Category: Machine Shop

Mechanical widgetry

Tour Easy Rear Running Light: LED Lens Assembly

Having discovered the need for careful alignment of the LED PCB with the lens, I paid more attention to detail this time around.

The LEDs arrive soldered to PCBs atop aluminum star heat spreaders, but the one I picked out of the bag looked slightly misaligned. Unsoldering it showed a smear of solder paste had melted across the central pad:

1 W LED PCB – errant solder

The LED has a die contact slug on the bottom which, I suppose, could be directly soldered to the spreader. For my simple needs, removing the errant solder, plunking the LED atop a layer of heatsink compound, and resoldering the leads should suffice:

1 W LED PCB – wire layout

The LED holder has a pair of slots aligning it with the LED leads on the PCB. The base of the holder sits flush against the PCB, so the wires must attach directly to the LED pads.

I ran the wires for the amber light through holes close to the pads:

1 W LED Running Light – heatsink fit

Which required chewing two passages in the base of the holder:

1 W LED Running Light – wiring

It turns out the 5° and 10° lenses are strongly conical and leave plenty of room around the LED to run a wire around the inside of the holder, so I drilled a pair of holes to put both wires on the same side of the circuit plate:

Tour Easy Rear Running Light – circuit plate attachment

The holder required minor surgery to let the wire double back on itself over the LED pad:

1 W LED Holder – wire passage

The wires thread through two holes drilled in the plastic holder:

Tour Easy Rear Running Light – clamped LED assembly

More urethane adhesive glues the PCB to the LED holder, with the clamp applying pressure to the lens to ensure the lens seats properly around the LED. It turned out that worked well and the light has a nicely rounded beam.

With the optics bonded together, metal-filled JB Weld epoxy attaches the heat spreader to the heatsink with good thermal conductivity:

Tour Easy Rear Running Light – clamped LED heatsink

The LED holder is a slide fit in the heatsink, so the clamps can keep the PCB flat on the bottom of the recess while the epoxy gets a good grip on all parts.

Now it’s just a matter of wiring everything up!

2021-09-23
Tour Easy Rear Running Light: LED Heatsink

Because the rear running light will have a higher duty cycle than the front light, I made the (admittedly too small) heatsink slightly longer, with a deeper recess to protect the lens from cargo on the rear rack:

Tour Easy Rear Running Light – boring LED recess

Boring that nice flat bottom is tedious; I must lay in a stock of aluminum tubing to simplify the process.

Drilling the holes went smoothly:

Tour Easy Rear Running Light – drilling LED heatsink

Those two holes fit a pair of pins aligning the circuit plate, with a screw and brass insert holding it to the heatsink. Scuffing a strip across the aluminum might give the urethane adhesive (you can see uncured globs on the pins) a better grip:

Tour Easy Rear Running Light – circuit plate attachment

The screw / insert /pins are glued into the plate to permanently bond it to the heatsink. The screw occupies only half of the insert, with the longer screw from the end cap pulling the whole affair together.

The two holes on the left pass both LED leads to one side of the circuit plate, where they connect to the current regulator and its sense resistor.

2021-09-22
Rear Running Light: Too-aggressive Turning

The same lathe fixture and double-sided duct tape trick I used for the amber running light’s end cap should have worked for this one, but only after I re-learned the lesson about taking sissy cuts:

Tour Easy Rear Running Light – end cap fixture – swirled adhesive

Yet another snippet of tape and sissy cuts produced a better result:

Tour Easy Rear Running Light – end cap

Protip: when you affix an aluminum disk bandsawed from a scrap of nonstick griddle to a lathe fixture, the adhesive will grip the disk in only one orientation.

2021-09-21

Rear Running Light: Tour Easy Seat Clamp

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

2021-09-20

Beverage Faucet Replacement

The lesser kitchen faucet began dribbling and required replacement, as there are no user serviceable parts within. One of the 3D printed adapters I built during the previous iteration had disintegrated:

Beverage faucet base plate adapter disintegration

The new faucet came with a somewhat different baseplate and I managed to conjure a firm, sealed mount from the various parts without further construction.

The nicely curved brass snout is the third in my collection. Surely they’ll come in handy for something!

While I was in a plumbing state of mind, I again replaced the spout O-rings in the never-sufficiently-to-be-damned American Standard Elite (hah!) faucet, as it was also dribbling.

This time, I used oxalic acid to remove the assorted scale and crud inside the spout. It seemed to be more effective than the usual white vinegar, although nothing seems to preserve the O-rings.

2021-09-18
Micro-Mark Bandsaw: Acetal Blade Guide

The Micro-Mark bandsaw has a metal blade guide below the table that contributes to the awful noise it makes while running, even when it’s not cutting anything. Having recently touched the Delrin = acetal rod stash, a simple project came to mind.

A doodle with the original metal guide dimensions:

Micro-Mark Bandsaw – metal blade guide dimensions

The 10 mm dimension is non-critical, so I started with a 1/2 inch acetal rod and turned the stub end to match.

A doodle suggested how to carve the slot with a 20.5 mil = 0.52 mm slitting saw, with the offset from a Z touchoff at the top:

Micro-Mark Bandsaw – acetal blade guide – slitting doodles

The V block setup required swapping out the overly long OEM screw for a shorter 5 mm SHCS to clear the Sherline’s motor:

Micro-Mark Bandsaw – acetal guide slitting

The end result looked pretty good:

Micro-Mark Bandsaw – acetal vs steel blade guides

And it looks like it pretty much belongs in the saw:

Micro-Mark Bandsaw – acetal blade guide installed

The 6 mm stud goes into a hole in the frame, where a setscrew holds it in place. You must remove the blade to extract / replace the guide, with the correct position having the end of the slot just touching the back of the blade.

The foam ring apparently keeps crud away from the stud on the backside; I doubt it’s mission-critical.

The saw became somewhat quieter; the ball bearing guides above the table now generate most of the racket. At some point I’ll try replacing them with a block, probably made from UHMW, with a simple slit to guide the blade.

Plastic guides may not last as long as the steel ones, but occasional replacements will be worth it if the saw runs quieter.

2021-09-16
Bondhus Wrench: Missing Ball

Around the beginning of the year, I updated my collection of somewhat worn hex wrenches with a set of metric and inch ball-end hex wrenches from Bondhus sold by and shipped fro m Amazon:

Bondhus hex wrenches – missing 7-64 ball

When I applied the 7/64 wrench to a setscrew, the missing ball came as a surprise.

Even though the inch wrench set doesn’t get a lot of use, it’s possible I broke the ball off during a previous adventure, but a look at the end shows the black oxide coating covering the end:

Bondhus hex wrenches – missing 7-64 ball – detail

Yeah, it was born that way.

I wonder if and how their lifetime guarantee works.

[Update: It does!]

Protip: as of this writing, the Amazon listing has two other “sizes” showing exactly the same set at significantly higher prices from two randomly named sellers:

Bondhus hex wrench set – Amazon listing

It is safe to assume Amazon no longer has its customers’ best interests in mind.

2021-09-15