StripMine

local times = 0
local j = 0

function Mine()
  while turtle.detect() == true do
    turtle.dig()
    sleep(0.50)
  end
  turtle.forward()
  sleep(0.50)
  while turtle.detectUp() == true do
    turtle.digUp()
    sleep(0.50)
  end
  turtle.digDown()
end

function Place(SlotNum)
  turtle.select(SlotNum)
  turtle.back()
  turtle.placeUp()
  turtle.forward()
end

function PlaceChest(SlotNum)
  turtle.select(SlotNum)
  turtle.back()
  turtle.placeDown()
  for I=1, 14 do
    turtle.select(I)
    turtle.dropDown()
  end
  turtle.forward()
end

print("Place chests in slot 15.")
print("Place torches in slot 16.")
term.write("How long is the mineshaft? ")
times = read()

function Digger()
  for i=1, times do
    j = j+1
    Mine()
    if j == 9 then
          Place(16)
          j = 0
    end
  end
end

function TunnelLeft()
  turtle.turnRight()
  Mine()
  Mine()
  Place(16)
  PlaceChest(15)
  Mine()
  turtle.turnRight()
end

function TunnelRight()
  turtle.turnLeft()
  Mine()
  Mine()
  Place(16)
  PlaceChest(15)
  Mine()
  turtle.turnLeft()
end

function EndLeft()
  turtle.turnLeft()
  Mine()
  Mine()
  Place(16)
  Mine()
  turtle.turnLeft()
end

function EndRight()
  turtle.turnRight()
  Mine()
  Mine()
  Place(16)
  Mine()
  turtle.turnRight()
end

function CheckFuel()
  if turtle.getFuelLevel() <= 1000 then
    term.write("Low Fuel, Please refuel. Hit any key to continue.")
    os.pullEvent("char")
  end
end

term.write("How many double shafts? ")
duration = read()

term.write("Which direction are you mining? ")
direction = read()

while( not (direction == "left" or direction == "right") ) do
        term.write("Invalid Answer! Try again (left/right): ")
        direction = read()
    end
    if direction == "left" then
        print("Mining Left")
        for i=1, duration do
          CheckFuel()
          Digger()
          EndLeft()
          Digger()
          TunnelLeft()
        end
    else
        print("Mining Right")
        for i=1, duration do
          CheckFuel()
          Digger()
          EndRight()
          Digger()
          TunnelRight()
        end
    end