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Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Tag: Thing-O-Matic

Using and tweaking a Makerbot Thing-O-Matic 3D printer

  • Wouxun KG-UV3D GPS+Voice Interface: Improved Case

    This case has a few refinements beyond that one, but it’s recognizably a descendant. The main changes:

    • The HT cable port on the side has a nice polygonal roof to reduce overhang
    • The serial connector sits in a recess to allow a thicker top plate
    • Smaller opening for the LEDs; I’ll get a window in this one, fer shure, yeah
    • 4-40 screws hold the base plate on; setscrews may work and look better

    Looks like I’ll be using blue filament for this version, having just discovered the last of the weird colors in the bottom of the 5 gallon bucket serving as a storage bin.

    A view from the top:

    Solid Model - Oblique Exploded Top
    Solid Model – Oblique Exploded Top

    And from the base:

    Solid Model - Oblique Exploded Base
    Solid Model – Oblique Exploded Base

    The OpenSCAD source code:

    // Wouxun KB-UV3D Battery Pack Case
    // Ed Nisley KE4ZNU July 2012
    
    include </home/ed/Thing-O-Matic/lib/MCAD/units.scad>
    include </home/ed/Thing-O-Matic/Useful Sizes.scad>
    
    // Layout options
    
    Layout = "Show";
    					// Overall layout: Fit Show
    					// Printing plates: Build1 .. Buildn (see bottom!)
    					// Parts: TT3 Audio DSub Shell Base Top
    					// Shapes: RadioBase Contact
    					// Speaker-mic mount: PlugPlate
    
    ShowGap = 10;		// spacing between parts in Show layout
    
    //- Extrusion parameters must match reality!
    //  Print with +1 shells and 3 solid layers
    
    ThreadThick = 0.25;
    ThreadWidth = 2.0 * ThreadThick;
    
    HoleWindage = 0.2;
    
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    
    Protrusion = 0.1;			// make holes end cleanly
    
    //----------------------
    // Dimensions
    
    CaseOverallHeight = 31.5;				// from battery surface, must clear PCBs!
    CaseOverallWidth = 56;
    CaseOverallLength = 80.25;				// inside of base to end of compartment
    
    BatteryClearance = 1.5;					// contact seal height = air gap to compartment
    
    // Interface to radio battery contacts
    //	Length = shell length
    //		calculated after everything else, so as to fill the compartment
    
    ContactDia = 6.0;				// use rounded contact for simplicity
    ContactRecess = IntegerMultiple(0.75,ThreadThick);	// recess for contact plate
    ContactGapX = 10.5;				// X space between contacts
    Contact1Y = 52.5;				// offset from base to edge of contact
    Contact2Y = 56.5;
    ContactStudDia = Clear4_40;
    ContactStudHead = IntegerMultiple(Head4_40,ThreadWidth);
    ContactStudHeadThick = Head4_40Thick;
    
    PlateWidthMin = 53.0;
    PlateWidthMax = 54.5;
    PlateThick = IntegerMultiple(ContactRecess + ContactStudHeadThick,ThreadThick);
    PlateAngle = atan(PlateThick/(PlateWidthMax/2 - PlateWidthMin/2));
    
    echo("Battery plate thick: ",PlateThick);
    
    // Offsets from battery surface to PCB centerlines
    //	TT3 must be above HT back shell for DB9 clearance
    //	These must cooperate with the numbers in the case shell module
    
    TT3Offset = 17.5 + PlateThick;
    AudioOffset = 4.0 + PlateThick;
    
    // Plate interface to base alignment holes and notches
    
    BaseWidthInner = PlateWidthMin;
    BaseWidthOuter = CaseOverallWidth;
    BaseLength = CaseOverallHeight;					// perpendicular to battery surface
    BaseThick = IntegerMultiple(1.0,ThreadThick);	// minimum sheet thickness below teeth
    BaseWidthTaper = 5.0;							// ramp across entire width
    
    BaseOpeningMax = 43.0;
    BaseOpeningMin = 33.0;
    BaseOpeningY = 5.3;
    BaseOpeningDepth = IntegerMultiple(2.25,ThreadThick);
    
    BaseTotalThick = BaseThick + BaseOpeningDepth;
    echo("Base min thick: ",BaseThick," total: " ,BaseTotalThick);
    
    BaseTabWidth = 6.0;
    BaseTabThick = 2.0;
    BaseTabGap = 7.0;
    BaseTabOC = BaseTabWidth + BaseTabGap;
    BaseToothSection = 3*BaseTabWidth + 2*BaseTabGap;
    
    BaseToothBase = 5.8;
    BaseToothTip = 2.8;
    BaseToothThick = 2.0;
    BaseToothAngle = atan(BaseOpeningDepth/0.6);
    BaseToothOC = BaseTabOC;
    
    WedgeAngle = atan(BaseWidthTaper/((BaseWidthOuter - BaseWidthInner)/2));
    
    BaseEndLip = ThreadThick;			// should be 0.25 mm or so
    BaseEndWidth = (PlateWidthMin - 3*BaseToothBase - 2*BaseToothTip)/2;
    BaseEndAngle = atan((BaseOpeningDepth - BaseEndLip)/BaseOpeningY);
    
    SwitchBody = [8.6,3.7,3.3];			// mode switch
    
    // Plate interface to HT battery latch, cables, and connectors
    
    TopThick = IntegerMultiple(5.5,ThreadThick);	// plate thickness for stiffness behind latch bar
    echo("Top plate thick: ",TopThick);
    
    DB9Recess = TopThick - 4.0;			// recess to max TT3 PCB clearance behind DB9 plate
    
    TabEngageLength = 1.6;				// tab engaging surface length
    TabWidth = 3.0;						//  ... width
    TabEngageHeight = 4.5;				//  ... above battery compartment floor
    TabHeight = 7.5;					// tab ramp top above battery compartment floor
    TabOC = 40.0;
    
    LatchBarWidth = 3.4;				// sliding latch mechanism (brass L stock)
    LatchBarDepth = 3.4;
    LatchBarThick = 0.35;
    
    echo(" ... minimum: ",TopThick - LatchBarDepth);
    
    SplitOffset = TT3Offset - 3.5;
    
    TopBevel = 1.0;						// bevel at top of battery compartment
    TopBevelAngle = 45;
    
    PinOffsetWidth = 2.5;				// choose to center in sides of case shell
    PinOffsetHeight = 13.5;				// above baseplate bottom
    PinDepth = 7.0;						// into case shell
    PinDia = 1.2;
    
    ShellLength = CaseOverallLength - BaseThick - TopThick;
    
    echo("Shell length: ",ShellLength);
    
    // Speaker-mic plug plate
    
    PlugBaseThick = 2.5;				// recess depth
    PlugFillThick = 3.0;				// outer plate thickness
    
    //----------------------
    // 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);
    }
    
    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);
    
    }
    
    //-------------------
    // Component parts
    
    //-----
    // TinyTrak3+ PCB and component envelope
    //	Some dimensions should feed into the case shell, but don't
    
    module TinyTrak3(Length = 1.0) {
    
    PCBThick = 1.6;
    PCBWide = 36.5;
    TopHigh = 9.5;
    TopWide = PCBWide - 1.5;
    BotHigh = 2.5;
    BotWide = 35.0;
    
    PCBx = PCBWide/2;
    PCBy = (PCBThick + HoleWindage)/2;
    URx = TopWide/2;
    URy = PCBy + TopHigh;
    LRx = BotWide/2;
    LRy = PCBy + BotHigh;
    
    linear_extrude(height=Length,center=false,convexity=2) {
    	polygon(points=[[URx,URy],[URx,PCBy],[PCBx,PCBy],[PCBx,-PCBy],[LRx,-PCBy],[LRx,-LRy],
    					[-LRx,-LRy],[-LRx,-PCBy],[-PCBx,-PCBy],[-PCBx,PCBy],[-URx,PCBy],[-URx,URy]
    				   ]);
    }
    }
    
    //-----
    // Interface PCB and component envelope
    //	Some dimensions should feed into the case shell, but don't
    
    module AudioInterface(Length = 1.0) {
    
    PCBThick = 2.0;
    PCBWide = 49.5;
    TopHigh = 9.0 + Protrusion;
    TopWide = 46.0;
    BotHigh = 3.0;
    BotWide = 44.0;
    
    PCBx = PCBWide/2;
    PCBy = (PCBThick + HoleWindage)/2;
    URx = TopWide/2;
    URy = PCBy + TopHigh;
    LRx = BotWide/2;
    LRy = PCBy + BotHigh;
    
    linear_extrude(height=Length,center=false,convexity=2) {
    	polygon(points=[[URx,URy],[URx,PCBy],[PCBx,PCBy],[PCBx,-PCBy],[LRx,-PCBy],[LRx,-LRy],
    					[-LRx,-LRy],[-LRx,-PCBy],[-PCBx,-PCBy],[-PCBx,PCBy],[-URx,PCBy],[-URx,URy]
    				   ]);
    }
    }
    
    //-----
    // DB-9 (DE-9) panel opening
    // http://www.interfacebus.com/Connector_D-Sub_Mechanical_Dimensions.html
    //  DB-9 shell mounts on outside surface of case
    // This is for the solder terminal side
    
    module DSubMin9(Length = 1.0) {
    
    Holex = 0.984/2 * inch;
    HoleDia = Tap4_40;
    
    URx = 0.769/2 * inch;
    URy = 0.432/2 * inch;
    
    	linear_extrude(height=Length,center=false,convexity=3) {
    	  polygon(points=[[URx,URy],[URx,-URy],[-URx,-URy],[-URx,URy]]);
    	  for (x = [-1,1]) {
    		translate([x*Holex,0,0])
    		  rotate(45) circle(r=(HoleDia + HoleWindage)/2,$fn=4);
    	  }
    	}
    
    }
    
    //-----
    // Central case shape
    //	This *should* depend directly on the circuit board sizes, but doesn't
    //	The "Offset" parameters attempt to bottle up all the board sizes
    //	Support in LED window must be hand-fit to work correctly... and isn't needed!
    
    module CaseShell(Length=(ShellLength),Holes="true") {
    
    // Polygon coordinates are in XY plane
    
    URx = 40.0/2;
    URy = CaseOverallHeight;
    
    MRx = CaseOverallWidth/2;
    MRy = 15.0;
    
    LRx = CaseOverallWidth/2;
    LRy = (LRx - PlateWidthMin/2)*tan(PlateAngle);
    
    BRx = PlateWidthMax/2;
    BRy = PlateThick - 0*Protrusion;
    
    PRx = PlateWidthMin/2;				// combined battery plate
    PRy = 0;
    
    ScrewOffset = 20.0;					// from top end of case
    
    LEDWindow = [26.0,5.0,6];			// with case aligned vertically
    LEDOffset = [15,URy,(Length + TopThick - 25.0)];
    
    TrimPot1 = [-14,TT3Offset,(Length + TopThick - 30)];
    TrimPot2 = [-14,TT3Offset,(Length + TopThick - 37.5)];
    
    HTCableDia = 3.5;
    HTCableOffset = AudioOffset + HTCableDia/2 + 1.0;
    
    rotate([90,0,180])
    	union() {
    	  difference() {
    
    		  linear_extrude(height=Length,center=false,convexity=5)
    			polygon(points=[[URx,URy],[MRx,MRy],[LRx,LRy],[BRx,BRy],[PRx,PRy],
    							[-PRx,PRy],[-BRx,BRy],[-LRx,LRy],[-MRx,MRy],[-URx,URy]]);
    
    		if (Holes) {
    		  translate([0,AudioOffset,-Protrusion])
    			AudioInterface(Length + 2*Protrusion);
    
    		  translate([0,TT3Offset,-Protrusion])
    			TinyTrak3(Length + 2*Protrusion);
    
    		  for (y = [TT3Offset,AudioOffset])
    			translate([-CaseOverallWidth,y,(Length - ScrewOffset)])
    			  rotate([0,90,0])
    				rotate(0)					// Z rotation puts point upward for printing
    				PolyCyl(Tap4_40,CaseOverallWidth);
    
    		  translate(LEDOffset)
    			rotate([90,90,0])
    			  translate([-LEDWindow[0]/2,-LEDWindow[1]/2,-Protrusion])
    			  cube(LEDWindow,center=false);
    
    		  for (p = [TrimPot1,TrimPot2])
    			translate(p)
    			  rotate([-90,90,0])				// Y rotation puts point upward for printing
    				PolyCyl(3.0,URy);
    
    		  for (x=[-1,1]) {
    			translate([x*(CaseOverallWidth/2 - PinOffsetWidth),
    					  PinOffsetHeight,
    					  (Length - PinDepth)])
    			  rotate(45)						// align hole sides with case sides
    				  PolyCyl(PinDia,2*TopThick);
    			translate([x*(CaseOverallWidth/2 - PinOffsetWidth),
    					  PinOffsetHeight,
    					  -PlateThick])
    			  rotate(45)						// align hole sides with case sides
    				  PolyCyl(PinDia,(PlateThick + PinDepth));
    		  }
    
    		  for (x=[-1,1])						// setscrews to secure base plate
    			translate([x*(CaseOverallWidth/2 - 3*Tap4_40),
    					  TT3Offset,-Protrusion])
    			  rotate(360/(5*4))
    				PolyCyl(Tap4_40,2*TopThick);
    
    		  translate([-(ContactGapX/2 + ContactDia/2),0,(Contact1Y + ContactDia/2)])
    			rotate([90,0,0])
    			  Contact();
    		  translate([+(ContactGapX/2 + ContactDia/2),0,(Contact2Y + ContactDia/2)])
    			rotate([90,0,0])
    			  Contact();
    
    		  translate([CaseOverallWidth/2,HTCableOffset,(Length - HTCableDia/4)])
    			rotate([0,90,0])
    			  cube([(HTCableDia/2 + Protrusion),HTCableDia,CaseOverallWidth],center=true);
    		  translate([0,HTCableOffset,(Length - HTCableDia/2)])
    			rotate([0,90,0])
    			  cylinder(r=(1/cos(30))*HTCableDia/2,h=CaseOverallWidth,$fn=6);
    		}
    	  }
    
    if (false)
    	  if (Holes)
    		translate(LEDOffset)						// support plug in LED window
    		  rotate([90,90,0])
    			translate([-0.95*LEDWindow[0]/2,-0.80*LEDWindow[1]/2,ThreadWidth/2])
    			  cube([0.95*LEDWindow[0],0.80*LEDWindow[1],2*ThreadWidth],center=false);
    
    	}
    
    }
    
    //-----
    // Battery contact recess
    //  This gets subtracted from the bottom plate in two places
    // 	Align points to print upward
    
    module Contact() {
    
    if (true)
    union() {													// vertical printing with case
    	translate([0,0,-(ContactRecess + Protrusion)/2])
    	  PolyCyl(ContactDia,(ContactRecess + Protrusion),8);
    	translate([0,0,-(PlateThick + Protrusion)])
    	  rotate(60/2)
    	  PolyCyl(ContactStudDia,PlateThick,6);
    	translate([0,0,-(ContactRecess + ContactStudHeadThick/3)])
    	  PolyCyl(ContactStudHead,ContactStudHeadThick,8);				// allow for solder blob
    }
    else
    union() {												// horizontal printing alone
    	translate([0,0,-(ContactRecess - Protrusion)/2])
    	  PolyCyl(ContactDia,(ContactRecess + Protrusion),8);
    	translate([0,0,-(PlateThick + Protrusion)])
    	  PolyCyl(ContactStudDia,(PlateThick + 2*Protrusion));
    	translate([0,0,-(ContactRecess + ContactStudHeadThick/3)])
    	  PolyCyl(ContactStudHead,ContactStudHeadThick,8);				// allow for solder blob
    }
    
    }
    
    //-----
    // Radio bottom locating feature
    //  This polygon gets subtracted from the battery pack base
    
    module RadioBase() {
    
    linear_extrude(height=(BaseOpeningDepth + Protrusion),center=false,convexity=5)
    polygon(points=[
    			[-BaseOpeningMax/2,-Protrusion],
    
    			[-BaseOpeningMin/2,BaseOpeningY],
    			[-(BaseToothOC/2 + BaseToothBase/2),BaseOpeningY],
    
    			[-(BaseToothOC/2 + BaseToothTip/2),(BaseOpeningY - BaseToothThick)],
    			[-(BaseToothOC/2 - BaseToothTip/2),(BaseOpeningY - BaseToothThick)],
    			[-(BaseToothOC/2 - BaseToothBase/2),BaseOpeningY],
    
    			[ (BaseToothOC/2 - BaseToothBase/2),BaseOpeningY],
    			[ (BaseToothOC/2 - BaseToothTip/2),(BaseOpeningY - BaseToothThick)],
    			[ (BaseToothOC/2 + BaseToothTip/2),(BaseOpeningY - BaseToothThick)],
    			[ (BaseToothOC/2 + BaseToothBase/2),BaseOpeningY],
    			[ BaseOpeningMin/2,BaseOpeningY],
    
    			[ BaseOpeningMax/2,-Protrusion],
    
    			[ (BaseTabOC + BaseTabWidth/2),-Protrusion],
    			[ (BaseTabOC + BaseTabWidth/2),BaseTabThick],
    			[ (BaseTabOC - BaseTabWidth/2),BaseTabThick],
    			[ (BaseTabOC - BaseTabWidth/2),-Protrusion],
    
    			[ BaseTabWidth/2,-Protrusion],
    			[ BaseTabWidth/2,BaseTabThick],
    			[-BaseTabWidth/2,BaseTabThick],
    			[-BaseTabWidth/2,-Protrusion],
    
    			[-(BaseTabOC + BaseTabWidth/2),-Protrusion],
    			[-(BaseTabOC + BaseTabWidth/2),BaseTabThick],
    			[-(BaseTabOC - BaseTabWidth/2),BaseTabThick],
    			[-(BaseTabOC - BaseTabWidth/2),-Protrusion],
    		  ],
    		  convexity=5
    );
    }
    
    //-----
    // Battery pack base
    
    module Base() {
    
    difference() {
    
    	rotate([-90,180,0])						// main case shape
    	  CaseShell(BaseTotalThick,false);
    
    	translate([0,0,BaseThick])				// radio base interface
    	  RadioBase();
    
    	translate([0,0,BaseThick])				// tooth bevel
    	  rotate([(-90 + BaseToothAngle),0,0])
    		translate([0,-0.5,0])
    		  cube([(BaseToothSection + 2*Protrusion),1.0,10],center=true);
    
    	translate([-BaseWidthOuter,				// surface slope
    			  -(BaseThick + BaseEndLip)/tan(BaseEndAngle),0])
    	  rotate([BaseEndAngle,0,0])
    		difference() {
    		  cube([2*BaseWidthOuter,3*BaseOpeningY,BaseOpeningDepth],center=false);
    		  translate([(BaseWidthOuter - (BaseToothSection + 2*Protrusion)/2),0,0])
    			cube([(BaseToothSection + 2*Protrusion),1.2*BaseOpeningY,BaseOpeningDepth],center=false);
    		}
    
    	for (x=[-1,1])							// alignment pin holes
    	  translate([x*(CaseOverallWidth/2 - PinOffsetWidth),PinOffsetHeight,-Protrusion])
    		rotate(45)							// align hole side with plate side
    		  PolyCyl(PinDia,2*TopThick);
    
    	for (x=[-1,1])							// mounting setscews
    	  translate([x*(CaseOverallWidth/2 - 3*Tap4_40),
    				TT3Offset,-Protrusion])
    		rotate(-360/(-5*4))
    		  PolyCyl(Tap4_40,2*TopThick);
    
    	translate([(-SwitchBody[0]/2),TT3Offset,-SwitchBody[2]/2])	// mode switch
    	  scale([1,1,2])
    		cube(SwitchBody);
    
    }
    }
    
    //-----
    // Top plate with latch
    //	Split around TinyTrak3 serial connector
    //	 ... which must be at the same height as in the shell!
    //	The cable hole sizes & locations are entirely ad-hoc
    
    module TopPlate() {
    
    Cable1Dia = 5.0;
    Cable2Dia = 5.0;
    CableHoleLength = TopThick + 2*Protrusion;
    CableHoleZ = -Protrusion;
    
    DB9Plate = [32.0,13.5,1.25];					// plate surrounding connector body
    
    difference() {
    
    	rotate([-90,180,180])
    	  CaseShell(TopThick,false);
    
    	translate([0,-TT3Offset,-Protrusion])
    	  DSubMin9(TopThick + 2*Protrusion);
    
    	translate([0,-TT3Offset,(TopThick - DB9Plate[2]/2)])
    	  cube([DB9Plate[0],DB9Plate[1],(DB9Plate[2] + Protrusion)],center=true);
    
    	translate([-CaseOverallWidth,-SplitOffset,-2*Protrusion])		// split the plate
    	  cube([2*CaseOverallWidth,4*Protrusion,(TopThick + 2*Protrusion)]);
    
    	translate([0,0,(TopThick - TopBevel)])
    	  rotate([-TopBevelAngle,0,0])
    		translate([-CaseOverallWidth,-TopThick,0])
    		  cube([2*CaseOverallWidth,2*TopThick,2*TopThick],center=false);
    
    	for (x=[-1,1])
    	  translate([(x*TabOC/2),
    				(-TabHeight/2 + Protrusion),
    				(TopThick - TabEngageLength/2 + Protrusion/2)])
    		rotate([90,0,0])
    		  cube([TabWidth,
    				(TabEngageLength + Protrusion),
    				(TabHeight + Protrusion)],center=true);
    
    	translate([-CaseOverallWidth,
    			  -(TabEngageHeight + LatchBarWidth - BatteryClearance),
    			  (TopThick - LatchBarDepth)])
    	  cube([2*CaseOverallWidth,(LatchBarWidth + LatchBarThick),(LatchBarDepth + Protrusion)]);
    
    	for (x=[-1,1])
    	  translate([(x*CaseOverallWidth/4),
    				-(TabEngageHeight + LatchBarWidth + Clear2_56/2 - BatteryClearance + Protrusion),
    				0]) {
    		translate([0,0,-Protrusion])
    		  rotate(45)						// align sides with slot
    			PolyCyl(Tap2_56,(TopThick + 2*Protrusion));
    		translate([0,0,(TopThick - LatchBarDepth)])
    		  rotate(60)						// align sides with slot
    			PolyCyl((Head2_56 + Protrusion),TopThick,6);		// extra extra clearance
    	  }
    
    	for (x=[-1,1])
    	  translate([x*(CaseOverallWidth/2 - PinOffsetWidth),-PinOffsetHeight,-Protrusion])
    		rotate(45)						// align hole side with plate side
    		  PolyCyl(PinDia,2*TopThick);
    
    	for (x=[-1,1])						// coincidentally line up with latch tabs
    	  translate([(x*TabOC/2),-(SplitOffset - 3.0),-Protrusion])
    		scale([1,1.7,1])
    		  PolyCyl(Cable1Dia,CableHoleLength,6);
    }
    
    }
    
    //-----
    // Speaker-Mic plug mounting plate
    
    module PlugPlate() {
    
    JackOC = 11.20;						// 14.25 OD - (3.58 + 2.58)/2
    
    JackScrewDia = 4.6;
    JackScrewOffsetX = 1.00;
    JackScrewOffsetY = 5.25;			//  mounting screw to edge of lower recess
    
    PlugBaseWidth = 9.25;				// lower section of plate
    PlugBaseLength = 22.0;
    PlugBaseRadius = 1.75;
    
    Plug3Offset = 5.25;					// edge of base recess to 3.5 mm jack
    
    Plug2BezelDia = 7.1;				// 2.5 mm plug
    Plug2BezelThick = 1.04;
    Plug2ScrewDia = 6.0;
    Plug3ScrewLength = 3.0;
    
    Plug3BezelDia = 8.13;				// 3.5 mm plug
    Plug3BezelThick = 1.6;
    Plug3ScrewDia = 7.95;
    Plug3ScrewLength = 4.0;
    
    PlugFillOffsetX = JackScrewOffsetX - 0.5;		// base recess CL to fill CL
    PlugFillOffsetY = -10.5;				//  ... to edge of fill plate
    PlugFillWidth = 11.0;
    PlugFillLength = 34.00;
    PlugFillRadius1 = 1.5;
    PlugFillRadius2 = 4.5;
    
    PlugFillOffsetYTotal = 0;
    
    BaseX = PlugBaseWidth/2 - PlugBaseRadius;
    BaseY = PlugBaseLength/2 - PlugBaseRadius;
    
    difference() {
    	union() {
    	  linear_extrude(height=PlugBaseThick,center=false,convexity=3)
    		hull() {
    		  translate([-BaseX,-BaseY,0])
    			circle(r=PlugBaseRadius,$fn=8);
    		  translate([-BaseX, BaseY,0])
    			circle(r=PlugBaseRadius,$fn=8);
    		  translate([ BaseX, BaseY,0])
    			circle(r=PlugBaseRadius,$fn=8);
    		  translate([ BaseX,-BaseY,0])
    			circle(r=PlugBaseRadius,$fn=8);
    		}
    
    	  translate([PlugFillOffsetX,
    				(PlugFillLength/2 - PlugBaseLength/2 + PlugFillOffsetY),
    				PlugBaseThick])
    		linear_extrude(height=PlugFillThick,center=false,convexity=5)
    		  hull() {
    			translate([0,-(PlugFillLength/2 - PlugFillRadius2),0])
    			  circle(r=PlugFillRadius2,$fn=10);
    			translate([-(PlugFillWidth/2 - PlugFillRadius1),-PlugBaseLength/2,0])
    			  circle(r=PlugFillRadius1,$fn=8);
    			translate([-(PlugFillWidth/2 - PlugFillRadius1),
    					  (PlugFillLength/2 - PlugFillRadius1),0])
    			  circle(r=PlugFillRadius1,$fn=8);
    			translate([(PlugFillWidth/2 - PlugFillRadius1),
    					  (PlugFillLength/2 - PlugFillRadius1),0])
    			  circle(r=PlugFillRadius1,$fn=8);
    			translate([(PlugFillWidth/2 - PlugFillRadius1),-PlugBaseLength/2,0])
    			  circle(r=PlugFillRadius1,$fn=8);
    		  }
    	}
    
    	translate([0,-JackOC/2,-Protrusion])
    	  rotate(360/16) {
    		PolyCyl(Plug3BezelDia,(Plug3BezelThick + Protrusion),8);
    		PolyCyl(Plug3ScrewDia,(PlugBaseThick + PlugFillThick + 2*Protrusion),8);
    	  }
    
    	translate([0,+JackOC/2,-Protrusion])
    	  rotate(360/16) {
    		PolyCyl(Plug2BezelDia,(Plug2BezelThick + Protrusion),8);
    		PolyCyl(Plug2ScrewDia,(PlugBaseThick + PlugFillThick + 2*Protrusion),8);
    	  }
    
    	translate([JackScrewOffsetX,-(PlugBaseLength/2 + JackScrewOffsetY),0])
    	  PolyCyl(JackScrewDia,(PlugBaseThick + PlugFillThick + Protrusion));
    }
    
    }
    
    //-------------------
    // Build things...
    
    ShowPegGrid();
    
    if (Layout == "TT3")
    TinyTrak3();
    
    if (Layout == "Audio")
    AudioInterface();
    
    if (Layout == "DSub")
    DSubMin9();
    
    if (Layout == "Shell")
    CaseShell(CaseOverallLength);
    
    if (Layout == "Top")
    TopPlate();
    
    if (Layout == "Base")
    Base();
    
    if (Layout == "RadioBase")
    RadioBase();
    
    if (Layout == "PlugPlate")
    PlugPlate();
    
    if (Layout == "Contact")
    rotate([180,0,0])
    	Contact();
    
    if (Layout == "Show" || Layout == "Fit") {
    
    translate([0,-ShellLength/2,0]) {
    
    	translate([0,(Layout == "Show")?-ShowGap:0,0])
    	  rotate([90,0,0])
    		color("SandyBrown") Base();
    
    	translate([0,0,0])
    	    color("LightGreen") render() CaseShell();
    
    	translate([-(CaseOverallWidth/2 + 10),50,CaseOverallHeight/2])
    	  rotate([0,-90,0])
    		color("Gold") PlugPlate();
    
    	translate([0,((Layout == "Show")?(ShellLength + ShowGap):ShellLength),0])
    	  rotate([-90,0,0])
    		color("BurlyWood") TopPlate();
    }
    }
    
    if (Layout == "Build1") {
    
    translate([5 + CaseOverallHeight,0,0])
    	rotate([0,0,90])
    	  Base();
    
    translate([-(5 + CaseOverallHeight),0,0])
    	rotate(90)
    	  TopPlate();
    
    }
    
    if (Layout == "Build2") {
    
    translate([0,-CaseOverallHeight/2,ShellLength])
    	rotate([-90,0,0])
    		CaseShell();
    
    }
    
    if (Layout == "Build3") {
    
    translate([0,0,(PlugBaseThick + PlugFillThick)])
    	rotate([180,0,0])
    	  PlugPlate();
    
    }
    
  • Fundamental 3D Printing Patents

    DIY 3D printing seems surrounded by Good Ideas that don’t happen, which led me to look up some of the early patents in the field. As nearly as I can tell, any bright idea one might have has already been patented; although you can usually get away with tinkering it up in your basement (because you’re not worth enough to interest the patent holder’s attorneys), anything beyond that will darken your skies with lawsuits.

    The granddaddy of all 3D extrusion machines seems to be US5121329 (Crump → Stratasys 1992-06-09): Apparatus and method for creating three-dimensional objects

    Exploring the patents referencing that one as a foundation should keep you busy for a while; the PDF has clicky links.

    Some fine tuning on the theme:

    US6085957 (Zinniel/Batchelder → Stratasys): Volumetric feed control for flexible filament

    US5303141 (Batchelder/et al → IBM): Model generation system having closed-loop extrusion nozzle positioning

    Congealing 3D objects in a vat of goo probably starts with 4575330 (Hull → MVP 1986-03-11): Apparatus for production of three-dimensional objects by stereolithography

    Remember: I’m not a patent attorney and my opinion is worthless…

    US5121329 - Figure 1
    US5121329 – Figure 1
  • Wouxun KG-UV3D GPS Interface: PCB Component Envelopes

    This doodle just emerged from the heap:

    TT3 and Interface PCB keepout dimensions
    TT3 and Interface PCB keepout dimensions

    It gives the envelope dimensions for the two PCBs in the quasi-extruded GPS interface case:

    HT-GPS Case - Trial fit - rear view
    HT-GPS Case – Trial fit – rear view

    The overall idea was to subtract the envelopes from the interior of the solid case and print the shell:

    HT-GPS Adapter Case - end view
    HT-GPS Adapter Case – end view

    Surprisingly, after minimal cleanout, the PCBs pretty much just slid into place and the setscrews locked them down.

    Now I can throw out that scrap of paper…

    The OpenSCAD source has the gory details; the actual dimensions don’t quite match the doodle, but that’s in the nature of fine tuning.

  • Quilting Pin Caps

    Mary has been quilting up a storm lately and is growing dissatisfied with the special safety pins she’s been using to hold the layers together. Long straight pins are ideal, except that maneuvering a large quilt through her sewing machine resembles stuffing a porcupine into a keyhole. A commercial solution costs nearly half a buck per pin, which seems unreasonably spendy for something you need by the hundreds.

    We kicked around some finger- and quilt-friendly dimensions and I cobbled up a solid model:

    Quilting Pin Cap
    Quilting Pin Cap

    Which turned into an array of small octagons that won’t roll off the table:

    Pin cap array on build platform
    Pin cap array on build platform

    We figured 25 would be enough to decide if this is workable and whether the dimensions fit fingers, pins, and quilts.

    Filling them with silicone rubber required one squirt each:

    Filling pin caps with silicone
    Filling pin caps with silicone

    The trick with the silicone rubber is to cut the snout so it fits flat on the cylinder top. Put the cylinders on a piece of non-stick paper (I used the back of the carrier for some double-sided tape, but wax paper would be better), hold one with tweezers, squirt in enough rubber to fill the cylinder solidly from bottom to top, then slide the snout sideways to smooth the surface.

    Wait for a day, pop them off, and remove any drool:

    Silicone-filled pin caps
    Silicone-filled pin caps

    It’s garden planting time right now, so it’ll take a while before I tweak the design and run off the next batch.

    I don’t know how to compute an actual cost for each of those things. I regard the entire Thing-O-Matic as fully depreciated and pretty much a sunk cost, which means the expense boils down to the incremental cost of plastic and silicone. All the Quality Shop Time is, of course, free… and maybe even therapeutic.

    The (trivially simple) OpenSCAD source code:

    // Quilting pin caps
    // Ed Nisley KE4ZNU April 2012
    
    //- Extrusion parameters must match reality!
    //  Print with +1 shells and 3 solid layers
    
    ThreadThick = 0.25;
    ThreadWidth = 2.0 * ThreadThick;
    
    HoleWindage = 0.2;
    
    function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
    
    Protrusion = 0.1;			// make holes end cleanly
    
    //----------------------
    // Dimensions
    
    ID = 5.0;
    OD = ID + 2*ThreadWidth;
    Length = 5.0;
    Sides = 8;
    
    //----------------------
    // 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);
    }
    
    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);
    
    }
    
    //----------------------
    // Build them!
    
    ShowPegGrid();
    
      rotate(180/Sides) {
    	difference() {
    	  PolyCyl(OD,Length,8);
    	  translate([0,0,-Protrusion])
    		PolyCyl(ID,(Length + 2*Protrusion),8);
    	}
      }
    
  • Replacement Oven Drawer Supports

    One of the oven drawer supports in our Sears Kenmore gas range cracked and I finally got around to replacing it:

    Cracked oven drawer slide and replacement
    Cracked oven drawer slide and replacement

    I originally thought the drawer slid on the large, blocky, well-supported lump. Nope, that delicate little tab must support half the weight of the drawer; the lump might support the drawer in another oven. Perhaps we shouldn’t store the Lesser and Least Cast Iron Pans in that drawer, but that’s where they fit best. The Greater Cast Iron Pan lives atop the stove, because it get used so often there’s no point in putting it away.

    One could, of course, Fire the Thing-O-Matic! to print brightly colored plastic bits (after the usual tedious 3D modeling & trial fitting), but replacement parts cost a buck each from RepairPartsDirect. I bought three, so as to have a complete backup set, and most of the $9 total went to postage & handling.

    Done!

  • Wouxun KG-UV3D GPS Interface: First Light

    The robust wire I  used for the external battery connection required a bit of diagonal cutter work to enlarge the hole in the top plate, but eventually everything fit together and the GPS interface box latched neatly onto the radio:

    HT-GPS Case - cabled top view
    HT-GPS Case – cabled top view

    The skein of cables:

    • Antenna: reverse SMA to UHF adapter = RG58 coax
    • GPS: TTL serial data from Byonics GPS2 receiver = DB-9 (OK, DE-9)
    • Helmet: mic + earbud = repurposed USB cable
    • PTT: 3.5 mm jack = repurposed audio cable
    • External power: 18 gauge zip cord + Powerpoles = repurposed speaker cable

    All in all, it looks pretty good:

    HT-GPS Case - cabled and powered
    HT-GPS Case – cabled and powered

    After a few rides to verify that this whole affair works, I must print up another case with slightly modified dimensions, add a plastic window over those cheerful LEDs on the TinyTrak3+ board, and mush an epoxy putty blob over the earphone and mic connections on that bright yellow plug plate. I’ve given up on the idea of having a cover for the top part of the battery compartment; there just isn’t enough space for such a thing and it’d be an impossibly delicate shell.

    The radio seems happy enough being fed 9 V from a bench supply (to match the upconverted lithium packs I’ve been using on the bikes), rather than 7.4 V from its standard lithium pack. A freshly charged battery comes pretty close to 9 V, so they can’t be too fussy. It idles at about 100 mA, with periodic blips to 140 mA when (I think) the TinyTrak3+ tickles the GPS receiver, regardless of the supply voltage. Goosing it with 13.8 V surely wouldn’t have a happy outcome…

    Lashed up like that on the bench, with the GPS receiver hanging out the basement window and the coax hitched to a bicone scanner antenna sitting inside the window, it generated APRS spots and the audio sounds OK, so the innards look good, too.

    2012-04-11 20:09:08 EDT: KE4ZNU-9>APT311,WA2YSM-15,WIDE1*,WIDE2-1,qAR,K2MHV-6:>Ed - Bike PL100 UV3D
    

    One downside: the TinyTrak3+ blurts its initial ID message instantly after being powered on, but the radio takes a few seconds to haul itself to its feet. As a result, the ID message never reaches the antenna. So it goes…

  • Wouxun KG-UV3D GPS Interface: Radio Power Contacts

    After considerable stalling, I filed the heads of two brass 4-40 screws down to about 1 mm, leaving just a hint of the slots in place. They’re a bit over 5 mm in diameter, smaller than the 7 mm I wanted to use, but have the compelling advantage of being Close Enough to get the rest of the hardware working. The gap between the interface PCB and the case is 3 mm, which turns out to be just about exactly the thickness of a 4-40 nut and flat washer, so I soldered a pair of them together as threaded spacers:

    HT-GPS Case - radio battery contacts
    HT-GPS Case – radio battery contacts

    The soldering looks worse than it really is; they’re secured all the way around.

    For the external battery connectors on the top, I ran a #33 drill through a pair of miniature crimp ring lugs to get a slip fit, then soldered them atop a pair of nickel-plated nuts. In normal use they’d be captured by the nuts, but I can’t figure out how to assemble them inside the case:

    HT-GPS Case - external power lugs
    HT-GPS Case – external power lugs

    Those are stainless steel 4-40 screw cutoffs, which I used because solder doesn’t adhere to stainless… I tinned the nuts and connectors, clamped the screws in a small vise, heated the nuts with a soldering iron, and applied the contacts with a tweezer. They snapped right into place and the solder fillet wrapped neatly around the entire lug.

    The heat from the soldering iron relaxed the insulator sleeves enough to remove nearly all trace of the crimping.

    With all that in hand, I ran the brass screws through the case, into the spacer nut+washer combo, through the PCB, and into the battery contact nuts. A bit of tedious pliers work snugged the screws and got everything lined up, then I tightened the spacers against the PCB and battery nuts on the other side. That’s completely invisible inside the case, so there aren’t any pictures, but the idea is that the studs sit flush inside their case recesses and clamping the PCB between the nuts shouldn’t put any stress on the PCB. We shall see.

    HT-GPS Case - radio contacts in place
    HT-GPS Case – radio contacts in place

    The slots became so shallow that a screwdriver doesn’t get any traction…