diff --git a/js/geo-polygon.js b/js/geo-polygon.js
index d7a25e16..519c6e9a 100644
--- a/js/geo-polygon.js
+++ b/js/geo-polygon.js
@@ -325,6 +325,31 @@ var gs_base_polygon = exports;
         return this;
     };
 
+    /**
+     * create square spiral (used for purge blocks)
+     */
+    PRO.centerSpiral = function(center, lenx, leny, offset, count) {
+        count *= 4;
+        offset /= 2;
+        let pos = { x: center.x - lenx/2, y: center.y + leny/2, z: center.z },
+            dir = { x: 1, y: 0, i: 0 }, t;
+        while (count-- > 0) {
+            this.push(newPoint(pos.x, pos.y, pos.z));
+            pos.x += dir.x * lenx;
+            pos.y += dir.y * leny;
+            switch (dir.i++) {
+                case 0: t = dir.x; dir.x = dir.y; dir.y = -t; break;
+                case 1: t = dir.x; dir.x = dir.y; dir.y = t; break;
+                case 2: t = dir.x; dir.x = dir.y; dir.y = -t; break;
+                case 3: t = dir.x; dir.x = dir.y; dir.y = t; break;
+            }
+            lenx -= offset/2;
+            leny -= offset/2;
+            dir.i = dir.i % 4;
+        }
+        return this;
+    };
+
     /**
      * add points forming a circle around a center point
      *
diff --git a/js/kiri-driver-fdm.js b/js/kiri-driver-fdm.js
index 023eb315..18e495c3 100644
--- a/js/kiri-driver-fdm.js
+++ b/js/kiri-driver-fdm.js
@@ -526,24 +526,27 @@ let gs_kiri_fdm = exports;
             }
         });
 
-        let blokpos, walkpos;
+        let blokpos, walkpos, blok;
         if (bounds.min.x < bounds.min.y) {
             let dx = ((bounds.max.x - bounds.min.x) - (extcount * 5)) / 2;
             blokpos = { x:bounds.min.x + dx, y: bounds.max.y + 5};
-            walkpos  = { x:10, y: 0};
+            walkpos  = { x:10, y:0 };
+            blok = { x:9, y:4 };
         } else {
             let dy = ((bounds.max.y - bounds.min.y) - (extcount * 5)) / 2;
             blokpos = { x:bounds.max.x + 5, y: bounds.min.y + dy};
-            walkpos  = { x:0, y: 10};
+            walkpos  = { x:0, y:10 };
+            blok = { x:4, y:9 };
         }
 
         // compute purge blocks
         extruders = extruders.map((ext,i) => {
             if (!ext) return ext;
-            let pos = {x:blokpos.x, y:blokpos.y, z:0},
+            let noz = device.extruders[i].extNozzle,
+                pos = {x:blokpos.x, y:blokpos.y, z:0},
                 rec = {
                     extruder: i,
-                    poly: BASE.newPolygon().centerRectangle(pos, 8, 8)
+                    poly: BASE.newPolygon().centerSpiral(pos, blok.x, blok.y, noz*2, 3)
                 };
             blokpos.x += walkpos.x;
             blokpos.y += walkpos.y;
@@ -555,7 +558,11 @@ let gs_kiri_fdm = exports;
             let rec = track[nozzle];
             if (rec) {
                 track[nozzle] = null;
-                return print.polyPrintPath(rec.poly.clone().setZ(z), start, layer, {tool:using || nozzle});
+                return print.polyPrintPath(rec.poly.clone().setZ(z), start, layer, {
+                    tool: using || nozzle,
+                    open: true,
+                    simple: true
+                });
             } else {
                 console.log({already_purged: nozzle, from: track, layer});
             }
diff --git a/js/kiri-print.js b/js/kiri-print.js
index 63c9480a..193e72e9 100644
--- a/js/kiri-print.js
+++ b/js/kiri-print.js
@@ -512,9 +512,10 @@ let gs_kiri_print = exports;
             printSpeed = options.rate || process.outputFeedrate,
             moveSpeed = process.outputSeekrate,
             minSpeed = process.outputMinSpeed,
-            closest = poly.findClosestPointTo(startPoint),
+            closest = options.simple ? poly.first() : poly.findClosestPointTo(startPoint),
             perimeter = poly.perimeter(),
             first = true,
+            close = !options.open,
             last = startPoint,
             wipeDist = options.wipe || 0,
             coastDist = options.coast || 0,
@@ -546,7 +547,7 @@ let gs_kiri_print = exports;
                 addOutput(output, point, shellMult, printSpeed, tool);
             }
             last = point;
-        }, true, closest.index);
+        }, close, closest.index);
 
         return output.last().point;
     };