diff --git a/src/DatabaseServices/Entity/Extrude.ts b/src/DatabaseServices/Entity/Extrude.ts
index ac822cf60..3731d7b3b 100644
--- a/src/DatabaseServices/Entity/Extrude.ts
+++ b/src/DatabaseServices/Entity/Extrude.ts
@@ -3,7 +3,7 @@ import { arrayClone, arrayLast, arrayRemoveIf, arraySortByNumber, arraySum } fro
 import { ColorMaterial } from "../../Common/ColorPalette";
 import { equalCurve } from "../../Common/CurveUtils";
 import { DisposeThreeObj } from "../../Common/Dispose";
-import { Vector2ApplyMatrix4 } from "../../Common/Matrix4Utils";
+import { Vector2ApplyMatrix4, matrixSetVector } from "../../Common/Matrix4Utils";
 import { Status, UpdateDraw } from "../../Common/Status";
 import { CSG } from "../../csg/core/CSG";
 import { CSG2Geometry, Geometry2CSG } from "../../csg/core/Geometry2CSG";
@@ -748,9 +748,19 @@ export class ExtrudeSolid extends Entity
     */
     ConverToLocalGroove(target: ExtrudeSolid): ExtrudeSolid[]
     {
-        if (isParallelTo(this.Normal, target.Normal))
+        let n1 = this.Normal;
+        let n2 = target.Normal;
+        if (isParallelTo(n1, n2))
         {
             target = target.Clone();
+            if (!equalv3(n1, n2))
+            {
+                let mtx = target._Matrix;
+                matrixSetVector(mtx, 2, n1);
+                let p = n1.setFromMatrixColumn(mtx, 3);
+                p.add(n2.multiplyScalar(target.thickness));
+                matrixSetVector(mtx, 3, p);
+            }
             if (this.GrooveCheckPosition(target) !== Status.True)
                 return [];