face with key openings below contacts

	Battery = [43.0,30.0,9.5]; // X = length, Y = width, Z = thickness

	Contacts = [[-0.75,6.0,6.2],[-0.75,16.0,6.2]]; // relative to battery edge, front, and bottom
	ContactOC = Contacts[1].y – Contacts[0].y;
	ContactCenter = Contacts[0].y + ContactOC/2;

	KeyBlocks = [[1.75,3.70,2.90],[1.75,3.60,2.90]]; // recesses in battery face set X position

	//- Pin dimensions

	ID = 0;
	OD = 1;
	LENGTH = 2;

	PinShank = [1.5,2.0,6.5]; // shank, flange, compressed length
	PinFlange = [1.5,2.0,0.5]; // flange, length included in PinShank
	PinTip = [0.9,0.9,2.5]; // extended spring-loaded tip

	PinChannel = PinFlange[LENGTH] + 0.5; // cut behind flange for solder overflow
	PinRecess = 3.0; // recess behind pin flange end for epoxy fill

	echo(str("Contact tip dia: ",PinTip[OD]));
	echo(str(" .. shank dia: ",PinShank[ID]));

	OverTravel = 0.5; // space beyond battery face at X origin

	//- Holder dimensions

	GuideRadius = ThreadWidth; // friction fit ridges
	GuideOffset = 7; // from compartment corners

	ThumbRadius = 10.0; // thumb opening at end of battery

	CornerRadius = 3*ThreadThick; // nice corner rounding

	CaseSize = [Battery.x + PinShank[LENGTH] + OverTravel + PinRecess + GuideRadius + WallThick,
	Battery.y + 2WallThick + 2GuideRadius,
	Battery.z + BaseThick + TopThick];

	CaseOffset = [-(PinShank[LENGTH] + OverTravel + PinRecess),-(WallThick + GuideRadius),0]; // position around battery

	LidOverhang = 2.0; // over top of battery for retention

	LidSize = [-CaseOffset.x + LidOverhang,CaseSize.y,TopThick];

	LidOffset = [0.0,CaseOffset.y,0];

	//- Wire struts

	StrutDia = 1.6; // AWG 14 = 1.6 mm
	StrutOC = 45;
	StrutSides = 3*4;

	StrutBase = [StrutDia,StrutDia + 4*WallThick,CaseSize.z – TopThick]; // ID = wire, OD=buildable

	//———————-
	// 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);
	}

	//——————-
	//– Guides for tighter friction fit

	module Guides() {
	translate([GuideOffset,-GuideRadius,0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);
	translate([GuideOffset,(Battery.y + GuideRadius),0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);
	translate([(Battery.x – GuideOffset),-GuideRadius,0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);
	translate([(Battery.x – GuideOffset),(Battery.y + GuideRadius),0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);
	translate([(Battery.x + GuideRadius),GuideOffset/2,0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);
	translate([(Battery.x + GuideRadius),(Battery.y – GuideOffset/2),0])
	PolyCyl(2*GuideRadius,(Battery.z – Protrusion),4);

	}

	//– Contact pins
	// Rotated to put them in their natural oriention
	// Aligned to put tip base / end of shank at Overtravel limit

	module PinShape() {

	translate([-(PinShank[LENGTH] + OverTravel),0,0])
	rotate([0,90,0])
	rotate(180/6)
	union() {
	PolyCyl(PinTip[OD],PinShank[LENGTH] + PinTip[LENGTH],6);
	PolyCyl(PinShank[ID],PinShank[LENGTH] + Protrusion,6); // slight extension for clean cuts
	PolyCyl(PinFlange[OD],PinFlange[LENGTH],6);
	}
	}

	// Position pins to put end of shank at battery face
	// Does not include recess access into case

	module PinAssembly() {

	union() {
	for (p = Contacts)
	translate([0,p.y,p.z])
	PinShape();

	translate([-(PinShank[LENGTH] + OverTravel) + PinChannel/2, // solder space
	ContactCenter,
	Contacts[0].z])
	cube([PinChannel,(Contacts[1].y – Contacts[0].y),PinFlange[OD]],center=true);

	for (j=[-1,1]) // wire channels
	translate([-(PinShank[LENGTH] + OverTravel – PinChannel/2),
	j*ContactOC/4 + ContactCenter,
	Contacts[0].z – PinFlange[OD]/2])
	rotate(180/6)
	PolyCyl(PinFlange[OD],CaseSize.z,6);
	}
	}

	//– Case with origin at battery corner

	module Case() {

	difference() {

	union() {

	difference() {
	union() {
	translate([(CaseSize.x/2 + CaseOffset.x), // basic case shape
	(CaseSize.y/2 + CaseOffset.y),
	(CaseSize.z/2 – BaseThick)])
	hull()
	for (i=[-1,1], j=[-1,1], k=[-1,1])
	translate([i*(CaseSize.x/2 – CornerRadius),
	j*(CaseSize.y/2 – CornerRadius),
	k*(CaseSize.z/2 – CornerRadius)])
	sphere(r=CornerRadius/cos(180/8),$fn=8); // cos() fixes undersize spheres!

	hull() // wire strut bases
	for (j=[-1,1])
	translate([0,j*StrutOC/2 + Battery.y/2,-BaseThick])
	rotate(180/StrutSides)
	cylinder(d=StrutBase[OD],h=StrutBase[LENGTH],$fn=StrutSides);

	translate([0,Battery.y/2,StrutBase[LENGTH]/2 – BaseThick])
	cube([2*StrutBase[OD],StrutOC,StrutBase[LENGTH]],center=true);
	}

	translate([-OverTravel,-GuideRadius,0])
	cube([(Battery.x + GuideRadius + OverTravel),
	(Battery.y + 2*GuideRadius),
	(Battery.z + Protrusion)]); // battery space
	}

	Guides(); // improve friction fit

	translate([-OverTravel,-GuideRadius,0]) // battery keying blocks
	cube(KeyBlocks[0] + [OverTravel,GuideRadius,0],center=false);
	translate([-OverTravel,(Battery.y – KeyBlocks[1].y),0])
	cube(KeyBlocks[1] + [OverTravel,GuideRadius,0],center=false);

	}

	translate([2*CaseOffset.x, // battery top access
	(CaseOffset.y – Protrusion),
	Battery.z])
	cube([2CaseSize.x,(CaseSize.y + 2Protrusion),(TopThick + Protrusion)]);

	if (false)
	translate([(CaseOffset.x – Protrusion), // battery insertion allowance
	(CaseOffset.y – Protrusion),
	Battery.z])
	cube([(CaseSize.x + 2Protrusion),(CaseSize.y + 2Protrusion),(TopThick + Protrusion)]);

	for (j=[-1,1]) // strut wires
	translate([0,j*StrutOC/2 + Battery.y/2,-(BaseThick + Protrusion)])
	PolyCyl(StrutBase[ID],StrutBase[LENGTH] + 2*Protrusion,6);

	for (i=[-1,1], j=[-1,1])
	translate([iStrutBase[OD],jStrutOC/2 + Battery.y/2,-(BaseThick + Protrusion)])
	rotate(180/StrutSides)
	PolyCyl(StrutBase[OD],StrutBase[LENGTH] + 2*Protrusion,StrutSides);

	translate([(Battery.x – Protrusion), // remove thumb notch
	(CaseSize.y/2 + CaseOffset.y),
	(ThumbRadius)])
	rotate([90,0,0])
	rotate([0,90,0])
	cylinder(r=ThumbRadius,
	h=(WallThick + GuideRadius + 2*Protrusion),
	$fn=22);

	PinAssembly();

	translate([CaseOffset.x + PinRecess + Protrusion,(Contacts[1].y + Contacts[0].y)/2,Contacts[0].z])
	translate([-PinRecess,0,0])
	cube([2*PinRecess,
	(Contacts[1].y – Contacts[0].y + PinFlange[OD]),
	2*PinFlange[OD]],center=true);

	}

	}

	// Lid position offset to match case

	module Lid() {

	difference() {
	translate([-LidSize.x/2 + LidOffset.x + LidOverhang,LidSize.y/2 + LidOffset.y,0])
	difference() {
	hull()
	for (i=[-1,1], j=[-1,1], k=[-1,1])
	translate([i*(LidSize.x/2 – CornerRadius),
	j*(LidSize.y/2 – CornerRadius),
	k*(LidSize.z – CornerRadius)]) // double thickness for flat bottom
	sphere(r=CornerRadius,$fn=8);

	translate([0,0,-LidSize.z/2]) // remove bottom
	cube([(LidSize.x + 2Protrusion),(LidSize.y + 2Protrusion),LidSize.z],center=true);

	translate([LidSize.x/8,0,0])
	cube([LidSize.x/4,0.75LidSize.y,4ThreadThick],center=true); // epoxy recess
	}

	translate([0,0,-(Contacts[0].z + PinFlange[OD])]) // punch wire holes
	PinAssembly();
	}

	}


	//——————-
	// Build it!

	if (Layout == "Case")
	Case();

	if (Layout == "Lid")
	Lid();

	if (Layout == "Pins") {
	color("Silver",0.5)
	PinShape();
	PinAssembly();
	}

	if (Layout == "Show") { // reveal pin assembly
	difference() {
	Case();

	translate([(CaseOffset.x – Protrusion),
	Contacts[1].y,
	Contacts[1].z])
	cube([(-CaseOffset.x + Protrusion),
	CaseSize.y,
	(CaseSize.z – Contacts[0].z + Protrusion)]);

	translate([(CaseOffset.x – Protrusion),
	(CaseOffset.y – Protrusion),
	0])
	cube([(-CaseOffset.x + Protrusion),
	Contacts[0].y + Protrusion – CaseOffset.y,
	CaseSize.z]);
	}

	translate([0,0,Battery.z + Gap])
	Lid();

	color("Silver",0.15)
	PinAssembly();

	}

	if (Layout == "Build") {
	translate([-(CaseSize.x/2 + CaseOffset.x),-(CaseOffset.y – BuildOffset),BaseThick])
	Case();
	translate([CaseSize.x/2,-LidSize.x/2,0])
	rotate(90)
	Lid();
	}

	if (Layout == "Fit") {
	Case();
	translate([0,0,(Battery.z + Gap)])
	Lid();
	color("Silver",0.25)
	PinAssembly();
	}

view raw NP-BX1 Battery Holder – Wire Posts.scad hosted with ❤ by GitHub

2018-12-12

Six Gallon Can Lid Adapter to Platform Bird Feeder

A House Finch suffering from Finch Eye Disease prompted me to sterilize our feeder, which meant providing a temporary feeder to keep the birds flying. Having an abundance of lids from six gallon plastic cans / buckets, this made sense:

Can Lid Feeder - installed — Can Lid Feeder – installed

Which required an adapter betwixt pole and lid:

Can Lid Feeder - assembled — Can Lid Feeder – assembled

Which requires a bit of solid modeling:

Can Lid Platform Feeder Mount - solid model - bottom — Can Lid Platform Feeder Mount – solid model – bottom

The lids have a central boss, presumably for stiffening, so the model includes a suitable recess:

Can Lid Platform Feeder Mount - solid model - support structure — Can Lid Platform Feeder Mount – solid model – support structure

As usual, automatically generated support fills the entire recess, so I designed a minimal support structure into the model and cracked it out with very little effort:

Can Lid Feeder - support structure — Can Lid Feeder – support structure

The tangle off to the right comes from a bridge layer with a hole in the middle, which never works well even with support:

Can Lid Platform Feeder Mount - Slic3r - bridge layer — Can Lid Platform Feeder Mount – Slic3r – bridge layer

Didn’t bother the birds in the least, though, so it’s all good.

I loves me my 3D printer …

The OpenSCAD source code as a GitHub Gist:

	// Adapter from steel pole to 5 gallon plastic can lid
	// Turns the lid into a improvised platform feeder
	// Ed Nisley – KE4ZNU – 2018-11

	Layout = "Build"; // Show Build

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

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

	Protrusion = 0.1; // make holes end cleanly

	// Sizes

	ID = 0;
	OD = 1;
	LENGTH = 2;

	Wall = 10; // minimum thickness or width for anything

	Boss = [15,50,9]; // central boss on lie
	Flange = [50,110,Boss[LENGTH] + Wall];

	echo(Boss);
	echo(Flange);

	Pole = [(23.5 + 4*HoleWindage),26,45]; // small end of steel pole

	Screw = [5.0,8.0,25.0]; // 5 mm or 10-32
	ScrewOC = 80; // lid mounting screws
	NumScrews = 3;

	NumSides = NumScrews24;
	$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);
	}

	//———————-
	// Build it

	module Bracket() {

	difference() {

	union() {
	rotate(180/(NumSides/2)) {
	cylinder(d=Flange[OD],h=Flange[LENGTH],$fn=NumSides/2); // fewer sides is OK
	cylinder(d=Pole[OD] + 2*Wall,h=Pole[LENGTH] + Flange[LENGTH],$fn=NumSides/2);
	}
	}

	translate([0,0,-Protrusion])
	rotate(180/NumSides)
	cylinder(d=Boss[OD],h=Boss[LENGTH] + Protrusion,$fn=NumSides);

	translate([0,0,-Protrusion])
	rotate(180/NumSides)
	cylinder(d=Pole[ID],h=2*(Pole[LENGTH] + Flange[LENGTH]),$fn=NumSides);

	for (i=[0:NumScrews-1])
	rotate(i*(360/NumScrews))
	translate([ScrewOC/2,0,-Protrusion])
	PolyCyl(Screw[ID],2*Flange[LENGTH],6);
	}

	}

	module Support() {

	NumRibs = NumSides/2;
	Rib = [0.95(Boss[OD] – Pole[ID])/2,2ThreadWidth,Boss[LENGTH] – ThreadThick];

	color("Yellow") {
	for (i=[0:NumRibs-1]) {
	a = i*360/NumRibs;
	rotate(a)
	translate([Pole[ID]/2 + Rib.x/2,0,Rib.z/2])
	cube(Rib,center=true);
	}
	rotate(180/NumSides)
	difference() {
	cylinder(d=Pole[ID] + 10ThreadWidth,h=1ThreadThick,$fn=NumSides);
	translate([0,0,-Protrusion])
	cylinder(d=Pole[ID],h=Rib.z + 2*Protrusion,$fn=NumSides);
	}
	}

	}

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

	if (Layout == "Build") {
	Bracket();
	Support();
	}

view raw Can Lid Platform Feeder Mount.scad hosted with ❤ by GitHub

2018-12-11

Dutchess Rail Trail: Maloney Rd Trailhead Ruts

It seems the DCW&WA SUV makes regular trips through the “No Motor Vehicles” bike access:

Maloney Rd Trailhead – 2018-11-07

If it’s not them, then it’s somebody following their example.

Just because you can do something, doesn’t mean you should … but, of course, the ordinary rules apply only to little people, not public servants.

Someone in the bike advocacy apparat once told me I’m the most cynical, bitter person they’d ever met, at least on the subject of getting along with public servants. As I see it, I came by my attitude honestly.

2018-12-10
Sterling Table Knife Repair

A sterling knife followed me home after a Thanksgiving gathering:

Sterling knife repair – powdered cement

The original cement, dating back to the middle of the last century, turned into friable dust around the blade tang:

Sterling knife repair – handle socket

I cleaned it out as best I could, buttered JB Quik epoxy around the tang and into the socket, joined the two, and let it cure in the natural position:

Sterling knife repair – curing

The rest of the knives in the set may need similar attention, but I’m not looking for trouble.

2018-12-09