gantry_sizey = 100;
gantry_top = 180;
gantry_bottom = -table_thick - table_height/2;
gantry_gap = 24;
gantry_thick = 12;
gantry_posl = 0 - gantry_gap;
gantry_posr = table_sizex + gantry_gap;
gantry_sizex = table_sizex + 2*gantry_gap;
gantry_clear = 80;
gantry_rail_size = 8;
gantry_rail_posy = gantry_sizey - gantry_thick - 2*gantry_rail_size;
gantry_rail_posz1 = gantry_clear + 10;
gantry_rail_posz2 = gantry_top - 10;