diff --git a/src/graphnet/models/graphs/utils.py b/src/graphnet/models/graphs/utils.py
index 85ea94d9d..9587010df 100644
--- a/src/graphnet/models/graphs/utils.py
+++ b/src/graphnet/models/graphs/utils.py
@@ -247,6 +247,7 @@ def __init__(self, x: np.ndarray, cluster_columns: List[int]) -> None:
         for i in range(len(self._counts)):
             self._padded_x[i, : self._counts[i]] = x[: self._counts[i]]
             x = x[self._counts[i] :]
+        return self.clustered_x
 
     def _add_column(
         self, column: np.ndarray, location: Optional[int] = None
@@ -266,6 +267,31 @@ def _add_column(
                 self.clustered_x, location, column, axis=1
             )
 
+    def _calculate_charge_sum(self, charge_index: int) -> np.ndarray:
+        """Calculate the sum of the charge."""
+        assert not hasattr(
+            self, "_charge_sum"
+        ), "Charge sum has already been calculated, \
+            re-calculation is not allowed"
+        self._charge_sum = self._padded_x[:, :, charge_index].sum(axis=1)
+        return self._charge_sum
+
+    def _calculate_charge_weights(self, charge_index: int) -> np.ndarray:
+        """Calculate the weights of the charge."""
+        assert not hasattr(
+            self, "_charge_weights"
+        ), "Charge weights have already been calculated, \
+            re-calculation is not allowed"
+        assert hasattr(
+            self, "_charge_sum"
+        ), "Charge sum has not been calculated, \
+            please run calculate_charge_sum"
+        self._charge_weights = (
+            self._padded_x[:, :, charge_index]
+            / self._charge_sum[:, np.newaxis]
+        )
+        return self._charge_weights
+
     def add_charge_threshold_summary(
         self,
         summarization_indices: List[int],
@@ -296,21 +322,8 @@ def add_charge_threshold_summary(
         """
         # convert the charge to the cumulative sum of the charge divided
         # by the total charge
-        self._charge_weights = self._padded_x[:, :, charge_index]
-
-        self._padded_x[:, :, charge_index] = self._padded_x[
-            :, :, charge_index
-        ].cumsum(axis=1)
-
-        # add the charge sum to the class if it does not already exist
-        if not hasattr(self, "_charge_sum"):
-            self._charge_sum = np.nanmax(
-                self._padded_x[:, :, charge_index], axis=1
-            )
-
-        self._charge_weights = (
-            self._charge_weights / self._charge_sum[:, np.newaxis]
-        )
+        self._calculate_charge_sum(charge_index)
+        self._calculate_charge_weights(charge_index)
 
         self._padded_x[:, :, charge_index] = (
             self._padded_x[:, :, charge_index]
@@ -374,31 +387,6 @@ def add_percentile_summary(
         self._add_column(percentiles_x, location)
         return self.clustered_x
 
-    def calculate_charge_sum(self, charge_index: int) -> np.ndarray:
-        """Calculate the sum of the charge."""
-        assert not hasattr(
-            self, "_charge_sum"
-        ), "Charge sum has already been calculated, \
-            re-calculation is not allowed"
-        self._charge_sum = self._padded_x[:, :, charge_index].sum(axis=1)
-        return self._charge_sum
-
-    def calculate_charge_weights(self, charge_index: int) -> np.ndarray:
-        """Calculate the weights of the charge."""
-        assert not hasattr(
-            self, "_charge_weights"
-        ), "Charge weights have already been calculated, \
-            re-calculation is not allowed"
-        assert hasattr(
-            self, "_charge_sum"
-        ), "Charge sum has not been calculated, \
-            please run calculate_charge_sum"
-        self._charge_weights = (
-            self._padded_x[:, :, charge_index]
-            / self._charge_sum[:, np.newaxis]
-        )
-        return self._charge_weights
-
     def add_counts(self, location: Optional[int] = None) -> np.ndarray:
         """Add the counts of the sensor to the summarization features."""
         self._add_column(np.log10(self._counts), location)