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.
Mechanical widgetry
Unsurprisingly, the mini-lathe lacks enough stiffness to apply enough force to hold a disk in place while turning its rim:
The old South Bend lathe had mojo, but those days are gone.
So drill and tap that fixture for an M3 screw, then stick some coarse sandpaper to it:
Snug the screw (a Torx T9 from the Small Drawer o’ Random M3 Screws) down on a rough-cut disk:
Sissy cuts remain the order of the day, but the screw applies plenty of clamping force and doesn’t require the hulking live center.
Finishing the PVC tubes reinforcing the vacuum cleaner adapters required fixtures on each end:
Because the tubes get epoxied into the adapters, there’s no particular need for a smooth surface finish and, in fact, some surface roughness makes for a good epoxy bond. The interior of a 3D printed adapter is nothing if not rough; the epoxy in between will be perfectly happy.
Turning the tubes started by just grabbing the conduit in the chuck and peeling the end that stuck out down to the finished diameter, because the conduit was thick-walled enough to let that work.
The remaining wall was so thin that the chuck would crunch it into a three-lobed shape, so the white ring in the chuck is a scrap of PVC pipe turned to fit the tube ID and provide enough reinforcement to keep the tube round.
The conduit ID isn’t a controlled dimension and was, in point of fact, not particularly round. It was, however, smooth, which counts for more than anything inside a tube carrying airborne fuzzy debris; polishing the interior of a lathe-bored pipe simply wasn’t going to happen.
The fixture on the other end started as a scrap of polycarbonate bandsawed into a disk with a hole center-drilled in the middle:
Stick it onto a disk turning fixture and sissy-cut the OD down a little smaller than the eventual tube OD:
Turn the end down to fit the tube ID, flip it around to center-drill the other side, stick it into the tube, and finally finish the job:
The nice layering effect along the tube probably comes from molding the conduit from recycled PVC with no particular concern for color matching.
A family portrait of the fixtures with a finished adapter:
A fine chunk of Quality Shop Time: solid modeling, 3D printing, mini-lathe turning, and even some coordinate drilling on the Sherline.
Being the domain expert for adapters between a new vacuum cleaner and old tools, this made sense (even though it’s not our vacuum):
The notch snaps into a Dirt Devil Power Stick vacuum cleaner and the tapered end fits a variety of old tools for other vacuum cleaners:
Having some experience breaking thin-walled adapters, these have reinforcement from a PVC tube:
A smear of epoxy around the interior holds the tube in place:
Building the critical dimensions with a 3D printed part simplified the project, because I could (and did!) tweak the OpenSCAD code to match the tapers to the tools. Turning four of those tubes from a chunk of PVC conduit, however, makes a story for another day.
The OpenSCAD source code as a GitHub Gist:
| // Dirt Devil nozzle adapter | |
| // Ed Nisley KE4ZNU 2021-10 | |
| // Tool taper shift | |
| Finesse = -0.1; // [-0.5:0.1:0.5] | |
| // PVC pipe liner | |
| PipeOD = 28.5; | |
| /* [Hidden] */ | |
| //- Extrusion parameters | |
| 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 | |
| TAPER_MIN = 0; | |
| TAPER_MAX = 1; | |
| TAPER_LENGTH = 2; | |
| Socket = [36.0,37.0,40.0]; | |
| LockringDia = 33.5; | |
| LockringWidth = 4.5; | |
| LockringOffset = 2.5; | |
| Tool = [Finesse,Finesse,0] + [30.0,31.1,30.0]; | |
| AdapterOAL = Socket[TAPER_LENGTH] + Tool[TAPER_LENGTH]; | |
| NumSides = 36; | |
| $fn = NumSides; | |
| //———————- | |
| // Useful routines | |
| module PolyCyl(Dia,Height,ForceSides=0) { // based on nophead's polyholes | |
| Sides = (ForceSides != 0) ? ForceSides : (ceil(Dia) + 2); | |
| FixDia = Dia / cos(180/Sides); | |
| cylinder(r=(FixDia + HoleWindage)/2,h=Height,$fn=Sides); | |
| } | |
| //——————- | |
| // Define it! | |
| module Adapter() { | |
| difference() { | |
| union() { | |
| difference() { | |
| cylinder(d1=Socket[TAPER_MIN],d2=Socket[TAPER_MAX],h=Socket[TAPER_LENGTH]); | |
| translate([0,0,LockringOffset]) | |
| cylinder(d=2*Socket[TAPER_MAX],h=LockringWidth); | |
| } | |
| cylinder(d=LockringDia,h=Socket[TAPER_LENGTH]); | |
| translate([0,0,LockringOffset + 0.75*LockringWidth]) | |
| cylinder(d1=LockringDia,d2=Socket[TAPER_MIN],h=0.25*LockringWidth); | |
| translate([0,0,Socket[TAPER_LENGTH]]) | |
| cylinder(d1=Tool[TAPER_MAX],d2=Tool[TAPER_MIN],h=Tool[TAPER_LENGTH]); | |
| } | |
| translate([0,0,-Protrusion]) | |
| PolyCyl(PipeOD,AdapterOAL + 2*Protrusion,NumSides); | |
| } | |
| } | |
| //———————- | |
| // Build it! | |
| Adapter(); | |
The taper in the code almost certainly won’t fit whatever tool you have: measure thrice, print twice, and maybe fit once …
The Bondhus Lifetime Guarantee works, as a replacement wrench just arrived:
A close look at the aligned tips suggests the defective wrench blank was mis-chucked in the machine cutting the ball end:
All’s well that ends well: thank you, Bondhus!
There being nothing like a good new problem to take one’s mind off all one’s old problems:
It’s basically the same as the lower blade guide, except coming from a stick of 5/8 inch acetal. A scant 6 mm stem goes into the vertical square rod, with a flat matching the setscrew coming up from the bottom to hold it in proper alignment.
I came within a heartbeat of cutting the slot parallel to the flat.
It worked OK while cutting a chunk of stout aluminum tube: so far, so good!
The impressive chunk of hardware is the OEM blade guide, with the brass tube for coolant flow all over the bearings. It’s mostly intended for use with the diamond blade, so I’ll swap it back in when I finally get around to cutting some slate for base plates.
The rear running light definitely has an industrial look:
The front of the light has plenty of clearance from the seat mesh:
Out on the road, the 1 W LED appears about as bright as automotive running lights:
The blink pattern makes it perfectly visible in sunlight, although I’d prefer somewhat larger optics:
In shaded conditions, it’s downright conspicuous:
At any reasonable distance, the 10° beam covers much of the road behind the bike:
You may not know what the occulting red light represents, but something ahead is worthy of your attention.
The Arduino source code producing the two dits:
// Tour Easy Running Light
// Ed Nisley - KE4ZNU
// September 2021
#include <morse.h>
#define PIN_OUTPUT 13
// second param: true = active low output
LEDMorseSender Morser(PIN_OUTPUT,true,(float)10.0);
void setup()
{
Morser.setup();
Morser.setMessage(String("qst de ke4znu "));
Morser.sendBlocking();
// Morser.setWPM((float)3.0);
Morser.setSpeed(75);
Morser.setMessage(String("i "));
}
void loop()
{
if (!Morser.continueSending())
Morser.startSending();
}
Looks good to me, anyhow.
Building the circuit support plate for the amber front running light was entirely too fiddly:
This was definitely easier:
Two pins fit in the small holes to align it with the LED heatsink, with an M3 stud and brass insert holding it in place:
The rectangular hole around the insert let me glop urethane adhesive over it to lock it into the plate, with more goop on the screw and pins to unify heatsink and plate.
The LED wires now emerge from the heatsink on the same side of the plate, simplifying the connections to the MP1584 regulator and current-sense resistor:
The paralleled 5.1 Ω and 3.3 Ω resistors form a 2.0 Ω resistor setting the LED current to 400 mA = 1 W at 2.6 V forward drop. They’re 1 W resistors dissipating a total of 320 mW and get barely warm.
The resistors and wires are stuck in place with clear adhesive, so things shouldn’t rattle around too much.
The OpenSCAD source code as a GitHub Gist:
| // Circuit plate for Tour Easy running lights | |
| // Ed Nisley – KE4ZNU – 2021-09 | |
| /* [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 | |
| LightID = 23.0; | |
| WallThick = 2.0; | |
| Screw = [3.0,6.8,4.0]; // M3 OD=washer, length=nut + washers | |
| Insert = [3.0,4.2,8.0]; // splined brass insert, minus splines | |
| InsertOffset = 10.0; // insert from heatsink end | |
| PinOD = 1.6; // alignment pins | |
| PinOC = 14.0; | |
| PinDepth = 5.0; | |
| Plate = [50.0,LightID,Insert[OD] + 4*ThreadThick]; // overall plate size | |
| WirePort = [10.0,3.0,2*Plate.z]; | |
| NumSides = 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, | |
| $fn=Sides); | |
| } | |
| // Circuit plate | |
| module Plate() { | |
| difference() { | |
| intersection() { | |
| cube(Plate,center=true); | |
| rotate([0,90,0]) | |
| cylinder(d=LightID,h=2*Plate.x,$fn=NumSides,center=true); | |
| } | |
| rotate([0,90,0]) rotate(180/6) | |
| translate([0,0,-Plate.x]) | |
| PolyCyl(Screw[ID],2*Plate.x,6); | |
| rotate([0,90,0]) rotate(180/6) | |
| translate([0,0,-Plate.x/2 – Protrusion]) | |
| PolyCyl(Insert[OD],Insert[LENGTH] + InsertOffset + Protrusion,6); | |
| translate([-Plate.x/2 + InsertOffset + Insert[LENGTH]/2,0,Plate.z/2]) | |
| cube([Insert[LENGTH],Insert[OD],Plate.z],center=true); | |
| for (j=[-1,1]) | |
| translate([-Plate.x/2,j*PinOC/2,0]) | |
| rotate([0,90,0]) rotate(180/6) | |
| translate([0,0,-PinDepth]) | |
| PolyCyl(PinOD,2*PinDepth,6); | |
| for (j=[-1,1]) | |
| translate([0,j*(Plate.y/2 – WirePort.y/2),0]) | |
| cube(WirePort,center=true); | |
| } | |
| } | |
| //- Build it | |
| Plate(); | |
The Smell of Molten Projects in the Morning 