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

Painting By Numbers, Redux

Five years later, the digits I painted with Rust-Oleum Rusty Metal Primer have weathered pretty well, while the original ink has fallen off the retroreflective sticker:

Mailbox numbers – original vs primer

As before, I wiped off the crud with denatured alcohol and painted neatly inside the lines. The other digits on both sides still look as good as the day I painted them, with only a few bubbles and nicks.

Memo to self: Next time, buy a big sheet of 3M retroreflective film, make a stencil by vinyl cutting, paint the entire number in one shot, and be done with it.

2020-06-20
Drill Press Vise Table Refresh

I built a small plywood work table for the drill press:

Drill press – scarred vise table

Obviously, that was a long time ago. It’s a plywood scrap with a small cleat screwed to its bottom, upon which one can position / clamp / hold / finagle smallish workpieces without worrying about drilling into the surface.

The most recent batch of aluminum backing plates prompted me to finally replace that relic:

Drill press – new vise table

The mill vise under the plywood grips the cleat and the whole affair rides on a Sears “Drill Press Milling Attachment Stock No 27585” which is basically a simple XY table with hand dials. It’s not rigid enough for actual milling (which you should never do on a drill press, anyway, because the end mill will pull itself out of the Jacobs chuck), but it’s good for tweaking the position before you drill something.

One should never hand-hold workpieces while drilling.

Don’t do as I do, do as I say. OK?

2020-06-19
Soaker Hose Clamps

Having figured out the geometry for two- and three-channel soaker hoses, I cranked out more clamps:

Soaker Hose Clamps – production

Actually, those are the remainder of two production runs devoted to reducing the amount of water sprinkling the garden paths. A 50 foot hose runs along both sides of one 14 foot bed, crosses the path, then continues along the adjacent bed. The hoses have (deliberate!) sprinkler holes along their porous rubber body and sometimes the layout puts a hole where it waters the path.

The blue silicone rubber strips provide a bit of sealing to prevent the absurdly high pressure water from streaming through the orange PETG clamps. It’s OK if the clamp leaks, but less flow is better!

I’m getting really good at making those aluminum backing plates and, in fact, I think it’s faster to run the blanks past the disk sander, then drill the holes, than to CNC-machine them. Could be wrong, but Quality Shop Time is not to be sniffed at.

2020-06-18
USB Wire Color Code: Grand Prize Blooper

Despite knowing the wire colors inside USB cables need not follow any particular convention, this still came as a surprise:

USB Cable – reversed red-black wires

Yes, that’s a negative indicator on the meter: it reads -5.020 V.

No, I didn’t swap the test probe banana plugs on the other end.

A bit of continuity testing shows the green and white data wires are also reversed, so whoever assembled the cable simply soldered the proper wire color sequence backwards onto both connectors. As long as you don’t cut the cable to reuse the connectors, it’s all good.

Memo to Self: Stop trusting, always verify!

2020-06-17
More WS2812 Failures

Even though I’m using what seem to be good-quality parts, one of the WS2812 RGB LEDs in a Glass Tile frame died:

Glass Tile – 2×2 – first WS2812B failure

It passed the Josh Sharpie Test:

Glass Tile – WS2812 failure – PCB unknown

After building the third Glass Tile unit, one of the LEDs didn’t light up due to an easily diagnosed problem:

Glass Tile – WS2812 failure – PCB cold solder – as found

A closer look:

Glass Tile – WS2812 failure – PCB cold solder

Shortly thereafter, the Nissan Fog Lamp developed an obvious beam problem:

Nissan Fog Lamp – failed WS2812 effect

The WS2812 had the proper voltages / signals at all its pins and was still firmly stuck to the central “heatsink”:

Nissan Fog Lamp – failed WS2812 detail

It also passed the Josh Sharpie Test:

Glass Tile – WS2812 failure – tape – unknown

I’m particularly surprised by this one, because eleven of the twelve flex-PCB WS2812s in the Hard Drive Platter light have been running continuously for years with no additional failures.

The alert reader will note the common factor: no matter what substrate the LED is (supposed to be) soldered to, no matter when I bought it, no matter what it’s wired into, a WS2812 will fail.

They’re all back in operation:

Glowing Algorithmic Art

Although nobody knows for how long …

Obviously, it’s time to refresh my programmable RGB LED stockpile!

2020-06-04

Garden Hose Valve Wrench: Reinforced

After five gardening seasons, my simple 3D printed wrench broke:

Hose Valve Knob - fractured — Hose Valve Knob – fractured

Although Jason’s comment suggesting carbon-fiber reinforcing rods didn’t prompt me to lay in a stock, ordinary music wire should serve the same purpose:

Hose Valve Knob - cut pins — Hose Valve Knob – cut pins

The pins are 1.6 mm diameter and 20 mm long, chopped off with hardened diagonal cutters. Next time, I must (remember to) grind the ends flat.

The solid model needs holes in appropriate spots:

Hose Valve Knob - Reinforced - Slic3r — Hose Valve Knob – Reinforced – Slic3r

Yes, I’m going to put round pins in square holes, without drilling the holes to the proper diameter: no epoxy, no adhesive, just 20 mm of pure friction.

The drill press aligns the pins:

Hose Valve Knob - pin ready — Hose Valve Knob – pin ready

And rams them about halfway down:

Hose Valve Knob - pin midway — Hose Valve Knob – pin midway

Close the chuck jaws and shove them flush with the surface:

Hose Valve Knob - pins installed — Hose Valve Knob – pins installed

You can see the pins and their solid plastic shells through the wrench stem:

Hose Valve Knob - assembled — Hose Valve Knob – assembled

Early testing shows the reinforced wrench works just as well as the previous version, even on some new valves sporting different handles, with an equally sloppy fit for all. No surprise: I just poked holes in the existing model and left all the other dimensions alone.

The OpenSCAD source code as a GitHub Gist:

	// Hose connector knob
	// Ed Nisley KE4ZNU – June 2015
	// 2020-05 add reinforcing rods

	Layout = "Build"; // [Knob, Stem, Show, Build]

	RodHoles = true;

	//- Extrusion parameters – must match reality!

	/* [Hidden] */

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

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

	Protrusion = 0.1;

	HoleWindage = 0.2;

	//——
	// Dimensions

	/* [Dimensions] */

	RodOD = 1.6;
	RodAngle = 35;

	/* [Hidden] */

	StemOD = 30.0; // max OD for valve-to-valve clearance

	BossOD = 16.0; // single-ended handle boss

	SlotWidth = 13.0;
	SlotHeight = 10.0;

	StemInset = 10.0;
	StemLength = StemInset + SlotHeight + 25.0;
	StemSides = 2*4;

	Align = 0180/StemSides; // 1 produces thinner jaw ends

	KnobOD1 = 70; // maximum dia without chamfer
	KnobOD2 = 60; // top dia

	KnobSides = 4*4;

	DomeHeight = 12; // dome shape above lobes

	KnobHeight = DomeHeight + 2*SlotHeight;

	DomeOD = KnobOD2 + (KnobOD1 – KnobOD2)*(DomeHeight/KnobHeight);

	DomeArcRad = (pow(KnobHeight,2) + pow(DomeOD,2)/4) / (2*DomeHeight);

	RodBCD = (StemOD + BossOD)/2;

	//- Adjust hole diameter to make the size come out right

	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);
	}

	//– Stem for valve handles

	module Stem() {

	difference() {
	rotate(Align)
	cylinder(d=StemOD,h=StemLength,$fn=StemSides);
	translate([0,0,SlotHeight/2 – Protrusion/2])
	cube([2*StemOD,SlotWidth,(SlotHeight + Protrusion)],center=true);
	translate([0,0,-Protrusion])
	cylinder(d=BossOD,h=SlotHeight,$fn=2*StemSides);
	if (RodHoles)
	for (i=[-1:1])
	rotate(i*RodAngle + 90)
	for (j=[-1,1])
	translate([j*RodBCD/2,0,-Protrusion])
	rotate(180/4)
	PolyCyl(RodOD,2*SlotHeight,4);
	}

	}


	//– Hand-friendly knob

	module KnobCap() {
	difference() {
	scale([1.0,0.75,1.0])
	rotate(180/KnobSides)
	intersection() {
	translate([0,0,(KnobHeight-DomeArcRad)])
	sphere(r=DomeArcRad,$fa=180/KnobSides);
	cylinder(r1=KnobOD1/2,r2=KnobOD2/2,h=KnobHeight,$fn=KnobSides);
	cylinder(r1=KnobOD2/2,r2=KnobOD1/2,h=KnobHeight,$fn=KnobSides);
	}
	translate([0,0,-Protrusion])
	rotate(Align)
	cylinder(d=(StemOD + 2*ThreadWidth),h=(StemInset + Protrusion),$fn=StemSides);
	}
	}

	//- Build it


	if (Layout == "Knob")
	KnobCap();

	if (Layout == "Stem")
	Stem();

	if (Layout == "Build") {
	translate([-KnobOD1/2,0,0])
	KnobCap();
	translate([StemOD/2,0,StemLength])
	rotate([180,0,0])
	Stem();
	}

	if (Layout == "Show") {
	translate([0,0,0])
	Stem();
	translate([0,0,StemLength – StemInset])
	KnobCap();
	}

view raw Hose Connector Knob.scad hosted with ❤ by GitHub

2020-06-02

Soaker Hose End Plug

One of the soaker hoses in Mary’s Vassar Farms garden split lengthwise near one end:

Soaker Hose Plug - hose split — Soaker Hose Plug – hose split

Although the hose is fully depreciated, I thought it’d be worthwhile to cut off the damaged end and conjure an end cap to see if a simple plug can withstand 100 psi water pressure.

A pair of Delrin (because I have it) plugs with serrations fill the hose channels, with the outer clamp squishing the hose against them:

Soaker Hose Plug - channel plugs - side view — Soaker Hose Plug – channel plugs – side view

In real life, they’ll be pushed completely into the hose, with a generous layer of silicone ~~snot~~ caulk improving their griptivity.

I started with 8 mm plugs, but they didn’t quite fill the channels:

Soaker Hose Plug - channel plugs - 8 mm test fit — Soaker Hose Plug – channel plugs – 8 mm test fit

Going to 8.5 mm worked better, although there’s really no way to force the granulated rubber shape into a snug fit around a cylinder:

Soaker Hose Plug - channel plugs test fit — Soaker Hose Plug – channel plugs test fit

Fortunately, they need not be leakproof, because leaking is what the hose does for a living. Well, did for a living, back before it died.

The clamps have a solid endstop, although it’s more to tidy the end than to hold the plugs in place:

Soaker Hose End Plug - Slic3r — Soaker Hose End Plug – Slic3r

The clamps need aluminum backing plates to distribute the stress evenly across their flat sides:

Soaker Hose Plug - installed — Soaker Hose Plug – installed

Those are 8-32 stainless steel screws. The standard 1 inch length worked out exactly right through no fault of my own.

The OpenSCAD source code as a GitHub Gist:

	// Rubber Soaker Hose End Plug
	// Ed Nisley KE4ZNU June 2019
	// 2020-05 Two-channel hose end plug

	Layout = "Hose"; // [Hose,Block,Show,Build]

	//- Extrusion parameters must match reality!

	/* [Hidden] */

	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
	// Hose lies along X axis

	HoseTubeOD = 12.0; // water tube diameter
	HoseTubeOC = 12.5; // .. spacing
	HoseWebThick = 7.8; // center joining tubes

	Hose = [100,25.0,HoseTubeOD]; // X=very long, Y=overall width, Z=thickness
	HoseSides = 12*4;

	PlugLength = 25.0; // plugs in hose channels

	PlateThick = 5.0; // end block thickness

	WallThick = 2.0; // overall minimum thickness

	Kerf = 0.75; // cut through middle to apply compression

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

	// 8-32 stainless screws
	Screw = [4.1,8.0,3.0]; // OD = head LENGTH = head thickness
	Washer = [4.4,9.5,1.0];
	Nut = [4.1,9.7,6.0];

	CornerRadius = Washer[OD]/2;

	ScrewOC = Hose.y + Washer[OD];

	echo(str("Screw OC: ",ScrewOC));

	BlockOAL = [PlugLength + PlateThick,ScrewOC + Washer[OD],2*WallThick + Hose.z]; // overall splice block size
	echo(str("Block: ",BlockOAL));

	//———————-
	// 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(d=(FixDia + HoleWindage),h=Height,$fn=Sides);
	}

	// Hose shape

	module HoseProfile() {

	rotate([0,-90,0])
	translate([0,0,-Hose.x/2])
	linear_extrude(height=Hose.x,convexity=4)
	union() {
	for (j=[-1,1]) // outer channels
	translate([0,j*HoseTubeOC/2])
	circle(d=HoseTubeOD,$fn=HoseSides);
	translate([0,0])
	square([HoseWebThick,HoseTubeOC],center=true);
	}

	}

	// Outside shape of splice Block
	// Z centered on hose rim circles, not overall thickness through center ridge

	module SpliceBlock() {
	difference() {
	hull()
	for (i=[-1,1], j=[-1,1]) // rounded block
	translate([i(BlockOAL.x/2 – CornerRadius),j(BlockOAL.y/2 – CornerRadius),-BlockOAL.z/2])
	cylinder(r=CornerRadius,h=BlockOAL.z,$fn=4*8);
	for (j=[-1,1]) // screw holes
	translate([0,
	j*ScrewOC/2,
	-(BlockOAL.z/2 + Protrusion)])
	PolyCyl(Screw[ID],BlockOAL.z + 2*Protrusion,6);
	cube([2BlockOAL.x,2BlockOAL.y,Kerf],center=true); // slice through center
	}
	}

	// Splice block less hose

	module ShapedBlock() {
	difference() {
	SpliceBlock();
	translate([(-Hose.x/2) + (BlockOAL.x/2) – PlateThick,0,0])
	HoseProfile();
	}
	}



	//———-
	// Build them

	if (Layout == "Hose")
	HoseProfile();

	if (Layout == "Block")
	SpliceBlock();

	if (Layout == "Show") {
	ShapedBlock();
	translate([(-Hose.x/2) + (BlockOAL.x/2) – PlateThick,0,0])
	color("Green",0.25)
	HoseProfile();
	}

	if (Layout == "Build") {
	SliceOffset = 0;
	intersection() {
	translate([SliceOffset,0,BlockOAL.z/4])
	cube([4BlockOAL.x,4BlockOAL.y,BlockOAL.z/2],center=true);
	union() {
	translate([0,0.6*BlockOAL.y,BlockOAL.z/2])
	ShapedBlock();
	translate([0,-0.6*BlockOAL.y,BlockOAL.z/2])
	rotate([0,180,0])
	ShapedBlock();
	}
	}
	}

view raw Soaker Hose End Plug.scad hosted with ❤ by GitHub

The original doodle, with dimensions vaguely related to the final model:

Soaker Hose End Plug - hose dimensions — Soaker Hose End Plug – hose dimensions

There is, as far as I can tell, no standardization of dimensions or shapes across manufacturers, apart from the threaded hose fittings.

2020-05-29

Tag: Repairs

Painting By Numbers, Redux

Drill Press Vise Table Refresh

Soaker Hose Clamps

USB Wire Color Code: Grand Prize Blooper

More WS2812 Failures

Garden Hose Valve Wrench: Reinforced

Soaker Hose End Plug