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.

Tag: Improvements

Making the world a better place, one piece at a time

  • Smashed Glass Coasters: Chipboard Variation

    Smashed Glass Coasters: Chipboard Variation

    The summer season brings iced drinks with condensation trickling down the mug and, alas, running off the smashed glass coasters:

    Printed Coaster - Set C - oblique
    Printed Coaster – Set C – oblique

    The hard parts of making those coasters involved converting the glass fragment outlines into vectors and arranging them in interesting patterns. However, with those files already in hand, making a similar coaster with chipboard “fragments” was straightforward:

    Chipboard Fragment Coaster - detail
    Chipboard Fragment Coaster – detail

    Slightly modify the OpenSCAD code to suit thinner chipboard:

    include <BOSL2/std.scad>
    
    fn = "Printed Fragment Coaster - 5 in Set B - Inkscape paths.svg";
    
    FragmentThick = 0.8;
    
    BaseThick = 2.0;
    RimHeight = 0.4;
    
    union() {
    
    
      linear_extrude(h=BaseThick)
        import(fn,id="Perimeter");
    
      color("Green")
        up(BaseThick)
          linear_extrude(h=FragmentThick)
            difference() {
              import(fn,id="Perimeter");
              import(fn,id="Recesses");
            }
    
      color("Red")
        up(BaseThick + FragmentThick)
        linear_extrude(h=RimHeight)
          difference() {
            import(fn,id="LipOut");
            import(fn,id="LipIn");
            import(fn,id="Island");
          }
    
    }
    

    Run the solid model through PrusaSlicer:

    Chipboard Fragment Coaster B - slicer preview
    Chipboard Fragment Coaster B – slicer preview

    And have a baseplate an hour later:

    Coaster Printing - in progress
    Coaster Printing – in progress

    While that’s buzzing away, tell LightBurn to cut chipboard instead of metallized paper, stick some craft adhesive sheet on the chipboard, and Fire The Laser:

    Chipboard Fragment Coaster - chipboard cutting
    Chipboard Fragment Coaster – chipboard cutting

    Remember to mirror the fragments, because you’re cutting them bottom-up.

    Do the same for the cork sheet going on the bottom, which does not require mirroring.

    I tossed the cardboard alignment fixtures I used to stick the cork onto the 3D printed baseplate, so make another one for each coaster.

    The top layer holds the baseplate:

    Chipboard Fragment Coaster - cork fixture - top
    Chipboard Fragment Coaster – cork fixture – top

    The cork + adhesive sheet is inset 0.5 mm from the edge of the baseplate, so the outline cut in the bottom layer of cardboard is just that much smaller:

    Chipboard Fragment Coaster - cork fixture - bottom
    Chipboard Fragment Coaster – cork fixture – bottom

    Although the time used to make a fixture isn’t deducted from your allotment, I’m not sure about making two identical fixtures, so I’m saving these for the next time.

    Then peel-n-stick the chipboard fragments in their recesses:

    Chipboard Fragment Coaster - variety
    Chipboard Fragment Coaster – variety

    The first baseplate didn’t have raised rims around the fragments (because there’s no need to retain any epoxy), but the result looked kinda … flat:

    Chipboard Fragment Coaster - flat top
    Chipboard Fragment Coaster – flat top

    Fixing that was a matter of not setting the rim height to zero in the OpenSCAD code.

    It’s perfectly functional even without a rim:

    Printed Coaster - chipboard inserts - sweaty mug
    Printed Coaster – chipboard inserts – sweaty mug

    Protip: White chipboard is a Terrible Idea™ in a quick-n-easy laser cuttery project. All the rest have only red or blue fragments for a good reason.

    Conversely, white PETG makes a nice contrast to the deep red and blue.

    Prosit!

  • Canning Pot Lid Knob Cleanup

    Canning Pot Lid Knob Cleanup

    Tomato Canning season has returned and my puny contributions involve maneuvering large pots of boiling water and, this time, cleaning up corrosion under the lid knob.

    The corroded OEM screw vs. the shiny stainless steel screw:

    Canning pot lid knob - OEM vs new screw
    Canning pot lid knob – OEM vs new screw

    The dark rim under the washer remained after hitting the area with sanding pad grits from 320 up through 1200, which seemed sufficient.

    The OEM screw had a self-tapping thread, but I’d rather use a machine screw with an insert. Start by lining up the existing screw hole on the drill press and clamping the knob firmly in position:

    Canning pot lid knob - hole alignment
    Canning pot lid knob – hole alignment

    Then drill to fit an M5 brass insert, while testing the hole depth:

    Canning pot lid knob - insert test fit
    Canning pot lid knob – insert test fit

    Slather the insert with JB Weld epoxy, seat it in the hole, cure overnight, assemble in reverse order, and the lid was ready for the next canning session:

    Canning pot lid handle - in use
    Canning pot lid handle – in use

    Yes, those are jars. The process is called canning:

    Canning pot lid handle - in use
    Canning pot lid handle – in use

    Get over it, like I had to.

  • Kitchen Cupboard Tray Liners

    Kitchen Cupboard Tray Liners

    Somewhat absorbent chipboard liners for the small trays / dishes under all the kitchen supplies in daily use:

    Cupboard tray liners - installed
    Cupboard tray liners – installed

    The tray bottom matched the flat surface of the top closely enough to let me lay a curve around the perimeter, with some attention to symmetry:

    Cupboard Tray - LightBurn curve fit
    Cupboard Tray – LightBurn curve fit

    Then Fire The Laser and it’s done!

    For applications where actual symmetry matters, you’d want to lay a quarter of the curve and duplicate it across the midlines. In this case, however, an eyeballometric fit was entirely Close Enough™.

    That was easy …

  • Tour Easy: E-Bike Brake Sensor Installation

    Tour Easy: E-Bike Brake Sensor Installation

    Having verified the brake sensors work and with some idea of their actuation distances, installing them on Mary’s Tour Easy involved no more than:

    • Remove the fairing
    • Unwrap three spiral looms from All The Cables
    • Wrestle the Julet connectors apart
    • Plug in the new sensors
    • Stick the sensors in the proper locations
    • Verify proper brake operation
    • Rewrap the looms
    • Install the fairing

    The “proper location” put the actuation point about halfway between the brake lever’s released and pulled positions. Given that the previous sensors lacked indicators, I don’t know where their actuation point might have been, other than likely too close to their released position.

    A slideshow of the front brake lever positions:

    • Tour Easy LED brake sensor - front released
    • Tour Easy LED brake sensor - front activated
    • Tour Easy LED brake sensor - front pulled

    Similarly for the rear brake lever positions:

    • Tour Easy LED brake sensor - rear released
    • Tour Easy LED brake sensor - rear activated
    • Tour Easy LED brake sensor - rear pulled

    Obviously, the rear brake lever sensor has the “dim” LEDs.

    There’s not much to go wrong and the first ride was uneventful, so we’ll declare victory until the sensors or magnets shift their position, despite the wraps holding their wires to the brake cables.

    The magnets come from power toothbrush heads, encased in urethane adhesive in 3D printed mounts.

    Stipulated: I sometimes over-do things.

    However, I am absolutely not going to back down from saying the lashup shown in this screen grab from the sensor installation video is utterly and completely wrong:

    E-bike Brake Sensor - suggested installation
    E-bike Brake Sensor – suggested installation

    Do not get me started, you know how I am. OK?

  • E-Bike Brake Sensor Bench Check

    E-Bike Brake Sensor Bench Check

    A pair of brake sensors with LED indicators arrived and should improve the situation on Mary’s bike.

    The connector pinout, as seen looking into the jack on the controller side of the cable:

    Bafang Brake Sensor pinout
    Bafang Brake Sensor pinout

    Of course, one cannot depend on color codes, but now we know it uses a 5 V supply. Some rummaging produced a suitable (“Julet”) connector, a cutoff USB cable, and a USB power supply:

    Tour Easy LED brake sensor - bench test harness
    Tour Easy LED brake sensor – bench test harness

    You’ll note the sensor’s signal wire is blue, not white, but red = 5 VDC and black = common on both sides of the splice. This is not to be sniffed at.

    With the disk magnet (supplied with the sensors) oriented edgewise to the sensor, so the magnetic field is largely cancelled, the maximum separation allowing the sensor to remain On is about 7 mm:

    Tour Easy LED brake sensor - edge - max ON
    Tour Easy LED brake sensor – edge – max ON

    The minimum distance allowing it to be Off is 8 mm:

    Tour Easy LED brake sensor - edge - min OFF
    Tour Easy LED brake sensor – edge – min OFF

    Orienting the disk face-on to the sensor increases the distances, because the magnetic field is not cancelled out in that direction. Similarly, positioning the magnet either above or below the plane of the sensor changes the results.

    The maximum On distance is now 20 mm:

    Tour Easy LED brake sensor - side - max ON
    Tour Easy LED brake sensor – side – max ON

    The minimum Off distance is 22 mm:

    Tour Easy LED brake sensor - side - min OFF
    Tour Easy LED brake sensor – side – min OFF

    The other magnet has a similar field strength and the other sensor responds at nearly the same distances, so they’re reasonably matched.

    The LEDs are, however, not well matched: one sensor is much brighter than the other. I only have one connector, so I cannot show both in the same picture. These pictures have the same exposure (1/120 s and f/1.7), with the top sensor appearing in the previous pictures:

    E-bike Brake Sensors - LED Brightness comparison
    E-bike Brake Sensors – LED Brightness comparison

    The red LEDs show a similar difference. I’m certain this doesn’t rise to the level of a warranty claim, because, hey, maybe the brighter one should be dimmer.

    Now, to fit them on Mary’s bike …

  • Mini-lathe Cross Slide and Compound Backlash Tweakage

    Mini-lathe Cross Slide and Compound Backlash Tweakage

    It being once again time to tweak the mini-lathe’s cross slide and compound backlash …

    The M3 slotted setscrew locking the cross slide’s DRO collar to the feed screw shaft had come loose:

    Mini-lathe - DRO slotted setscrew
    Mini-lathe – DRO slotted setscrew

    Although it has a cone point, presumably to center the slot in the feed screw, an M3 cup point hex setscrew works just fine:

    Mini-lathe - DRO hex setscrew
    Mini-lathe – DRO hex setscrew

    A hex socket is much easier to tighten securely.

    The handle sits against a black washer that looks like it should rest against the aluminum spacer covering the DRO shaft, but it doesn’t. Contrary to what I originally thought, that gap doesn’t contribute to the backlash (given a tight setscrew!), but a filler shim makes it look less like an afterthought:

    Mini-lathe - cross slide handle shim
    Mini-lathe – cross slide handle shim

    What does contribute to the backlash is a loose adjusting screw holding the follower nut against the feed screw:

    Mini-lathe - cross slide backlash screws
    Mini-lathe – cross slide backlash screws

    The mini-lathe manual (page 17) and online references give the tedious process required to adjust the two cap screws and the setscrew to remove (nearly all of) the backlash. While I had the screws out, I took the opportunity to dribble oil through the cap screw holes onto the feed screw along as much of its length as was reachable.

    Adjusting the gib screws is also a good idea, as is renewing the oil along the ways.

    With all that done, the cross slide moves easily without slop and the backlash is a tolerable 0.1 mm.

    The compound feed screw does not have any backlash adjustment, so fitting a suitable shim between the handle and the DRO spacer is essential:

    Mini-lathe - compound handle shim
    Mini-lathe – compound handle shim

    That one looked nice, but was somewhat too thick.

    This time around I could laser-cut and 3D print shims (16 mm OD, 10 mm ID) in a variety of thicknesses, some combination of which would surely fill the gap without binding:

    Mini-lathe - handle backlash shims
    Mini-lathe – handle backlash shims

    The gnarly clear rings over on the left are the original punched-and-trimmed PETG shims. The fabric-looking ones are PTFE sheets intended for heat-press transfer machines, which Mary has used as a slider sheet to let fabric move easily over her sewing machines. The black one in the middle is 1.5 mm acrylic.

    The bright white rings are 3D printed from a few lines of OpenSCAD code:

    Washers = [0.5,0.6,0.7,0.8,1.2];
    
    for (i = [0:len(Washers)-1])
      right(i*20.0 - 40.0)
        tube(Washers[i],od=16.0,id=(10.0 + HoleWindage),anchor=BOTTOM);
    

    Print them with 0.1 mm layers in PETG, add a PTFE shim or two, and fiddle about enough to get minimum backlash with reasonable turning force.

    The compound feed screw now has 0.16 mm of backlash, which is as good as it’s going to get.

    Right now, the only thing preventing the handle from turning on the shaft is the chunky lockwasher gouging both the handle and the cap screw in the end of the shaft, with the side effect of putting far too much pressure on the spacer shims. I want setscrews in the handles bearing on flats filed in the feed screw shafts to put those awful screws + lockwashers out of business, which seems like a good Sherline project.

  • Layered Paper 8×10 inch Gluing Fixture

    Layered Paper 8×10 inch Gluing Fixture

    An embiggened version of the 8×8 inch fixture, built with MDF for improved durability & flatness:

    Layered Paper 8×10in Gluing Fixture - block
    Layered Paper 8×10in Gluing Fixture – block

    That’s an 8×8 quilt pattern as a quick fit check. Should I cut more of those, I’d install rivnuts in the obvious locations:

    Layered Paper 8×10in Gluing Fixture - front overview
    Layered Paper 8×10in Gluing Fixture – front overview

    The white layer is 1 mm thick chipboard with the rivnut heads flush at its surface:

    Layered Paper 8×10in Gluing Fixture - front detail
    Layered Paper 8×10in Gluing Fixture – front detail

    The perspective makes the fit look much worse than it is.

    The back side has squishy foam feet keeping the M3 screws off the table:

    Layered Paper 8×10in Gluing Fixture - back detail
    Layered Paper 8×10in Gluing Fixture – back detail

    The large rectangle on the LightBurn tool layer helped align the 8×12 inch MDF stock. The smaller squares show where the 8×8 inch square will fit and confirmed the hole locations:

    Gluing Fixture - 200x200-250mm - LightBurn layout
    Gluing Fixture – 200×200-250mm – LightBurn layout

    The LightBurn SVG layout is a GitHub Gist, which also includes the template layout for cutting Letter pages to fit the fixture.