// my feeble attempt at generating a ball bearing using bb's.
// my alu block is 140.9mm square, so this will have
// to shrink as this bearing is now 148.3mm, or find wider
// stock
dmtr=98.00; // in mm's of ID,squeeze it a hair.
height=6.33; // in mm's
// everything below is generated center=true
// which means we're dealing in radius
ctr_ht=(height * .50000); // mults are faster
halfd=(dmtr *.50000); // rad of inner diameter
echo(11, halfd);
innr=(halfd+ctr_ht); // sub to move innr ID to dmtr
echo(13, innr);
outd=(dmtr+height*2.000);// outer face dia 147.6mm
echo(15, outd);
bb=4.3625; // .005mm more than a crosman bb so its not
// preloaded but snug. Smaller= tighter fit 
// how many bb's?
racedia=dmtr+ctr_ht;
racircum=racedia*PI;
//echo(21, PI, racedia, racircum);
bbs=racircum/bb;
echo(23, bbs);
$fn=1440;
//echo(25, bb, $fn);

rotate_extrude()
    translate([innr,0,0]) 
    difference()
    {
        square(height, center = true);
        circle(d=bb);
        square([.26*height, 1.1*height],center=true);
    }