Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.
The Power Wheels Racer taking shape at SquidWrench let out The Big Stink at the Mini Maker Faire a few weeks ago, so I brought some test equipment to the regular Weekly Doing and helped with the autopsy.
The PWM motor controller purports to do 60 A at up to 50 V, but removing the cover showed it wasn’t going to do any more controlling:
Motor Controller – smoked housing
That smudge came from a rank of detonated MOSFETs:
Motor Controller – exploded MOSFET
Other MOSFETs had unsoldered themselves:
Motor Controller – unsoldered MOSFETs
Explosively:
Motor Controller – solder ejecta
I brought along an ancient Sears starter-motor ammeter to measure the motor current:
Sears 244-2145 Starter Ammeter – front
The magnetic field around the wire directly drives the meter movement, with two guides for the 75 A and 400 A ranges, and none of that newfangled Hall effect nonsense to contend with:
Sears 244-2145 Starter Ammeter – wire guides
Yeah, that says FEB 79; I’ve been collecting tools for quite a while…
I slapped the motor connectors directly on the battery terminals, holding them with small locking pliers after discovering that the wires got way too hot, way too fast. A snippet of retroreflective tape on the motor sprocket and a laser tach gave us the speed:
12 V: 1600 RPM @ 40 A
24 V: 2400 RPM @ > 100 A
The AmpFlow E30-400 motor data sheet confirmed that those numbers were grossly wrong. Unloaded, it should spin at 5700 RPM at 24 V while drawing 3.2 A (thus, 2800 RPM at 12 V & 1.6 A).
Diassembling the motor showed it hadn’t escaped the carnage:
Motor – charred windings
Those windings should be the usual amber enamel-over-copper, not charred black. The excessive current and reduced speed suggests many shorted turns inside the rotor.
Protip: never disassemble a working DC motor, because you’ll demagnetize the stator. The motor should still run when you put it back together, but the reduced magnetic field will wreck the performance.
As nearly as we could tell, one of the motor wires shorted to the frame when it got pinched under the seat; that’s an easy mistake to make and shows why compulsive wire neatness pays off big time. Shorting the controller output blew the transistors and, after raising the seat to look underneath, the motor would cook itself without generating much torque while you figure out what happened.
As far as I’m concerned, if you’ve never blown up anything that severely, you’re not building interesting stuff and definitely not trying hard enough.
The next iteration should work better!
Thanks to Dragorn of Kismet for stepping into the stench with phone camera in hand…
The Epson R380 started making an odd thwapping noise, which turned out to be the ink tubes from the Continuous Ink Supply System slapping the overly complex interior of the printer. They seemed a bit loose, but it took some searching before I found the top of the clamp that holds them in place:
Epson R380 CISS hose clamp – broken
It’s the white rectangle nestled in front of the ink cartridges, where it fits perfectly into a convenient slot and looks like it grew there.
I briefly considered 3D printing a replacement, but came to my senses:
Epson R380 CISS hose clamp – fixed
That should be good until the silicone rubber tubes finally break after a bazillion flex cycles…
So this device showed up in an envelope with a letter telling us we’d won a contest if, of course, the number on the device matched the number in the letter:
CodeKase device
I wonder if anybody else had second thoughts about pulling what’s obviously an insulating sheet holding two contacts apart? In this day and age, getting the victim to blow his own fingers off probably counts as a win.
Maybe it comes from having read The White Plague at an impressionable age. Who could resist getting a Nice Thing in the mail?
The number matched, of course, but the letter’s finer print said the prize would be one of:
A new car of some sort
A flat screen TV
A cheap electronic trinket
A three-day / two night vacation
In order to claim your prize, you had to call an 800 number. The much finer print revealed the odds of winning the first three of those prizes was somewhere around 300,000:1. “Winning” the vacation was essentially a slam-dunk proposition, of course, and probably tells you everything you need to know about the course of the phone call.
It’s apparently economical to send out this much hardware to reel in new “customers”:
CodeKase device – parts
Using the metal disk from a membrane switch as a spring to push the coin cell against the contact wires is a nice touch. This is apparently the optimized version that uses a single lithium cell in place of two alkaline buttons; the cell “socket” on the other end consists of vestigial lumps.
I harvested the lithium cell and the blue LED, of course…
More about CodeKase, direct from the source. I like “Step Five: Recycle Your CodeKase”…
Mary started doing “ruler quilting” that involves sewing seams aligned with templates, only to find that the thumbscrew holding the (modified) presser foot obscures the view to the left of the needle:
Kenmore Model 158 – OEM Presser Foot Screw
The screw looked to be 6-32 and I wanted to use a socket head cap screw, but thread turns out to be 6-40. Having previously bought the Brownell’s Fillister Head Screw Assortment specifically to solve that problem, all I had to do was cut the screw to length:
Kenmore Model 158 – Small Presser Foot Screw
The washer epoxied to the screw provides a bit more bearing surface.
Rather than putz with a screwdriver, this handle locates itself around the screw head; turn until the blade clicks into the screw slot, then tighten or loosen as needed:
Kenmore Model 158 – Presser Foot – Driver and Screw
The slot holds a chunk of spring steel (barely visible in the driver’s snout in group photo above) that accounts for the fat shaft around the screw head:
Presser Foot Screw Driver – top – Slic3r
I think the shaft could be a few millimeters narrower, but a bit of meat around the ends of the blade will support it against the torque.
The screw head slot is about 1 mm and the blade is 0.75 mm. I chopped the blade to fit by whacking the spring with a poorly tempered cold chisel, then flexing across the impact line until it broke. That chisel needed sharpening anyhow.
A dab of epoxy along the slot edges holds the blade in place. I inserted it flush with the top of the socket, then lined up the screw and pushed, with the steel bottomed out in the screw head and riding down for a perfect fit.
Then it’s all good!
The OpenSCAD source code:
// Presser Foot Screw Driver for Kenmore Model 158
// Ed Nisley - KE4ZNU - December 2015
use <knurledFinishLib_v2.scad>
//- Extrusion parameters must match reality!
// Print with 2 shells and 3 solid layers
ThreadThick = 0.20;
ThreadWidth = 0.40;
HoleWindage = 0.3; // extra clearance to improve hex socket fit
Protrusion = 0.1; // make holes end cleanly
inch = 25.4;
//----------------------
// Dimensions
SocketDia = 5.75; // generous fit on 6-40 fillister screw head
SocketDepth = 3.2;
Blade = [9.0,1.0,ceil(SocketDepth + 5)]; // inserted metal driver blade
echo(str("Blade: ",Blade));
ShaftDia = 1.5*Blade[0]; // un-knurled section diameter
ShaftLength = 10.0; // ... length
KnurlLen = 10.0; // length of knurled section
KnurlDia = 18.0; // ... diameter at midline of knurl diamonds
KnurlDPNom = 30; // Nominal diametral pitch = (# diamonds) / (OD inches)
DiamondDepth = 1.0; // ... depth of diamonds
DiamondAspect = 2; // length to width ratio
KnurlID = KnurlDia - DiamondDepth; // dia at bottom of knurl
NumDiamonds = ceil(KnurlDPNom * KnurlID / inch);
echo(str("Num diamonds: ",NumDiamonds));
NumSides = 4*NumDiamonds; // 4 facets per diamond
KnurlDP = NumDiamonds / (KnurlID / inch); // actual DP
echo(str("DP Nom: ",KnurlDPNom," actual: ",KnurlDP));
DiamondWidth = (KnurlID * PI) / NumDiamonds;
DiamondLenNom = DiamondAspect * DiamondWidth; // nominal diamond length
DiamondLength = KnurlLen / round(KnurlLen/DiamondLenNom); // ... actual
TaperLength = 0.50*DiamondLength;
KnobOAL = 2*TaperLength + KnurlLen + ShaftLength;
//----------------------
// 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() {
render(convexity=10)
translate([0,0,TaperLength]) // knurled cylinder
knurl(k_cyl_hg=KnurlLen,
k_cyl_od=KnurlDia,
knurl_wd=DiamondWidth,
knurl_hg=DiamondLength,
knurl_dp=DiamondDepth,
e_smooth=DiamondLength/2);
color("Orange") // lower tapered cap
cylinder(r1=ShaftDia/2,
r2=(KnurlDia - DiamondDepth)/2,
h=(TaperLength + Protrusion),
$fn=NumSides);
color("Orange") // upper tapered cap
translate([0,0,(TaperLength + KnurlLen - Protrusion)])
cylinder(r2=ShaftDia/2,
r1=(KnurlDia - DiamondDepth)/2,
h=(TaperLength + Protrusion),
$fn=NumSides);
color("Moccasin") // cylindrical extension
translate([0,0,(2*TaperLength + KnurlLen - Protrusion)])
cylinder(r=ShaftDia/2,h=(ShaftLength + Protrusion),$fn=NumSides);
}
translate([0,0,(KnobOAL - SocketDepth + Protrusion)])
PolyCyl(SocketDia,(SocketDepth + Protrusion),8); // screw head socket
translate([0,0,KnobOAL - (Blade[2] - Protrusion)/2])
cube(Blade + [0,0,Protrusion],center=true);
}
An improved version of the 3D printed plastic bits going into the Hard Drive Platter Mood Light:
Hard Drive Mood Light – improved – solid model – Show view
The central pillar now has cutouts behind the Neopixel strips so you (well, I) can solder directly to the larger half-pads on the back, plus a boss on the top for better wire management:
Hard Drive Mood Light – improved – Pillar – solid model
I’m not entirely satisfied with the little slots for the strip edges; the resolution limits of 3D printing call for larger openings, but there’s not much meat around those pins up the edge.
The base becomes much larger to hold the Arduino Pro Mini and gains an optional slot to let the programming cable reach the outside:
Hard Drive Mood Light – improved – Base – solid model
The cap has a boss matching the one atop the pillar:
Hard Drive Mood Light – improved – Cap – solid model
Both the cap & base have center features recessed by two thread thicknesses to let their rims apply a slight clamping force on the platters.
Our Larval Engineer says it really needs an internal battery with maybe four hours of runtime, a charging base station (ideally with inductive power transfer), buttons (or, better, a tilt switch / accelerometer) for mode selection, and perhaps a microphone to synchronize lighting effects with music. To my horror, her co-op job seems to have exposed her to Marketeers…
We do, however, agree that the Cap would look better in lathe-turned brass with a non-tarnish clearcoat.
The OpenSCAD source code:
// Hard Drive Platter Mood Light
// Ed Nisley KE4ZNU November 2015
Layout = "Spacers"; // Build Show Pixel LEDString Platters Pillar Spacers TopCap Base
CablePort = true;
ShowDisks = 2; // number of disks in Show layout
//- 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;
OD = 1;
LENGTH = 2;
Platter = [25.0,95.0,1.27]; // hard drive platters - must match actual thickness!
LEDStringCount = 3; // number of LEDs on each strip
LEDStripCount = 4; // number of strips (verify locating pin holes & suchlike)
WireSpace = 1.0; // allowance for wiring along strip ends
Pixel = [13.0, 1000 / 144, 0.6]; // smallest indivisible unit of LED strip
PixelMargin = [1.0, 1.0, 2.0]; // LED and circuitry atop the strip
BeamAngle = 120; // LED viewing angle
BeamShape = [
[0,0],
[Platter[OD]*cos(BeamAngle/2),-Platter[OD]*sin(BeamAngle/2)],
[Platter[OD]*cos(BeamAngle/2), Platter[OD]*sin(BeamAngle/2)]
];
PillarSides = 12*4;
PillarCore = Platter[ID] - 2*(Pixel[2] + PixelMargin[2] + 2.0); // LED channel distance across pillar centerline
PillarLength = LEDStringCount*Pixel[1] + Platter[LENGTH];
echo(str("Pillar core size: ",PillarCore));
echo(str(" ... length:"),PillarLength);
PCB = [34.5,17.5,1.6]; // Arduino Pro Mini (or whatever) PCB size
PCBClearTop = 5.0;
PCBClearBot = 5.0;
PCBHeight = PCB[2] + PCBClearBot + PCBClearTop;
PCBRadius = sqrt(pow(Platter[ID]/2 + PCB[1],2) + pow(PCB[0]/2,2));
echo(str("PCB Corner radius: ",PCBRadius));
CoaxConn = [7.8,11.2,5.0]; // power connector
Cap = [Platter[ID] + 4.0,Platter[ID] + 4.0 + 10*2*ThreadWidth,2*WireSpace + 6*ThreadThick]; // cap over top of pillar
CapSides = 8*4;
BaseClearHeight = max(PCBHeight,CoaxConn[OD]);
Base = [2.0 + 2*PCBRadius,2.0 + 2*PCBRadius + CoaxConn[LENGTH],BaseClearHeight + 6*ThreadThick];
BaseSides = 8*4;
Screw = [1.5,2.0,20.0]; // screws used to secure cap & pillar
Spacer = [Platter[ID],(Platter[ID] + 2*8),(Pixel[1] - Platter[LENGTH])];
echo(str("Spacer OD: ",Spacer[OD]));
echo(str(" ... thick:",Spacer[LENGTH]));
LEDStripProfile = [
[0,0],
[Pixel[0]/2,0],
[Pixel[0]/2,Pixel[2]],
[(Pixel[0]/2 - PixelMargin[0]),Pixel[2]],
[(Pixel[0]/2 - PixelMargin[0]),(Pixel[2] + PixelMargin[2])],
[-(Pixel[0]/2 - PixelMargin[0]),(Pixel[2] + PixelMargin[2])],
[-(Pixel[0]/2 - PixelMargin[0]),Pixel[2]],
[-Pixel[0]/2,Pixel[2]],
[-Pixel[0]/2,0]
];
//----------------------
// 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,
$fn=Sides);
}
//- Locating pin hole with glue recess
// Default length is two pin diameters on each side of the split
PinOD = 1.70;
module LocatingPin(Dia=PinOD,Len=0.0) {
PinLen = (Len != 0.0) ? Len : (4*Dia);
translate([0,0,-ThreadThick])
PolyCyl((Dia + 2*ThreadWidth),2*ThreadThick,4);
translate([0,0,-2*ThreadThick])
PolyCyl((Dia + 1*ThreadWidth),4*ThreadThick,4);
translate([0,0,-(PinLen/2 + ThreadThick)])
PolyCyl(Dia,(PinLen + 2*ThreadThick),4);
}
//----------------------
// Pieces
//-- LED strips
module OnePixel() {
render()
rotate([-90,0,0]) rotate(180) // align result the way you'd expect from the dimensions
difference() {
linear_extrude(height=Pixel[1],convexity=3)
polygon(points=LEDStripProfile);
translate([-Pixel[0]/2,Pixel[2],-PixelMargin[0]])
cube([Pixel[0],2*PixelMargin[2],2*PixelMargin[0]]);
translate([-Pixel[0]/2,Pixel[2],Pixel[1]-PixelMargin[0]])
cube([Pixel[0],2*PixelMargin[2],2*PixelMargin[0]]);
}
}
module LEDString(n = LEDStringCount) {
for (i=[0:n-1])
translate([0,i*Pixel[1]])
// resize([0,Pixel[1] + 2*Protrusion,0])
OnePixel();
}
//-- Stack of hard drive platters
module Platters(n = LEDStringCount + 1) {
color("gold",0.4)
for (i=[0:n-1]) {
translate([0,0,i*Pixel[1]])
difference() {
cylinder(d=Platter[OD],h=Platter[LENGTH],center=false,$fn=PillarSides);
cylinder(d=Platter[ID],h=3*Platter[LENGTH],center=true,$fn=PillarSides);
}
}
}
//-- Pillar holding the LED strips
module Pillar() {
difflen = PillarLength + 2*Protrusion;
// render(convexity=5)
difference() {
linear_extrude(height=PillarLength,convexity=4)
difference() {
rotate(180/(12*4))
circle(d=Platter[ID] - 1*ThreadWidth,$fn=PillarSides);
for (i=[0:LEDStripCount-1]) // clearance for LED beamwidth, may not actually cut surface
rotate(i*360/LEDStripCount)
translate([PillarCore/2,0,0])
polygon(points=BeamShape);
for (i=[0:LEDStripCount-1]) // LED front clearance
rotate(i*360/LEDStripCount)
translate([(PillarCore/2 + Pixel[2]),(Pixel[0] - 2*PixelMargin[0])/2])
rotate(-90)
square([Pixel[0] - 2*PixelMargin[0],Platter[ID]]);
}
for (i=[0:LEDStripCount-1]) // LED strip slots
rotate(i*360/LEDStripCount)
translate([PillarCore/2,0,-Protrusion])
linear_extrude(height=difflen,convexity=2)
rotate(-90)
polygon(points=LEDStripProfile);
difference() { // wiring recess on top surface, minus boss
for (i=[0,90])
rotate(i)
translate([0,0,(PillarLength - (WireSpace/2 - Protrusion))])
cube([(PillarCore + 2*Protrusion),Pixel[0] - 2*PixelMargin[0],WireSpace],center=true);
cylinder(d=3*Screw[OD],h=PillarLength + Protrusion,$fn=CapSides);
}
for (i=[0:LEDStripCount-1]) // wiring recess on bottom surface
rotate(i*90)
translate([PillarCore/2 - (WireSpace - Protrusion)/2,0,WireSpace/2 - Protrusion])
cube([WireSpace + Protrusion,Pixel[0] - 2*PixelMargin[0],WireSpace],center=true);
for (j=[0:LEDStringCount-1]) // platter spacer alignment pins
for (i=[0:LEDStripCount-1])
rotate(i*360/LEDStripCount + 180/LEDStripCount)
translate([(Platter[ID] - 1*ThreadWidth)/2,0,(j*Pixel[1] + Pixel[1]/2 + Platter[LENGTH]/2)])
rotate([0,90,0])
rotate(45)
LocatingPin();
translate([0,0,-Protrusion]) // central screw hole
rotate(180/4)
PolyCyl(Screw[ID],difflen,4);
if (false)
for (i=[-1,1]) // vertical wire channels
rotate(i*360/LEDStripCount + 180/LEDStripCount)
translate([PillarCore/2 - 2.0,0,-Protrusion])
PolyCyl(2.0,difflen,4);
for (i=[-1,1]) // locating pins
rotate(i*360/LEDStripCount - 180/LEDStripCount)
translate([PillarCore/2 - 2.0,0,0])
LocatingPin();
}
}
//-- Spacers to separate platters
module Spacers() {
difference() {
linear_extrude(height=Spacer[LENGTH],convexity=4)
difference() {
rotate(180/PillarSides)
circle(d=Spacer[OD],$fn=PillarSides);
for (i=[0:LEDStripCount-1]) // clearance for LED beamwidth, may not actually cut surface
rotate(i*360/LEDStripCount)
translate([PillarCore/2,0,0])
polygon(points=BeamShape);
for (i=[0:LEDStripCount-1]) // LED front clearance
rotate(i*360/LEDStripCount)
translate([(PillarCore/2 + Pixel[2]),(Pixel[0] - 2*PixelMargin[0])/2])
rotate(-90)
square([Pixel[0] - 2*PixelMargin[0],Platter[ID]]);
rotate(180/PillarSides)
circle(d=Spacer[ID],$fn=PillarSides); // central pillar fits in the hole
}
for (i=[0:LEDStripCount-1])
rotate(i*360/LEDStripCount + 180/LEDStripCount)
translate([Platter[ID]/2,0,(Pixel[1] - Platter[LENGTH])/2])
rotate([0,90,0])
rotate(45)
LocatingPin();
}
}
//-- Cap over top of pillar
module TopCap() {
difference() {
cylinder(d1=(Cap[OD] + Cap[ID])/2,d2=Cap[OD],h=Cap[LENGTH],$fn=CapSides); // outer lid
translate([0,0,-Protrusion])
PolyCyl(Screw[ID],Cap[LENGTH] + WireSpace + Protrusion,4); // screw hole
translate([0,0,Cap[LENGTH] - 2*WireSpace])
difference() {
cylinder(d=Cap[ID],h=2*Cap[LENGTH],$fn=CapSides); // cutout
cylinder(d=3*Screw[OD],h=Cap[LENGTH],$fn=CapSides); // boss
}
translate([0,0,Cap[LENGTH] - 2*ThreadThick])
cylinder(d=Cap[ID]/2,h=2*ThreadThick + Protrusion,$fn=CapSides); // recess boss
}
}
//-- Base below pillar
module Base() {
SideWidth = 0.5*Base[OD]*sin(180/BaseSides); // close enough
difference() {
union() {
difference() {
cylinder(d=Base[OD],h=Base[LENGTH],$fn=BaseSides); // outer base
translate([0,0,6*ThreadThick]) // main cutout
cylinder(d=Base[ID],h=Base[LENGTH],$fn=BaseSides);
rotate(180/BaseSides)
translate([0,0,Base[LENGTH] - BaseClearHeight/2]) // power connector hole
rotate([90,0,0]) rotate(180/8)
PolyCyl(CoaxConn[ID],Base[OD],8);
}
translate([0,0,Base[LENGTH]/2]) // recess pillar support below rim
cube([PillarCore,PillarCore,Base[LENGTH] - 2*ThreadThick],center=true);
}
for (i=[0:LEDStripCount-1]) // wiring recesses
rotate(i*90)
translate([PillarCore/2 - (WireSpace - Protrusion)/2,0,Base[LENGTH] - 4*WireSpace/2])
cube([WireSpace + Protrusion,PillarCore - 4*WireSpace,4*WireSpace],center=true);
translate([0,0,-Protrusion])
PolyCyl(Screw[ID],2*Base[LENGTH],4); // screw hole
translate([0,0,-Protrusion]) // screw head recess
rotate(180/8)
PolyCyl(8.5,Base[LENGTH] - 3.0 + Protrusion,8);
for (i=[-1,1]) // locating pins
rotate(i*360/LEDStripCount - 180/LEDStripCount)
translate([PillarCore/2 - 2.0,0,Base[LENGTH] - ThreadThick])
LocatingPin();
if (CablePort)
translate([0,Platter[ID]/2 + PCB[1],Base[LENGTH] - 3.0 + Protrusion])
rotate(-90)
cube([PCB[1],Base[OD],3.0]);
}
}
//----------------------
// Build it
if (Layout == "Pixel")
OnePixel();
if (Layout == "LEDString")
LEDString(LEDStringCount);
if (Layout == "Platters")
Platters(LEDStringCount + 1);
if (Layout == "Pillar")
Pillar(LEDStringCount);
if (Layout == "TopCap")
TopCap();
if (Layout == "Base")
Base();
if (Layout == "Spacers")
Spacers();
if (Layout == "Show") {
Pillar();
for (i=[0:LEDStripCount-1]) // LED strips
rotate(i*360/LEDStripCount)
translate([PillarCore/2,0,Platter[LENGTH]/2])
rotate([90,0,90])
color("lightblue") LEDString();
if (true)
for (j=[0:max(1,ShowDisks - 2)]) // spacers
translate([0,0,(j*Pixel[1] + Platter[LENGTH])])
color("cyan") Spacers();
for (j=[0:max(2,ShowDisks - 2)]) // spacer alignment pins
for (i=[0:LEDStripCount-1])
rotate(i*360/LEDStripCount + 180/LEDStripCount)
translate([(Platter[ID] - 1*ThreadWidth)/2,0,(j*Pixel[1] + Pixel[1]/2 + Platter[LENGTH]/2)])
rotate([0,90,0])
rotate(45)
color("Yellow",0.25) LocatingPin(Len=4);
translate([0,0,PillarLength + 3*Cap[LENGTH]])
rotate([180,0,0])
TopCap();
translate([0,0,-2*Base[LENGTH]])
Base();
if (ShowDisks > 0)
Platters(ShowDisks);
}
// Ad-hoc build layout
if (Layout == "Build") {
if (true)
Pillar();
if (true)
translate([0,(Platter[ID] + Cap[OD])/2,0])
TopCap();
if (true)
translate([0,-(Platter[ID] + Base[OD])/2,0])
Base();
Ybase = Spacer[OD] * (LEDStringCount%2 ? (LEDStringCount - 1) : (LEDStringCount - 2)) / 4;
if (true)
for (i=[0:LEDStringCount]) // build one extra set of spacers!
translate([(i%2 ? 1 : -1)*(Spacer[OD] + Base[OD])/2, // alternate X sides to shrink Y space
(i%2 ? i-1 : i)*Spacer[OD]/2 - Ybase, // same Y for even-odd pairs in X
0])
Spacers();
}
It should come as no surprise that hard drive platters have different thicknesses:
Hard Drive Platter Thickness
The thicker ones measure 1.25 mm, which is near enough to 50 mils to suggest they date back to the Good Old Days. The three thinner ones in the middle are 0.77 mm = 30 mil and could be slightly younger than dirt. There’s more where these came from and I expect more variation on the theme.
The beveled edges make the platters look thinner than they really are; they’re firmly clamped together with no space between them.
After donating the never–sufficiently-to-be-damnedSamsungvacuumcleaner (and all its remaining bags & doodads) to a nonprofit’s tag sale, we picked up a Sears Kenmore Progressive vacuum cleaner that seemed to be the least awful of the current offerings. Unlike all previous vacuum cleaners, its tools & doodads have complex plastic fittings with latches and keyways and all manner of gimcrackery. The designers seem to have hands and legs of far-above-average size, but that’s another rant.
All this came to a head when I attempted to vacuum the fuzz out of the refrigerator’s evaporator coils, because the long snout that reaches the back of the refrigerator doesn’t fit the aperture in the giant handle.
Well, at least I can fix that…
The first step involved modeling the plastic fitting that snaps into the handle:
Which spits out two suitable shapes with the proper positions and alignments:
Kenmore Male Fitting – Latch detail – Solid model
The magic wand for the refrigerator originally slid into the Samsung’s metal pipe, so I put a slightly tapered cylinder inside a somewhat more tapered exterior (which seems chunky enough to withstand my flailing around under the refrigerator), then topped it off with the male fitting:
Refrigerator Coil Wand Adapter
The Kenmore crevice tool snaps under the gargantuan plastic handle, which limits it to being 6.5 inches long, totally unable to reach into any of the nontrivial crevices around here, and in the way when it’s not being used. Some rummaging turned up a longer crevice tool from the Electrolux That Came With The House™, an old-school tool that slipped over its pipe. Modeling a straight cylinder inside a tapered cylinder that fits the tool didn’t take long:
Crevice Tool Adapter
Flushed with success, I found a smaller floor brush than the new Kenmore, with dimensions similar to the Electrolux snout, so another module appeared:
Floor Brush Adapter
All of them build with the latch end upward to avoid needing support structure, with a 5 mm brim for good platform adhesion:
Floor Brush Adapter – Slic3r preview
I printed them during the PDS Mini Maker Faire as examples of Useful Things You Can Do With a 3D Printer:
Kenmore Vacuum Cleaner – Tool Adapters
As I pointed out to nearly everybody, the Big Lie about 3D printing is that you’ll just download somebody else’s model to solve your problem. In general, that won’t work, because nobody else has your problem; if you can’t do solid modeling, there’s no point in you having a 3D printer. There’s also no point in going to Kinko’s to get a standardized 3D printed doodad, because you can just order a better-looking injection-molded part directly from Sears (or an aftermarket source) and be done with it.
I loves me some good OpenSCAD action on my Makergear M2, though…
The OpenSCAD source code:
// Kenmore vacuum cleaner nozzle adapters
// Ed Nisley KE4ZNU November 2015
// Layout options
Layout = "CreviceTool"; // MaleFitting CoilWand FloorBrush CreviceTool
//- 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=2*OEMTube[LENGTH] + 2*Protrusion);
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();
}
}
//----------------------
// Build it!
if (Layout == "MaleFitting")
MaleFitting();
if (Layout == "CoilWand")
CoilWand();
if (Layout == "FloorBrush")
FloorBrush();
if (Layout == "CreviceTool")
CreviceTool();
The Smell of Molten Projects in the Morning 