diff --git a/src/geo/point.js b/src/geo/point.js
index a4e18fdf..217de354 100644
--- a/src/geo/point.js
+++ b/src/geo/point.js
@@ -80,7 +80,10 @@
     };
 
     PRO.round = function(precision) {
-        return newPoint(ROUND(this.x,precision), ROUND(this.y,precision), ROUND(this.z,precision));
+        return newPoint(
+            this.x.round(precision),
+            this.y.round(precision),
+            this.z.round(precision));
     };
 
     PRO.addFacet = function(facet) {
@@ -91,7 +94,6 @@
 
     PRO.rekey = function() {
         this._key = undefined;
-        // this.key = [this.x,this.y,this.z].join(',');
     };
 
     PRO.toString = function() {
@@ -394,7 +396,9 @@
         let point = this, i;
         if (Array.isArray(poly)) {
             for (i=0; i<poly.length; i++) {
-                if (point.isInPolygonOnly(poly[i])) return true;
+                if (point.isInPolygonOnly(poly[i])) {
+                    return true;
+                }
             }
             return false;
         }
diff --git a/src/kiri/conf.js b/src/kiri/conf.js
index 3148c141..1e3ae0f3 100644
--- a/src/kiri/conf.js
+++ b/src/kiri/conf.js
@@ -319,6 +319,7 @@
                     sliceSupportGap: 1,
                     sliceSupportSize: 5,
                     sliceSupportArea: 0.1,
+                    sliceSupportSpan: 5,
                     sliceSupportExtra: 0,
                     sliceSupportAngle: 50,
                     sliceSupportNozzle: 0,
diff --git a/src/kiri/init.js b/src/kiri/init.js
index ea27864d..552e80f8 100644
--- a/src/kiri/init.js
+++ b/src/kiri/init.js
@@ -1718,7 +1718,8 @@
             sliceSupportArea:    UC.newInput(LANG.sp_area_s, {title:LANG.sp_area_l, bound:UC.bound(0.0,200.0), convert:UC.toFloat, modes:FDM}),
             sliceSupportExtra:   UC.newInput(LANG.sp_xpnd_s, {title:LANG.sp_xpnd_l, bound:UC.bound(0.0,200.0), convert:UC.toFloat, modes:FDM}),
             fdmSep:              UC.newBlank({class:"pop-sep", modes:FDM}),
-            sliceSupportAngle:   UC.newInput(LANG.sp_angl_s, {title:LANG.sp_angl_l, bound:UC.bound(0.0,90.0), convert:UC.toFloat, modes:FDM, xshow:isNotBelt}),
+            sliceSupportAngle:   UC.newInput(LANG.sp_angl_s, {title:LANG.sp_angl_l, bound:UC.bound(0.0,90.0), convert:UC.toFloat, modes:FDM, show:() => !UI.sliceSupportEnable.checked}),
+            sliceSupportSpan:    UC.newInput(LANG.sp_span_s, {title:LANG.sp_span_l, bound:UC.bound(0.0,200.0), convert:UC.toFloat, modes:FDM, show:() => UI.sliceSupportEnable.checked}),
             sliceSupportEnable:  UC.newBoolean(LANG.sp_auto_s, onBooleanClick, {title:LANG.sp_auto_l, modes:FDM, show:isNotBelt}),
 
             sliceSupportGen:     UC.newRow([
diff --git a/src/kiri/slicer.js b/src/kiri/slicer.js
index 61fb8307..178d2f96 100644
--- a/src/kiri/slicer.js
+++ b/src/kiri/slicer.js
@@ -685,8 +685,8 @@
 
         // create point map, unique point list and point group arrays
         input.forEach(function(line) {
-            p1 = cachedPoint(line.p1.round(4));
-            p2 = cachedPoint(line.p2.round(4));
+            p1 = cachedPoint(line.p1.round(5));
+            p2 = cachedPoint(line.p2.round(5));
             addConnected(p1,p2);
             addConnected(p2,p1);
         });
diff --git a/src/mode/fdm/slice.js b/src/mode/fdm/slice.js
index ca3eec1b..a41742c8 100644
--- a/src/mode/fdm/slice.js
+++ b/src/mode/fdm/slice.js
@@ -1272,7 +1272,7 @@
             .setLayer('pts', { line: 0xdd33dd, check: 0xdd33dd })
             .addPolys(points.map(p => base.newPolygon().centerRectangle(p, 0.8, 0.8)))
             .setLayer('dtr', { line: 0x0, check: 0x0 })
-            .addPolys(down_traces)
+            .addPolys(POLY.setZ(down_traces.clone(true),slice.z));
             ;
 
         if (supports.length === 0) {