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
The blade on one of the Jonas vegetable peelers cracked, which suggests it’s the counterfeit version:
I grooved the metal pin running through the handle:
A brass tube from the Little Tray o’ Cutoffs and some epoxy should hold things together forevermore:
The rainbow colors come from an instantly aborted attempt to silver-solder the parts together. The fact that I even tried a stunt like that shows I’m definitely not the brightest bulb in the chandelier these days.
Having recently emptied the OXO pepper grinder we (mistakenly?) bought as a salt mill, I took it apart for a deep rinsing and cleanup:
It turns out the somewhat corroded square shaft is aluminum, neither the cheap steel I expected nor the stainless steel it should be. Perhaps OXO cost-reduced the shaft, discovered aluminum is a poor choice in a saline environment, and changed the packaging to compensate?
Removing / installing the Jesus clip requires careful whacking with a hollow-tip punch against the shaft, with the whole affair laid flat on shop towels, the handle held down to prevent rotation, and the wrap-around body capturing the escaping clip.
Shaft corrosion as of Summer 2020:
Soaking the body in hot water got rid of salt crusts and filled the shell with water. There being no way to completely dry the thing, I parked it in the sun for a day, refilled it, and was unsurprised when the (dried) salt turned into an assortment of moist crystals.
We obviously need a real salt mill …
I’ll be talking about e-bikes and the solid modeling required to hang a Bafang motor and battery on your favorite bike for the Poughkeepsie Chapter of the ACM at 1930 EDT this evening:
It’s a Zoom meeting, so (in the unlikely event you have nothing better to do) you could actually “attend”. The ACM meeting description and the Meetup announcement will get you there.
A PDF of the presentation slides (remember slides?) includes copious linkies to sources / blog posts / distractions:
If you’re only in it for the geometry, the OpenSCAD source code lives slumbers in a pair of GitHub Gists:
Enjoy …
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!
The Smell of Molten Projects in the Morning 