Bike Helmet Mirror: Brasswork Clamp

A bit of Quality Shop Time produced a slight improvement to the clamp holding the mirror to the stalk:

Helmet Mirror Ball Mount - mirror joint brasswork
Helmet Mirror Ball Mount – mirror joint brasswork

The general idea is to hold the wave washer (it’s mashed under the flat washer, honest) above those bumps on the plate holding the mirror and stalk balls. It’s a few millimeters from the end of a ¼ inch brass rod, drilled for the M3 screw, and reduced to 4.5 mm with a parting tool to clear the bumps.

While I was at it, I made two spare mirrors, just to have ’em around:

Helmet Mirror Ball Mount - new vs old
Helmet Mirror Ball Mount – new vs old

The new ball mount looks downright svelte compared to the old Az-El mount, doesn’t it?

I should replace the steel clamp plates with a stainless-steel doodad of some sort to eliminate the unsightly rust, but that’s definitely in the nature of fine tuning.

Bike Helmet Mirror: Ball Mount

Nine years ago, I didn’t know how enough to design a bike helmet mirror with a ball mount, but even an old dog can learn a new trick:

Helmet Mirror Ball Mount - on helmet
Helmet Mirror Ball Mount – on helmet

However, it’s worth noting my original, butt-ugly Az-El mounts lasted for all of those nine years, admittedly with adjustments along the way, which is far more than the commercial mounts making me unhappy enough to scratch my itch.

The mount adapts the split spherical clamp from the daytime running light:

Helmet Mirror Mount - Ball
Helmet Mirror Mount – Ball

Scaling it down for a 10 mm polypropylene ball around the base of the 30 mm inspection mirror’s shaft simplified everything:

Helmet Mirror Ball Mount - drilled ball test
Helmet Mirror Ball Mount – drilled ball test

I’m reasonably sure I couldn’t have bought 100 polypro balls for eight bucks a decade ago, but we’ll never know. Drilling the hole was a complete botch job, about which more later. The shaft came from a spare mirror mount I made up a while ago; a new shaft appears below.

The solid model, like Gaul, is in three parts divided:

Helmet Mirror Ball Mount - Slic3r
Helmet Mirror Ball Mount – Slic3r

The helmet plate (on the right) has a slight indent more-or-less matching the helmet curvature and gets a layer of good double-stick foam tape. The clamp base (on the left) has a pair of brass inserts epoxied into matching recesses below the M3 clearance holes:

Helmet Mirror Ball Mount - inserts
Helmet Mirror Ball Mount – inserts

A layer of epoxy then sticks the helmet plate in place, with the inserts providing positive alignment:

Helmet Mirror Ball Mount - plates
Helmet Mirror Ball Mount – plates

The clamp screws pull the inserts against the plastic in the clamp base, so they can’t pull out or through, and the plates give the epoxy enough bonding surface that (I’m pretty sure) they won’t ever come apart.

I turned down a 2 mm brass insert to fit inside the butt end of the mirror shaft and topped it off with a random screw harvested from a dead hard drive:

Helmet Mirror Ball Mount - assembled - rear view
Helmet Mirror Ball Mount – assembled – rear view

At the start, it wasn’t obvious the shaft would stay stuck in the ball, so I figured making it impossible to pull out would eliminate the need to find it by the side of the road. As things turned out, the clamp exerts enough force to ensure the shaft ain’t goin’ nowhere, so I’ll plug future shafts with epoxy.

The front side of the clamp looks downright sleek:

Helmet Mirror Ball Mount - assembled - front view
Helmet Mirror Ball Mount – assembled – front view

Well, how about “chunky”?

The weird gray-black highlights are optical effects from clear / natural PETG, rather than embedded grunge; it looks better in person. I should have used retina-burn orange or stylin’ black.

This mount is much smaller than the old one and should, in the event of a crash, not cause much injury. Based on how the running light clamp fractures, I expect the clamp will simply tear out of the base on impact. In the last decade, neither of us has crashed, so I don’t know what the old mount would do.

The clamp is 7 mm thick (front-to-back), set by the M3 washer diameter, with 1.5 mm of ball sticking out on each side. The model has a kerf one thread high (0.25 mm) between the pieces to add clamping force and, with the screws tightened down, moving the ball requires a disturbingly large effort. I added a touch of rosin and that ball straight-up won’t move, which probably means the shaft will bend upon droppage; I have several spare mirrors in stock.

On the other paw, the ball turns smoothly in the clamp and it’s easy to position the shaft as needed: much better than the old Az-El mount!

The inspection mirror hangs from a double ball joint which arrives with a crappy screw + nut. I epoxied the old mirror mount nut in place, but this time around I drilled the plates for a 3 mm stainless SHCS, used a wave washer for a bit of flexible force, and topped it off with a nyloc nut:

Helmet Mirror Ball Mount - mirror joint
Helmet Mirror Ball Mount – mirror joint

I’m unhappy with how it looks and don’t like how the washer hangs in free space between those bumps, so I may eventually turn little brass fittings to even things out. It’s either that or more epoxy.

So far, though, it’s working pretty well and both units meet customer requirements.

The OpenSCAD source code as a GitHub Gist:

// Bike helmet mirror mount - ball joint
// Ed Nisley KE4ZNU 2020-09
/* [Layout options] */
Layout = "Build"; // [Build, Show, Plate, Base, Clamp]
//-- Extrusion parameters
// Extrusion parameters
/* [Hidden] */
ThreadThick = 0.25;
ThreadWidth = 0.40;
HoleWindage = 0.2;
function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
function IntegerLessMultiple(Size,Unit) = Unit * floor(Size / Unit);
Protrusion = 0.1; // make holes end cleanly
inch = 25.4;
ID = 0;
OD = 1;
LENGTH = 2;
//- Basic dimensions
MountDia = 30.0; // footprint on helmet
BallDia = 10.0;
BallRad = BallDia / 2;
WallThick = IntegerMultiple(2.0,ThreadWidth);
FloorThick = IntegerMultiple(2.0,ThreadThick);
CornerRound = 2.0;
Insert = [3.0,4.0,4.0]; // threaded brass insert
Screw = [3.0,5.5,25.0]; // clamp screw
Washer = [3.7,7.0,0.7]; // washer
ShowGap = 2.0;
BuildGap = 5.0;
//-- Helmet Interface Plate
ScrewOC = BallDia + 2*WallThick + Screw[ID];
echo(str("Screw OC: ",ScrewOC));
Clamp = [ceil(Washer[OD]), // barely holds washer under screw
ScrewOC + Washer[OD], // minimal clearance for washer
BallDia +2*FloorThick // screw fits through insert
];
Kerf = ThreadThick;
echo(str("Clamp: ",Clamp));
HelmetCX = 60.0; // empirical helmet side curve
HelmetMX = 3.0;
HelmetRX = (pow(HelmetMX,2) + pow(HelmetCX,2)/4)/(2*HelmetMX);
HelmetPlateC = MountDia;
HelmetPlateTheta = atan(HelmetPlateC/HelmetRX);
HelmetPlateM = 2*HelmetRX*pow(sin(HelmetPlateTheta/4),2);
echo(str("Plate indent: ",HelmetPlateM));
HelmetPlateThick = max(FloorThick,0.6*Insert[LENGTH]) + HelmetPlateM;
echo(str("Screw length: ",Clamp.z + Insert[LENGTH]));
MountSides = 2*3*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,$fn=Sides);
}
//----------------------
// Clamp frame around ball
module ClampFrame() {
difference() {
union() {
hull()
for (i=[-1,1], j=[-1,1]) {
translate([i*(Clamp.x/2 - CornerRound),j*(Clamp.y/2 - CornerRound),Clamp.z/2 - CornerRound])
sphere(r=CornerRound,$fn=24);
translate([i*(Clamp.x/2 - CornerRound),j*(Clamp.y/2 - CornerRound),-Clamp.z/2])
cylinder(r=CornerRound,$fn=24);
}
for (j=[-1,1])
translate([0,j*ScrewOC/2,0])
rotate(180/12)
cylinder(d=Washer[OD],h=Clamp.z/2,$fn=12);
}
sphere(d=BallDia + HoleWindage,$fn=48);
cube([2*MountDia,2*MountDia,Kerf],center=true);
for (j=[-1,1])
translate([0,j*ScrewOC/2,-Screw[LENGTH]])
rotate(180/6)
PolyCyl(Screw[ID],2*Screw[LENGTH],6);
}
}
module ClampSelect(Section) {
XlateZ = (Section == "Top") ? Clamp.z/2 :
(Section == "Bottom") ? -Clamp.z/2 :
0;
intersection(convexity=5) {
ClampFrame();
translate([0,0,XlateZ])
cube([2*Clamp.x,2*Clamp.y,Clamp.z + 2*Protrusion],center=true);
}
}
//----------------------
// Concave plate fitting helmet shell
module HelmetPlate() {
render()
difference() {
cylinder(d=MountDia,h=HelmetPlateThick,$fn=MountSides);
translate([0,0,HelmetPlateThick - HelmetPlateM + HelmetRX])
sphere(r=HelmetRX,$fn=128);
for (j=[-1,1])
translate([0,j*ScrewOC/2,-Protrusion]) {
PolyCyl(Insert[OD],0.6*Insert[LENGTH] + Protrusion,6);
PolyCyl(Screw[ID],2*HelmetPlateThick,6);
}
}
}
//----------------------
// Base of clamp ring
module MountBase() {
difference() {
union() {
cylinder(d=MountDia,h=FloorThick,$fn=MountSides);
translate([0,0,FloorThick + Clamp.z/2])
ClampSelect("Bottom");
}
for (j=[-1,1])
translate([0,j*ScrewOC/2,-Protrusion])
rotate(180/6)
PolyCyl(Insert[OD],0.6*Insert[LENGTH] + Protrusion,6);
}
}
//----------------------
// Lash it together
if (Layout == "Plate") {
HelmetPlate();
}
if (Layout == "Base") {
MountBase();
}
if (Layout == "Clamp") {
ClampFrame();
}
if (Layout == "Show") {
rotate([180,0,0])
HelmetPlate();
translate([0,0,ShowGap]) {
MountBase();
color("Ivory",0.3)
translate([0,0,Clamp.z/2 + FloorThick + ShowGap/2])
sphere(d=BallDia);
translate([0,0,Clamp.z/2 + FloorThick + ShowGap])
ClampSelect("Top");
}
}
if (Layout == "Build") {
translate([MountDia/2 + BuildGap,0,0])
HelmetPlate();
translate([-(MountDia/2 + BuildGap),0,0])
MountBase();
translate([0,MountDia/2 + BuildGap,Clamp.z/2])
rotate([0,180,0])
rotate(90)
ClampSelect("Top");
}

The original doodles include a bit of dress-up fairing that didn’t make the cut:

Helmet Mirror Ball Mount - doodles
Helmet Mirror Ball Mount – doodles

Tour Easy Daytime Running Light: Second Fracture

While clearing some overhanging brush along the rail trail, I probably wedged a branch between the LC40 flashlight and the fairing:

Fairing Flashlight Mount - brush clearing
Fairing Flashlight Mount – brush clearing

Aaaand twisted it enough to fracture the mount:

Fairing Flashlight Mount - another fracture
Fairing Flashlight Mount – another fracture

A closer look shows the infill just ripped apart:

Fairing Flashlight Mount - another failure - detail
Fairing Flashlight Mount – another failure – detail

I can’t be sure that’s what happened, because the mount actually failed several miles later, after I hit one of the potholes along Raymond Avenue. Fortunately, I saw it swinging away from the fairing, hanging by its last few threads, and managed to grab it before it vanished.

Fairing Flashlight Mount - Catch a Falling Mount
Fairing Flashlight Mount – Catch a Falling Mount

I set Slic3r for 30% infill on the replacement, but the running light been riding my fairing for three years and seems strong enough under normal use.

Rt 376 at Zach’s Way: Near Right Hook

We exchanged waves as he rode by Vassar Farms:

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 0
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 0

Although I can rarely hang with real roadies, I can put the fear in ’em for a while, so the chase is on.

About 25 seconds later, I’m southbound on Rt 376, accelerating past 20 mph = 30 feet/s. The overtaking pickup, which I haven’t noticed yet, is signaling a right turn at Zach’s Way, 350 feet ahead:

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 1
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 1

The pickup enters my field of view, but I can’t see the turn signals:

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 2
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 2

Two seconds later, the driver is braking:

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 3
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 3

During the next three seconds, the driver realizes I’m going much much faster than your usual cyclist and is braking hard:

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 4
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 4

My startled shout (“Don’t even think about it!“) may be misinterpreted, but I try to be friendly,

Rt 376 SB Marker 1124 Zachs Way - Near Right Hook - 2020-07-19 - 5
Rt 376 SB Marker 1124 Zachs Way – Near Right Hook – 2020-07-19 – 5

Alas, the cyclist turned into Boardman Road and all that adrenaline went to waste.

Elapsed time since the fender appeared: six seconds.

Harvesting 18650 Lithium Cells

With a Dutchess County Household Hazardous Waste Collection Day coming up, I’ve been harvesting usable lithium cells from a variety of old batteries:

Harvested 18650 3P lithium batteries
Harvested 18650 3P lithium batteries

The pile of 18650 3P blocks over on the right are some obviously corroded deaders and the lowest performers from these tests:

Harvested 3P 18650 Packs
Harvested 3P 18650 Packs

I doubt they’ll get recycled, as there’s entirely too much overhead involved in dismantling boxes full of cells like these, but I hope they’ll get a decent burial somewhere.

Rt 376 at Red Oaks Mill: Semitrailer Squeeze Play

We’re southbound on NYS Rt 376, approaching the Wappinger Creek bridge at mile marker 1102, avoiding the overgrowth coming through the guide rail:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 01
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 01

Avoiding the pothole growing across the right wheel track:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 02
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 02

Normally, I ride to the left of that pothole, down the middle of the lane, so it’s easier to avoid the next section of overgrowth through the guide rail:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 03
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 03

This time, we’re as far to the right as we can get, because we’re being overtaken by a semitrailer trash hauler:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 04
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 04

Which is proceeding as far to the left as the driver can possibly squeeze it:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 05
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 05

Half a lane is more than we sometimes get:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 06
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 06

Away he goes:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 07
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 07

We always try to be friendly, because we’re sure to meet again some day:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - 2020-07-15 - 08
Rt 376 SB Marker 1102 – Royal Semi Squeeze – 2020-07-15 – 08

Mary says he waved back, so it’s all good.

Elapsed time: about twelve seconds.

For whatever it’s worth, eight years ago, NYS DOT Region 8 South Dutchess Residency did a much better job of clearing the overgrowth along Rt 376:

Rt 376 SB Marker 1102 - Royal Semi Squeeze - Google StreetView 2012-04
Rt 376 SB Marker 1102 – Royal Semi Squeeze – Google StreetView 2012-04

That was then, this is now.