diff --git a/technic/machines/mv/alloy_furnace.lua b/technic/machines/mv/alloy_furnace.lua
index 1809262..e70df1c 100644
--- a/technic/machines/mv/alloy_furnace.lua
+++ b/technic/machines/mv/alloy_furnace.lua
@@ -260,9 +260,9 @@ minetest.register_abm(
 		   end
 		   meta:set_int("tube_time", tube_time)
 
-		   -- The machine shuts down if we have nothing to smelt and no tube is connected
-		   -- or if we have nothing to send with a tube connected.
-		   if inv:is_empty("src") and (not output_tube_connected or inv:is_empty("dst")) then
+		   -- The machine shuts down if we have nothing to smelt since we tube stuff
+		   -- out while being idle.
+		   if inv:is_empty("src") then
 		      next_state = 1
 		   end
 		   ----------------------
diff --git a/technic/machines/mv/electric_furnace.lua b/technic/machines/mv/electric_furnace.lua
index c6a1651..a0eff21 100644
--- a/technic/machines/mv/electric_furnace.lua
+++ b/technic/machines/mv/electric_furnace.lua
@@ -259,11 +259,11 @@ minetest.register_abm(
 		      end
 		   end
 		   meta:set_int("tube_time", tube_time)
-		   
-		   -- The machine shuts down if we have nothing to smelt and no tube is connected
-		   -- or if we have nothing to send with a tube connected.
-		   if inv:is_empty("src") and (not output_tube_connected or inv:is_empty("dst")) then
-		   next_state = 1
+
+		-- The machine shuts down if we have nothing to smelt since we tube stuff
+		-- out while being idle.
+		if inv:is_empty("src") then
+			next_state = 1
 		end
 		----------------------
 		
diff --git a/technic/machines/mv/grinder.lua b/technic/machines/mv/grinder.lua
index 84710c9..84a885a 100644
--- a/technic/machines/mv/grinder.lua
+++ b/technic/machines/mv/grinder.lua
@@ -237,9 +237,9 @@ minetest.register_abm(
 			end
 			meta:set_int("tube_time", tube_time)
 
-			-- The machine shuts down if we have nothing to grind and no tube is connected
-			-- or if we have nothing to send with a tube connected.
-			if inv:is_empty("src") and (not output_tube_connected or inv:is_empty("dst")) then
+			-- The machine shuts down if we have nothing to smelt since we tube stuff
+			-- out while being idle.
+			if inv:is_empty("src") then
 				next_state = 1
 			end