//Helical "herringbone" gear for RepRap Ormerod extruder. //Based on iamburny's gear set (still fits the same "small" gear), see //http://www.thingiverse.com/thing:242536 //Licensed under Creative Commons Attribution-ShareAlike //http://creativecommons.org/licenses/by-sa/3.0/ $fn=200; include ; include ; gap = 29.884; //distance between centres of gears height=10; module bigGear( pressure_angle=30, twist=200, dia = 45.3, teeth=34, circles=0) { pitch =dia / (teeth /180); //Big Gear gear (number_of_teeth=teeth, circular_pitch=pitch, pressure_angle=pressure_angle, clearance = 0.2, gear_thickness = height/2*0.2, rim_thickness = height/2, rim_width = 2.5, hub_thickness = 3, hub_diameter=12, bore_diameter=5, circles=circles, twist=twist/teeth, circle_facets=3, involute_facets=6); mirror([0,0,1]) gear (number_of_teeth=teeth, circular_pitch=pitch, pressure_angle=pressure_angle, clearance = 0.2, gear_thickness = height/2, //flat bottom rim_thickness = height/2, rim_width = 1, hub_thickness = 4, hub_diameter=12, bore_diameter=3, circles=circles, twist=twist/teeth, circle_facets=3, involute_facets=6); } difference() { bigGear(); translate([0,0, (height/2)-5.1]) hexagon_prism(5.2,3.1); //Nut Trap hole translate([0,0, -(height/2)-0.1]) cylinder(h=5.2,r=1.7); //thread hole difference() { //top bevel cylinder(30,30,0); cylinder(28,28,0); } mirror([0,0,180]) difference() { //bottom bevel cylinder(30,30,0); cylinder(28,28,0); } }