diff --git a/src/Add-on/BoardBatchCurtail.ts b/src/Add-on/BoardBatchCurtail.ts
index 61182b250..e16bbbee0 100644
--- a/src/Add-on/BoardBatchCurtail.ts
+++ b/src/Add-on/BoardBatchCurtail.ts
@@ -63,10 +63,10 @@ export class BoardBatchCurtail implements Command
             let size = sizeBox.getSize(new Vector3);
             let v = new Vector3(1, 1, 1);
 
-            let frontBox = new Box3(sizeBox.min.clone().sub(v), sizeBox.max.clone().sub(new Vector3(-1, size.y / 2, -1)));
-            let rightBox = new Box3(sizeBox.min.clone().add(new Vector3(size.x / 2, -1, -1)), sizeBox.max.clone().add(v));
-            let backBox = new Box3(sizeBox.min.clone().add(new Vector3(-1, size.y / 2, -1)), sizeBox.max.clone().add(v));
-            let leftBox = new Box3(sizeBox.min.clone().sub(v), sizeBox.max.clone().sub(new Vector3(size.x / 2, -1, -1)));
+            let frontBox = new Box3(sizeBox.min.clone().sub(v), sizeBox.max.clone().sub(new Vector3(-1, size.y * (1 - 1e-3), -1)));
+            let rightBox = new Box3(sizeBox.min.clone().add(new Vector3(size.x * (1 - 1e-3), -1, -1)), sizeBox.max.clone().add(v));
+            let backBox = new Box3(sizeBox.min.clone().add(new Vector3(-1, size.y * (1 - 1e-3), -1)), sizeBox.max.clone().add(v));
+            let leftBox = new Box3(sizeBox.min.clone().sub(v), sizeBox.max.clone().sub(new Vector3(size.x * (1 - 1e-3), -1, -1)));
             return { front: frontBox, right: rightBox, left: leftBox, back: backBox };
         };