The New Hotness

With the amber front running light blinking away, it’s time to replace the decade-old Planet Bike Superflash behind the seat:

The new mount descends directly from the clamps holding the fairing strut on the handlebars and various hose clamps:

Rear Running Light Seat Clamp - solid model — Rear Running Light Seat Clamp – solid model

The central block has two quartets of brass inserts epoxied inside:

Rear Running Light Seat Clamp - sectioned - solid model — Rear Running Light Seat Clamp – sectioned – solid model

That means I can install the light, then mount the whole affair on the bike, without holding everything together while fiddling with overly long screws.

A trial fit with the not-yet-cut-to-length 25.3 (-ish) PVC pipe body tube:

Rear Running Light - Tour Easy seat clamp trial fit — Rear Running Light – Tour Easy seat clamp trial fit

The aluminum plates have the standard used-car finish: nice polish over deep scratches.

Although I’ve been thinking of mounting the light below the seat rail, as shown, it can also sit above the rail.

Mary hauls seedlings and suchlike to the garden in a plastic drawer bungied to the rack, with the SuperFlash serving as an anchor point; this light may need fine tuning for that purpose.

The OpenSCAD source code as a GitHub Gist:

	// Rear running light clamp for Tour Easy seat strut
	// Ed Nisley – KE4ZNU – 2021-09

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

	Section = true;

	/* [Hidden] */

	ThreadThick = 0.25;
	ThreadWidth = 0.40;

	HoleWindage = 0.2;

	Protrusion = 0.1; // make holes end cleanly

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

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

	inch = 25.4;

	//———————-
	// Dimensions
	// Light case along X axis, seat strut along Y, Z=0 at strut centerline

	LightOD = 25.4 + HoleWindage;

	StrutOD = 5/8 * inch + HoleWindage;

	PlateThick = 1/16 * inch;

	WallThick = 2.0;

	Kerf = ThreadThick;

	Screw = [3.0,6.8,4.0]; // M3 OD=washer, length=nut + washers
	Insert = [3.0,5.4,8.0 + 1.0]; // splined brass insert

	RoundRadius = IntegerMultiple(Screw[OD]/2,0.5); // corner rounding

	ScrewOC = [IntegerMultiple(StrutOD + 2*WallThick + Screw[ID],1.0),
	IntegerMultiple(LightOD + 2*WallThick + Screw[ID],1.0)];

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

	BlockSize = [ScrewOC.x + Insert[OD] + 2*WallThick,
	ScrewOC.y + Insert[OD] + 2*WallThick,
	LightOD + StrutOD + 3*WallThick];

	echo(str("Block: ",BlockSize));

	BaseOffset = -(WallThick + LightOD/2); // block bottom to centerline
	StrutOffset = LightOD/2 + WallThick + StrutOD/2; // light centerline to strut centerline

	echo(str("Strut screw min: ",IntegerMultiple(PlateThick + WallThick + StrutOD/2 + Insert[LENGTH]/2,1.0)));
	echo(str("Light screw min: ",IntegerMultiple(PlateThick + WallThick + LightOD/2 + Insert[LENGTH]/2,1.0)));

	NumSides = 234;

	//———————-
	// 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);
	}

	// Block with light along X axis

	module Block() {

	difference() {
	hull()
	for (i=[-1,1], j=[-1,1])
	translate([i(BlockSize.x/2 – RoundRadius),j(BlockSize.y/2 – RoundRadius),BaseOffset])
	cylinder(r=RoundRadius,h=BlockSize.z,$fn=NumSides);

	for (i=[-1,1], j=[-1,1])
	translate([iScrewOC.x/2,jScrewOC.y/2,BaseOffset – Protrusion])
	rotate(180/8)
	PolyCyl(Screw[ID],BlockSize.z + 2*Protrusion,8);

	for (i=[-1,1], j=[-1,1])
	translate([iScrewOC.x/2,jScrewOC.y/2,0]) {
	translate([0,0,-Protrusion])
	rotate(180/8)
	PolyCyl(Insert[OD],Insert[LENGTH] + 1*Protrusion,8);
	translate([0,0,(StrutOffset – Insert[LENGTH] – Kerf/2 + Protrusion)])
	rotate(180/8)
	PolyCyl(Insert[OD],Insert[LENGTH] + 1*Protrusion,8);
	}

	translate([-BlockSize.x,0,0])
	rotate([0,90,0])
	cylinder(d=LightOD,h=2*BlockSize.x,$fn=NumSides);

	translate([0,BlockSize.y,StrutOffset])
	rotate([90,0,0])
	cylinder(d=StrutOD,h=2*BlockSize.y,$fn=NumSides);

	translate([0,0,StrutOffset])
	cube([2BlockSize.x,2BlockSize.y,Kerf],center=true);

	cube([2BlockSize.x,2BlockSize.y,Kerf],center=true);

	}

	}


	//- Build it

	if (Layout == "Block")
	if (Section)
	difference() {
	Block();
	rotate(atan(ScrewOC.y/ScrewOC.x))
	translate([0,BlockSize.y,0])
	cube(2*BlockSize,center=true);
	}
	else
	Block();

	if (Layout == "Show") {
	Block();

	color("Green",0.25)
	translate([-BlockSize.x,0,0])
	rotate([0,90,0])
	cylinder(d=LightOD,h=2*BlockSize.x,$fn=NumSides);

	color("Green",0.25)
	translate([0,BlockSize.y,StrutOffset])
	rotate([90,0,0])
	cylinder(d=StrutOD,h=2*BlockSize.y,$fn=NumSides);
	}

	if (Layout == "Build") {
	translate([-1.2*BlockSize.x,0,-BaseOffset])
	difference() {
	Block();
	translate([0,0,BlockSize.z])
	cube(2*BlockSize,center=true);
	}

	translate([1.2*BlockSize.x,0,StrutOD/2 + WallThick])
	difference() {
	rotate([180,0,0])
	translate([0,0,-StrutOffset])
	Block();
	translate([0,0,BlockSize.z])
	cube(2*BlockSize,center=true);
	}

	translate([0,0,StrutOffset – Kerf/2])
	rotate([180,0,0])
	intersection() {
	Block();
	translate([0,0,StrutOffset/2])
	cube([2BlockSize.x,2BlockSize.y,StrutOffset],center=true);
	}
	}

view raw Rear Running Light Seat Clamp.scad hosted with ❤ by GitHub

The New Hotness

Rear Running Light: Tour Easy Seat Clamp