Hello Discuss,

Is there a way to make this render faster?  It takes 20 minutes.  In addition any movement in OpenSCAD preview frame goes very slowly and jerks

Thank you

// Steve's handle
// Bob Roos
// August 9, 2023

include <BOSL2/std.scad> //or screws or threading
include <BOSL2/threading.scad> //or screws or threading
include <BOSL2/screws.scad> //or screws or threading
$fn = 72;

Dstem = 6.25;
Dbase = 32.5;
Dmid = 23.5;
Danchor = 9.2;
Dsphere = 10.34;
Dhole = 5.25;
Hbase = 3.2;
Hmid = 5.25-Hbase;
Hanchor = 3;
Hoverall = 20;
Depth = 5;
Screw = "6-32";
OuterCount = 22;
InnerCount = 28;
T=2;

difference(){
union(){
cyl(d=Dbase,h=T);
for (i =[0:OuterCount-1]){
rotate(i16.35) right(Dbase/2-1.05) up(.8)xcyl(d=5,h=2,rounding=1);
}
for (i =[0:InnerCount-1]){
rotate(i12.85) right(Dmid/2-1.9) up(1.4)ycyl(d=7,h=1.75,rounding=.75);
}
up(2.5)cyl(d=Dmid-9.5,h=5,rounding=1.5);
up(5)cyl(d=7,h=2.5,rounding=1);
up(9.5)sphere(d=Dsphere);
down()cyl(d=Dstem,h=5);
}
down(1.5)tube(od=1.5*Dbase,id=Dstem,h=2);
up(10)xcyl(d=5,h=12);

down(4)screw_hole("#6-32,.85",thread=true);
*cuboid([Dbase,Dbase,Dbase],anchor=BOTTOM+LEFT);  //cutaway
}

SupportGrid(num=9,size=5,height=1.8);

module SupportGrid (num=10,size=10,height=2) {
// grid parms
window_num = num; // number of windows
window_size = size; // size of individual windows
strut_size = .4; // size of the struts
height = height;
// grid itself
translate([-(window_num * (window_size + strut_size))/2,(window_num * (window_size + strut_size))/2,-2.5])  union(){
for (i = [0:window_num]) {
rotate ([90, 0, 0])
translate ([0, 0, (window_size + strut_size) * i])
cube (size=[window_num * (window_size + strut_size), height, strut_size]);
}

    for (i = [0:window_num]) {
        rotate ([0, 0, 270])
        translate ([0, (window_size + strut_size) * i, 0])
        cube (size=[window_num * (window_size + strut_size), strut_size,height]);
        }
} 

}

--
Best regards,
Bob                          mailto:roosbob@wybatap.com

As originally written, on my antique desktop with 2021.01 it took about
an hour.

One of my mantras is that you never want to set $fn at the top level,
because it then applies to both large circles (where it may not be large
enough) and to small circles (where it may be too large).  Instead, set
$fs and $fa.  Exact values depend on how perfect you need your circles
to be.  I tried $fs=0.5 and $fa=1, which is probably finer than
necessary, and that dropped the render time to 17 minutes.  (It dropped
the complexity of the result by a factor of about three.)  Raising $fs
to 1 dropped the render time to 5 minutes.

$fs=1 / $fa=1 means "have each segment of a circle be no more than one
unit ($fs=1), with a maximum of 360 sides ($fa=1 degree)".

The two parameters both control the number of sides.  $fs controls small
circles, to make sure they don't have sides so small you wouldn't see
the difference.  $fa controls large circles, to make sure that they
don't have sides that are smoother than you can perceive.

Raising $fa to 2 didn't change the result; the circles here aren't large
enough.  With one-unit sides, a circle would have to have a diameter of
~114 units to have more than 360 sides.  But you might set it to 5
anyway; that would make large circles be 72-gons, which is what your $fn
setting was getting you.  You can see the sides on a large 72-gon.  I
don't know about on one with a diameter of only 30 or so mm.

Only use $fn to control the number of sides on a particular object, when
you want to generate a regular polygon.

If you really need super-smooth circles, consider setting $fs and $fa
high for development, and then set them to the values you really need
for a final render.  Print some samples to see what settings will really
make a difference in the result.

You can get a small benefit (10%?) by getting rid of the threads on the
screw hole.  Can you really print 6-32 threads?

Also:  you probably want your slicer to generate the support grid.  It
will probably do a better job than you will, keeping the walls thin,
putting some tiny separation between them and the model, and keeping the
supports away from the sides of the central shaft.