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
These herringbone gears were part of updating my old Thing-O-Matic:
But, as the saying goes, that’s not a herringbone gear. This is a herringbone gear:
We always read the signage:
They’re parked in front of the National Museum of Industrial History in Bethlehem, PA.
Obviously, the good folks at Park Tool never anticipated a three-cross spoke pattern on a 20 inch wheel:
It’s my trusty Park Tool TM-1 Spoke Tension Meter, unchanged since shortly after the turn of the millennium.
For future reference, the rebuilt wheel spoke tensions came out around 25, slightly lower than the 27-ish I measured on Mary’s bike; it didn’t occur to me to measure the tension until after I’d relaxed the spokes. I’ll ride it for a while before doing any tweakage.
The spoke pattern is pretty close to four-cross, due to the large-flange Phil Wood hubs:
Which makes for a hella-strong wheel, particularly seeing as how it’s very lightly loaded. The Tour Easy we got for our lass came with a radially spoked rim around a Phil hub.
I transferred the hub and laced spokes intact to the new rim by the simple expedient of duct-taping the spokes into platters, removing the nipples, stacking the rims, sliding the spokes across into their new homes, reinstalling the nipples, then tightening as usual.
The front rim on my Tour Easy developed a distinct bulge, of the sort usually caused by ramming something, but I’m not Danny McAskell and the bulge got worse over the course of a few weeks, suggesting the rim was deforming under tire pressure. Having ridden it upwards of 35 k miles with plenty of trailer towing and too much crushed-stone trail riding, the brake tracks were badly worn and it’s time for a new rim.
An Amazon seller had an identical (!) rim, except for the minor difference of having a hole sized for a Schraeder valve stem, rather than the Presta valves on the original rims. One can buy adapters / grommets, but what’s the fun in that?
The brake track walls are 1.5 mm thick on the new rim and a scant 1.0 mm on the old rim, so, yeah, it’s worn.
A few measurements to get started (and for future reference):
If you don’t have an A drill, a 15/64 inch drill is only half a mil larger and, sheesh, anything close will be fine.
Introduce a suitable brass rod to Mr Lathe:
Break all the edges and drop it in place:
One could argue for swaging the adapter to fit flush against the curved rim, but commercial adapters don’t bother with such refinements and neither shall I.
The 7.0 mm length got shortened to fit flush with the center of the rim:
It’s brass, because the rim is heaviest on the far side where the steel pins splicing the ends live, and, with the tube & tire installed, the rim came out almost perfectly balanced. Which makes essentially no difference whatsoever, of course.
The shiny new rim sports shiny new reflector tape (from the same stockpile, of course).
That was easy …
Ten months ago, I cleaned the corrosion off our favorite cheese slicer:
After cleaning, I coated it with XTC-3D epoxy:
We’ve been using it daily ever since and it spends most of its life drip-drying in the dish drainer. I added a third opening to the cheerful orange measuring spoon holder just for the slicer.
A few weeks ago I noticed corrosion once again growing on the handle:
I think the rot comes from water diffusing through the epoxy, rather than gross leaks through damage or pinholes. The tip of the handle has the most corrosion, probably due to the water drop hanging there, even though it also has the thickest epoxy coating: it cured with the handle pointing downward.
Verily, rust never sleeps …
The glaring white ring around the drain comes from Magic Porcelain Chip Fix epoxy:
What looks like a blob on the left side covers the missing chip, with the rest of the ring filled in to make it look like I knew what I was doing. The drain dried out while we were on vacation, having been scrubbed clean before we left, making for the best surface preparation I could provide.
As it turns out, our resident iron bacteria took about a week to set up shop along the bottom of the ring, producing a pair of small rust-colored dots that will inevitably spread to encompass the whole thing. They’re endemic in the plumbing, impossible to kill off, and nothing more than an unsightly nuisance.
The running lights on our Tour Easy fairing sit just about perfectly level, despite how they appear in relation to the fairing edge:
And, because they’re firmly attached to the fairing mount, there’s no way to tilt them to extract the 18650 cell.
This took entirely too long to figure out:
The LC40 end caps have a recess exactly where it’ll do the most good: capturing the tab inside the cap means it can’t interfere with the rear contact spring:
Swapping cells no longer requires muttering!
A soaker hose leaped under a descending garden fork and accumulated a nasty gash:
Mary deployed a spare and continued the mission, while I pondered how to fix such an odd shape.
For lack of anything smarter, I decided to put a form-fitting clamp around the hose, with silicone caulk buttered around the gash to (ideally) slow down any leakage:
As usual, some doodling got the solid model started:
A hose formed from chopped rubber doesn’t really have consistent dimensions, so I set up the model to spit out small test pieces:
Lots and lots of test pieces:
Each iteration produced a better fit, although the dimensions never really converged:
The overall model looks about like you’d expect:
The clamp must hold its shape around a hose carrying 100 psi (for real!) water, so I put 100 mil aluminum backing plates on either side. Were you doing this for real, you’d shape the plates with a CNC mill, but I just bandsawed them to about the right size and transfer-punched the hole positions:
Some drill press action with a slightly oversize drill compensated for any misalignment and Mr Disk Sander rounded the corners to match the plastic block:
A handful of stainless steel 8-32 screws holds the whole mess together:
These hoses spend their lives at rest under a layer of mulch, so I’m ignoring the entire problem of stress relief at those sharp block edges. We’ll see how this plays out in real life, probably next year.
I haven’t tested it under pressure, but it sure looks capable!
The OpenSCAD source code as a GitHub Gist:
| // Rubber Soaker Hose Splice | |
| // Ed Nisley KE4ZNU July 2018 | |
| Layout = "Build"; // Hose Block Show Build | |
| TestFit = false; // true to build test fit slice from center | |
| //- Extrusion parameters must match reality! | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| HoleWindage = 0.2; | |
| Protrusion = 0.1; // make holes end cleanly | |
| inch = 25.4; | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| //———- | |
| // Dimensions | |
| // Hose lies along X axis | |
| Hose = [200,27.0,12.0]; // X = longer than anything else | |
| Block = [80.0,50.0,4.0 + Hose.z]; // overall splice block size | |
| echo(str("Block: ",Block)); | |
| Kerf = 0.1; // cut through middle to apply compression | |
| ID = 0; | |
| OD = 1; | |
| LENGTH = 2; | |
| // 8-32 stainless screws | |
| Screw = [4.1,8.0,3.0]; // OD = head LENGTH = head thickness | |
| Washer = [4.4,9.5,1.0]; | |
| Nut = [4.1,9.7,6.0]; | |
| CornerRadius = Washer[OD]/2; | |
| NumScrews = 3; // screws along each side of cable | |
| ScrewOC = [(Block.x – 2*CornerRadius) / (NumScrews – 1), | |
| Block.y – 2*CornerRadius, | |
| 2*Block.z // ensure complete holes | |
| ]; | |
| echo(str("Screw OC: x=",ScrewOC.x," y=",ScrewOC.y)); | |
| //———————- | |
| // 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(d=(FixDia + HoleWindage),h=Height,$fn=Sides); | |
| } | |
| // Hose shape | |
| // This includes magic numbers measured from reality | |
| module HoseProfile() { | |
| RimThick = 10.0; // outer sections | |
| RimOD = RimThick; | |
| RimFlatRecess = -0.7; // recess to front flat surface | |
| OuterOC = Hose.y – RimOD; // outer tube centers | |
| RecessM = 1.5; // back recess chord | |
| RecessC = OuterOC; | |
| RecessR = (pow(RecessM,2) + pow(RecessC,2)/4) / (2*RecessM); | |
| RidgeM = 1.0; // front ridge chord | |
| RidgeC = 8.0; | |
| RidgeR = (pow(RidgeM,2) + pow(RidgeC,2)/4) / (2*RidgeM); | |
| NumSides = 12*4; | |
| rotate([0,-90,0]) | |
| translate([0,0,-Hose.x/2]) | |
| linear_extrude(height=Hose.x,convexity=4) | |
| difference() { | |
| union() { | |
| for (j=[-1,1]) // outer channels | |
| translate([0,j*OuterOC/2]) | |
| circle(d=RimOD,$fn=NumSides); | |
| translate([-RimOD/4,0]) // rear flat fill | |
| square([RimOD/2,OuterOC],center=true); | |
| translate([(RimOD/4 + RimFlatRecess),0]) // front flat fill | |
| square([RimOD/2,OuterOC],center=true); | |
| intersection() { | |
| translate([Hose.z/2,0]) | |
| square([Hose.z,OuterOC],center=true); | |
| translate([-RidgeR + RimOD/2 + RimFlatRecess + RidgeM,0]) | |
| circle(r=RidgeR,$fn=NumSides); | |
| } | |
| } | |
| translate([-(RecessR + RimOD/2 – RecessM),0]) | |
| circle(r=RecessR,$fn=2*NumSides); | |
| } | |
| } | |
| // Outside shape of splice Block | |
| // Z centered on hose rim circles, not overall thickness through center ridge | |
| module SpliceBlock() { | |
| difference() { | |
| hull() | |
| for (i=[-1,1], j=[-1,1]) // rounded block | |
| translate([i*(Block.x/2 – CornerRadius),j*(Block.y/2 – CornerRadius),-Block.z/2]) | |
| cylinder(r=CornerRadius,h=Block.z,$fn=4*8); | |
| for (i = [0:NumScrews – 1], j=[-1,1]) // screw holes | |
| translate([-(Block.x/2 – CornerRadius) + i*ScrewOC.x, | |
| j*ScrewOC.y/2, | |
| -(Block.z/2 + Protrusion)]) | |
| PolyCyl(Screw[ID],Block.z + 2*Protrusion,6); | |
| cube([2*Block.x,2*Block.y,Kerf],center=true); // slice through center | |
| } | |
| } | |
| // Splice block less hose | |
| module ShapedBlock() { | |
| difference() { | |
| SpliceBlock(); | |
| HoseProfile(); | |
| } | |
| } | |
| //———- | |
| // Build them | |
| if (Layout == "Hose") | |
| HoseProfile(); | |
| if (Layout == "Block") | |
| SpliceBlock(); | |
| if (Layout == "Bottom") | |
| BottomPlate(); | |
| if (Layout == "Top") | |
| TopPlate(); | |
| if (Layout == "Show") { | |
| difference() { | |
| SpliceBlock(); | |
| HoseProfile(); | |
| } | |
| color("Green",0.25) | |
| HoseProfile(); | |
| } | |
| if (Layout == "Build") { | |
| SliceOffset = TestFit && !NumScrews%2 ? ScrewOC.x/2 : 0; | |
| intersection() { | |
| translate([SliceOffset,0,Block.z/4]) | |
| if (TestFit) | |
| cube([ScrewOC.x/2,4*Block.y,Block.z/2],center=true); | |
| else | |
| cube([4*Block.x,4*Block.y,Block.z/2],center=true); | |
| union() { | |
| translate([0,0.6*Block.y,Block.z/2]) | |
| ShapedBlock(); | |
| translate([0,-0.6*Block.y,Block.z/2]) | |
| rotate([0,180,0]) | |
| ShapedBlock(); | |
| } | |
| } | |
| } |
The Smell of Molten Projects in the Morning 