OpenSCAD Source Code: Square Chain Mail Armor

Chain Mail Square Armor.scad

// Chain Mail Armor Buttons
// Ed Nisley KE4ZNU - December 2014

Layout = "Build";			// Link Button LB Joiner Joiners Build PillarMod

//-------
//- Extrusion parameters must match reality!
//  Print with 1 shell and 2+2 solid layers

ThreadThick = 0.25;
ThreadWidth = 0.40;

HoleWindage = 0.2;

Protrusion = 0.1; 				// make holes end cleanly

function IntegerMultiple(Size,Unit) = Unit * ceil(Size / Unit);

//-------
// Dimensions

//- Set maximum sheet size

SheetSizeX = 125;	// 170 for full sheet on M2
SheetSizeY = 125;	// 230 ...

//- Diamond or rectangular sheet?

Diamond = false;					// true = rotate 45 degrees, false = 0 degrees for square

BendAround = "X";					// X or Y = maximum flexibility *around* designated axis

Cap = true;										// true = build bridge layers over links
CapThick = 4 * ThreadThick;						// flat cap on link: >= 3 layers for solid bridging

Armor = true && Cap;							// true = build armor button atop (required) cap
ArmorThick = IntegerMultiple(2.0,ThreadThick);	// height above cap surface

ArmorSides = 4;
ArmorAngle = true ? 180/ArmorSides : 0;			// true -> rotate half a side for best alignment

//- Link bar sizes

BarThick = 3 * ThreadThick;
BarWidth = 3.3 * ThreadWidth;

BarClearance = 3 * ThreadThick;		// vertical clearance above & below bars

VertexHack = false;						// true to slightly reduce openings to avoid coincident vertices

//- Compute link sizes from those values

//- Absolute minimum base link: bar width + corner angle + build clearance around bars
//  rounded up to multiple of thread width to ensure clean filling
BaseSide = IntegerMultiple((4*BarWidth + 2*BarWidth/sqrt(2) + 3*(2*ThreadWidth)),ThreadWidth);

BaseHeight = 2*BarThick + BarClearance;           // both bars + clearance

echo(str("BaseSide: ",BaseSide," BaseHeight: ",BaseHeight));
//echo(str(" Base elements: ",4*BarWidth,", ",2*BarWidth/sqrt(2),", ",3*(2*ThreadWidth)));
//echo(str(" total: ",(4*BarWidth + 2*BarWidth/sqrt(2) + 3*(2*ThreadWidth))));

BaseOutDiagonal = BaseSide*sqrt(2) - BarWidth;
BaseInDiagonal = BaseSide*sqrt(2) - 2*(BarWidth/2 + BarWidth*sqrt(2));

echo(str("Outside diagonal: ",BaseOutDiagonal));

//- On-center distance measured along coordinate axis
//   the links are interlaced, so this is half of what you think it should be...

LinkOC = BaseSide/2 + ThreadWidth;

LinkSpacing = Diamond ? (sqrt(2)*LinkOC) : LinkOC;
echo(str("Base spacing: ",LinkSpacing));

//- Compute how many links fit in sheet

MinLinksX = ceil((SheetSizeX - (Diamond ? BaseOutDiagonal : BaseSide)) / LinkSpacing);
MinLinksY = ceil((SheetSizeY - (Diamond ? BaseOutDiagonal : BaseSide)) / LinkSpacing);
echo(str("MinLinks X: ",MinLinksX," Y: ",MinLinksY));

NumLinksX = ((0 == (MinLinksX % 2)) && !Diamond) ? MinLinksX + 1 : MinLinksX;
NumLinksY = ((0 == (MinLinksY % 2) && !Diamond)) ? MinLinksY + 1 : MinLinksY;
echo(str("Links X: ",NumLinksX," Y: ",NumLinksY));

//- Armor button base

ButtonHeight = BaseHeight + BarClearance + CapThick;
echo(str("ButtonHeight: ",ButtonHeight));

//- Armor ornament size & shape
//	 Fine-tune OD & ID to suit the number of sides...

TotalHeight = ButtonHeight + ArmorThick;
echo(str("Overall Armor Height: ",TotalHeight));

ArmorOD = 1.0 * BaseSide;						// tune for best base fit
ArmorID = 10 * ThreadWidth;						// make the tip blunt & strong

//-------

module ShowPegGrid(Space = 10.0,Size = 1.0) {

  RangeX = floor(95 / Space);
  RangeY = floor(125 / Space);

	for (x=[-RangeX:RangeX])
	  for (y=[-RangeY:RangeY])
		translate([x*Space,y*Space,Size/2])
		  %cube(Size,center=true);

}


//-------
// Create link with armor button as needed

module Link(Topping = false) {
	
LinkHeight = (Topping && Cap) ? ButtonHeight : BaseHeight;

render(convexity=3)
rotate((BendAround == "X") ? 90 : 0)
	rotate(Diamond ? 45 : 0)
		union() {
			difference() {
				translate([0,0,LinkHeight/2])									// outside shape
					intersection() {
						cube([BaseSide,BaseSide,LinkHeight],center=true);
						rotate(45)
							cube([BaseOutDiagonal,BaseOutDiagonal,(LinkHeight + 2*Protrusion)],center=true);
					}
	
				translate([0,0,(BaseHeight + BarClearance + 0*ThreadThick - Protrusion)/2])
					intersection() {											// inside shape
						cube([(BaseSide - 2*BarWidth),
								(BaseSide - 2*BarWidth),
								(BaseHeight + BarClearance + 0*ThreadThick + (VertexHack ? Protrusion/2 : 0))],
								center=true);
						rotate(45)
							cube([BaseInDiagonal,
									BaseInDiagonal,
									(BaseHeight + BarClearance + 0*ThreadThick + (VertexHack ? Protrusion/2 : 0))],
									center=true);
					}

				translate([0,0,((BarThick + 2*BarClearance)/2 + BarThick)])		// openings for bars
					cube([(BaseSide - 2*BarWidth - 2*BarWidth/sqrt(2) - (VertexHack ? Protrusion/2 : 0)),
						(2*BaseSide),
						BarThick + 2*BarClearance - Protrusion],
						center=true);
					
				translate([0,0,(BaseHeight/2 - BarThick)])
					cube([(2*BaseSide),
						(BaseSide - 2*BarWidth - 2*BarWidth/sqrt(2) - (VertexHack ? Protrusion/2 : 0)),
						BaseHeight],
						center=true);
					
			}

 			if (Topping && Armor)
				translate([0,0,(ButtonHeight - Protrusion)])		// sink slightly into the cap
					rotate(ArmorAngle)
					cylinder(d1=ArmorOD,d2=ArmorID,h=(ArmorThick + Protrusion), $fn=ArmorSides);
		}

}


//-------
// Create split buttons to join sheets

module Joiner() {
	
	translate([-LinkSpacing,0,0])
		difference() {
			Link(false);
			translate([0,0,BarThick + BarClearance + TotalHeight/2 - Protrusion])
				cube([2*LinkSpacing,2*LinkSpacing,TotalHeight],center=true);
		}
		
	translate([LinkSpacing,0,0])
		intersection() {
			translate([0,0,-(BarThick + BarClearance)])
				Link(true);
			translate([0,0,TotalHeight/2])
				cube([2*LinkSpacing,2*LinkSpacing,TotalHeight],center=true);
		}
		
}


//-------
// Build it!

//ShowPegGrid();

if (Layout == "Link") {
	Link(false);
}

if (Layout == "Button") {
	Link(true);
}

if (Layout == "LB") {
	color("Brown") Link(true);
	translate([LinkSpacing,LinkSpacing,0])
		color("Orange") Link(false);
}

if (Layout == "Build")
	for (ix = [0:(NumLinksX - 1)],
		 iy = [0:(NumLinksY - 1)]) {
			x = (ix - (NumLinksX - 1)/2)*LinkSpacing;
			y = (iy - (NumLinksY - 1)/2)*LinkSpacing;
			translate([x,y,0])
			color([(ix/(NumLinksX - 1)),(iy/(NumLinksY - 1)),1.0]) 
				if (Diamond)
					Link((ix + iy) % 2);					// armor at odd,odd & even,even points
				else
					if ((iy % 2) && (ix % 2))				// armor at odd,odd points
                        Link(true);
					else if (!(iy % 2) && !(ix % 2))		// connectors at even,even points
						Link(false);
	}

if (Layout == "Joiner")
	Joiner();

if (Layout == "Joiners") {
	NumJoiners = max(MinLinksX,MinLinksY)/2;
	for (iy = [0:(NumJoiners - 1)]) {
		y = (iy - (NumJoiners - 1)/2)*2*LinkSpacing + LinkSpacing/2;
		translate([0,y,0])
			color([0.5,(iy/(NumJoiners - 1)),1.0]) 
				Joiner();
	}
}

if (Layout == "PillarMod")					// Slic3r modification volume to eliminate pillar infill
	translate([0,0,(BaseHeight + BarClearance)/2])
		cube([1.5*SheetSizeX,1.5*SheetSizeY,BaseHeight + BarClearance],center=true);

More detail on my blog at http://wp.me/poZKh-5x9