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.

Category: Machine Shop

Mechanical widgetry

  • Engraved Popsicle Sticks

    Engraved Popsicle Sticks

    Having found a handful of popsicle sticks on my desk, I had to finish this up:

    Popsicle stick markers - engraving
    Popsicle stick markers – engraving

    The fixture has the same layout as the craft stick version, sized to fit the smaller sticks. They’re a bit thicker than the chipboard sheet, but match up well enough for the purpose.

    Even though the sticks don’t have much room for cutout letters, I had to try it anyway:

    Popsicle stick markers - finished
    Popsicle stick markers – finished

    Aligning the template to the fixture uses LightBurn’s Print-and-Cut tool, which seems easier than nailing the fixture to the laser platform.

    I suppose if they ever make actual popsicles with wood handles, they can tell who gets which one.

    For whatever it’s worth, the larger craft stick markers in the garden remain in good shape.

  • Miroco Floor Lamp Base Details

    Miroco Floor Lamp Base Details

    The pole of our much-repaired Miroco floor lamp screws into a weighted base:

    Miroco floor lamp base - assembled
    Miroco floor lamp base – assembled

    Because the lamp has a big nut apparently holding the pole socket to the base, I figured a dab of threadlock on the pole or the base would solve the problem: lock the pole to the socket, then remove the nut to disassemble when needed. That turned out to be a Bad Idea™.

    The socket is a plastic part separate from the base cover plate:

    Miroco floor lamp base - socket
    Miroco floor lamp base – socket

    A pair of keys prevent the socket from rotating in the hole:

    Miroco floor lamp base - socket in place
    Miroco floor lamp base – socket in place

    Four threaded bosses (two visible there) hold the rim of the cover to the weight, with the socket doing the hard work.

    A fender washer atop the weight distributes stress from the pole:

    Miroco floor lamp base - weight top washer
    Miroco floor lamp base – weight top washer

    Another fender washer on the bottom of the weight lets the nut jam against steel, rather than soft plastic:

    Miroco floor lamp base - weight bottom washer
    Miroco floor lamp base – weight bottom washer

    FWIW, the nut is either a perfect 15/16 inch or, more likely, a sloppy 24 mm.

    In any event, permanently locking the pole to that socket will also lock the pole to the base, with no way to dismantle the lamp when I must once again repair it.

    Perhaps a wrap of PTFE tape on the threads will stiffen it enough?

    Certain better looking than black duct tape …

  • MaxLite Candelabra CFL: FAIL

    MaxLite Candelabra CFL: FAIL

    The bathroom ceiling fixture has a nightlight position that we use occasionally, but eventually the little 7 W Christmas Tree bulb failed and I installed this hulk from a box of CFL bulbs a friend scrapped out after switching to LED bulbs:

    MaxLite CFL - overview
    MaxLite CFL – overview

    I never tested whether it actually drew 3 W, but, hey I could feel good. Right? Right?

    Anyhow, this one failed after a few years, too. The “bulb” envelope looked like it might make an attractive blinkie or glowie, so I decided to harvest it.

    The candelabra screw base felt loose and popped off with a push:

    MaxLite CFL - overflow cap
    MaxLite CFL – overflow cap

    Perhaps they chose the envelope before finalizing the circuitry?

    This is why you need a lathe in your shop:

    MaxLite CFL - lathe cutting
    MaxLite CFL – lathe cutting

    It wasn’t particularly well centered, so that was done dead slow and finished with a few hand turns of the chuck. Obviously, I need a crank for the spindle.

    The rest of the circuitry is pretty well packed under that tall cap:

    MaxLite CFL - circuitry
    MaxLite CFL – circuitry

    Pulling the PCB out revealed the tube wiring:

    MaxLite CFL - tube wires
    MaxLite CFL – tube wires

    Cut the wires and chuck it up again:

    MaxLite CFL - envelope turning setup
    MaxLite CFL – envelope turning setup

    Turn dead slow again until it breaks through:

    MaxLite CFL - envelope breakthrough
    MaxLite CFL – envelope breakthrough

    Then finish by hand:

    MaxLite CFL - tube and envelope
    MaxLite CFL – tube and envelope

    It’s too cute to throw out, but … sheesh you can see why recycling this stuff is so difficult.

    For whatever it’s worth, I replaced it with a 3 W LED candelabra bulb that is way too bright.

  • Knitting Stitch Counters: Material Tests

    Knitting Stitch Counters: Material Tests

    Our Young Engineer knits during rare moments of downtime and sketched an idea for stitch counters to mark progress between those moments. There being nothing like a new project to take one’s mind off all of one’s previous projects:

    Stitch Counters - overview
    Stitch Counters – overview

    These are more along the lines of feasibility / material tests than finished products, so you’ll see plenty of rough edges.

    Prior to doing this, we agreed that 3 mm material was probably too thick, particularly given the small scale: the hexagons are 10 mm edge-to-edge with a 1.5 mm hole for the jump ring.

    The jump rings are (mostly) 8 mm OD, which may or may not be the right diameter for all possible knitting needles.

    The count sequence goes 10 20 10 40 50 10 with alternating colors:

    Stitch Counters - red and blue
    Stitch Counters – red and blue

    Those came from 3 mm red and blue transparent acrylic, looking entirely too much like candy. Cutting two identical layouts from two different materials, then swapping a few counters, gives me two related-but-different sets. This idea is also subject to revision.

    I like the set of 3 mm acrylic mirror counters colored with Sharpie:

    Stitch Counters - mirror
    Stitch Counters – mirror

    Alas, the unprotected mirror backing won’t survive long in the real world and Sharpie ink tends to stress-crack the acrylic. Bonding a thin colored sheet / gel filter to the back with an adhesive sheet in between would work, although I don’t look forward to the fiddly alignment. Bonus: sticky edges are a nonstarter in this application.

    A setup error produced a set of unmarked counters that might still come in handy for something:

    PXL_20230507_150124595 - Stitch Counters - blue blank
    PXL_20230507_150124595 – Stitch Counters – blue blank

    Trolase acrylic 1/16 inch = 1.5 mm sheets produce the most visible legends, in a relentlessly industrial sort of way:

    Stitch Counters - Trolase
    Stitch Counters – Trolase

    Those have a single thin layer atop a white or black base sheet, but three-layer 1.5 mm Trolase sheets with matching top and bottom colors (cladding on a white core) would look better.

    If you can’t decide on a color, go clear:

    Stitch Counters - clear
    Stitch Counters – clear

    All of those appear on a background of some thin DIY plywood:

    Stitch Counters - veneer plywood sheets
    Stitch Counters – veneer plywood sheets

    The bottom sheet is very pale veneer that came with a layer of genuine 3M 468 transfer tape with 200MP adhesive. I stuck three different veneers on three 100×50 mm rectangles of the stuff to make 1.5 mm thick “plywood”. The adhesive sheet provides lateral strength, not the wood fibers, so it’s not quite as easy to tear as the broken fragment would suggest.

    The results look passable, although there’s room for improvement:

    Stitch Counters - veneer plywood
    Stitch Counters – veneer plywood

    After engraving & cutting, I slathered them with clear polyurethane finish and hung them up to dry:

    Stitch Counters - wood finish curing
    Stitch Counters – wood finish curing

    I like the effect, but using the pale veneer for the bottom layer made them look identical from that side. Worse, two of the three top layer veneers had nearly identical colors (one has more grain) after the finish cured.

    More thought seems in order, but at least I’ve explored some of the solution space.

  • Dirt Devil Stick Vacuum: Floor Brush Salvage

    Dirt Devil Stick Vacuum: Floor Brush Salvage

    The knuckle joint on the Dirt Devil stick vacuum failed, so it followed us home instead of leaping into the trash:

    Dirt Devil - broken swivel joint
    Dirt Devil – broken swivel joint

    Although the fitting seems to be made of ABS, it’s now missing major chunks of plastic in the high-stress areas, so rebuilding it seems not worth the effort.

    Because we don’t have any carpets and this one will never leave the basement, I extracted the carpet beater brush and its motor, only to find Yet Another Example of poor assembly practices:

    Dirt Devil - stray strands
    Dirt Devil – stray strands

    It’s a 12 V (-ish, I didn’t measure whatever comes out of the vacuum head) DC motor and those errant strands aren’t quite long enough to meet in the middle. The yellow rectangle is a thermal fuse that would be shorted out if the strands were a bit longer.

    The broken joint lets the head swivel from side to side, but the elevation joint is still good. If I don’t expect too much, the thing might still suffice for extracting dust from under the benches:

    Dirt Devil - taped joint
    Dirt Devil – taped joint

    Worst case, I can swap in a classic floor brush using one of the adapters I made a while ago:

    Dirt Devil adapters - assembled
    Dirt Devil adapters – assembled

    That was easy, if only because I skipped the hard part …

  • Bafang vs. Tour Easy: Chain Guide

    Bafang vs. Tour Easy: Chain Guide

    After adding the Bafang motor to my Tour Easy, the chain has fallen off the chainring a few times, prompting the gap filler between the motor and the chainring spider. That this has never happened to Mary’s essentially identical Tour Easy suggests I have a different shift technique, but adding a chain catcher seemed easier than re-learning shifting:

    Chain Catcher - top view
    Chain Catcher – top view

    It’s more properly called a “chain guide” and is basically a shifter cage minus the mechanism:

    Chain Catcher - side view
    Chain Catcher – side view

    Because the Tour Easy frame has a 25 mm tube where the guide’s clamp expects a minimum 31.8 mm tube, a 3D printed adapter fills the gap:

    Chain Catcher adapter ring - solid model
    Chain Catcher adapter ring – solid model

    The hole is off-center because it seemed like a good idea, although it’s not strictly necessary. The flange helps align the pieces while tightening the clamp screw.

    The guide cage clears the chain on all sides while up on the work stand, but there’s nothing like getting out on the road to find out why something doesn’t work as you expect.

    The OpenSCAD source code as a GitHub Gist:

    // Chain catcher adapter ring
    // Ed Nisley – KE4ZNU – 2023-05
    /* [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
    TubeOD = 26.0; // frame tube with silicone tape
    Clamp = [35.0,39.0,12.0]; // Chain catcher clamp ring
    Flange = [Clamp[ID],Clamp[OD],3*ThreadThick];
    Kerf = 1.0;
    Offset = (Clamp[ID] – TubeOD)/2 – 3*ThreadWidth;
    NumSides = 2*3*4;
    //———————–
    $fn=NumSides;
    difference() {
    union() {
    cylinder(d=Flange[OD],h=Flange[LENGTH]);
    cylinder(d=Clamp[ID],h=Clamp[LENGTH]+Flange[LENGTH]);
    }
    cube([2*Flange[OD],Kerf,3*Clamp[LENGTH]],center=true);
    translate([0,Offset,0])
    cylinder(d=TubeOD,h=3*Clamp[LENGTH],center=true);
    }

  • Bafang Motor: Chain Gap Filler

    Bafang Motor: Chain Gap Filler

    When the chain falls off the top of the chainring toward the motor, the part remaining engaged with the chainring will inevitably drag the rest into the gap between the motor and the chainring spider, whereupon it will jam firmly in place and be almost impossible to extract. Preventing this means filling the gap, which required several iterations:

    Bafang motor gap filler - prototypes
    Bafang motor gap filler – prototypes

    The Bafang motor has a cover held in place by seven M3 flat-head screws, shown here below a test filler using pan head screws:

    Bafang motor gap filler - installed
    Bafang motor gap filler – installed

    Contrary to what you might think, the five screws that obviously sit on five points of a hexagon do not in fact sit 60° apart. How you find this out is by making the obvious layout, including the two screws bracketing the pinion gear in the lower right, then applying windage:

    Bafang motor housing gap filler - hole adjustments
    Bafang motor housing gap filler – hole adjustments

    That’s one of the paper templates seen above, with laser-cut holes 60° apart and ugly holes punched at the actual screw locations. Then you scan and overlay that image with the LightBurn layout and twiddle the hole locations to make the answer come out right:

    Bafang motor housing gap filler - hole adjustments - LB overlay
    Bafang motor housing gap filler – hole adjustments – LB overlay

    With that in hand, I cut a 1 mm acrylic shape to measure the clearance between the motor + filler and the chainring spider, with pan-head screws replacing the original flat-head screws:

    Bafang motor gap filler - top view
    Bafang motor gap filler – top view

    That’s a single piece of 2.5 mm acrylic I used after discovering a pair of the 1 mm acrylic shapes fit with space to spare: hooray for rapid prototyping.

    A test chain drop suggested it might suffice:

    Bafang motor gap filler - test
    Bafang motor gap filler – test

    If I were so inclined, 3 mm acrylic with countersunk holes and slightly longer flat-head screws would probably work, but I’ll use this until it fails to prevent a chain snag.

    The careful observer will have noted the stress crack extending radially inward from the upper-right screw, which I am carefully avoiding doing anything about, pending the aforementioned failure.

    The LightBurn layout as a GitHub Gist:

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