diff --git a/src/kiri/mode/cam/op-area.js b/src/kiri/mode/cam/op-area.js
index b4e2a96a..938be92f 100644
--- a/src/kiri/mode/cam/op-area.js
+++ b/src/kiri/mode/cam/op-area.js
@@ -222,7 +222,7 @@ class OpArea extends CamOp {
             } else
             if (mode === 'trace') {
                 let { tr_type  } = op;
-                let zs = down ? base_util.lerp(zTop, zBottom || area.minZ(), down) : [ bounds.min.z ];
+                let zs = down ? base_util.lerp(zTop, op.thru ? zBottom : area.minZ(), down) : [ bounds.min.z ];
                 let zroc = 0;
                 let zinc = 1 / zs.length;
                 for (let z of zs) {
diff --git a/src/kiri/mode/cam/op-outline.js b/src/kiri/mode/cam/op-outline.js
index 11efd33c..7fd52c55 100644
--- a/src/kiri/mode/cam/op-outline.js
+++ b/src/kiri/mode/cam/op-outline.js
@@ -49,6 +49,7 @@ class OpOutline extends CamOp {
                 steps: op.wide ? op.steps + 1 : 1,
                 surfaces: {},
                 tool,
+                thru: true,
                 tr_type: 'outside',
             }));
         } else {
@@ -75,6 +76,7 @@ class OpOutline extends CamOp {
                 spindle,
                 surfaces: {},
                 tool,
+                thru: true,
                 tr_type: 'outside',
             }));
             if (!inside) {
diff --git a/src/kiri/mode/cam/op-rough.js b/src/kiri/mode/cam/op-rough.js
index 4f8f1774..77724c70 100644
--- a/src/kiri/mode/cam/op-rough.js
+++ b/src/kiri/mode/cam/op-rough.js
@@ -96,7 +96,8 @@ class OpRough extends CamOp {
                 ov_botz: op.ov_botz,
                 ov_topz: op.ov_topz,
                 areas: { [widget.id]: areas.map(p => p.toArray()) },
-                surfaces: {}
+                surfaces: {},
+                thru: true
             }));
         }