diff --git a/release.md b/release.md
index 2eb7d8ad..57dc47fb 100644
--- a/release.md
+++ b/release.md
@@ -6,6 +6,7 @@ Full docs @ https://docs.grid.space/projects/kiri-moto
 # Release 3.9
 
 * more graceful handling of security contexts blocking SharedArrayBuffer
+* CAM add dogbones support to traces ops
 * CAM add scripted contour filtering (to be extended to other ops)
 * CAM add calculation of taper length from angle
 * CAM add open poly-line offsetting with trace op
diff --git a/src/kiri-mode/cam/client.js b/src/kiri-mode/cam/client.js
index cd29cfb4..f3dc994d 100644
--- a/src/kiri-mode/cam/client.js
+++ b/src/kiri-mode/cam/client.js
@@ -1378,6 +1378,8 @@ CAM.init = function(kiri, api) {
         plunge:  'camTracePlunge',
         bottom:  'camTraceBottom',
         offover: 'camTraceOffOver',
+        dogbone: 'camTraceDogbone',
+        revbone: 'camTraceDogbone',
         select:  'camTraceMode'
     }).inputs = {
         tool:     UC.newSelect(LANG.cc_tool, {}, "tools"),
@@ -1393,8 +1395,10 @@ CAM.init = function(kiri, api) {
         down:     UC.newInput(LANG.cc_sdwn_s, {title:LANG.cc_sdwn_l, convert:UC.toFloat, units:true}),
         thru:     UC.newInput(LANG.cc_thru_s, {title:LANG.cc_thru_l, convert:UC.toFloat, units:true}),
         offover:  UC.newInput(LANG.cc_offd_s, {title:LANG.cc_offd_l, convert:UC.toFloat, units:true, show:() => poppedRec.offset !== "none"}),
-        sep:      UC.newBlank({class:"pop-sep", modes:MCAM, show:zBottom, poop:true }),
+        sep:      UC.newBlank({class:"pop-sep", modes:MCAM, poop:true }),
         bottom:   UC.newBoolean(LANG.cf_botm_s, undefined, {title:LANG.cf_botm_l, show:(op,conf) => conf.process.camZBottom}),
+        dogbone:  UC.newBoolean(LANG.co_dogb_s, undefined, {title:LANG.co_dogb_l}),
+        revbone:  UC.newBoolean(LANG.co_dogr_s, undefined, {title:LANG.co_dogr_l, show:(op) => poppedRec.dogbone}),
         sep:      UC.newBlank({class:"pop-sep"}),
         menu: UC.newRow([
             UC.newButton(undefined, func.traceAdd, {icon:'<i class="fas fa-plus"></i>'}),
diff --git a/src/kiri-mode/cam/ops.js b/src/kiri-mode/cam/ops.js
index 8f80fc0e..67c43092 100644
--- a/src/kiri-mode/cam/ops.js
+++ b/src/kiri-mode/cam/ops.js
@@ -1000,6 +1000,9 @@ class OpTrace extends CamOp {
             return slice;
         }
         function followZ(poly) {
+            if (op.dogbones) {
+                CAM.addDogbones(poly, toolDiam / 5, !op.revbone);
+            }
             let z = poly.getZ();
             let slice = newSliceOut(z);
             slice.camTrace = { tool, rate, plunge };
diff --git a/src/kiri-mode/cam/slice.js b/src/kiri-mode/cam/slice.js
index f0d4dc1c..c5547e13 100644
--- a/src/kiri-mode/cam/slice.js
+++ b/src/kiri-mode/cam/slice.js
@@ -292,18 +292,25 @@ CAM.addDogbones = function(poly, dist, reverse) {
     if (Array.isArray(poly)) {
         return poly.forEach(p => CAM.addDogbones(p, dist));
     }
-    if (poly.open) return;
+    // if (poly.open) return;
+    let open = poly.open;
     let isCW = poly.isClockwise();
     if (reverse || poly.parent) isCW = !isCW;
     let oldpts = poly.points.slice();
     let lastpt = oldpts[oldpts.length - 1];
     let lastsl = lastpt.slopeTo(oldpts[0]).toUnit();
     let newpts = [ ];
-    for (let i=0; i<oldpts.length + 1; i++) {
+    for (let i=0; i<oldpts.length + (open ? 0 : 1); i++) {
         let nextpt = oldpts[i % oldpts.length];
         let nextsl = lastpt.slopeTo(nextpt).toUnit();
         let adiff = lastsl.angleDiff(nextsl, true);
         let bdiff = ((adiff < 0 ? (180 - adiff) : (180 + adiff)) / 2) + 180;
+        if (open && i === 0) {
+            lastsl = nextsl;
+            lastpt = nextpt;
+            newpts.push(nextpt);
+            continue;
+        }
         if (isCW && adiff > 45) {
             let newa = base.newSlopeFromAngle(lastsl.angle + bdiff);
             newpts.push(lastpt.projectOnSlope(newa, dist));
diff --git a/web/kiri/lang/en.js b/web/kiri/lang/en.js
index e4c2a54d..a38b1bc9 100644
--- a/web/kiri/lang/en.js
+++ b/web/kiri/lang/en.js
@@ -496,6 +496,8 @@ self.kiri.lang['en-us'] = {
     co_menu:        "outline",
     co_dogb_s:      "dogbones",
     co_dogb_l:      ["insert dogbone cuts","into inside corners"],
+    co_dogr_s:      "reverse bones",
+    co_dogr_l:      ["reverse dogbone direction"],
     co_clrt_s:      "clear top",
     co_clrt_l:      ["cut starting at the top of stock","when stock is enabled"],
     co_wide_s:      "wide cutout",