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
The dark spot in the grass, barely visible over on the left, is a dinner-plate-size snapping turtle recently teleported from the middle of Rt 376 just north of Robinson Lane:
The driver of the white van managed to stop both lanes during the rescue and, judging from the lack of gore, handled the snapper without incurring organic damage.
Color me impressed!
In addition to sawing through the side of the cable ferrule, the front derailleur cable began breaking at the edge of the derailleur arm:
It wouldn’t have survived another ride!
Dan pointed out CNC machined aluminum cable clamps are a thing, but those are sized for larger frame tubes than the 1.0 inch steel used on our Tour Easy ‘bents and, although I’ve shimmed everything else on the frame, I wanted to tweak the cable angle to match the arm on the derailleur.
A bit of OpenSCAD wrangling produces a likely candidate:
That’s a bulked-up revision of the prototype:
Done up in orange PETG, it demonstrated the idea worked, but two perimeter threads wrapped around 15% infill isn’t quite up to the task. Note the split along the screw on the far half and various irregularities around the ferrule.
The cable angle isn’t quite right, either, as the proper compound angle would, alas, aim the cable into the pedal crank. The bulky bushings get in the way of putting the ferrule where it should be with the screws aligned in a tidy manner, so I must get used to the jaunty angle.
The bulkier version, done with 50% infill and four perimeter threads, has the same tilt angle, but the ferrule sits further from the screws:
The view from the left side shows the cable angles slightly to the rear, but the smaller angle should make it happier:
Probably should have used black PETG. Next time, for sure!
The OpenSCAD source code as a GitHub Gist:
| // Tour Easy Derailleur Cable Clamp | |
| // Ed Nisley KE4ZNU – June 2017 | |
| /* [Build Options] */ | |
| Layout = "Build"; // [Build, Show] | |
| /* [Extrusion] */ | |
| ThreadThick = 0.25; // [0.20, 0.25] | |
| ThreadWidth = 0.40; // [0.40] | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| /* [Hidden] */ | |
| Protrusion = 0.01; // [0.01, 0.1] | |
| HoleWindage = 0.2; | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| /* [Cable Clamp] */ | |
| FrameOD = 25.7; // Tour Easy has hard inch tubing + paint | |
| Ferrule = [1.5,5.1,12.0]; // cable ferrule | |
| EntryPoint = [0,13,60]; // cable entry to derailleur, +Y to rear of bike | |
| CableTilt = -20; // tilt from parallel to frame tube | |
| CableTheta = 0; // rotation around clamp from +X axis | |
| /* [Screws and Inserts] */ | |
| ClampScrew = [3.0,5.5,35.0]; // M3 button / socket head cap screw | |
| ClampWasher = [3.7,7.0,0.7]; // M3 washer | |
| ClampNut = [3.0,6.0,4.0]; // M3 nylock nut | |
| /* | |
| ClampScrew = [4.0,7.0,25.0]; // M4 button head cap screw | |
| ClampWasher = [4.5,9.0,0.8]; // M4 washer | |
| ClampNut = [4.0,8.0,5.0]; // M4 nylock nut | |
| */ | |
| NutShift = -0; // slide bushing toward nut for clearance | |
| //- Set clamp ring dimensions | |
| WallThick = 10.0; | |
| BushingSides = 8; | |
| Bushing = [ClampScrew[ID], | |
| // ClampWasher[OD]/cos(180/8) + 4*ThreadWidth, | |
| Ferrule[LENGTH]/cos(180/BushingSides), | |
| ClampScrew[LENGTH] – 2*ClampWasher[LENGTH] – ClampNut[LENGTH]]; | |
| Ring = [FrameOD + HoleWindage,FrameOD + 2*WallThick,Ferrule[LENGTH]]; | |
| ClampScrewOC = IntegerMultiple(FrameOD + ClampWasher[OD],1); | |
| echo(str(" screw OC: ",ClampScrewOC)); | |
| ClampKerf = 0.75; // kerf between separated halves | |
| NumSides = 8*4; | |
| //- Adjust hole diameter to make the size come out right | |
| 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,$fn=Sides); | |
| } | |
| // Construct things | |
| module ClampRing() { | |
| difference() { | |
| union() { | |
| cylinder(d=Ring[OD],h=Ring[LENGTH],$fn=NumSides); // basic ring | |
| for (j=[-1,1]) // screw bushings | |
| translate([Bushing[LENGTH]/2 + NutShift,j*ClampScrewOC/2,Ring[LENGTH]/2]) | |
| rotate([0,-90,0]) rotate(180/BushingSides) | |
| cylinder(d=Bushing[OD],h=Bushing[LENGTH],$fn=BushingSides); | |
| intersection() { | |
| rotate([CableTilt,0,CableTheta]) // reinforce cable ferrule | |
| translate([(Ring[ID] + Ring[OD])/4,0,Ferrule[LENGTH]/2]) | |
| rotate(180/8) | |
| cylinder(d=3*Ferrule[OD] + 0*ThreadWidth,2*Ferrule[LENGTH],center=true,$fn=8); | |
| cylinder(d=2*Ring[OD],h=Ring[LENGTH],$fn=NumSides); // basic ring | |
| } | |
| } | |
| translate([0,0,-Protrusion]) // frame tube | |
| cylinder(d=Ring[ID],h=Ring[LENGTH] + 2*Protrusion,$fn=NumSides); | |
| rotate([CableTilt,0,CableTheta]) // cable ferrule | |
| translate([(Ring[ID] + Ring[OD])/4,0,-0.25*Ferrule[LENGTH]]) { | |
| rotate(180/8) | |
| PolyCyl(Ferrule[OD],Ferrule[LENGTH],8); | |
| rotate(-22.5) | |
| PolyCyl(Ferrule[ID],2*Ferrule[LENGTH],4); | |
| } | |
| for (j=[-1,1]) // screw holes | |
| translate([Ring[OD]/2,j*ClampScrewOC/2,Ring[LENGTH]/2]) | |
| rotate([0,-90,0]) rotate(180/6) | |
| PolyCyl(Bushing[ID],Ring[OD],6); | |
| for (i=[-1,1], j=[-1,1]) // screw & nut seats | |
| translate([i*(Bushing[LENGTH]/2) + NutShift,j*ClampScrewOC/2,Ring[LENGTH]/2]) | |
| rotate([0,i*90,0]) rotate(180/BushingSides) | |
| cylinder(d=Bushing[OD],h=Bushing[LENGTH],$fn=BushingSides); | |
| translate([0,0,Ring[LENGTH]/2]) // slice it apart | |
| cube([ClampKerf,2*Ring[OD],2*Ring[LENGTH]],center=true); | |
| } | |
| } | |
| //- Build things | |
| if (Layout == "Show") { | |
| translate(EntryPoint) | |
| cube(1,center=true); | |
| ClampRing(); | |
| } | |
| if (Layout == "Build") { | |
| ClampRing(); | |
| } |
The weeds are once again taking over the shoulder along Rt 376 south of Red Oaks Mill:
New shoots from the Japanese Knotweed stand just north of Maloney Rd have begun punching through the asphalt along the edge of the shoulder.
This section is in the purview of NYS DOT’s Dutchess South Residency, extending south of Red Oaks Mill to the end of Rt 376 near Hopewell. In contrast, DOT’s Dutchess North Residency continues to keep Rt 376 well-trimmed northward from Red Oaks Mill to Poughkeepsie. I’ve never gotten any explanation why the two Residencies have such strikingly different weed-control standards.
Spotted while in the midst of replacing my Tour Easy’s rear grip shifter:
As you might expect, the cable saws through the side of its ferrule and the brazed-on frame fitting, because it’s been basically impossible (for me, anyhow) to find a replacement derailleur duplicating whatever the good folks at Easy Racers shipped back in 2001.
On the upside, this derailleur’s cable entry has a nicely rounded ramp eliminating the need for my brass cable pulley widget.
Memo to Self: Perhaps running the cable around a bearing anchored to the frame fitting would help?
I’ve obviously forgotten to fix this for several years, so putting it here may serve as a Round Tuit.
This little critter was chugging across the Dutchess Rail Trail near the ponds north of Page Industrial Park, so I stopped to lend a hand:
The plastron looked like a brightly colored jewel:
Perhaps plastrons start out with all the pigment they’ll ever have, then fade from bright orange to yellow-brown as they spread out.
If you’re not paying attention, you’d think “pebble” or “dog turd”. Neither of which you should ride over, of course, but … teleporting a tiny turtle to the drainage ditch on the far side seemed to increase the world’s net happiness.
The pix are tight crops from the AS30V’s 170° FOV images, which means they’re way grittier than you’d expect from a “full HD” image.
The gashes don’t look like much:
Not even from the side:
When they happened, I knew where to look, because the Kevlar-belted Primo Comet had two conspicuous bulges surrounding debris jammed between the tread and the carcass along the sidewall: the gashes were wide open!
Much to my astonishment, the tire hadn’t gone instantly flat.
Some screwdriver probing in the leftmost gash produced this nasty glass chip:
AFAICT, the smooth side slid over the internal Kevlar belt as the edge sliced between the rubber tread and the carcass. I think the top entered first, with the somewhat crushed end hitting the pavement on each revolution:
The other gash emitted a somewhat smaller chip.
I rode over something crunchy, most likely the remains of a beer bottle, in a shaded section along Rt 376, and we stopped a few driveways later to diagnose a once-per-revolution thump from the front tire. The tube still wasn’t losing pressure, even after extracting the glass, so I continued the mission; it was a fine day for a ride!
I later filled those gashes (plus a few others) with silicone rubber to keep grit out. It’s surely a feel-good gesture, but maybe it’ll help the tire reach the end of its tread life.
You can judge our “riding environment” by the tire’s condition …
As always, we knew this wouldn’t end well for the small lump just in front of the car’s rear wheel (clicky for more, albeit fuzzy, dots):
So I stopped to lend a hand:
A fumbling hand, as it turned out, on the turtle’s slippery shell:
A belly-up turtle in the middle of the road knows the solution to the Halting Problem.
I hoped a secluded spot under a pine tree was closer to its destination:
However, if the turtle is a female in search of an egg-laying site, then she and all her progeny must cross Vassar Road in the other direction to reach the Mighty Wappinger Creek.
We’ll teleport them if we see them, too …
The Smell of Molten Projects in the Morning 