diff --git a/notes.md b/notes.md
index 9cc78127..407fdbed 100644
--- a/notes.md
+++ b/notes.md
@@ -60,6 +60,7 @@
 
 # CAM
 
+* `B` increase tab height by z bottom
 * `B` prevent z delta cuts when not contouring
 * `B` climb vs conventional not fully consistent after refactor
 * `B` outside cutting direction in roughing mode inverted
diff --git a/src/kiri/slicer2.js b/src/kiri/slicer2.js
index 0a6b986b..debd1568 100644
--- a/src/kiri/slicer2.js
+++ b/src/kiri/slicer2.js
@@ -399,6 +399,13 @@
                 array.push(opt.down ? zmax : zmin);
             }
 
+            if (opt.flats && opt.off) {
+                // add over and under all flats by 'off'
+                array.appendAll(Object.keys(this.zFlat).map(v => parseFloat(v))).sort((a,b) => {
+                    return opt.down ? b-a : a-b;
+                });
+            }
+
             return array.map(v => parseFloat(v.toFixed(2)));
         }
     }
diff --git a/src/mode/cam/slice.js b/src/mode/cam/slice.js
index 22ef3adc..8eae3408 100644
--- a/src/mode/cam/slice.js
+++ b/src/mode/cam/slice.js
@@ -121,7 +121,7 @@
         });
         let tslices = [];
         let tshadow = [];
-        let tzindex = slicer.interval(minStepDown, { fit: true, off: 0.01, down: true });
+        let tzindex = slicer.interval(minStepDown, { fit: true, off: 0.01, down: true, flats: true });
         let terrain = slicer.slice(tzindex, { each: (data, index, total) => {
             tshadow = POLY.union(tshadow.appendAll(data.tops), 0.01, true);
             tslices.push(data.slice);
@@ -146,7 +146,7 @@
 
         // create facing slices
         if (procFacing || proc.camRoughTop) {
-            let shadow = shadowTop.tops.clone();
+            let shadow = tshadow.clone();
             let inset = POLY.offset(shadow, (roughToolDiam / (procRoughIn ? 2 : 1)));
             let facing = POLY.offset(inset, -(roughToolDiam * proc.camRoughOver), { count: 999, flat: true });
             let zdiv = ztOff / roughDown;