diff --git a/Cura/gui/machineCom.py b/Cura/gui/machineCom.py
index 605d05c..ffd8165 100644
--- a/Cura/gui/machineCom.py
+++ b/Cura/gui/machineCom.py
@@ -1,7 +1,7 @@
 from __future__ import absolute_import
 import __init__
 
-import os, glob, wx, threading, sys
+import os, glob, wx, threading, sys, time
 
 from serial import Serial
 
@@ -108,7 +108,7 @@ class MachineCom():
 		if port == None:
 			port = profile.getPreference('serial_port')
 		if baudrate == None:
-			baudrate = profile.getPreference('serial_baud')
+			baudrate = int(profile.getPreference('serial_baud'))
 		self.serial = None
 		if port == 'AUTO':
 			programmer = stk500v2.Stk500v2()
@@ -116,6 +116,7 @@ class MachineCom():
 				try:
 					programmer.connect(port)
 					programmer.close()
+					print "Connecting to: %s %i" % (port, baudrate)
 					self.serial = Serial(port, baudrate, timeout=5)
 					break
 				except ispBase.IspError:
@@ -131,9 +132,10 @@ class MachineCom():
 
 	def readline(self):
 		if self.serial == None:
-			return ''
+			return None
 		ret = self.serial.readline()
-		print "Recv: " + ret.rstrip()
+		if ret != '':
+			print "Recv: " + ret.rstrip()
 		return ret
 	
 	def close(self):
@@ -144,5 +146,6 @@ class MachineCom():
 	def sendCommand(self, cmd):
 		if self.serial == None:
 			return
+		print 'Send: ' + cmd
 		self.serial.write(cmd + '\n')
 
diff --git a/Cura/gui/printWindow.py b/Cura/gui/printWindow.py
index 7b28a45..d061330 100644
--- a/Cura/gui/printWindow.py
+++ b/Cura/gui/printWindow.py
@@ -1,22 +1,31 @@
 from __future__ import absolute_import
 import __init__
 
-import wx
+import wx, threading
+
+from gui import machineCom
 
 printWindowHandle = None
 
 def printFile(filename):
 	global printWindowHandle
-	print "Want to print: " + filename
 	if printWindowHandle == None:
 		printWindowHandle = printWindow()
 	printWindowHandle.Show(True)
 	printWindowHandle.Raise()
+	printWindowHandle.LoadGCodeFile(filename)
 
 class printWindow(wx.Frame):
 	"Main user interface window"
 	def __init__(self):
 		super(printWindow, self).__init__(None, -1, title='Printing')
+		self.machineCom = None
+		self.thread = None
+		self.gcodeList = None
+		self.printIdx = None
+		self.bufferLineCount = 4
+		self.sendCnt = 0
+		
 		self.SetSizer(wx.BoxSizer())
 		self.panel = wx.Panel(self)
 		self.GetSizer().Add(self.panel, 1, flag=wx.EXPAND)
@@ -30,21 +39,99 @@ class printWindow(wx.Frame):
 		
 		self.sizer.Add(boxsizer, pos=(0,0), span=(4,1), flag=wx.EXPAND)
 		
-		self.sizer.Add(wx.Button(self.panel, -1, 'Connect'), pos=(0,1))
-		self.sizer.Add(wx.Button(self.panel, -1, 'Load GCode'), pos=(1,1))
-		self.sizer.Add(wx.Button(self.panel, -1, 'Print GCode'), pos=(2,1))
-		self.sizer.Add(wx.Button(self.panel, -1, 'Cancel print'), pos=(3,1))
+		self.connectButton = wx.Button(self.panel, -1, 'Connect')
+		self.loadButton = wx.Button(self.panel, -1, 'Load GCode')
+		self.printButton = wx.Button(self.panel, -1, 'Print GCode')
+		self.cancelButton = wx.Button(self.panel, -1, 'Cancel print')
+		self.sizer.Add(self.connectButton, pos=(0,1))
+		self.sizer.Add(self.loadButton, pos=(1,1))
+		self.sizer.Add(self.printButton, pos=(2,1))
+		self.sizer.Add(self.cancelButton, pos=(3,1))
 		self.sizer.Add(wx.Gauge(self.panel, -1), pos=(4,0), span=(1,2), flag=wx.EXPAND)
 		self.sizer.AddGrowableRow(3)
 		self.sizer.AddGrowableCol(0)
 		
 		self.Bind(wx.EVT_CLOSE, self.OnClose)
+		self.connectButton.Bind(wx.EVT_BUTTON, self.OnConnect)
+		self.loadButton.Bind(wx.EVT_BUTTON, self.OnLoad)
+		self.printButton.Bind(wx.EVT_BUTTON, self.OnPrint)
+		self.cancelButton.Bind(wx.EVT_BUTTON, self.OnCancel)
 		
 		self.Layout()
 		self.Fit()
 		self.Centre()
 	
+	def OnConnect(self, e):
+		if self.machineCom != None:
+			self.machineCom.close()
+			self.thread.join()
+		self.machineCom = machineCom.MachineCom()
+		self.thread = threading.Thread(target=self.PrinterMonitor)
+		self.thread.start()
+	
+	def OnLoad(self, e):
+		pass
+	
+	def OnPrint(self, e):
+		if self.machineCom == None:
+			return
+		if self.gcodeList == None:
+			return
+		if self.printIdx != None:
+			return
+		self.printIdx = 1
+		self.sendLine(0)
+		self.sendCnt = self.bufferLineCount
+	
+	def OnCancel(self, e):
+		pass
+	
 	def OnClose(self, e):
 		global printWindowHandle
 		printWindowHandle = None
+		if self.machineCom != None:
+			self.machineCom.close()
+			self.thread.join()
 		self.Destroy()
+
+	def LoadGCodeFile(self, filename):
+		gcodeList = ["M110"]
+		for line in open(filename, 'r'):
+			if ';' in line:
+				line = line[0:line.find(';')]
+			line = line.strip()
+			if len(line) > 0:
+				gcodeList.append(line)
+		print "Loaded: %s (%d)" % (filename, len(gcodeList))
+		self.gcodeList = gcodeList
+
+	def sendLine(self, lineNr):
+		if lineNr >= len(self.gcodeList):
+			return
+		checksum = reduce(lambda x,y:x^y, map(ord, "N%d%s" % (lineNr, self.gcodeList[lineNr])))
+		self.machineCom.sendCommand("N%d%s*%d" % (lineNr, self.gcodeList[lineNr], checksum))
+
+	def PrinterMonitor(self):
+		skipCount = 0
+		while True:
+			line = self.machineCom.readline()
+			if line == None:
+				return
+			while self.sendCnt > 0:
+				self.sendLine(self.printIdx)
+				self.printIdx += 1
+				self.sendCnt -= 1
+			if self.printIdx != None:
+				if line.startswith("ok"):
+					if skipCount > 0:
+						skipCount -= 1
+					else:
+						self.sendLine(self.printIdx)
+						self.printIdx += 1
+				elif "resend" in line.lower() or "rs" in line:
+					try:
+						lineNr=int(line.replace("N:"," ").replace("N"," ").replace(":"," ").split()[-1])
+					except:
+						if "rs" in line:
+							lineNr=int(line.split()[1])
+					self.printIdx = lineNr