diff --git a/src/kiri-mode/cam/tool.js b/src/kiri-mode/cam/tool.js
index e0b26b5d..aa45cdc6 100644
--- a/src/kiri-mode/cam/tool.js
+++ b/src/kiri-mode/cam/tool.js
@@ -166,11 +166,11 @@ class Tool {
 CAM.Tool = Tool;
 
 CAM.calcTaperAngle = function(rad, len) {
-    return (Math.atan(rad / len) * RAD2DEG).round(1);
+    return (Math.atan(rad / len) * RAD2DEG);
 };
 
 CAM.calcTaperLength = function(rad, angle) {
-    return rad / Math.tan(angle);
+    return (rad / Math.tan(angle));
 };
 
 CAM.getToolDiameter = function(settings, id) {
diff --git a/src/kiri-mode/cam/topo4.js b/src/kiri-mode/cam/topo4.js
index ed24d4b3..4720e727 100644
--- a/src/kiri-mode/cam/topo4.js
+++ b/src/kiri-mode/cam/topo4.js
@@ -289,7 +289,7 @@ class Topo4 {
                 }
             }
             if (mz === -Infinity) {
-                mz = Math.max(lz, 0);
+                mz = zBottom; // Math.min(0, lz)
             } else if (zBottom && mz < zBottom) {
                 mz = zBottom;
             }
diff --git a/src/kiri/init.js b/src/kiri/init.js
index 40eadeb6..036fda37 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -1156,7 +1156,7 @@ gapp.register("kiri.init", [], (root, exports) => {
         if (tool.type === 'tapermill') {
             ui.toolTaperAngle.value = kiri.driver.CAM.calcTaperAngle(
                 (tool.flute_diam - tool.taper_tip) / 2, tool.flute_len
-            );
+            ).round(1);
         } else {
             ui.toolTaperAngle.value = 0;
         }
@@ -1278,10 +1278,10 @@ gapp.register("kiri.init", [], (root, exports) => {
                 const angle = parseFloat(ev.target.value);
                 const len = CAM.calcTaperLength(rad, angle * DEG2RAD);
                 selectedTool.flute_len = len;
-                ui.toolTaperAngle.value = angle;
+                ui.toolTaperAngle.value = angle.round(1);
                 ui.toolFluteLen.value = selectedTool.flute_len.round(4);
             } else {
-                ui.toolTaperAngle.value = CAM.calcTaperAngle(rad, selectedTool.flute_len);
+                ui.toolTaperAngle.value = CAM.calcTaperAngle(rad, selectedTool.flute_len).round(1);
             }
         } else {
             ui.toolTaperAngle.value = 0;