gistfile1.txt

// carbon fiber 12mm tubing as smooth rods. Print th4ese in PLA at 0.2mm layer height.

$fn=32;

lm12uu_length = 24;
lm12uu_id=12;
lm12uu_od=20.0;

id_clearance =1;

n = 5;

layer_height = 0.2;

difference() {
	cylinder(r=lm12uu_od / 2, h=lm12uu_length - layer_height);
	difference() {
		cylinder(r=lm12uu_id / 2 + id_clearance, h=lm12uu_length - layer_height);
		linear_extrude(height = lm12uu_length - layer_height, twist = 540 / n, slices = (lm12uu_length - layer_height))
			for (i=[0:360/n]) {
				rotate(360 / n * i)
					translate([lm12uu_id / 2 / sqrt(2), lm12uu_id / 2 / sqrt(2)])
						square([lm12uu_id, lm12uu_id]);
			}
	}
	translate([0, 0, -1 + layer_height])
		cylinder(r1=lm12uu_id / 2 + id_clearance + 1, r2=0, h=lm12uu_id / 2 + id_clearance + 1);
	translate([0, 0, lm12uu_length - layer_height * 2 - (lm12uu_id / 2 + id_clearance)])
		cylinder(r2=lm12uu_id / 2 + id_clearance + 1, r1=0, h=lm12uu_id / 2 + id_clearance + 1);
	translate([0, 0, -1])
		cylinder(r=4.0, h=lm12uu_length + 2);
}