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OpenSCAD source code: Loop Antenna splice block
// Ribbon cable loop antenna splice
// Ed Nisley KE4ZNU December 2016
Layout = "Text";
//- Extrusion parameters must match reality!
ThreadThick = 0.25;
ThreadWidth = 0.40;
HoleWindage = 0.2;
Protrusion = 0.1; // make holes end cleanly
inch = 25.4;
function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);
//----------
// Dimensions
Cable = [200,48.0,1.5]; // X = longer than anything else
Splice = [15.0,53.0,5.0]; // epoxy blob around joints
Foam = [15.0,Splice[1],2.0];
CornerRadius = 5.0;
ID = 0;
OD = 1;
LENGTH = 2;
Insert = [3.9,4.6 - 0.1,5.8]; // 4-40 knurled brass insert
Screw = [2.7,5.5,2.0]; // OD = head LENGTH = head thickness
Washer = [3.0,8.0,0.8];
BlockOA = [60.0, // convenient length
Splice[1] + 4*Washer[OD], // clearance around washer on top
2*(Insert[LENGTH] + 2*ThreadThick)]; // insert sets both thicknesses
NumScrews = 2; // screws along each side of cable
ScrewOC = [BlockOA[0] / NumScrews,
BlockOA[1] - 2*Washer[OD],
2*BlockOA[2] // ensure complete holes
];
TextThick = 3*ThreadThick; // depth of text into surface
TextFit = HoleWindage/2; // clearance around text polygons
//----------------------
// 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(d=(FixDia + HoleWindage),h=Height,$fn=Sides);
}
//-----
// Blocky model of cable + splice + wire tap for subtraction
module Antenna() {
union() {
cube(Cable,center=true);
cube(Splice,center=true);
for (i=[-1,1])
translate([0,-Splice[1]/2,0])
cube([Splice[0]/2,Splice[1],2*Foam[2]],center=true);
}
}
// Outside shape of splice Block, less screw clearance
module SpliceBlock() {
difference() {
hull()
for (i=[-1,1], j=[-1,1])
translate([i*(BlockOA[0]/2 - CornerRadius),j*(BlockOA[1]/2 - CornerRadius),-BlockOA[2]/2])
cylinder(r=CornerRadius,h=BlockOA[2],$fn=4*8);
for (i = [0:NumScrews - 1], j=[-1,1])
translate([-BlockOA[0]/2 + ScrewOC[0]/2 + i*ScrewOC[0],j*ScrewOC[1]/2,-(BlockOA[2]/2 + Protrusion)])
PolyCyl(Screw[ID],BlockOA[2] + 2*Protrusion,6);
}
}
// Splice block less cable
module ShapedBlock() {
difference() {
SpliceBlock();
Antenna();
}
}
// Bottom
module BottomPlate() {
difference() {
ShapedBlock();
translate([0,0,BlockOA[2]/2])
cube(BlockOA + 2*[Protrusion,Protrusion,0],center=true);
Antenna(Splice);
for (i = [0:NumScrews - 1], j=[-1,1])
translate([-BlockOA[0]/2 + ScrewOC[0]/2 + i*ScrewOC[0],j*ScrewOC[1]/2,-(BlockOA[2]/2 + Protrusion)])
PolyCyl(Insert[OD],2*Insert[LENGTH],6);
for (i=[-1,1])
translate([i*((BlockOA[0] - Foam[0] + Protrusion)/2),0,(BlockOA[2]/2 - Cable[2]/2 - Foam[2])])
cube([Foam[0] + Protrusion,Foam[1],BlockOA[2]],center=true);
}
}
// Top
module TopPlate() {
difference() {
ShapedBlock();
translate([0,0,-BlockOA[2]/2])
cube(BlockOA + 2*[Protrusion,Protrusion,0],center=true);
Antenna(Splice);
for (i=[-1,1])
translate([i*((BlockOA[0] - Foam[0] + Protrusion)/2),0,-(BlockOA[2]/2 - Cable[2]/2 - Foam[2])])
cube([Foam[0] + Protrusion,Foam[1],BlockOA[2]],center=true);
rotate(90) {
translate([0,6,BlockOA[2]/2 - TextThick])
TextHack("KE4ZNU",8,0.0,1.15,TextThick + Protrusion);
translate([0,-6,BlockOA[2]/2 - TextThick])
TextHack("2016·12",6,0.0,1.20,TextThick + Protrusion);
}
}
}
module TextHack(Text="sample",Size=10,Offset=0.0,Space=1.0,Thick=ThreadThick) {
linear_extrude(height=Thick,convexity=10)
offset(r=Offset)
text(Text,font=":bold",size=Size,spacing=Space,halign="center",valign="center");
}
//----------
// Build them
if (Layout == "Antenna")
Antenna();
if (Layout == "SpliceBlock")
SpliceBlock();
if (Layout == "ShapedBlock")
ShapedBlock();
if (Layout == "Bottom")
BottomPlate();
if (Layout == "Top")
TopPlate();
if (Layout == "Text") {
translate([0,6,0])
TextHack("KE4ZNU",8,-TextFit,1.15,TextThick);
translate([0,-6,0])
TextHack("2016·12",6,-TextFit,1.20,TextThick);
}
if (Layout == "Show") {
translate([0,0,5])
TopPlate();
translate([0,0,-5])
BottomPlate();
color("Orange",0.2)
Antenna();
}
if (Layout == "Build") {
translate([0,-0.6*BlockOA[1],BlockOA[2]/2])
rotate([180,0,0])
TopPlate();
translate([0,0.6*BlockOA[1],BlockOA[2]/2])
BottomPlate();
}
@ednisley

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ednisley commented Dec 20, 2016

More details on my blog at http://wp.me/poZKh-6ng

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