diff --git a/bring b/bring
index 1f65a4c..6dfd2c1 100644
--- a/bring
+++ b/bring
@@ -19,7 +19,7 @@ if message == "ack" then
 
 	print("He returned safely :)")
 elseif message == "empty" then
-	printf("There is no " .. args[1])
+	print("There is no " .. args[1])
 else
 	print("No slave responded for " .. args[1])
 end
diff --git a/slave b/slave
index 04a8638..66ac7a7 100644
--- a/slave
+++ b/slave
@@ -1,24 +1,55 @@
 local args = { ... }
+local threshold = 5
+
+local function count_total()
+	local c = 0
+	for i = 1, 9 do c = c + turtle.getItemCount(i) end
+	return c
+end
+
+local function count_space()
+	local c = 0
+	for i = 1, 9 do c = c + turtle.getItemSpace(i) end
+	return c
+end
 
 rednet.open("right")
 while true do
 	-- we are using wireless to get the distance
 	-- so the master should be aligned with the slaves
-	local id, mess, dist = rednet.receive()
+	local id, mess, dist = rednet.receive(1)
 	if mess == args[1] then
-		rednet.send(id, "ack")
-		turtle.up()
-		for i = 1, dist do turtle.back() end
+		if count_total() < threshold then
+			rednet.send(id, "empty")
+		else
+			rednet.send(id, "ack")
+
+			-- Wait for the pipes to be empty (and not leak)
+			rs.setOutput("left", false)
+			sleep(1)
 
-		print("I will leave again in 5 seconds...")
-		sleep(5)
-		print("Bye!")
+			-- GO!!!
+			turtle.up()
+			for i = 1, dist do turtle.forward() end
 
-		for i = 1, dist do turtle.forward() end
-		turtle.down()
-		rednet.send(id, "return")
+			print("I will leave again in 5 seconds...")
+			sleep(5)
+			print("Bye!")
+
+			for i = 1, dist do turtle.back() end
+			turtle.down()
+			rednet.send(id, "return")
+			print("Back home :)")
+		end
 	end
-end
 
--- TODO: activate redstone for the buildcraft engine
+	-- This will power the engine next to the turtle
+	-- We don't want to fill if we're full
+	-- NOTE: we can't use the side of the modem...
+	if count_space() > threshold then
+		rs.setOutput("left", true)
+	else
+		rs.setOutput("left", false)
+	end
+end