Added rack_herringbone and tweaked cap bolt MCAD.

MCAD @ 19cb7ca3

-Subproject commit 9a958fd11b0a6b5f8becd37c4f8a42f585abfcd8
+Subproject commit 19cb7ca3706a22ae7d0972270a8a9eef7c2fac63

rack_herringbone.scad

+// Parametric Modular Rack Mark "Ckaos" Moissette
+//Based on the work of MattMoses and Fdavies :
+//http://forums.reprap.org/read.php?1,51452,52099#msg-52099
+//and Forrest Higgs:
+// http://technocraticanarchist.blogspot.com/2010/01/high-speed-alternative-to-belts.html
+//It is licensed under the Creative Commons - GNU GPL license.
+// © 2011 by Mark "Ckaos" Moissette
+//more info at :www.kaosat.net and
+//http://www.thingiverse.com/thing:6011
+
+
+pi=3.1415926535897932384626433832795;
+innerRadius=3.1;//shaft radius, in mm
+borders=2.5;//how thick should the borders around the central "shaft" be, in mm
+diametralPitch=12;
+numberOfTeeth=10;
+pressureAngle=20*pi/180;
+centerAngle=25;//angle at center of teeth
+
+
+//example usage
+//rack(innerRadius,borders,diametralPitch,numberOfTeeth,pressureAngle,centerAngle);
+
+
+module rack(innerRadius,borders,P,N,PA,CA)
+{
+	// P = diametral pitch
+	// N = number of teeth
+	// PA = pressure angle in radians
+	// x, y = linear offset distances
+	a = 1/P; // addendum (also known as "module")
+	d = 1.25/P; // dedendum (this is set by a standard)
+	multiplier=20;//20
+	height=(d+a)*multiplier;
+	
+	
+	// find the tangent of pressure angle once
+	tanPA = tan(PA*(180/pi));
+	// length of bottom and top horizontal segments of tooth profile
+	botL = (pi/P/2 - 2*d*tanPA)*multiplier;
+	topL =( pi/P/2 - 2*a*tanPA)*multiplier;
+
+	slantLng=tanPA*height;
+	realBase=2*slantLng+topL;
+	
+	
+	offset=topL+botL+2*slantLng;
+	length=(realBase+botL)*N;
+
+	supportSize=(innerRadius+borders)*2;
+
+	//calculate tooth params
+	basesegmentL=realBase/2;
+	basesegmentW=supportSize/2;
+
+	topsegmentL=topL/2;
+	topsegmentW=supportSize/2;
+
+	baseoffsetY=tan(CA)*basesegmentW;
+	topoffsetY=tan(CA)*topsegmentW;
+	
+	//calculate support params
+
+	totalSupportLength=(N)*(offset);
+	supportL=totalSupportLength/2;
+	supportW=supportSize/1.99;
+	
+	echo("Total length",totalSupportLength+baseoffsetY);
+	echo("Total height",supportSize);
+
+	
+	rotate([90,90,0])
+	{
+	translate([-supportSize/2,supportSize/2,0])
+	{
+	union()
+	{
+		difference()
+		{
+			support(supportL,supportW,supportSize,baseoffsetY);
+			rotate([90,90,0]) 
+			{cylinder(h=length+10,r=innerRadius,center=true,$fn=100);}
+		}
+
+	
+		for (i = [0:N-1]) 
+		{
+			translate([0,i*offset-length/2+realBase/2,supportSize/2+height/2]) 
+			{	
+				
+				tooth(basesegmentL,basesegmentW,topsegmentL,topsegmentW,height,baseoffsetY,topoffsetY);
+				
+			}
+		}
+	}
+	
+	}
+	}
+}
+
+module support(supportL,supportW,height,offsetY)
+{
+	 tooth(supportL,supportW,supportL,supportW,height,offsetY,offsetY);
+}
+
+
+
+module tooth(basesegmentL,basesegmentW,topsegmentL,topsegmentW,height,baseoffsetY,topoffsetY)//top : width*length, same for base
+{
+	
+	////////////////
+	basePT1=[
+	-basesegmentW,
+	basesegmentL-baseoffsetY,
+	-height/2];
+
+	basePT2=[
+	0,
+	basesegmentL,
+	-height/2];
+
+	basePT3=[
+	basesegmentW,
+	basesegmentL-baseoffsetY,
+	-height/2];
+
+	basePT4=[
+	basesegmentW,
+	basesegmentL-(baseoffsetY+basesegmentL*2),
+	-height/2];
+	
+	basePT5=[
+	0,
+	-basesegmentL,
+	-height/2];
+
+	basePT6=[
+	-basesegmentW,
+	basesegmentL-(baseoffsetY+basesegmentL*2),
+	-height/2];
+	//////////////////////////
+	topPT1=[
+	-topsegmentW,
+	topsegmentL-topoffsetY,
+	height/2];
+
+	topPT2=[
+	0,
+	topsegmentL,
+	height/2];
+
+	topPT3=[
+	topsegmentW,
+	topsegmentL-topoffsetY,
+	height/2];
+
+	topPT4=[
+	topsegmentW,
+	topsegmentL-(topoffsetY+topsegmentL*2),
+	height/2];
+	
+	topPT5=[
+	0,
+	-topsegmentL,
+	height/2];
+
+	topPT6=[
+	-topsegmentW,
+	topsegmentL-(topoffsetY+topsegmentL*2),
+	height/2];
+	//////////////////////////
+
+	//////////////////////////
+
+	polyhedron(
+	points=[
+		basePT1,
+		basePT2,
+		basePT3,
+		basePT4,
+		basePT5,
+		basePT6,
+		topPT1,
+		topPT2,
+		topPT3,
+		topPT4,
+		topPT5,
+		topPT6],
+	triangles=[
+	//base
+	[5,1,0],
+	[4,1,5],
+	[4,2,1],
+	[3,2,4],	
+
+	//front
+	[1,6,0],
+	[7,6,1],
+	[2,7,1],
+	[8,7,2],
+	//back
+	[11,10,5],
+	[5,10,4],
+	[10,9,4],
+	[4,9,3],	
+	//side 1
+	[0,11,5],
+	[6,11,0],
+	//side 2
+	[3,8,2],
+	[9,8,3],
+	//top
+	[9,10,8],
+	[10,7,8],
+	[11,7,10],
+	[6,7,11],
+	]
+	);
+}
+
+module demo_gear(position,diametralPitch)
+{
+	wheelSize=12;
+rotate([0,90,180])
+translate(position)
+
+{
+gear (
+	number_of_teeth=8,
+	circular_pitch=300, 
+	pressure_angle=19.34,
+	gear_thickness=wheelSize/2,
+	rim_thickness=wheelSize/2,
+	hub_thickness=0,
+	bore_diameter=2,
+	backlash=0,twist=centerAngle,involute_facets=15);
+
+translate([0,0,wheelSize/2])
+rotate([0,0,-centerAngle])
+gear (
+	number_of_teeth=8,
+	circular_pitch=300, 
+	pressure_angle=19.34,
+	gear_thickness=wheelSize/2,
+	rim_thickness=wheelSize/2,
+	hub_thickness=0,
+	bore_diameter=2,
+	backlash=0,twist=-centerAngle,involute_facets=15);
+
+}
+
+}
+
+