diff --git a/src/main/java/satisfactory/Test.java b/src/main/java/satisfactory/Test.java
index b139876..4ce4530 100644
--- a/src/main/java/satisfactory/Test.java
+++ b/src/main/java/satisfactory/Test.java
@@ -99,7 +99,10 @@ public class Test {
 		Recipe recipe = b.getRecipe();
 		System.out.println(recipe);
 		//plot(Database.GasFilter, "rubber",1);
-		plot(Database.RadioControlUnit, "alu", 1);
+		plot(Database.AluminumCasing, "aluCase", 1);
+		SumResult ac = SumResult.sum(new Production(Database.AluminumCasing,1));
+		plot2(ac.getProduction(), "aluCase_sum");
+		//System.exit(128);
 		Item i = Database.AluminumIngot;
 		//plot2(SumResult.sum(i, 1),"rubber_");
 		//plot(i, "rcu_hierarchy",1);
diff --git a/src/main/java/satisfactory/items/Item.java b/src/main/java/satisfactory/items/Item.java
index 35d3637..fa909f7 100644
--- a/src/main/java/satisfactory/items/Item.java
+++ b/src/main/java/satisfactory/items/Item.java
@@ -105,4 +105,5 @@ public abstract class Item {
 	public Recipe getPreference() {
 		return preference;
 	}
+
 }
diff --git a/src/main/java/satisfactory/items/Recipe.java b/src/main/java/satisfactory/items/Recipe.java
index 0422311..0ed6520 100644
--- a/src/main/java/satisfactory/items/Recipe.java
+++ b/src/main/java/satisfactory/items/Recipe.java
@@ -107,6 +107,16 @@ public class Recipe {
 		return inputs;
 	}
 
+	public Map<Item,Integer> getByProducts(Item reference){
+		if (!outputs.containsKey(reference)){
+			return null;
+		}
+		return outputs.entrySet().stream().filter(itemIntegerEntry -> isByProduct(reference, itemIntegerEntry.getKey())).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
+	}
+	public boolean isByProduct(Item reference, Item test){
+		return !reference.equals(test) && outputs.containsKey(reference) && outputs.containsKey(test);
+	}
+
 	public Graph<Item, DefaultWeightedEdge> buildGraph(Item target) {
 		System.out.println("buildGraph(" + target.getName() + ") @ "+ name);
 		Graph<Item, DefaultWeightedEdge> graph = new DefaultDirectedWeightedGraph<>(DefaultWeightedEdge.class);
@@ -139,6 +149,16 @@ public class Recipe {
 		return n / r.getProductionRate(target);
 	}
 
+	private double getRequiredProcessRuns(Item product, Double productWantedPerMinute) {
+		int productPerProcess = product.getRecipe().outputs.get(product);
+		return productWantedPerMinute / productPerProcess;
+	}
+
+	private double getByproductRate(Item main, Item product, double production){
+		double runs = getRequiredProcessRuns(main, production);
+		return product.getRecipe().outputs.get(product) * runs;
+	}
+
 	public SumResult sum(Item target, int prodPerMinute) {
 		Graph<Item, DefaultWeightedEdge> buildGraph = buildGraph(target);
 		Graph<Item, ProductionEdge> production = new DefaultDirectedWeightedGraph<>(ProductionEdge.class);
@@ -148,13 +168,19 @@ public class Recipe {
 		map.put(target, (double) prodPerMinute);
 		production.addVertex(target);
 		production.addEdge(target, target, new ProductionEdge(target, target, prodPerMinute, processesNeeded(target, prodPerMinute)));
+		Set<Item> visited = new HashSet<>();
 		while (!queue.isEmpty()) {
 			Item item = queue.remove();
-			// next items
-			buildGraph.incomingEdgesOf(item)
-					.stream()
-					.map(buildGraph::getEdgeSource)
-					.forEach(queue::add);
+			if (visited.contains(item)){
+				System.out.println("hint: already processed " + item.getName()+ "! Skip!");
+				//continue;
+			} else {
+				// next items
+				buildGraph.incomingEdgesOf(item)
+						.stream()
+						.map(buildGraph::getEdgeSource)
+						.forEach(queue::add);
+			}
 			// *this* item
 			double sum = 0;
 			Set<Item> byProducts = new HashSet<>();
@@ -162,9 +188,9 @@ public class Recipe {
 				Item product = buildGraph.getEdgeTarget(edge);
 				Double productWantedPerMinute = map.get(product);
 				System.out.println(item.getName());
-				if (item.getRecipe().outputs.containsKey(product)) {
+				if (item.getRecipe().outputs.containsKey(product)) { // TODO: method isByProduct
 					// product is by-product, no forward dependency
-					System.out.println("BY-PRODUCT " + item.getName() + " -> " + product.getName());
+					System.out.println("BY-PRODUCT " + item.getName() + " -> " + product.getName() + "... "+ queue);
 					byProducts.add(product);
 					continue;
 				}
@@ -173,8 +199,7 @@ public class Recipe {
 					break;
 				}
 				double amountNeeded = buildGraph.getEdgeWeight(edge);
-				int productPerProcess = product.getRecipe().outputs.get(product);
-				double requiredProcesRuns = productWantedPerMinute / productPerProcess;
+				double requiredProcesRuns = getRequiredProcessRuns(product, productWantedPerMinute);
 				double requiredInput = amountNeeded * requiredProcesRuns;
 				sum += requiredInput;
 
@@ -185,12 +210,15 @@ public class Recipe {
 				map.put(item, sum);
 			}
 			if (!byProducts.isEmpty()) {
+				double finalSum = sum;
 				byProducts.forEach(item1 -> {
 					production.addVertex(item1);
 					// TODO: calculate produced amount
-					production.addEdge(item, item1, new ProductionEdge(item, item1, 0, 0));
+					double byproductRate = getByproductRate(item, item1, finalSum);
+					production.addEdge(item, item1, new ProductionEdge(item, item1, byproductRate, processesNeeded(item, finalSum)));
 				});
 			}
+			visited.add(item);
 		}
 		map.forEach((item, aDouble) -> {
 			System.out.println(item.getName() + ": " + aDouble);