diff --git a/MachineTool/DemoBuildMachineTool.cs b/MachineTool/DemoBuildMachineTool.cs
index 6990d23..ce66233 100644
--- a/MachineTool/DemoBuildMachineTool.cs
+++ b/MachineTool/DemoBuildMachineTool.cs
@@ -43,6 +43,9 @@ namespace Sample.MachineTool
                 "[O][Y][X][C][w];[O][Z][B][S][t]");
             if (dst.ToolMountTransformer is StaticTranslation st)
                 st.Trans = new vec3d_t(-72.40, 72.40, 176.44);
+            //the spindle turns the tool about its own axis: the rotation's pivot
+            //sits on the tool mount's origin, where the offset above moved it.
+            dst.SpindleTransformer.Pivot = new vec3d_t(-72.40, 72.40, 176.44);
             dst.TransformerB.Pivot = new vec3d_t(-72.4, -177.4, 225.94);
             Dictionary<string, Solid> solidMap = new Dictionary<string, Solid>()
             {