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.
Things around the home & hearth
Despite having sworn a mighty oath to the contrary, I found myself doing this again:
A strut on the other end of the dowel split across its face:
The white stuff is wood-filled epoxy, normally used to repair rotted wood, left over from another project. I’ll claim this tests its mechanical strength against peeling forces.
Easily determined by inspection: a sensible person would toss the rack, but …
The mailing tube arrived with contents intact, although the USPS inlet scanning didn’t work and the tube pretty much teleported across several states without leaving any tracking data behind. The recipient suggested several modifications to the caps:
Review of user experience of tube end:
The ribs on the endcap are very good at holding the cap on, so much so that I had to use a prying implement to remove it, which cracked the flange.
Would consider less depth on the cap, and possibly another layer on the flange.
Some continuous process improvement (a.k.a OpenSCAD hackage) produced a swoopy threaded cap with thumb-and-finger grips:
The finger grips are what’s left after stepping a sphere out of the cap while rotating it around the middle:
That worked out surprisingly well, with the deep end providing enough of a vertical-ish surface to push against.
The two hex holes fit a pin wrench, because the grips twist only one way: outward. The wrench eliminates the need for a flange, as you can now adjust the cap insertion before slathering packing tape over the ends. Man, I loves me some good late binding action!
A three-start thread seemed like overkill, but was quick & easy. The “thread form” consists of square rods sunk into the cap perimeter, with one edge sticking out:
They’re 1.05 times longer than the cap perimeter facets to make their ends overlap, although they’re not tapered like the ones in the broom handle dingus, because it didn’t (seem to) make any difference to the model’s manifoldhood.
Not needing any endcaps right now, I built one for show-n-tell:
The OpenSCAD source code as a GitHub Gist:
| // Mailing tube end cap | |
| // Ed Nisley KE4ZNU – June 2017 | |
| Layout = "Build"; | |
| Model = "Screw"; | |
| //- Extrusion parameters – must match reality! | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| Protrusion = 0.1; | |
| HoleWindage = 0.2; | |
| //- Screw sizes | |
| inch = 25.4; | |
| TubeID = 2 * inch; | |
| TubeWall = 0.1 * inch; | |
| CapInsert = 15.0; | |
| CapRim = 6*ThreadThick; | |
| CapWall = 3*ThreadWidth; | |
| NumFlanges = 3; | |
| FlangeHeight = 3*ThreadThick; | |
| FlangeWidth = ThreadWidth/2; | |
| FlangeSpace = CapInsert / (NumFlanges + 1); | |
| ThumbHoleOD = 20.0; | |
| ThumbHoleAngle = 100; | |
| ThumbHoleSteps = 10; | |
| SpannerPinOD = 5.0; | |
| HelixOD = 4*ThreadThick; | |
| HelixHeight = 0.75*CapInsert; | |
| HelixAngle = atan(HelixHeight/(PI*TubeID)); | |
| HelixStarts = 3; | |
| OAHeight = CapInsert + CapRim; | |
| NumRibs = 3*4; | |
| NumSides = 3*NumRibs; | |
| //- 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,$fn=Sides); | |
| } | |
| module ScrewCap() { | |
| union() { | |
| difference() { | |
| cylinder(d=TubeID,h=OAHeight,$fn=NumSides); | |
| for (a=[0,180]) | |
| for (i=[0:ThumbHoleSteps-1]) | |
| rotate(a + i*ThumbHoleAngle/ThumbHoleSteps) | |
| translate([TubeID/4,0,-i*ThumbHoleOD/(2*ThumbHoleSteps)]) | |
| sphere(d=ThumbHoleOD); | |
| for (a=[0,180]) | |
| rotate(a – 60) | |
| translate([0.75*TubeID/2,0,-Protrusion]) | |
| rotate(0*180/6) | |
| PolyCyl(SpannerPinOD,0.75*CapInsert,6); | |
| } | |
| for (s=[0:HelixStarts-1]) | |
| for (i=[0:NumSides-1]) | |
| rotate(i*360/NumSides + 180/NumSides + s*360/HelixStarts) | |
| translate([TubeID/2 – 0.25*HelixOD,0,i*HelixHeight/NumSides + HelixOD]) | |
| rotate([90 + HelixAngle,0,0]) | |
| cylinder(d=HelixOD,h=1.05*PI*TubeID/NumSides,center=true,$fn=4); | |
| } | |
| } | |
| module PushCap() { | |
| difference() { | |
| cylinder(d=TubeID,h=OAHeight,$fn=NumSides); | |
| translate([0,0,CapWall]) | |
| cylinder(d=TubeID – 2*CapWall,h=OAHeight,$fn=NumSides); | |
| } | |
| for (i=[1:NumFlanges]) | |
| translate([0,0,i*FlangeSpace]) | |
| difference() { | |
| cylinder(d=TubeID + 2*FlangeWidth,h=FlangeHeight,$fn=NumSides); | |
| translate([0,0,-Protrusion]) | |
| cylinder(d=TubeID – 2*CapWall,h=FlangeHeight + 2*Protrusion,$fn=NumSides); | |
| } | |
| for (i=[0:NumRibs-1]) | |
| rotate(i*360/NumRibs) | |
| translate([0,-ThreadWidth,CapWall + ThreadThick]) | |
| cube([TubeID/2 – CapWall/2,2*ThreadWidth,CapInsert + CapRim – CapWall – ThreadThick],center=false); | |
| translate([0,0,CapInsert]) { | |
| difference() { | |
| cylinder(d=TubeID + 2*TubeWall,h=CapRim,$fn=NumSides); | |
| translate([0,0,-Protrusion]) | |
| cylinder(d=TubeID – 3*2*CapWall,h=2*CapRim,$fn=NumSides); | |
| } | |
| } | |
| } | |
| //- Build things | |
| if (Model == "Push") | |
| if (Layout == "Show") | |
| PushCap(); | |
| else if (Layout == "Build") | |
| translate([0,0,OAHeight]) | |
| rotate([180,0,0]) | |
| PushCap(); | |
| if (Model == "Screw") | |
| if (Layout == "Show") | |
| ScrewCap(); | |
| else if (Layout == "Build") | |
| translate([0,0,OAHeight]) | |
| rotate([180,0,0]) | |
| ScrewCap(); |
One of the leather strap anchors on Mary’s giant haul-everything-to-a-concert(*) handbag pulled its rivet through the canvas fabric:
We knotted the strap around the zippered opening and completed the mission.
Of course, it wouldn’t have pulled through if they’d splurged on washers, but noooo too expensive:
Some rummaging produced a pan-head M3 screw of suitable length:
A slightly battered acorn nut was a special treat for the inside, with another washer to keep me happy:
That was easy!
(*) At Tanglewood, where they don’t strip-search you on the way in, tow-behind coolers seemed de rigueur, and a good time was had by all.
Spotted this impressive array at an apartment building:
That’s just for one wing; the other end of the building has a similar installation. Each apartment has an electric stove and gas heat / AC.
The plumbing!
Last summer I followed the procedure that should turn off (one of) the ersatz “Yellow Pages” directories littering our driveway.
This just arrived:
Seeing as how they have the wrong town in my address, there’s still another excuse available.
My guess: they’re paid by tonnage of books delivered and have a powerful incentive to continue delivering all of them, no matter what gets in the way.
You absolutely cannot make this stuff up.
The ample padding around this bag of fragile pecans leaves nothing to be desired:
They’re firmly held in place on all sides, well protected from injury, and survived their shipping ordeal unscathed: not a bruise or break to be found. Well done!
That’s not always the case. A padded envelope recently arrived with an obvious wound:
Which came from its completely unprotected contents:
Fortunately, the fragile glass front plate of that OLED managed to put itself flat against a small box inside the otherwise empty bag. it wasn’t broken, but due only to good fortune.
“Static sensitive parts enclosed”, indeed …
Faced with a need to send documents rolled up in a tube, rather than folded flat, I sawed off a suitable length of cardboard tube from the heap, then discovered a distinct lack of end caps.
Well, once again, it’s 3D printing to the rescue:
The small ribs probably don’t actually do anything, but seemed like a nice touch.
They’re somewhat less boring from the bottom:
The fancy spider supports that big flat top and provides some crush resistance. The flat flange should collect the edge of the packing tape wrapped around the ends.
A firm shove installs them, so the size worked out perfectly:
Add a wrap of tape to each end, affix the USPS label, and they went out with the next day’s mail, PETG hair and all.
The OpenSCAD source code as a GitHub Gist:
| // Mailing tube end cap | |
| // Ed Nisley KE4ZNU – June 2017 | |
| Layout = "Build"; | |
| //- Extrusion parameters – must match reality! | |
| ThreadThick = 0.25; | |
| ThreadWidth = 0.40; | |
| function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit); | |
| Protrusion = 0.1; | |
| HoleWindage = 0.2; | |
| //- Screw sizes | |
| inch = 25.4; | |
| TubeID = 2 * inch; | |
| TubeWall = 0.1 * inch; | |
| CapInsert = 15.0; | |
| CapRim = 1.0; | |
| CapWall = 3*ThreadWidth; | |
| NumFlanges = 3; | |
| FlangeHeight = 3*ThreadThick; | |
| FlangeWidth = ThreadWidth/2; | |
| FlangeSpace = CapInsert / (NumFlanges + 1); | |
| OAHeight = CapInsert + CapRim; | |
| NumRibs = 3*4; | |
| NumSides = 3*NumRibs; | |
| //- 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); | |
| } | |
| module TubeCap() { | |
| difference() { | |
| cylinder(d=TubeID,h=OAHeight,$fn=NumSides); | |
| translate([0,0,CapWall]) | |
| cylinder(d=TubeID – 2*CapWall,h=OAHeight,$fn=NumSides); | |
| } | |
| for (i=[1:NumFlanges]) | |
| translate([0,0,i*FlangeSpace]) | |
| difference() { | |
| cylinder(d=TubeID + 2*FlangeWidth,h=FlangeHeight,$fn=NumSides); | |
| translate([0,0,-Protrusion]) | |
| cylinder(d=TubeID – 2*CapWall,h=FlangeHeight + 2*Protrusion,$fn=NumSides); | |
| } | |
| for (i=[0:NumRibs-1]) | |
| rotate(i*360/NumRibs) | |
| translate([0,-ThreadWidth,CapWall + ThreadThick]) | |
| cube([TubeID/2 – CapWall/2,2*ThreadWidth,CapInsert + CapRim – CapWall – ThreadThick],center=false); | |
| translate([0,0,CapInsert]) { | |
| difference() { | |
| cylinder(d=TubeID + 2*TubeWall,h=CapRim,$fn=NumSides); | |
| translate([0,0,-Protrusion]) | |
| cylinder(d=TubeID – 3*2*CapWall,h=2*CapRim,$fn=NumSides); | |
| } | |
| } | |
| } | |
| //- Build things | |
| if (Layout == "Show") | |
| TubeCap(); | |
| if (Layout == "Build") | |
| translate([0,0,OAHeight]) | |
| rotate([180,0,0]) | |
| TubeCap(); |
The Smell of Molten Projects in the Morning 