Sorry, THIS IS NOT THE GANN FAN. IT'S THE FIB SPEED RESISTANCE FAN...redone in 7.5 degree spreads. The lowest angle is actually a 3.25 (extra). To turn the fan backwards and keep the same angle settings just use the purple lines. They are set for the 1 line (orange 45 degree line) to match when they are square...1:1 If you change the size of the fan the angles will not be 15, 22.5 etc. They will all change in relation to each other and the scale. Just move the WHOLE fan, NOT by the drag bars...IF you want to keep 45 degrees etc. otherwise...do what you want. You can always get square back by putting the orange line dead on the purple. Auto square. Enjoy