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.

Author: Ed

  • MPCNC: GCMC Configuration

    The default GCMC prolog(ue) spits out some G-Codes that GRBL doesn’t accept, requiring tweaks to the incantation.

    A first pass at a useful prolog, minus the offending codes:

    cat ~/.config/gcmc/prolog.gcmc 
    (prolog begins)
    G17 (XY plane)
    G21 (mm)
    G40 (no cutter comp)
    G49 (no tool length comp)
    G80 (no motion mode)
    G90 (abs distance)
    G94 (units per minute)
    (prolog ends)
    

    Including any of the usual “end of program” M-Codes in the epilog(ue) causes GRBL to pause before exiting the program, so leave only a placeholder:

    cat ~/.config/gcmc/epilog.gcmc 
    (epilog begins)
    (M2) (allow program to continue)
    (epilog ends)
    

    Having done a git clone into /opt/gcmc before building the program, the GCMC library routines live in:
    /opt/gcmc/library

    Limiting numeric values to two decimal places makes sense:
    -P 2

    With all that in hand, unleashing the compiler on an unsuspecting source file requires this jawbreaker:

    gcmc -P 2 -I /opt/gcmc/library \
    -G ~/.config/gcmc/prolog.gcmc \
    -g ~/.config/gcmc/epilog.gcmc \
    -o cycloids.ngc \
    cycloids.gcmc
    

    One might, of course, tuck all that into a little script, rather than depend on extracting it from the bash history as needed.

    The resulting G-Code file looks about right:

    head cycloids.ngc
    (prolog begins)
    G17 (XY plane)
    G21 (mm)
    G40 (no cutter comp)
    G49 (no tool length comp)
    G80 (no motion mode)
    G90 (abs distance)
    G94 (units per minute)
    (prolog ends)
    F2500.00
    [pi@MPCNC tmp]$ head -25 cycloids.ngc
    (prolog begins)
    G17 (XY plane)
    G21 (mm)
    G40 (no cutter comp)
    G49 (no tool length comp)
    G80 (no motion mode)
    G90 (abs distance)
    G94 (units per minute)
    (prolog ends)
    F2500.00
    G0 Z1.00
    (-- tracepath at Z=-1.00mm --)
    G0 X-145.50 Y-30.00
    G1 Z-1.00
    G1 X-145.51 Y-29.93
    
    ... vast snippage ...
    
    G1 X175.50 Y30.00
    G1 Z1.00
    G0 Z25.00
    (epilog begins)
    (M2)
    (epilog ends)
    

    Then it’s just a matter of tweaking cycloids.gcmc to make interesting things happen:

    GGMC Cycloids test patterns
    GGMC Cycloids test patterns
  • MPCNC: Tool Length Probe Station

    Having a tool length probe station on the Sherline, I had to build one for the MPCNC:

    MPCNC Tool Length Probe - plotter pen
    MPCNC Tool Length Probe – plotter pen

    It’s little more than a flange atop a wide base:

    MPCNC Tool Length Probe - Slic3r preview
    MPCNC Tool Length Probe – Slic3r preview

    The flange offset puts the switch actuator on the midline of the base, not that that matters, and the base features rounded corners and a suitable legend, because I can.

    I clipped the PCB’s through-hold leads nearly flush and stuck it to the flange with 3M permanent foam tape, which seems to work much better than screws & inserts for simple things that need never come apart.

    The Protoneer CNC Shield includes a Probe input on the GRBL-compliant A5, although it took me a while to find the legend on the SCL pin in the I2C header. I moved the endstop power jumper to another header, then conjured a quick-and-dirty connector:

    Protoneer CNC Shield - Tool Probe Wiring
    Protoneer CNC Shield – Tool Probe Wiring

    When I embed the endstop switch PCB in epoxy, I’ll add a drop to the connector while engaging in Magical Thinking. The whole Arduino + CNC Shield must go into an enclosure after I finish measuring the motor currents.

    To forestall discussions about switch repeatability and accuracy, suffice it to say the MPCNC doesn’t claim to be much more than a woodworking router, so those switches seem Good Enough.

    The OpenSCAD source code as a GitHub Gist:

    // MPCNC Tool Length Probe Station
    // Ed Nisley KE4ZNU – 2017-12-08
    /* [Extrusion] */
    ThreadThick = 0.25; // [0.20, 0.25]
    ThreadWidth = 0.40; // [0.40]
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    /* [Hidden] */
    Protrusion = 0.1; // [0.01, 0.1]
    HoleWindage = 0.2;
    /* [Sizes] */
    EndstopPCB = [40.0,16.5,1.6]; // endstop PCB
    ComponentHeight = 6.0; // max component height above PCB
    SwitchOffset = [35.0,21.0,4.75]; // touch point center from lower left PCB corner
    SwitchTravel = 2.5; // first touch to switch actuation
    TapeThick = 1.0; // foam mounting tape
    WallThick = 4.0; // basic wall & floor thickness
    BaseRadius = 5.0;
    Base = [IntegerMultiple(EndstopPCB[0] + 2*BaseRadius,20),
    IntegerMultiple(EndstopPCB[2] + TapeThick + WallThick + 2*BaseRadius,2*25),
    2.0];
    NumSides = 8*4;
    TextDepth = 2*ThreadThick;
    //- Build it
    union() {
    difference() {
    hull()
    for (i=[-1,1], j=[-1,1])
    translate([i*(Base[0]/2 – BaseRadius),j*(Base[1]/2 – BaseRadius),0])
    resize([0,0,Base[2]])
    intersection() {
    cylinder(r=BaseRadius,h=BaseRadius,$fn=NumSides);
    sphere(r=BaseRadius,$fn=NumSides);
    }
    translate([0,0,Base[2] – TextDepth])
    linear_extrude(height=TextDepth + Protrusion) {
    translate([0,-10,0])
    text(text="MPCNC",size=8,spacing=1.05,font="Arial:style=Bold",halign="center");
    translate([0,-18,0])
    text(text="Tool Probe",size=6,spacing=1.05,font="Arial:style=Regular",halign="center");
    }
    }
    translate([0,
    WallThick/2 + TapeThick + SwitchOffset[2],
    (EndstopPCB[1] – Protrusion)/2 + Base[2]])
    cube([EndstopPCB[0],WallThick,EndstopPCB[1] + Protrusion],center=true);
    }

    The original doodles show a severely over-complexicated solution desperately searching for an actual problem:

    MPCNC Tool Length Probe - doodles
    MPCNC Tool Length Probe – doodles

    Putting a large flat pan at the end of a relatively long lever arm, with the pivot arranged to put the pan level at the switch actuation point, made sense at the time. Give the relatively small tools I expect to use, directly ramming them into the switch lever should work just as well.

    Putting all that complexity in harm’s way seemed like a Bad Idea when I sat down and looked at it in cold blood.

  • Finger Wrench

    A friend recommended a Finger Wrench and it looks useful, indeed:

    Finger Wrench
    Finger Wrench

    That’s a 10-32 socket head cap screw, on the large end of the screws I normally use.

    The orange PETG required a bit of smoothing around the overhangs, but should work well enough. The dark tinge near the bottom comes from the black filament I used for the MPCNC’s Z Axis sensor and won’t affect its operation in the least.

    Done with one perimeter thread and a 3 mm brim to glue down the bottom:

    Finger Wrench - Slic3r preview
    Finger Wrench – Slic3r preview

    That was easy …

  • Cycliq Fly6 Failure and Teardown

    Cycliq Fly6 Failure and Teardown

    My Cycliq Fly6 continued to shut down during rides, even with a new video-rated card, suggesting:

    • The fault resides in the camera
    • The Samsung card is just fine

    Following all the steps recommended by Cycliq Tech Support didn’t improve the situation. It’s just under two years old and thus outside the warranty, so they advised me to buy their new, not-quite-released-yet Fly6, now with Bluetooth / ANT+ / phone app / shiny, but still with a non-replaceable battery.

    Seeing as how the Fly6 works as well as it ever did, apart from the minor issue of shutting down both dependably and intermittently, the problem is almost certainly a bad battery. Cycliq does not offer a repair service, nor a battery replacement service; being based in Australia probably contributes to not wanting to get into those businesses. You’re supposed to responsibly recycle the Whole Damn Thing when the battery goes bad. Which, inevitably, it does.

    Protip: anything with a non-replaceable battery is a toy, not a tool.

    The most recent ride gave some evidence supporting a bad battery. The first shutdown happened after about half an hour and it gave off three battery status beeps (four = full charge, as at the start of the ride) when I restarted it a few minutes later. It shut down again a few minutes later while we were stopped at a traffic signal and gave off one lonely charge beep when I reached back to restart it, indicating a very low battery voltage. The battery voltage (and the number of startup beeps) increased with longer delays between shutdown and restart, but after the first shutdown it’s never very enthusiastic.

    Having nothing to lose, let’s see what’s inside:

    Cycliq Fly6 Teardown from inside
    Cycliq Fly6 Teardown from inside

    Don’t do as I did: you should extract the MicroSD card before you dismantle the camera.

    Remove the rubber plugs sealing the four case screws:

    Fly6 - Exterior screw plugs out
    Fly6 – Exterior screw plugs out

    The case pops open, with a ribbon cable between the LEDs and the main circuit board:

    Fly6 - Case opened
    Fly6 – Case opened

    Pull the ribbon cable latch away from the connector before pulling the cable out.

    It’s amazing what you find inside a blinky taillight these days:

    Fly6 - PCB Top side
    Fly6 – PCB Top side

    I’m sure there’s a fancy 32 bit RISC computer in the big chip, along with plenty of flash ROM just below it. The clutter over on the right seems to be the power supply. Yeah, it has a camera in addition to blinky LED goodness, plus USB charging, so eight bits of microcontroller aren’t nearly enough.

    There’s supposed to be some nanotech waterproofing protecting everything inside. It sure looks like magic to me and, in any event, solders just like a layer of ordinary air.

    Note: the case screws are slightly longer than the PCB retaining screws:

    Fly6 - Case and PCB Screws
    Fly6 – Case and PCB Screws

    The underside of the PCB has even more teeny parts, along with, mirabile dictu, a battery connector and (most likely) battery charging stuff:

    Fly6 - PCB Underside
    Fly6 – PCB Underside

    A plastic piece holds the “Rechargeable Li-Ion Battery Pack” in place:

    Fly6 - Battery in place
    Fly6 – Battery in place

    A strip of gooey adhesive holding the mic and speaker wires in place also glues the battery strap to the case, but it will yield to gentle suasion from a razor knife.

    Pause to count ’em up:

    • Four case screws (longer)
    • Three PCB screws
    • Two battery screws

    It looked a lot like an ordinary 18650 lithium cell to me and, indeed, it is:

    Fly6 - Battery - label
    Fly6 – Battery – label

    More razor knife work removes the outer shrinkwrap. The cell has a protection PCB under the black cardboard cover:

    Fly6 - Battery Protection PCB - on 18650 cell
    Fly6 – Battery Protection PCB – on 18650 cell

    I don’t know what the yellow wire does:

    Fly6 - Battery Protection PCB - wire side
    Fly6 – Battery Protection PCB – wire side

    The FS8205A on the left may be an SII S8205 protection IC preset and packaged for a single cell:

    Fly6 - Battery Protection PCB - components
    Fly6 – Battery Protection PCB – components

    After all that, yeah, it’s a dead battery:

    Fly6 OEM 18650 - EOL - 2017-12-06
    Fly6 OEM 18650 – EOL – 2017-12-06

    The red curve shows the in-circuit charge state after taking it apart, the green curve comes from charging the bare cell in my NiteCore D4 charger. I have no idea what the nominal current drain might be, but a 0.25 Ah capacity is way under those Tenergy cells.

    A new cell-with-tabs should arrive next week, whereupon I’ll solder the protection circuit in place, wrap it up, pop it back in the case, and see how it behaves.

  • Epson R380 Continuous Ink Supply Tubes

    After fixing the yellow ink tube, the Epson R380 printer occasionally gave off a horrible clunk as the tubes slapped around inside the frame. This routing seems much quieter and, as you can see from the marks on the tubes, leaves much less free to flop around:

    Epson R380 Printer - CISS tube routing
    Epson R380 Printer – CISS tube routing

    I cut a small collar (to the left of the white block with the red cable tie) to guide the tubing up over the edge of the ink cartridge holder, with a ramp from the upper edge and raised edges to hold the tubes in place, from a block of black closed-cell foam. It seems perfectly happy to do its job without anything other than the tubes holding it in place atop the cartridges.

    There’s also a block of foam filling a gap under the printer’s top frame member (along the far left edge of the picture) to cushion the tubes as they whack against the edge.

    So far, so good.

    I’ve dumped a few more tanks of waste ink down the drain. When this printer eventually gives up, I’ll get a color laser and move on.

  • Salty Spider

    An unusual ingredient in the water softener salt reservoir:

    Spider atop Water Softener Salt
    Spider atop Water Softener Salt

    They’re everywhere!

    I figured it found a way in and can find its own way out, so I just closed the lid and backed carefully away …

  • MPCNC: Z Axis Upward Homing with Opto Proximity Sensor

    Homing the MPCNC’s Z axis at the bottom end of its travel made no sense, but the Z stage lacks a convenient spot to mount / trigger a switch at the top of its travel, so this sufficed for initial tests & fiddling:

    MPCNC - Z min endstop
    MPCNC – Z min endstop

    The EMT rail carrying the switch moves downward, tripping the lever when it hits the MPCNC’s central assembly.

    Somewhat to my surprise, a TRCT5000-based optical proximity sensor (harvested from the Kenmore 158 Crash Test Dummy’s corpse) and a strip of black electrical tape work perfectly:

    MPCNC - Z Axis Opto Proximity Endstop
    MPCNC – Z Axis Opto Proximity Endstop

    The PCB wears a shiny new epoxy coat:

    MPCNC - Epoxy-coated Endstop - Opto Prox Sensor
    MPCNC – Epoxy-coated Endstop – Opto Prox Sensor

    I soldered the wires (harvested from the previous endstop) directly to the PCB, because the pinout isn’t the same and fewer connectors should be better.

    The mount uses black PETG, rather than translucent orange, in hope of IR opacity, and wraps around the EMT rail at (roughly) the 2 mm standoff producing the peak response:

    IR Reflective Sensor module - TCRT5000 - response vs distance
    IR Reflective Sensor module – TCRT5000 – response vs distance

    In truth, I set the gap by eyeballometric guesstimation to make the entire mount arc sit equidistant from the EMT:

    MPCNC - Z Opto Prox Endstop - top view
    MPCNC – Z Opto Prox Endstop – top view

    The mount includes the 2 mm spacing around the EMT OD and puts the sensor tip flush with the arc OD, so it should be pretty close:

    TCRT5000 Z Axis Endstop Mount - solid model
    TCRT5000 Z Axis Endstop Mount – solid model

    A strip of 3M permanent tape, cut to clear the 608 bearings, affixes the mount to the MPCNC’s central assembly. The solid model now includes a midline reference notch, with a height rounded up to the next-highest multiple of 2.0 mm. It needs a loop to anchor the cable.

    The blue twiddlepot sets the comparator threshold midway between the response over black tape (incorrectly on = too low) and bare EMT (incorrectly off = too high), in the hope of noise immunity. The range spanned nearly half of the pot rotation, so I think it’s all good.

    The sensor doesn’t trip when the edge of the tape exactly meets its midline, which meant I had to trim a strip of tape to suit. As part of setting the twiddlepot, I shut off the Z axis motor and laid some test strips on the EMT:

    MPCNC - Z Axis Opto Prox Endstop - Test Tape
    MPCNC – Z Axis Opto Prox Endstop – Test Tape

    I spun the leadscrew with one hand, held the sensor with the other, twiddled the trimpot, trimmed the upper and lower ends of the tape, and generally had a fine time. The sensor responds equally well to a half-wide strip of tape (in the upper picture), with the distinct advantage of not encroaching on the 608 bearing tracks.

    The GRBL setup now homes Y and Z toward the positive end of their travel, with X still toward the negative end while a set of extension cables remains in transit around the planet.

    The OpenSCAD source code as a GitHub Gist:

    // TCRT5000 Z Axis Endstop Mount
    // Ed Nisley KE4ZNU – 2017-12-04
    /* [Build Options] */
    Layout = "Show"; // [Build, Show, Block]
    Section = true; // show internal details
    /* [Extrusion] */
    ThreadThick = 0.25; // [0.20, 0.25]
    ThreadWidth = 0.40; // [0.40]
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    /* [Hidden] */
    Protrusion = 0.01; // [0.01, 0.1]
    HoleWindage = 0.2;
    ID = 0;
    OD = 1;
    LENGTH = 2;
    /* [Sizes] */
    RailOD = 23.5; // actual rail OD
    OptoPCB = [32.5,14.2,1.6]; // prox sensor PCB
    ComponentHeight = 5.0; // max component height above PCB
    OptoSensor = [5.8,10.2,10.5]; // sensor head below PCB
    OptoOffset = 3.0; // sensor head center from PCB edge
    OptoRange = 2.0; // sensor to rail distance
    TapeThick = 1.0; // foam mounting tape
    WallThick = 4.0; // basic wall thickness
    Block = [WallThick + OptoRange + RailOD/2 + (OptoPCB[0] – OptoOffset),
    RailOD/2 + OptoRange + OptoSensor[2] – TapeThick,
    IntegerMultiple(OptoPCB[1] + 2*WallThick,2.0)]; // basic block shape
    echo(str("Block: ",Block));
    NumSides = 6*4;
    //- 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);
    }
    //- Shapes
    // Main block constructed with PCB along X, opto sensor at Y=0
    module PCBBlock() {
    difference() {
    translate([-(WallThick + OptoRange + RailOD/2),
    (-Block[1] + RailOD/2 + OptoRange),
    -Block[2]/2])
    cube(Block,center=false);
    for (i=[-(RailOD/2 + OptoRange + WallThick),
    (OptoPCB[0] – OptoOffset)])
    translate([i,0,0])
    rotate([90,0,0]) rotate(45)
    cube([2*ThreadWidth,2*ThreadWidth,2*Block[2]],center=true);
    translate([0,(RailOD/2 + OptoRange),0])
    cylinder(d=(RailOD + 2*OptoRange),
    h=(Block[2] + 2*Protrusion),
    $fn=NumSides,center=true);
    rotate([90,0,0])
    cube(OptoSensor + [0,0,Block[1]],center=true);
    }
    }
    //- Build things
    if (Layout == "Block")
    PCBBlock();
    if (Layout == "Show") {
    translate([0,-(RailOD/2 + OptoRange),0])
    PCBBlock();
    color("Yellow",0.5)
    cylinder(d=RailOD,h=2*Block[2],$fn=NumSides,center=true);
    }
    if (Layout == "Build")
    translate([0,0,OptoSensor[2] – TapeThick])
    rotate([90,0,0])
    PCBBlock();

    The original doodles, including a bunch of ideas left on the cutting room floor:

    MPCNC Z Opto Proximity Sensor Endstop - doodles
    MPCNC Z Opto Proximity Sensor Endstop – doodles