A rotating bearing designed with OpenSCADRevised .stl file to correct issue noted by BSchuler. The revised OpenSCAD code is below://Bearing Dimensions //Basic Inputs t=8; //thickness of bearing OR=30; //Outer Radius of outer bearing race IR=18; //Inner Radius of inner bearing race PCT=.8; //Percent of t or d used to determine ball size//Derived Inputs d=OR-IR; //difference between Outer & Inner Radius of races echo("bearing thickness=",t); echo("Outer-Inner Bearing Radius=",d); BR=(PCT/2)min(t,d); //Ball bearing radius echo("BR=",BR); BC=(OR+IR)/2; //Radius of ball bearing circle GP=BR/3; //Half of Gap between inner and outer race, set at 1/3 ball radius M=1.01; //Multiplier to make space between races larger than ball bearing N=round(((2BCPI)/(2BR))+.5)-1; //Number of balls in bearing echo("N=",N);$fn=50; //Increase to 100 or greater to improve smoothness of bearings & races but this significantly increases time to render//difference forms races of bearing difference(){ //disk forming OD of bearing cylinder(t,OR,OR,center=true); //remove ring to form Id of outer race and Od of inner race rotate_extrude(convexity=20)translate([BC,0,0])circle(MBR,center=true); //remove disk to form ID of inner race cylinder(t,IR,IR,center=true); //opening between inner and outer race translate([0,0,0])difference(){ cylinder(t+2,BC+GP,BC+GP,center=true); cylinder(t+2,BC-GP,BC-GP,center=true);}} //adds ball bearings within race for (i=[1:N])rotate(i360/N*[0,0,1])translate([BC,0,0])sphere(BR,center=true);