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

  • Dr. Who Cookie Cutters

    These Dr. Who themed cookie cutters came out nearly perfect:

    Dr Who Cookie Cutters
    Dr Who Cookie Cutters

    Each consists of an outer cutter rim and an inner dough press that fit neatly together.

    The STL files contain a few triangle errors that seem to be typical of objects made with Google Sketchup, but the final G-Code came out fine despite a few Skeinforge warnings.

    No strings, no cleanup, no muss, no fuss: the printer is back in operation once again!

    The relevant Skeinforge 45 settings, about which more later:

    • 0.25 mm layer thickness + 0.50 mm thread width
    • First layer: 9 mm/s perimeter + 15 mm/s infill
    • Other layers: 20 mm/s perimeter  + 60 mm/s infill
    • 250 mm/s travel (!)
    • +0 extra shells, 3 solid layers
    • 0.20 infill + 45°/90° rectangular
    • 200 °C extrusion + 110 °F platform

    Dimension plugin settings:

    • Filament dia = 2.96 mm, FPD = 0.93 (natural ABS from MBI)
    • Retraction 2 mm @ 60 mm/s, min 1 mm travel

    I’m not a big Dr. Who fan, but I know someone who is…

  • Shower Basket Sucker Relocation

    The outer suckers on the basket in the corner of the shower didn’t line up with the tiles; either tile dimensions have changed in the last half-century or it’s a hard-metric basket. It didn’t look right when I installed it (now that is a grandiose term if I’ve ever misused one), so (when the thing fell off and landed with a clatter a few days ago) I drilled two additional holes as far away from the corner as I could, using a step drill to prevent the plastic from shattering, and it’s all good.

    Shower basket - redrilled
    Shower basket – redrilled

    Sometimes, they’re easy…

    You’ll note that I heroically resisted the urge to fire the Thing-O-Matic to print some kind of weird-ass safety-orange interposer plate, just because I could.

  • HP 50g Calculator Screen Protector

    A week or so after I got my HP 49GX calculator, I managed to drop a vernier caliper on it. Interior points downward, of course, putting a nice divot on the non-glare plastic over the LCD panel.

    A week or so after I got my HP 50g calculator, I applied a screen protector sheet harvested from the lifetime supply I bought for my original Zire 71, back in the day.

    HP 50g calculator screen protector
    HP 50g calculator screen protector

    The fact that it’s an almost perfect fit and that the calculator sports a monochrome LCD with lower resolution is a sad commentary on the state of the calculator art.

    Taking that picture in low-angle full sunlight makes the protector sheet look awful. In actual use, it’s nearly invisible. Haven’t dropped anything on it yet, either.

    And, yes, I did cut it out around the HP logo button in the upper right corner.

  • Brita Pitcher Lid Hinge Redux

    Well, that fix didn’t last nearly as long as I’d hope, although I must admit whacking the pitcher lid against the refrigerator door certainly hastened its demise.

    So I found a suitable screw in the Tiny Box o’ Teeny Screws (in a sub-container of eyeglass repair screws), drilled a snug hole where the plastic pin used to be (entirely by hand on the drill press, feeding the lid into the drill), and snapped everything together again:

    Brita pitcher lid hinge - screw
    Brita pitcher lid hinge – screw

    The remaining plastic pin had a fracture at its base, but I just glued it and will defer installing a screw until it finishes disintegrating. At some point we’re going to be forced to buy a new pitcher…

  • Zire 71 Printed Button Shield

    After fixing that old plate, I just had to do this:

    Zire 71 protector - solid model
    Zire 71 protector – solid model

    Which pretty much fills up the build platform:

    Zire 71 protector - on build platform
    Zire 71 protector – on build platform

    And fits perfectly:

    Zire 71 protector in place
    Zire 71 protector in place

    It’s printed with 100% infill to produce a solid plastic plate.

    In retrospect, I think it’d work better if I put the notch on the bottom side with a bit of support, so that the glass-smooth surface faced the Zire. Maybe next time?

    The OpenSCAD source code:

    // Protector plate for Zire 71 PDA
    // Ed Nisley KE4ZNU - Jan 2012
    
    //-------
    //- Extrusion parameters must match reality!
    //  Print with +0 shells, 3 solid layers, 0.2 infill
    
    ThreadThick = 0.25;
    ThreadWidth = 2.0 * ThreadThick;
    
    Protrusion = 0.1;           // make holes end cleanly
    
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    function IntegerMultipleMin(Size,Unit) = Unit * floor(Size / Unit);
    
    //-------
    // Dimensions
    
    $fn=8*4;
    
    Length = 110;
    Width = 73;
    Thickness = IntegerMultiple(2.0,ThreadThick);
    CornerRadius = 5.0;
    
    NotchLength = 20;
    
    PocketWidth = 22;
    PocketLength = 12;
    PocketRadius = 3.0;
    PocketOffsetX = -1;
    PocketOffsetY = 10;
    
    SlotLength = 20;
    SlotWidth = IntegerMultiple(8.0,ThreadWidth);
    SlotDepth = IntegerMultiple(0.75,ThreadThick);
    
    //-------
    
    module ShowPegGrid(Space = 10.0,Size = 1.0) {
    
      Range = floor(50 / Space);
    
        for (x=[-Range:Range])
          for (y=[-Range:Range])
            translate([x*Space,y*Space,Size/2])
              %cube(Size,center=true);
    }
    
    //-------
    // Outer section of plate
    //  with nice rounded edges
    
    module PlateHalf() {
    
      translate([0,0,Thickness/2])
        difference() {
          minkowski(convexity=3) {
            cube([(Width - SlotWidth)/2 - 2*CornerRadius,(Length - 2*CornerRadius),(Thickness - 2*Protrusion)],center=true);
            cylinder(r=CornerRadius,h=Protrusion);
          }
          translate([PocketOffsetX,PocketOffsetY - Length/2,0])
            minkowski() {
              cube([PocketWidth - 2*PocketRadius,PocketLength - 2*PocketRadius,Thickness],center=true);
              cylinder(r=PocketRadius,h=Protrusion);
            }
        }
    }
    
    //-------
    
    ShowPegGrid();
    
    translate([(Width - SlotWidth)/4 + SlotWidth/2,0,0])
      PlateHalf();
    
    translate([-(Width - SlotWidth)/4 - SlotWidth/2,0,0])
      mirror([1,0,0])
        PlateHalf();
    
    difference() {
      translate([0,0,(Thickness - SlotDepth)/2])
        cube([SlotWidth + 2*Protrusion,Length - 2*SlotLength + SlotWidth,(Thickness - SlotDepth)],center=true);
      for (Index=[-1,1])
        translate([0,(Index*(Length/2 - SlotLength + SlotWidth/2)),-Protrusion])
          cylinder(r=SlotWidth/2,h=Thickness + 2*Protrusion);
    }
    
  • Zire 71 Button Shield Repair

    My decrepit Zire 71 PDA (remember PDAs?) has a cute little joystick dingus that, when pressed, displays the clock. That’s great, except that it stands proud of the surface by just enough to be constantly pressed by my pants fabric. Hence, the need for a button shield… which, after all these years, snapped at an obvious high-stress spot:

    Broken Zire button shield
    Broken Zire button shield

    A dab of solvent glue, a few minutes of finger pressure, and let it cure overnight. That was easy.

    But then it occurred to me that this was a broken plastic part and I had a 3D printer…

  • Thing-O-Matic: Dummy Load Fan Replacement

    Dummy load fan replacement
    Dummy load fan replacement

    The fan on the dummy load that consumes the required minimum current to keep the ATX power supply happy wasn’t starting up reliably. That’s not surprising: I connected it to 5 V rather than the rated 12 V, because the load heatsink needs just a whisper of air flow to stay barely above room temperature, so it’s barely turning over and has no spare torque at all.

    It turns out the heatsink really doesn’t need any forced air flow, despite having the fins oriented crosswise. Without the fan, it stabilizes just above comfortable-to-the-touch, a bit hotter than I’d prefer.

    While I had the hood up for the HBP rebuild, though, I swapped in another fan and the heatsink is now cool to the touch. I did clean that dust off the fins, too.

    If this one also fails at +5 V, I’ll fiddle the wiring to put it across the +12 V and +5 V supplies, where it’ll see 7 V. That should improve its disposition…