In the first case, you want to rotate around the y axis. On Thu, Mar 3, 2022 at 2:33 PM Hendrik <blindguydiy@gmail.com> wrote: > Hi > > > > With the new coordination system learning I am trying to figure out how to > correctly rotate a cylinder to cut out wholes on the side of a upright > cylinder. > > > > Say I want to cut wholes in my hollowed out cylinder that is upright must > I rotate around the x or z to make the whole cylinder horizontal left to > right or the x axis? > > And for instance I need to cut front and bck wholes on the y axis so the > cylinder is laying front to back or back to front so the cylinder head > faces me and the other side faces away from me. Sorry it sounds trivial > but struggling to get my head around it. > > > > Thank you. > > > > Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986> for > Windows > > > _______________________________________________ > OpenSCAD mailing list > To unsubscribe send an email to discuss-leave@lists.openscad.org >

cylinder(h=40, r=10, center=true);

rotate([0,90,0]) cylinder(h=20, r=5, center=true);

difference() {
    cylinder(h=40, r=10, center=true);
    rotate([0,90,0]) cylinder(h=20, r=5, center=true);
}

On 3/3/2022 12:33 PM, Hendrik wrote: > > With the new coordination system learning I am trying to figure out > how to correctly rotate a cylinder to cut out wholes on the side of a > upright cylinder. > You'll have a vertical cylinder, and then you'll want to subtract a horizontal cylinder.  To get a horizontal cylinder you can rotate around either the X axis (yields a cylinder along the Y axis), or around the Y axis (yields a cylinder along the X axis). Let's say that you want a 10-unit-radius cylinder that's 40 units tall, and you want to cut out a 5-unit-radius hole. It's simplest if you do this with everything centered on the origin.  More general cases will require translation - if, for instance, you want to cut *two* holes. Here's your base cylinder: cylinder(h=40, r=10, center=true); Here's the horizontal cylinder that you want to subtract from it.  This one runs left-right.  The height is not important, except that it's got to be taller than the diameter of the cylinder you're subtracting from. rotate([0,90,0]) cylinder(h=20, r=5, center=true); and here's subtracting them: difference() { cylinder(h=40, r=10, center=true); rotate([0,90,0]) cylinder(h=20, r=5, center=true); }