StripMine

-- -------------------------------------------------------------------------- --
-- Strip Miner : BHGp2V48
--
-- Turtle script to dig out a strip mine. Starting from initial position a
-- 1x2x8 tunnel is dug out with a torch either end, bridging gaps. At the end of
-- each tunnel the turtle will dig out 3 to the left and then start the next
-- 1x2x8 tunnel to the left again. This is repeated 'till we're out of fuel, torches
-- or room.
--
-- -------------------------------------------------------------------------- --
--
-- INVENTORY:
-- [1][2][3][4]
-- [5][6][7][8]
-- [9][A][B][C]
-- [D][E][F][0]
--
-- 1 : Fuel
-- 2 : Torches
-- 3 : Bridge material
-- 4 :
-- Rest should be empty.
--
-- -------------------------------------------------------------------------- --

local function CheckFuel()
  if turtle.getFuelLevel() < 64 and turtle.getItemCount( 1 ) > 1 then
    turtle.select( 1 )
    turtle.refuel( 1 )
  end
  return
end

local function PlaceTorch()
  if turtle.getItemCount( 2 ) > 1 then
    turtle.select( 2 )
    turtle.place()
  end
  return
end

local function DigBranch()
  for step = 1, 9 do
    while turtle.detect() do
      turtle.dig()
    end
    turtle.forward()
    while turtle.detectUp() do
      turtle.digUp()
    end
    while not turtle.detectDown() do
      turtle.select( 3 )
      turtle.placeDown()
    end
    CheckFuel()
  end
  return
end

local function DigTurn()
  while turtle.detect() do
    turtle.dig()
  end
  turtle.forward()

  turtle.turnLeft()
  turtle.turnLeft()
  PlaceTorch()
  turtle.turnLeft()
  turtle.turnLeft()

  while turtle.detectUp() do
    turtle.digUp()
  end
  while not turtle.detectDown() do
    turtle.select( 3 )
    turtle.placeDown()
  end
  while turtle.detect() do
    turtle.dig()
  end
  turtle.forward()

  while turtle.detectUp() do
    turtle.digUp()
  end
  while not turtle.detectDown() do
    turtle.select( 3 )
    turtle.placeDown()
  end
  while turtle.detect() do
    turtle.dig()
  end
  turtle.forward()
  while turtle.detectUp() do
    turtle.digUp()
  end
  CheckFuel()
  return
end

-- Start
CheckFuel()
while turtle.getFuelLevel() > 16 and turtle.getItemCount( 1 ) > 1 and turtle.getItemCount( 2 ) > 1 do
  DigBranch()
  turtle.turnLeft()
  DigTurn()
  turtle.turnLeft()

  DigBranch()
  turtle.turnRight()
  DigTurn()
  turtle.turnRight()
end