diff --git a/web/app/sketcher/helpers.js b/web/app/sketcher/helpers.js
deleted file mode 100644
index c2970c5c..00000000
--- a/web/app/sketcher/helpers.js
+++ /dev/null
@@ -1,143 +0,0 @@
-import Vector from '../math/vector'
-import {Styles} from './viewer2d'
-import * as fetch from './fetchers'
-import * as math from '../math/math'
-import {EndPoint} from './viewer2d'
-import {Arc} from './shapes/arc'
-import {Constraints} from './parametric'
-
-/** @constructor */
-function FilletTool(viewer) {
-  this.viewer = viewer;
-}
-
-FilletTool.prototype.makeFillet = function(point1, point2) {
-  function shrink(point1) {
-    var a, b;
-    if (point1.id === point1.parent.a.id) {
-      a = point1.parent.b;
-      b = point1.parent.a;
-    } else {
-      a = point1.parent.a;
-      b = point1.parent.b;
-    }
-    var d = math.distanceAB(a, b);
-    var k = 4 / 5;
-    b.x = a.x + (b.x - a.x) * k; 
-    b.y = a.y + (b.y - a.y) * k;
-    return new Vector(a.x - b.x, a.y - b.y, 0);
-  }
-  
-  var v1 = shrink(point1);
-  var v2 = shrink(point2);
-  
-  if (v1.cross(v2).z > 0) {
-    var _ = point1;
-    point1 = point2;
-    point2 = _;
-  }
-  
-  var vec = new Vector();
-  vec.setV(point2);
-  vec._minus(point1);
-  vec._multiply(0.5);
-  vec._plus(point1);
-  
-  var arc = new Arc(
-      new EndPoint(point1.x, point1.y), 
-      new EndPoint(point2.x, point2.y), 
-      new EndPoint(vec.x, vec.y));
-  point1.parent.layer.objects.push(arc);
-  var pm = this.viewer.parametricManager;
-  arc.stabilize(this.viewer);
-  pm._add(new Constraints.Tangent( arc, point1.parent));
-  pm._add(new Constraints.Tangent( arc, point2.parent));
-  pm._add(new Constraints.Coincident( arc.a, point1));
-  pm._add(new Constraints.Coincident( arc.b, point2));
-
-  //function otherEnd(point) {
-  //  if (point.parent.a.id === point.id) {
-  //    return point.parent.b;
-  //  } else {
-  //    return point.parent.a;
-  //  }
-  //}
-  //
-  //pm._add(new Constraints.LockConvex(arc.c, arc.a, otherEnd(point1)));
-  //pm._add(new Constraints.LockConvex(otherEnd(point2), arc.b, arc.c));
-  
-  var solver = pm.solveWithLock([]);
-//  var solver = pm.solveWithLock([point1._x, point1._y, point2._x, point2._y]);
-  pm.notify();
-  this.viewer.refresh();
-};
-
-FilletTool.prototype.mouseup = function(e) {
-  var candi = this.getCandidate(e);
-  if (candi == null) return;
-  var point1 = candi[0];
-  var point2 = candi[1];
-  
-  var pm = this.viewer.parametricManager;
-  for (var i = 0; i < pm.subSystems.length; i++) {
-    var subSys = pm.subSystems[i];
-    for (var j = 0; j < subSys.constraints.length; j++) {
-      var c = subSys.constraints[j];
-      if (c.NAME === 'coi' && 
-          ((c.a.id === point1.id && c.b.id === point2.id) ||
-           (c.b.id === point1.id && c.a.id === point2.id)))   {
-        pm.remove(c);
-        this.makeFillet(point1, point2);
-        this.viewer.deselectAll();
-        return;
-      }
-    }        
-  }
-};
-
-function isLine(line) {
-  return line != null && line._class === 'TCAD.TWO.Segment';
-}
-
-FilletTool.prototype.getCandidate = function(e) {
-  var picked = this.viewer.pick(e);
-  if (picked.length > 0) {
-    var res = fetch.sketchObjects(picked, true, ['TCAD.TWO.EndPoint']);
-    if (res == null) return null;
-    var point1 = res[0];
-    if (!isLine(point1.parent)) return;
-    var line2 = null;
-    for (var i = 0; i < point1.linked.length; i++) {
-      var point2 = point1.linked[i];
-      if (isLine(point2.parent)) {
-        return [point1, point2];
-      }
-    }
-  }
-  return null;
-};
-
-FilletTool.prototype.keydown = function(e) {};
-FilletTool.prototype.keypress = function(e) {};
-FilletTool.prototype.keyup = function(e) {};
-FilletTool.prototype.cleanup = function(e) {};
-
-FilletTool.prototype.mousemove = function(e) {
-  var needRefresh = false;
-  if (this.viewer.selected.length != 0) {
-    this.viewer.deselectAll();
-    needRefresh = true;
-  }
-  var candi = this.getCandidate(e);
-  if (candi != null) {
-    this.viewer.mark(candi[0], Styles.SNAP);
-    needRefresh = true;
-  }
-  if (needRefresh) {
-    this.viewer.refresh();
-  }
-};
-FilletTool.prototype.mousedown = function(e) {};
-FilletTool.prototype.mousewheel = function(e) {};
-
-export {FilletTool}
\ No newline at end of file
diff --git a/web/app/sketcher/sketcher-app.js b/web/app/sketcher/sketcher-app.js
index c1a02c07..afa703fd 100644
--- a/web/app/sketcher/sketcher-app.js
+++ b/web/app/sketcher/sketcher-app.js
@@ -7,7 +7,7 @@ import {AddPointTool} from './tools/point'
 import {AddSegmentTool} from './tools/segment'
 import {AddArcTool} from './tools/arc'
 import {EditCircleTool} from './tools/circle'
-import {FilletTool} from './helpers'
+import {FilletTool} from './tools/fillet'
 import {ReferencePointTool} from './tools/origin'
 import {InputManager} from './input-manager'
 
diff --git a/web/app/sketcher/tools/fillet.js b/web/app/sketcher/tools/fillet.js
new file mode 100644
index 00000000..00e4cdfd
--- /dev/null
+++ b/web/app/sketcher/tools/fillet.js
@@ -0,0 +1,138 @@
+import Vector from '../../math/vector'
+import {Styles} from '../viewer2d'
+import * as fetch from '../fetchers'
+import * as math from '../../math/math'
+import {EndPoint} from '../shapes/point'
+import {Arc} from '../shapes/arc'
+import {Constraints} from '../parametric'
+import {Tool} from './tool'
+
+export class FilletTool extends Tool {
+  
+  constructor(viewer) {
+    super('fillet', viewer);  
+    this.viewer = viewer;
+  }
+  
+  makeFillet(point1, point2) {
+    function shrink(point1) {
+      var a, b;
+      if (point1.id === point1.parent.a.id) {
+        a = point1.parent.b;
+        b = point1.parent.a;
+      } else {
+        a = point1.parent.a;
+        b = point1.parent.b;
+      }
+      var d = math.distanceAB(a, b);
+      var k = 4 / 5;
+      b.x = a.x + (b.x - a.x) * k;
+      b.y = a.y + (b.y - a.y) * k;
+      return new Vector(a.x - b.x, a.y - b.y, 0);
+    }
+  
+    var v1 = shrink(point1);
+    var v2 = shrink(point2);
+  
+    if (v1.cross(v2).z > 0) {
+      var _ = point1;
+      point1 = point2;
+      point2 = _;
+    }
+  
+    var vec = new Vector();
+    vec.setV(point2);
+    vec._minus(point1);
+    vec._multiply(0.5);
+    vec._plus(point1);
+  
+    var arc = new Arc(
+      new EndPoint(point1.x, point1.y),
+      new EndPoint(point2.x, point2.y),
+      new EndPoint(vec.x, vec.y));
+    point1.parent.layer.objects.push(arc);
+    var pm = this.viewer.parametricManager;
+    arc.stabilize(this.viewer);
+    pm._add(new Constraints.Tangent( arc, point1.parent));
+    pm._add(new Constraints.Tangent( arc, point2.parent));
+    pm._add(new Constraints.Coincident( arc.a, point1));
+    pm._add(new Constraints.Coincident( arc.b, point2));
+  
+    //function otherEnd(point) {
+    //  if (point.parent.a.id === point.id) {
+    //    return point.parent.b;
+    //  } else {
+    //    return point.parent.a;
+    //  }
+    //}
+    //
+    //pm._add(new Constraints.LockConvex(arc.c, arc.a, otherEnd(point1)));
+    //pm._add(new Constraints.LockConvex(otherEnd(point2), arc.b, arc.c));
+  
+    var solver = pm.solveWithLock([]);
+  //  var solver = pm.solveWithLock([point1._x, point1._y, point2._x, point2._y]);
+    pm.notify();
+    this.viewer.refresh();
+  }
+  
+  mouseup(e) {
+    var candi = this.getCandidate(e);
+    if (candi == null) return;
+    var point1 = candi[0];
+    var point2 = candi[1];
+  
+    var pm = this.viewer.parametricManager;
+    for (var i = 0; i < pm.subSystems.length; i++) {
+      var subSys = pm.subSystems[i];
+      for (var j = 0; j < subSys.constraints.length; j++) {
+        var c = subSys.constraints[j];
+        if (c.NAME === 'coi' &&
+          ((c.a.id === point1.id && c.b.id === point2.id) ||
+          (c.b.id === point1.id && c.a.id === point2.id)))   {
+          pm.remove(c);
+          this.makeFillet(point1, point2);
+          this.viewer.deselectAll();
+          return;
+        }
+      }
+    }
+  }
+  
+  static isLine(line) {
+    return line != null && line._class === 'TCAD.TWO.Segment';
+  }
+  
+  getCandidate(e) {
+    var picked = this.viewer.pick(e);
+    if (picked.length > 0) {
+      var res = fetch.sketchObjects(picked, true, ['TCAD.TWO.EndPoint']);
+      if (res == null) return null;
+      var point1 = res[0];
+      if (!FilletTool.isLine(point1.parent)) return;
+      var line2 = null;
+      for (var i = 0; i < point1.linked.length; i++) {
+        var point2 = point1.linked[i];
+        if (FilletTool.isLine(point2.parent)) {
+          return [point1, point2];
+        }
+      }
+    }
+    return null;
+  }
+  
+  mousemove(e) {
+    var needRefresh = false;
+    if (this.viewer.selected.length != 0) {
+      this.viewer.deselectAll();
+      needRefresh = true;
+    }
+    var candi = this.getCandidate(e);
+    if (candi != null) {
+      this.viewer.mark(candi[0], Styles.SNAP);
+      needRefresh = true;
+    }
+    if (needRefresh) {
+      this.viewer.refresh();
+    }
+  }
+}