diff --git a/release.md b/release.md
index 8ae013b9..eac680c7 100644
--- a/release.md
+++ b/release.md
@@ -19,9 +19,10 @@ Full docs @ https://docs.grid.space/projects/kiri-moto
 * add option to ignore z bottom in CAM contouring
 * add CAM pocket option to ignore interior features (outline only)
 * add CAM Z bottom visualization, make it relative to stock instead of part
-* add CAM z bottom inversion option to flip operator
+* add CAM Z bottom inversion option to flip operator
 * add CAM custom gcode operator (can be used for pausing, too)
 * add optional CAM operation notes (helps with many similar ops)
+* add option to limit CAM trace ops to Z bottom limit (when in use)
 * extend url loading of workspaces to all formats
 * alert when healing is enabled and non-manifold geometries are detected
 * fix thin output start and end point tracking which broke retraction
diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index 55a58eca..542205d9 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -1077,6 +1077,7 @@ CAM.init = function(kiri, api) {
         down:    'camTraceDown',
         rate:    'camTraceSpeed',
         plunge:  'camTracePlunge',
+        bottom:  'camTraceBottom',
         select:  'camTraceMode'
     }).inputs = {
         tool:     UC.newSelect(LANG.cc_tool, {}, "tools"),
@@ -1090,6 +1091,8 @@ CAM.init = function(kiri, api) {
         plunge:   UC.newInput(LANG.cc_plng_s, {title:LANG.cc_plng_l, convert:UC.toInt, units:true}),
         sep:      UC.newBlank({class:"pop-sep"}),
         select:   UC.newSelect(LANG.cc_sele_s, {title:LANG.cc_sele_l}, "select"),
+        sep:      UC.newBlank({class:"pop-sep", show:(op,conf) => conf.process.camZBottom}),
+        bottom:   UC.newBoolean(LANG.cf_botm_s, undefined, {title:LANG.cf_botm_l, show:(op,conf) => conf.process.camZBottom}),
         menu: UC.newRow([
             UC.newButton(undefined, func.traceAdd, {icon:'<i class="fas fa-plus"></i>'}),
             UC.newButton(undefined, func.traceDone, {icon:'<i class="fas fa-check"></i>'}),
diff --git a/src/kiri-mode/cam/ops.js b/src/kiri-mode/cam/ops.js
index 77895459..ce823143 100644
--- a/src/kiri-mode/cam/ops.js
+++ b/src/kiri-mode/cam/ops.js
@@ -772,6 +772,7 @@ class OpTrace extends CamOp {
         let { settings, widget, sliceAll, zMax, zTop, zThru, tabs } = state;
         let { updateToolDiams, cutTabs, cutPolys, healPolys, color } = state;
         let { process, stock } = settings;
+        let { camStockClipTo, camZBottom } = process;
         // generate tracing offsets from chosen features
         let sliceOut = this.sliceOut = [];
         let areas = op.areas[widget.id] || [];
@@ -807,7 +808,7 @@ class OpTrace extends CamOp {
             } else {
                 slice.camLines = [ poly ];
             }
-            if (process.camStockClipTo && stockRect) {
+            if (camStockClipTo && stockRect) {
                 slice.camLines = cutPolys([stockRect], slice.camLines, z, true);
             }
             slice.output()
@@ -929,9 +930,13 @@ class OpTrace extends CamOp {
                 }
                 break;
             case "clear":
+                const zbo = widget.track.top - widget.track.box.d;
                 let zmap = {};
                 for (let poly of polys) {
                     let z = poly.getZ();
+                    if (op.bottom && camZBottom) {
+                        z = Math.max(z, camZBottom) - zbo;
+                    }
                     (zmap[z] = zmap[z] || []).push(poly);
                 }
                 for (let [zv, polys] of Object.entries(zmap)) {
diff --git a/src/kiri-mode/cam/topo.js b/src/kiri-mode/cam/topo.js
index 5b7f1ac9..1167acb0 100644
--- a/src/kiri-mode/cam/topo.js
+++ b/src/kiri-mode/cam/topo.js
@@ -32,7 +32,7 @@ class Topo {
             bounds = widget.getBoundingBox().clone(),
             tolerance = contour.tolerance,
             flatness = contour.flatness || 0.005,
-            bridge = contour.bridging || 10,
+            bridge = contour.bridging || 0,
             proc = settings.process,
             shadow = tshadow,
             minX = bounds.min.x,
diff --git a/src/kiri/conf.js b/src/kiri/conf.js
index a726bec1..a29ad62f 100644
--- a/src/kiri/conf.js
+++ b/src/kiri/conf.js
@@ -500,6 +500,7 @@ const conf = exports({
                 camTraceSpeed: 250,
                 camTracePlunge: 200,
                 camTraceLines: false,
+                camTraceBottom: false,
                 camPocketSpindle: 1000,
                 camPocketTool: 1000,
                 camPocketOver: 0.5,