diff --git a/SkeinPyPy/newui/mainWindow.py b/SkeinPyPy/newui/mainWindow.py
index 9088888..65ca69b 100644
--- a/SkeinPyPy/newui/mainWindow.py
+++ b/SkeinPyPy/newui/mainWindow.py
@@ -84,7 +84,7 @@ class mainWindow(configBase.configWindowBase):
 		configBase.TitleRow(left, "Accuracy")
 		c = configBase.SettingRow(left, "Layer height (mm)", 'layer_height', '0.2', 'Layer height in millimeters.\n0.2 is a good value for quick prints.\n0.1 gives high quality prints.')
 		validators.validFloat(c, 0.0)
-		validators.warningAbove(c, 0.31, "Thicker layers then 0.3mm usually give bad results and are not recommended.")
+		validators.warningAbove(c, lambda : (float(profile.getProfileSetting('nozzle_size')) * 80 / 100), "Thicker layers then %.2fmm (80%% nozzle size) usually give bad results and are not recommended.")
 		c = configBase.SettingRow(left, "Wall thickness (mm)", 'wall_thickness', '0.8', 'Thickness of the walls.\nThis is used in combination with the nozzle size to define the number\nof perimeter lines and the thickness of those perimeter lines.')
 		validators.validFloat(c, 0.0)
 		validators.wallThicknessValidator(c)
@@ -105,6 +105,7 @@ class mainWindow(configBase.configWindowBase):
 		c = configBase.SettingRow(right, "Print speed (mm/s)", 'print_speed', '50', 'Speed at which printing happens. A well adjusted Ultimaker can reach 150mm/s, but for good quality prints you want to print slower. Printing speed depends on a lot of factors. So you will be experimenting with optimal settings for this.')
 		validators.validFloat(c, 1.0)
 		validators.warningAbove(c, 150.0, "It is highly unlikely that your machine can achieve a printing speed above 150mm/s")
+		validators.printSpeedValidator(c)
 		
 		configBase.TitleRow(right, "Temperature")
 		c = configBase.SettingRow(right, "Printing temperature", 'print_temperature', '0', 'Temperature used for printing. Set at 0 to pre-heat yourself')
diff --git a/SkeinPyPy/newui/preview3d.py b/SkeinPyPy/newui/preview3d.py
index 8bdcc22..14d3b0e 100644
--- a/SkeinPyPy/newui/preview3d.py
+++ b/SkeinPyPy/newui/preview3d.py
@@ -343,12 +343,13 @@ class PreviewGLCanvas(glcanvas.GLCanvas):
 						for i in xrange(0, len(path['list'])-1):
 							v0 = path['list'][i]
 							v1 = path['list'][i+1]
+
+							# Calculate line width from ePerDistance (needs layer thickness and filament diameter)
 							dist = (v0 - v1).vsize()
 							if dist > 0 and layerThickness > 0:
 								extrusionMMperDist = (v1.e - v0.e) / (v0 - v1).vsize()
 								lineWidth = extrusionMMperDist * filamentArea / layerThickness / 2
 
-							#TODO: Calculate line width from ePerDistance (needs layer thickness, steps_per_E and filament diameter)
 							normal = (v0 - v1).cross(util3d.Vector3(0,0,1))
 							normal.normalize()
 							v2 = v0 + normal * lineWidth
diff --git a/SkeinPyPy/newui/validators.py b/SkeinPyPy/newui/validators.py
index d9d141a..7a2bedb 100644
--- a/SkeinPyPy/newui/validators.py
+++ b/SkeinPyPy/newui/validators.py
@@ -1,6 +1,9 @@
 from __future__ import absolute_import
 import __init__
 
+import types
+import math
+
 from newui import profile
 
 SUCCESS = 0
@@ -53,8 +56,12 @@ class warningAbove():
 	def validate(self):
 		try:
 			f = float(self.setting.GetValue())
-			if f >= self.minValueForWarning:
-				return WARNING, self.warningMessage
+			if isinstance(self.minValueForWarning, types.FunctionType):
+				if f >= self.minValueForWarning():
+					return WARNING, self.warningMessage % (self.minValueForWarning())
+			else:
+				if f >= self.minValueForWarning:
+					return WARNING, self.warningMessage
 			return SUCCESS, ''
 		except ValueError:
 			#We already have an error by the int/float validator in this case.
@@ -86,3 +93,27 @@ class wallThicknessValidator():
 			#We already have an error by the int/float validator in this case.
 			return SUCCESS, ''
 
+class printSpeedValidator():
+	def __init__(self, setting):
+		self.setting = setting
+		self.setting.validators.append(self)
+
+	def validate(self):
+		try:
+			nozzleSize = float(profile.getProfileSetting('nozzle_size'))
+			layerHeight = float(profile.getProfileSetting('layer_height'))
+			printSpeed = float(profile.getProfileSetting('print_speed'))
+			
+			printVolumePerMM = layerHeight * nozzleSize
+			printVolumePerSecond = printVolumePerMM * printSpeed
+			#Using 10mm3 per second with a 0.4mm nozzle (normal max according to Joergen Geerds)
+			maxPrintVolumePerSecond = 10 / (math.pi*(0.2*0.2)) * (math.pi*(nozzleSize/2*nozzleSize/2))
+			
+			if printVolumePerSecond > maxPrintVolumePerSecond:
+				return WARNING, 'You are trying to print more then %.1fmm^3 of filament per second. This might cause filament slipping.' % (maxPrintVolumePerSecond)
+			
+			return SUCCESS, ''
+		except ValueError:
+			#We already have an error by the int/float validator in this case.
+			return SUCCESS, ''
+