/// ARRAY SIZE

// size of the array
num_hdd_x = 4;
num_hdd_y = 5;


/// PRIMARY DIMENSIONS

// space above hdd available for air flow
cooling_height = 10;

// thickness of the support bar
bar_thickness = 10;

// length hdd is standing out to be grabbed
hdd_standout = 25;


/// METAL PARTS: SCREWS AND RAILS

// outer diameter of thread rod and nut used for support
rod_diameter = 4;
nut_diameter = 6;
nut_height = 3;

// dimensions of the L-shaped rail between front and back
rail_width = 15;
rail_height = rail_width;
rail_thickness = 1;


/// HDD SIZE (from spec)

// dimensions of HDDs; not model-specific
hdd_width = 101.6;
hdd_height = 25.4;
hdd_length = 146;


/// PRINTER SPECIFICATION

// assumed space deviation of the resulting form; used to leave space
// in holes so that screws and rods do not stuck
pla_epsilon = 0.1;


/// COMPUTED VARIABLES

// dimension of a single hdd tray (hdd + space around)
tray_height = hdd_height + max(cooling_height, 2 * bar_thickness + 10 * pla_epsilon);
tray_width = hdd_width + bar_thickness;


/// PCB DIMENSIONS

// free space around backplanes
backplane_margin = 1;

// dimensions of the backplane PCB
backplane_width  = tray_width / 2 + 2 * bar_thickness;
backplane_height = tray_height - 2 * backplane_margin;
backplane_thickness = 1.6;

// offsets of the backplane relative to the hdd
backplane_hoffset = -backplane_margin - bar_thickness/2;
backplane_voffset =  backplane_margin;

// display only: dimensions and offsets of the SATA connector relative
// to the backplane
backplane_con_width = 45;
backplane_con_height = 5;
backplane_con_depth = 10;
backplane_con_hoffset = 5 - backplane_hoffset;
backplane_con_voffset = 15;


/// OPENSCAD HACKS

// a length larger than any constructed feature; use to simulate
// infinitely long structures (for difference operations)
large = 1000;

// A small quantity that does not change the print results. Use to
// displace surfaces of CSG operations to prevent them from overlapping.
epsilon = 0.0001;