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.
Cruisin’ the streets
So the hydration pack I’ve been using for a few years started piddling all over the floor, whereupon some debugging revealed a pinhole leak where the large thermally sealed flange meets the bag side. Nothing, but nothing adheres to the polyethylene (or some such) bag material, but a blob of acrylic caulk (armored with a layer of electrical tape, not shown) may suffice for a while.
I did the same thing to the other side as a prophylactic measure…
Of late my Tour Easy has developed a squeak at the pedal-go-round rate. It has Performance Bike Campus pedals, with SPD cleats on one side and a rat-trap surface on the other, and only the SPD side squeaked.
Turns out that the two little mounting screws holding the cleat dingus worked their way loose.
I should probably ease some lube under that plate, just to be sure, but the simple fix worked fine…
(And, yeah, I should clean it, just once, to see what it’s like, right?)
My speedometer stored 39.3 mph max somewhere near that point, downhill along nice S curves that end, alas, in that abrupt left turn at the creek. By glancing across the field inside the corner, hoping for the best, and clipping the yellow line, I can emerge at 20+ mph, but some day that’ll have a bad outcome.
I can’t hold that pace on the flats, of course, but the 22 mile ride came out at 15 mph average and, unlike the guy on the Rail Trail about five miles later, I wasn’t trying to find a more comfortable position on the saddle.
News Flash: when you go Rail Trail dueling, don’t match your knobby-tire mountain bike against a faired Tour Easy, even if the TE driver is the canonical Fat Old Guy with a Beard and the bike carries all manner of racks and packs and accoutrements. Heh!
Having managed to mislay my dingy yellow kickstand plate, I made two more and this time hit ’em with fluorescent red paint. Ought to be unforgettable for another few years…
In theory, you’re supposed to apply a white undercoat. I hosed ’em down with many drippy, runny coats of red and it’s all good. This ain’t art and they get thrown on the ground, so what’s the point of being fancy?
This is the slightly smaller mount corresponding to the OpenSCAD code there for the two-section inspection mirror shaft, hot from the printer:
It’s about the same as the previous version, despite trimming a few millimeters from the diameters and spacings:
I’ll print the next one in a darker color. At least it’s not pink…
The OpenSCAD source:
// Helmet mirror mount
// Ed Nisley KE4ZNU June 2011
include </home/ed/Thing-O-Matic/lib/MCAD/units.scad>
include </home/ed/Thing-O-Matic/lib/MCAD/boxes.scad>
include </home/ed/Thing-O-Matic/lib/visibone_colors.scad>
//-- Layout Control
Layout = "Build"; // Build Fit Show None
Examine = "None"; // AzMount ElMount ElBody ElPlate HelmetPlate None
//-- Extrusion parameters
ThreadThick = 0.33;
ThreadWT = 2.0;
ThreadWidth = ThreadThick * ThreadWT;
HoleWindage = 0; // enlarge hole dia by this amount
//-- Useful sizes
Tap2_56 = 0.070 * inch;
Clear2_56 = 0.082 * inch;
Head2_56 = 0.156 * inch;
Head2_56Thick = 0.055 * inch;
Nut2_56Dia = 0.204 * inch;
Nut2_56Thick = 0.065 * inch;
Tap3_48 = 0.079 * inch;
Clear3_48 = 0.096 * inch;
Head3_48 = 0.184 * inch;
Head3_48Thick = 0.058 * inch;
Nut3_48Dia = 0.201 * inch;
Nut3_48Thick = 0.073 * inch;
Tap4_40 = 0.089 * inch;
Clear4_40 = 0.110 * inch;
Head4_40 = 0.211 * inch;
Head4_40Thick = 0.065 * inch;
Nut4_40Dia = 0.228 * inch;
Nut4_40Thick = 0.086 * inch;
//-- Azimuth Mount
AzMountDia = 12.0;
AzMountLength = 14.0;
AzFacets = 30;
echo(str("Azmuth mount dia: ",AzMountDia," length: ",AzMountLength));
//-- Mirror sizes
MirrorShaftDia = 3.60;
MirrorShaftOffset = -1.5; // vertical offset from center of AzMountBody
MirrorShoulderLen = 3*MirrorShaftDia;
MirrorShoulderDia = min(AzMountDia,MirrorShaftDia + 6*ThreadWidth);
MirrorStudDia = Tap3_48;
MirrorStudLen = 2.0;
//-- Elevation Mount / Body / Plate
ElMountDia = AzMountDia;
ElMountLength = 2.0 + ElMountDia;
ElMountBase = 2.0;
ElMountRounding = 2.0;
ElMountFacets = AzFacets;
ElBodyWidth = ElMountDia;
ElBodyBlockLength = ElMountLength + AzMountLength/2 - MirrorShaftOffset;
ElBodyThick = 8.0;
echo(str("Elevation body overall: ",(ElBodyBlockLength + ElBodyWidth/2)," width: ",ElBodyWidth));
ElPlateTall = ElBodyBlockLength + 0.70*ElBodyWidth;
ElPlateWidth = 1.25 * ElPlateTall;
ElPlateThick = Nut3_48Thick + 3*ThreadThick;
ElPlatePlusX = ElPlateThick + (ElMountDia/2 + ElMountBase) + ElBodyThick;
echo(str("Elevation plate tall: ",ElPlateTall," width: ",ElPlateWidth));
ElArcRadius = (3/4) * ElBodyBlockLength;
ElArcThick = 4*ThreadWidth;
ElArcHeight = (1/2) * ElBodyThick;
ElArcAngle = 35;
ElArcFacets = 32;
ElPlateFacets = 52;
//-- Helmet Interface Plate
HelmetCX = 60.0;
HelmetMX = 4.0;
HelmetRX = (pow(HelmetMX,2) + pow(HelmetCX,2)/4)/(2*HelmetMX);
HelmetPlateC = max(ElPlateTall,ElPlateWidth);
HelmetPlateTheta = atan(HelmetPlateC/HelmetRX);
HelmetPlateM = 2*HelmetRX*pow(sin(HelmetPlateTheta/4),2);
HelmetPlateThick = ThreadThick*(ceil(HelmetPlateM/ThreadThick) + 1);
//-- Bearing Interfaces
BearingWidth = 3*ThreadWidth;
BearingOverlap = 3*ThreadThick;
BearingClearance = 1*ThreadThick;
BearingStudDia = min(AzMountDia,ElBodyWidth) - 2*BearingWidth;
//-- Convenience values
Protrusion = 0.1; // make holes look good
//----------------------
// Useful routines
module PolyCyl(Dia,Height) { // based on nophead's polyholes
Sides = ceil(Dia) + 2;
FixDia = Dia / cos(180/Sides);
cylinder(r=(FixDia + HoleWindage)/2,
h=Height,
$fn=Sides);
}
PegSize = 1.0;
module ShowPegGrid(Size) {
for (x=[-5:5])
for (y=[-5:5])
translate([x*10,y*10,Size/2])
cube(Size,center=true);
}
//----------------------
// Azimuth Mount
module AzMount() {
difference() {
union() {
cylinder(r=AzMountDia/2,h=AzMountLength,$fn=AzFacets); // body
translate([0,0,AzMountLength/2 + MirrorShaftOffset])
rotate([-90,0,0])
cylinder(r=MirrorShoulderDia/2,
h=MirrorShoulderLen,$fn=AzFacets); // mirror shaft shoulder
if (Layout != "Fit")
for (y=[0:1]) // shoulder support
translate([-AzMountDia/2,(4*y + AzMountDia/2 + ThreadWidth),0])
difference() {
cube([AzMountDia,2*ThreadWidth,AzMountLength/6]);
translate([AzMountDia/2,-Protrusion,AzMountLength/2 + MirrorShaftOffset])
rotate([-90,0,0])
cylinder(r=MirrorShoulderDia/2,h=ThreadWidth + 2*Protrusion);
}
}
translate([0,-Head3_48/2,AzMountLength/2 + MirrorShaftOffset])
rotate([-90,0,0])
PolyCyl(MirrorShaftDia,(AzMountDia + MirrorShoulderLen)); // mirror shaft
translate([0,-(Head3_48/2 - Protrusion),AzMountLength/2 + MirrorShaftOffset])
rotate([90,0,0])
PolyCyl(MirrorStudDia,MirrorStudLen+Protrusion); // mirror stud
translate([0,0,
Head3_48Thick - (AzMountLength - MirrorShaftDia)/2 + MirrorShaftOffset - Protrusion])
PolyCyl(Head3_48,AzMountLength + Protrusion); // mounting screw head
translate([0,0,-Protrusion])
cylinder(r=(Clear3_48 + HoleWindage)/2,
h=(AzMountLength + 2*Protrusion),
$fn=ceil(Clear3_48)+2); // mounting screw clearance
translate([0,0,AzMountLength/2 + Head3_48Thick + MirrorShaftDia/2 + MirrorShaftOffset - Protrusion])
cylinder(r1=(Head3_48/cos(180/7) + HoleWindage)/2,
r2=Clear3_48/2,
h=(3*ThreadThick + Protrusion),
$fn=7); // overhang support
translate([0,0,AzMountLength/2 + MirrorShaftOffset])
rotate([0,90,0])
PolyCyl(Tap2_56,AzMountDia/2 + Protrusion); // setscrew hole
translate([0,0,AzMountLength - (BearingOverlap + BearingClearance)])
PolyCyl(BearingStudDia,
BearingOverlap + BearingClearance + Protrusion); // bearing surface
}
}
//----------------------
// Elevation Mount
module ElMount() {
difference() {
union() {
translate([(ElMountDia/4 + ElMountBase/2),0,(ElMountLength/2 + BearingOverlap)])
rotate([0,90,0])
cube([ElMountLength,ElMountDia,(ElMountDia/2 + ElMountBase)],
center=true); // mounting block
translate([0,0,BearingOverlap]) {
// color([0.4,0.3,0.3,0.7])
cylinder(r=ElMountDia/2,
h=ElMountLength - ElMountDia/2,
$fn=ElMountFacets); // cylinder to Az
// color([0.3,0.4,0.3,0.7])
translate([0,0,ElMountLength - ElMountDia/2]) { // curved interface
intersection() {
cylinder(r=ElMountDia/2,h=ElMountDia/2,$fn=ElMountFacets);
translate([0,ElMountDia/2,0])
rotate([90,0,0])
cylinder(r=ElMountDia/2,h=ElMountDia,$fn=ElMountFacets);
}
}
}
cylinder(r=(BearingStudDia - HoleWindage)/2,h=BearingOverlap); // bearing stud
}
translate([0,0,-Protrusion])
PolyCyl(Tap3_48,(3/4)*ElMountLength + BearingOverlap + Protrusion); // AzMount screw
}
}
//----------------------
// Elevation Body
module ElBody() {
difference() {
union() {
translate([-ElBodyBlockLength,-ElBodyWidth/2,0])
cube([ElBodyBlockLength,ElBodyWidth,ElBodyThick]);
translate([0,0,ElBodyThick])
cylinder(r=(ElBodyWidth - 2*BearingWidth)/2,h=BearingOverlap);
cylinder(r=ElBodyWidth/2,h=ElBodyThick,$fn=ElMountFacets);
}
PolyCyl(Clear3_48,ElBodyThick + BearingOverlap + Protrusion);
translate([0,0,-Protrusion])
PolyCyl(Head3_48,Head3_48Thick);
translate([-ElArcRadius,0,ElBodyThick - ElArcHeight/2])
rotate([0,-90,0])
PolyCyl(Tap2_56,ElBodyBlockLength - ElArcRadius + Protrusion);
translate([0,0,ElBodyThick - (ElArcHeight + BearingClearance)])
difference() {
cylinder(r=ElArcRadius + (ElArcThick/2 + BearingClearance),
h=ElArcHeight + BearingClearance + Protrusion,
$fn=ElArcFacets);
cylinder(r=ElArcRadius - (ElArcThick/2 + BearingClearance),
h=ElArcHeight + BearingClearance + Protrusion,
$fn=ElArcFacets);
}
}
}
//----------------------
// Elevation Plate
module ElPlate() {
union() {
difference() {
translate([ElBodyWidth/2 - ElPlateTall/2,0,0])
scale([ElPlateTall,ElPlateWidth,1.0])
cylinder(r=0.5,h=ElPlateThick,$fn=ElPlateFacets);
translate([0,0,-Protrusion])
PolyCyl(Tap3_48,ElPlateThick + 2*Protrusion);
translate([0,0,ElPlateThick - (BearingOverlap + BearingClearance)])
PolyCyl(BearingStudDia,(BearingOverlap + BearingClearance) + Protrusion);
translate([0,0,-Protrusion])
cylinder(r=Nut3_48Dia/2,h=(1.1*Nut3_48Thick + Protrusion),$fn=6);
}
translate([0,0,ElPlateThick])
difference() {
cylinder(r=ElArcRadius + ElArcThick/2,
h=ElArcHeight,
$fn=ElArcFacets);
cylinder(r=ElArcRadius - ElArcThick/2,
h=ElArcHeight + Protrusion,
$fn=ElArcFacets);
rotate([0,0,90 - ElArcAngle])
translate([ElArcRadius + ElArcThick,0,ElArcHeight/2])
cube([2*ElArcRadius + ElArcThick,
2*ElArcRadius + ElArcThick,
ElArcHeight + Protrusion],
center=true);
rotate([0,0,-(90 - ElArcAngle)])
translate([ElArcRadius + ElArcThick,0,ElArcHeight/2])
cube([2*ElArcRadius + ElArcThick,
2*ElArcRadius + ElArcThick,
ElArcHeight + Protrusion],
center=true);
}
}
}
//----------------------
// Helmet Interface Plate
module HelmetPlate() {
difference() {
scale([ElPlateTall,ElPlateWidth,1.0])
cylinder(r=0.5,h=HelmetPlateThick,$fn=ElPlateFacets);
translate([0,0,HelmetRX + HelmetPlateThick - HelmetPlateM])
sphere(r=HelmetRX,$fn=256,$fs=0.1);
}
}
//----------------------
// Lash it together
if (Examine == "AzMount")
AzMount();
if (Examine == "ElMount")
ElMount();
if (Examine == "ElBody")
ElBody();
if (Examine == "ElPlate")
ElPlate();
if (Examine == "HelmetPlate")
HelmetPlate();
if ((Layout == "Build" || Layout == "Show") && Examine == "None") {
translate([-10,-20,0])
rotate([0,0,90]) // mis-align top fill from ElMount
AzMount();
translate([-10,20,ElMountLength + BearingOverlap])
rotate([0,180,-90])
ElMount();
translate([0,0,0])
rotate([0,0,0])
ElBody();
translate([10,15,0])
rotate([0,0,215]) // mis-align top fill from ElBody
ElPlate();
translate([20,-20,0])
rotate([0,0,-45])
HelmetPlate();
if (Layout == "Show")
ShowPegGrid(PegSize);
}
if ((Layout == "Fit") && Examine == "None") {
translate([0,0,-(AzMountLength/2 + MirrorShaftOffset)])
color(MFG) AzMount();
translate([0,0,AzMountLength/2 - MirrorShaftOffset - BearingOverlap])
color(DHC) ElMount();
// color([ 0/255, 204/255, 204/255,0.5]) ElMount();
translate([ElMountDia/2 + ElMountBase,0,0])
rotate([0,90,0])
color(DFC) ElBody();
translate([ElPlatePlusX,0,0])
rotate([180,90,0])
color(LHC) ElPlate();
translate([ElPlatePlusX,0,ElPlateTall/2 - ElBodyWidth/2])
rotate([0,90,0])
color(LWM) HelmetPlate();
}
It has nothing to do with the load o’ tools in the left underseat bag on my Tour Easy. It has everything to do with the fact that we ride on the shoulder of crowned roads.
Here’s a cross-section of one defunct Schwalbe Marathon rear tire with the tread obviously thicker on the left side, which would be the right side of the mounted tire:
Maybe I should change the tires more often?
Printing went smoothly after two preliminary passes to work out the sizes and alignments; this is the second pass, which you can tell because the mirror shoulder has three supports instead of the two shown in the solid model:
One view of the parts, with the mirror shaft in place:
Another view, showing the bottom of the Elevation Plate with the recessed nut:
Assembling the two glue joints required an overnight clamping:
Then a layer of double-stick foam tape affixes it firmly to the helmet:
It’s a bit too big and way ugly, but works pretty much as expected.
Two lengths of heatshrink tubing now lock the mirror shaft sections in place; they tended to rotate slightly under normal vibration.
The OpenSCAD code and model have a few modifications from this object. The next one won’t have the third section of mirror shaft, which makes the shoulder and Az Mount smaller, and the Az Mount is 1 mm closer to the El Body. That shaves a few millimeters off the whole thing.
The mirror clamp out there on the end is much too large and has too many fiddly parts. I think a little printed doodad would work, but that’s in the nature of fine tuning.
The Smell of Molten Projects in the Morning 