diff --git a/erpnext/manufacturing/doctype/manufacturing_settings/manufacturing_settings.json b/erpnext/manufacturing/doctype/manufacturing_settings/manufacturing_settings.json
index 23c223e..a5bdecd 100644
--- a/erpnext/manufacturing/doctype/manufacturing_settings/manufacturing_settings.json
+++ b/erpnext/manufacturing/doctype/manufacturing_settings/manufacturing_settings.json
@@ -9,33 +9,26 @@
  "document_type": "Master", 
  "fields": [
   {
-   "allow_on_submit": 0, 
-   "default": "30", 
-   "description": "Maximum Overtime allowed against an workstation.\n( in mins )", 
-   "fieldname": "max_overtime", 
-   "fieldtype": "Float", 
-   "hidden": 0, 
-   "ignore_user_permissions": 0, 
-   "in_filter": 0, 
-   "in_list_view": 1, 
-   "label": "Maximum Overtime", 
-   "no_copy": 0, 
+   "description": "Will not allow to make time logs outside \"Workstation operation timings\"", 
+   "fieldname": "dont_allow_overtime", 
+   "fieldtype": "Check", 
+   "label": "Don't allow overtime", 
    "permlevel": 0, 
-   "precision": "", 
-   "print_hide": 0, 
-   "read_only": 0, 
-   "report_hide": 0, 
-   "reqd": 0, 
-   "search_index": 0, 
-   "set_only_once": 0, 
-   "unique": 0
+   "precision": ""
   }, 
   {
-   "default": "No", 
+   "default": "", 
    "fieldname": "allow_production_on_holidays", 
-   "fieldtype": "Select", 
+   "fieldtype": "Check", 
+   "in_list_view": 1, 
    "label": "Allow Production on Holidays", 
-   "options": "Yes\nNo", 
+   "options": "", 
+   "permlevel": 0, 
+   "precision": ""
+  }, 
+  {
+   "fieldname": "column_break_3", 
+   "fieldtype": "Column Break", 
    "permlevel": 0, 
    "precision": ""
   }, 
@@ -44,6 +37,7 @@
    "description": "Delay in start time of production order operations if automatically make time logs is used.\n(in mins)", 
    "fieldname": "operations_start_delay", 
    "fieldtype": "Float", 
+   "in_list_view": 1, 
    "label": "Operations Start Delay", 
    "permlevel": 0, 
    "precision": ""
@@ -57,7 +51,7 @@
  "is_submittable": 0, 
  "issingle": 1, 
  "istable": 0, 
- "modified": "2014-12-18 16:22:26.052642", 
+ "modified": "2014-12-22 12:43:15.261503", 
  "modified_by": "Administrator", 
  "module": "Manufacturing", 
  "name": "Manufacturing Settings", 
diff --git a/erpnext/manufacturing/doctype/production_order/production_order.json b/erpnext/manufacturing/doctype/production_order/production_order.json
index f34e83c..da2bd5b 100644
--- a/erpnext/manufacturing/doctype/production_order/production_order.json
+++ b/erpnext/manufacturing/doctype/production_order/production_order.json
@@ -123,24 +123,40 @@
    "read_only": 0
   }, 
   {
+   "fieldname": "planned_start_date", 
+   "fieldtype": "Datetime", 
+   "label": "Planned Start Date", 
+   "permlevel": 0, 
+   "precision": ""
+  }, 
+  {
+   "fieldname": "planned_end_date", 
+   "fieldtype": "Datetime", 
+   "label": "Planned End Date", 
+   "permlevel": 0, 
+   "precision": ""
+  }, 
+  {
    "fieldname": "column_break_13", 
    "fieldtype": "Column Break", 
    "permlevel": 0, 
    "precision": ""
   }, 
   {
-   "fieldname": "production_start_date", 
+   "fieldname": "actual_start_date", 
    "fieldtype": "Datetime", 
-   "label": "Production Start Date", 
+   "label": "Actual Start Date", 
    "permlevel": 0, 
-   "precision": ""
+   "precision": "", 
+   "read_only": 1
   }, 
   {
-   "fieldname": "production_end_date", 
+   "fieldname": "actual_end_date", 
    "fieldtype": "Datetime", 
-   "label": "Production End Date", 
+   "label": "Actual End Date", 
    "permlevel": 0, 
-   "precision": ""
+   "precision": "", 
+   "read_only": 1
   }, 
   {
    "fieldname": "warehouses", 
@@ -331,7 +347,7 @@
  "idx": 1, 
  "in_create": 0, 
  "is_submittable": 1, 
- "modified": "2014-12-18 15:06:41.802390", 
+ "modified": "2014-12-19 14:23:50.701164", 
  "modified_by": "Administrator", 
  "module": "Manufacturing", 
  "name": "Production Order", 
diff --git a/erpnext/manufacturing/doctype/production_order/production_order.py b/erpnext/manufacturing/doctype/production_order/production_order.py
index 5fb92d1..a075f74 100644
--- a/erpnext/manufacturing/doctype/production_order/production_order.py
+++ b/erpnext/manufacturing/doctype/production_order/production_order.py
@@ -64,8 +64,8 @@
 
 		self.planned_variable_cost, self.actual_variable_cost = 0.0, 0.0
 		for d in self.get("production_order_operations"):
-			d.actual_variable_cost = flt(d.hour_rate) * flt(d.actual_operation_time) / 60 \
-				if d.actual_operation_time else d.time_in_mins
+
+			d.actual_variable_cost = flt(d.hour_rate) * flt(d.actual_operation_time) / 60
 
 			self.planned_variable_cost += flt(d.variable_cost)
 			self.actual_variable_cost += flt(d.actual_variable_cost)
@@ -254,14 +254,16 @@
 			if filters[key]:
 				conditions += " and " + key + ' = "' + filters[key].replace('"', '\"') + '"'
 
-	data = frappe.db.sql("""select name,production_item, production_start_date, production_end_date from `tabProduction Order`
+	data = frappe.db.sql("""select name,production_item, production_start_date, production_end_date
+		from `tabProduction Order`
 		where ((ifnull(production_start_date, '0000-00-00')!= '0000-00-00') \
 				and (production_start_date between %(start)s and %(end)s) \
 			or ((ifnull(production_start_date, '0000-00-00')!= '0000-00-00') \
-				and production_end_date between %(start)s and %(end)s)){conditions}""".format(conditions=conditions), {
+				and production_end_date between %(start)s and %(end)s)) {conditions}
+		""".format(conditions=conditions), {
 			"start": start,
 			"end": end
-			}, as_dict=True, update={"allDay": 0})
+		}, as_dict=True, update={"allDay": 0})
 	return data
 
 @frappe.whitelist()
diff --git a/erpnext/manufacturing/doctype/production_order/test_production_order.py b/erpnext/manufacturing/doctype/production_order/test_production_order.py
index 945e986..49db178 100644
--- a/erpnext/manufacturing/doctype/production_order/test_production_order.py
+++ b/erpnext/manufacturing/doctype/production_order/test_production_order.py
@@ -74,19 +74,19 @@
 		prod_order.production_order_operations[0].update({
 			"planned_start_time": "2014-11-25 00:00:00",
 			"planned_end_time": "2014-11-25 10:00:00",
-			"hour_rate": 10	 
+			"hour_rate": 10
 		})
 
 		prod_order.insert()
-		
+
 		d = prod_order.production_order_operations[0]
 
 		from erpnext.manufacturing.doctype.production_order.production_order import make_time_log
 		from frappe.utils import cstr
 		from frappe.utils import time_diff_in_hours
-		
+
 		prod_order.submit()
-		
+
 		time_log = make_time_log( prod_order.name, cstr(d.idx) + ". " + d.operation, \
 			d.planned_start_time, d.planned_end_time, prod_order.qty - d.qty_completed)
 
@@ -100,11 +100,11 @@
 		manufacturing_settings = frappe.get_doc({
 			"doctype": "Manufacturing Settings",
 			"maximum_overtime": 30,
-			"allow_production_on_holidays": "No"
+			"allow_production_on_holidays": 0
 		})
-		
+
 		manufacturing_settings.save()
-		
+
 		prod_order.load_from_db()
 		self.assertEqual(prod_order.production_order_operations[0].status, "Completed")
 		self.assertEqual(prod_order.production_order_operations[0].qty_completed, prod_order.qty)
@@ -114,13 +114,13 @@
 
 		self.assertEqual(prod_order.production_order_operations[0].actual_operation_time, 600)
 		self.assertEqual(prod_order.production_order_operations[0].actual_operating_cost, 6000)
-		
+
 		time_log.cancel()
 
 		prod_order.load_from_db()
 		self.assertEqual(prod_order.production_order_operations[0].status, "Pending")
 		self.assertEqual(prod_order.production_order_operations[0].qty_completed, 0)
-		
+
 		self.assertEqual(prod_order.production_order_operations[0].actual_operation_time, 0)
 		self.assertEqual(prod_order.production_order_operations[0].actual_operating_cost, 0)
 
@@ -132,5 +132,5 @@
 			"docstatus": 0
 		})
 		self.assertRaises(OverProductionError, time_log2.save)
-		
+
 test_records = frappe.get_test_records('Production Order')
diff --git a/erpnext/manufacturing/doctype/production_order_operation/production_order_operation.json b/erpnext/manufacturing/doctype/production_order_operation/production_order_operation.json
index 13b49c1..f17a055 100644
--- a/erpnext/manufacturing/doctype/production_order_operation/production_order_operation.json
+++ b/erpnext/manufacturing/doctype/production_order_operation/production_order_operation.json
@@ -277,7 +277,7 @@
   }, 
   {
    "allow_on_submit": 1, 
-   "depends_on": "eval:doc.docstatus==1", 
+   "depends_on": "eval:(doc.docstatus==1 && doc.status!=\"Completed\")", 
    "fieldname": "make_time_log", 
    "fieldtype": "Button", 
    "label": "Make Time Log", 
@@ -292,7 +292,7 @@
  "is_submittable": 0, 
  "issingle": 0, 
  "istable": 1, 
- "modified": "2014-12-18 12:18:51.655535", 
+ "modified": "2014-12-19 12:49:49.918120", 
  "modified_by": "Administrator", 
  "module": "Manufacturing", 
  "name": "Production Order Operation", 
diff --git a/erpnext/manufacturing/doctype/workstation/workstation.json b/erpnext/manufacturing/doctype/workstation/workstation.json
index 21cafc0..37932bc 100644
--- a/erpnext/manufacturing/doctype/workstation/workstation.json
+++ b/erpnext/manufacturing/doctype/workstation/workstation.json
@@ -154,14 +154,14 @@
    "fieldname": "workstation_operation_hours", 
    "fieldtype": "Table", 
    "label": "Workstation Operation Hours", 
-   "options": "Workstation Operation Hours", 
+   "options": "Workstation Operation Hour", 
    "permlevel": 0, 
    "precision": ""
   }
  ], 
  "icon": "icon-wrench", 
  "idx": 1, 
- "modified": "2014-12-18 13:01:47.143326", 
+ "modified": "2014-12-22 14:18:40.253034", 
  "modified_by": "Administrator", 
  "module": "Manufacturing", 
  "name": "Workstation", 
diff --git a/erpnext/manufacturing/doctype/workstation/workstation.py b/erpnext/manufacturing/doctype/workstation/workstation.py
index a0b150c..b95ca45 100644
--- a/erpnext/manufacturing/doctype/workstation/workstation.py
+++ b/erpnext/manufacturing/doctype/workstation/workstation.py
@@ -5,12 +5,13 @@
 import frappe
 import datetime
 from frappe import _
-from frappe.utils import flt, cint
+from frappe.utils import flt, cint, getdate, formatdate, comma_and
 
 from frappe.model.document import Document
 
 class WorkstationHolidayError(frappe.ValidationError): pass
 class WorkstationIsClosedError(frappe.ValidationError): pass
+class OverlapError(frappe.ValidationError): pass
 
 class Workstation(Document):
 	def update_bom_operation(self):
@@ -22,51 +23,58 @@
 				(self.hour_rate, bom_no[0], self.name))
 
 	def on_update(self):
+		self.validate_overlap_for_operation_timings()
+
 		frappe.db.set(self, 'total_variable_cost', flt(self.hour_rate_electricity) +
-		flt(self.hour_rate_consumable) + flt(self.hour_rate_rent))
+			flt(self.hour_rate_consumable) + flt(self.hour_rate_rent))
 		frappe.db.set(self, 'hour_rate', flt(self.hour_rate_labour) + flt(self.total_variable_cost))
+
 		self.update_bom_operation()
 
+	def validate_overlap_for_operation_timings(self):
+		for d in self.get("workstation_operation_hours"):
+			existing = frappe.db.sql_list("""select idx from `tabWorkstation Operation Hours`
+				where parent = %s and name != %s
+					and (
+						(start_time between %s and %s) or
+						(end_time between %s and %s) or
+						(%s between start_time and end_time))
+				""", (self.name, d.name, d.start_time, d.end_time, d.start_time, d.end_time, d.start_time))
 
+		if existing:
+			frappe.throw(_("Row #{0}: Timings conflicts with row {1}").format(d.idx, comma_and(existing)), OverlapError)
 
 @frappe.whitelist()
 def get_default_holiday_list():
 	return frappe.db.get_value("Company", frappe.defaults.get_user_default("company"), "default_holiday_list")
 
-def check_if_within_operating_hours(workstation, from_time, to_time):
-	if check_workstation_for_operation_time(workstation, from_time, to_time):
-		frappe.throw(_("Time Log timings outside workstation Operating Hours !"), WorkstationIsClosedError)
+def check_if_within_operating_hours(workstation, from_datetime, to_datetime):
+	if not is_within_operating_hours(workstation, from_datetime, to_datetime):
+		frappe.throw(_("Time Log timings outside workstation operating hours"), WorkstationIsClosedError)
 
-	if frappe.db.get_value("Manufacturing Settings", "None", "allow_production_on_holidays") == "No":
-		msg = check_workstation_for_holiday(workstation, from_time, to_time)
-		if msg != None:
-			frappe.throw(msg, WorkstationHolidayError)
+	if not cint(frappe.db.get_value("Manufacturing Settings", "None", "allow_production_on_holidays")):
+		check_workstation_for_holiday(workstation, from_datetime, to_datetime)
 
-def check_workstation_for_operation_time(workstation, from_time, to_time):
-	start_time = datetime.datetime.strptime(from_time,'%Y-%m-%d %H:%M:%S').strftime('%H:%M:%S')
-	end_time = datetime.datetime.strptime(to_time,'%Y-%m-%d %H:%M:%S').strftime('%H:%M:%S')
-	max_time_diff = frappe.db.get_value("Manufacturing Settings", "None", "max_overtime")
+def is_within_operating_hours(workstation, from_datetime, to_datetime):
+	if not cint(frappe.db.get_value("Manufacturing Settings", None, "dont_allow_overtime")):
+		return True
 
-	for d in frappe.db.sql("""select time_to_sec(timediff( start_time, %s))/60 as st_diff ,
-		time_to_sec(timediff( %s, end_time))/60 as et_diff from `tabWorkstation Operation Hours`
-		where parent = %s and (%s <start_time or %s > end_time )""",
-		(start_time, end_time, workstation, start_time, end_time), as_dict=1):
-		if cint(d.st_diff) > cint(max_time_diff):
-			return 1
-		if cint(d.et_diff) > cint(max_time_diff):
-			return 1
+	start_time = datetime.datetime.strptime(from_datetime,'%Y-%m-%d %H:%M:%S').strftime('%H:%M:%S')
+	end_time = datetime.datetime.strptime(to_datetime,'%Y-%m-%d %H:%M:%S').strftime('%H:%M:%S')
 
-def check_workstation_for_holiday(workstation, from_time, to_time):
+	for d in frappe.db.sql("""select start_time, end_time from `tabWorkstation Operation Hours`
+		where parent = %s and ifnull(enabled, 0) = 1""", workstation, as_dict=1):
+			if d.end_time >= start_time >= d.start_time and d.end_time >= end_time >= d.start_time:
+				return True
+
+def check_workstation_for_holiday(workstation, from_datetime, to_datetime):
 	holiday_list = frappe.db.get_value("Workstation", workstation, "holiday_list")
-	start_date = datetime.datetime.strptime(from_time,'%Y-%m-%d %H:%M:%S').strftime('%Y-%m-%d')
-	end_date = datetime.datetime.strptime(to_time,'%Y-%m-%d %H:%M:%S').strftime('%Y-%m-%d')
-	msg = _("Workstation is closed on the following dates as per Holiday List:")
-	flag = 0
-	for d in frappe.db.sql("""select holiday_date from `tabHoliday` where parent = %s and holiday_date between
-		%s and %s """,(holiday_list, start_date, end_date), as_dict=1):
-		flag = 1
-		msg = msg + "\n" + d.holiday_date
-	if flag ==1:
-		return msg
-	else:
-		return None
+	if holiday_list:
+		applicable_holidays = []
+		for d in frappe.db.sql("""select holiday_date from `tabHoliday` where parent = %s
+			and holiday_date between %s and %s """, (holiday_list, getdate(from_datetime), getdate(to_datetime))):
+				applicable_holidays.append(formatdate(d[0]))
+
+		if applicable_holidays:
+			frappe.throw(_("Workstation is closed on the following dates as per Holiday List: {0}")
+				.format(holiday_list) + "\n" + "\n".join(applicable_holidays), WorkstationHolidayError)
diff --git a/erpnext/manufacturing/doctype/workstation_operation_hours/__init__.py b/erpnext/manufacturing/doctype/workstation_operation_hour/__init__.py
similarity index 100%
rename from erpnext/manufacturing/doctype/workstation_operation_hours/__init__.py
rename to erpnext/manufacturing/doctype/workstation_operation_hour/__init__.py
diff --git a/erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.json b/erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.json
new file mode 100644
index 0000000..ebfa0ef
--- /dev/null
+++ b/erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.json
@@ -0,0 +1,129 @@
+{
+ "allow_copy": 0, 
+ "allow_import": 0, 
+ "allow_rename": 0, 
+ "creation": "2014-12-22 14:18:20.786493", 
+ "custom": 0, 
+ "docstatus": 0, 
+ "doctype": "DocType", 
+ "document_type": "", 
+ "fields": [
+  {
+   "allow_on_submit": 0, 
+   "fieldname": "start_time", 
+   "fieldtype": "Time", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "in_filter": 0, 
+   "in_list_view": 1, 
+   "label": "Start Time", 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "read_only": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_on_submit": 0, 
+   "fieldname": "column_break_2", 
+   "fieldtype": "Column Break", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "in_filter": 0, 
+   "in_list_view": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "read_only": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_on_submit": 0, 
+   "fieldname": "end_time", 
+   "fieldtype": "Time", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "in_filter": 0, 
+   "in_list_view": 1, 
+   "label": "End Time", 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "read_only": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_on_submit": 0, 
+   "fieldname": "section_break_2", 
+   "fieldtype": "Column Break", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "in_filter": 0, 
+   "in_list_view": 0, 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "read_only": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "unique": 0
+  }, 
+  {
+   "allow_on_submit": 0, 
+   "default": "1", 
+   "fieldname": "enabled", 
+   "fieldtype": "Check", 
+   "hidden": 0, 
+   "ignore_user_permissions": 0, 
+   "in_filter": 0, 
+   "in_list_view": 1, 
+   "label": "Enabled", 
+   "no_copy": 0, 
+   "permlevel": 0, 
+   "precision": "", 
+   "print_hide": 0, 
+   "read_only": 0, 
+   "report_hide": 0, 
+   "reqd": 0, 
+   "search_index": 0, 
+   "set_only_once": 0, 
+   "unique": 0
+  }
+ ], 
+ "hide_heading": 0, 
+ "hide_toolbar": 0, 
+ "in_create": 0, 
+ "in_dialog": 0, 
+ "is_submittable": 0, 
+ "issingle": 0, 
+ "istable": 1, 
+ "modified": "2014-12-22 14:18:31.091653", 
+ "modified_by": "Administrator", 
+ "module": "Manufacturing", 
+ "name": "Workstation Operation Hour", 
+ "name_case": "", 
+ "owner": "Administrator", 
+ "permissions": [], 
+ "read_only": 0, 
+ "read_only_onload": 0, 
+ "sort_field": "modified", 
+ "sort_order": "DESC"
+}
\ No newline at end of file
diff --git a/erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.py b/erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.py
similarity index 84%
rename from erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.py
rename to erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.py
index dfac1f8..1b8c519 100644
--- a/erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.py
+++ b/erpnext/manufacturing/doctype/workstation_operation_hour/workstation_operation_hour.py
@@ -5,5 +5,5 @@
 import frappe
 from frappe.model.document import Document
 
-class WorkstationOperationHours(Document):
+class WorkstationOperationHour(Document):
 	pass
diff --git a/erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.json b/erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.json
deleted file mode 100644
index 8a064ca..0000000
--- a/erpnext/manufacturing/doctype/workstation_operation_hours/workstation_operation_hours.json
+++ /dev/null
@@ -1,76 +0,0 @@
-{
- "allow_copy": 0, 
- "allow_import": 0, 
- "allow_rename": 0, 
- "creation": "2014-10-29 13:00:43.921508", 
- "custom": 0, 
- "docstatus": 0, 
- "doctype": "DocType", 
- "document_type": "", 
- "fields": [
-  {
-   "allow_on_submit": 0, 
-   "fieldname": "start_time", 
-   "fieldtype": "Time", 
-   "hidden": 0, 
-   "ignore_user_permissions": 0, 
-   "in_filter": 0, 
-   "in_list_view": 1, 
-   "label": "Start Time", 
-   "no_copy": 0, 
-   "permlevel": 0, 
-   "precision": "", 
-   "print_hide": 0, 
-   "read_only": 0, 
-   "report_hide": 0, 
-   "reqd": 0, 
-   "search_index": 0, 
-   "set_only_once": 0, 
-   "unique": 0
-  }, 
-  {
-   "fieldname": "section_break_2", 
-   "fieldtype": "Column Break", 
-   "permlevel": 0, 
-   "precision": ""
-  }, 
-  {
-   "allow_on_submit": 0, 
-   "fieldname": "end_time", 
-   "fieldtype": "Time", 
-   "hidden": 0, 
-   "ignore_user_permissions": 0, 
-   "in_filter": 0, 
-   "in_list_view": 1, 
-   "label": "End Time", 
-   "no_copy": 0, 
-   "permlevel": 0, 
-   "precision": "", 
-   "print_hide": 0, 
-   "read_only": 0, 
-   "report_hide": 0, 
-   "reqd": 0, 
-   "search_index": 0, 
-   "set_only_once": 0, 
-   "unique": 0
-  }
- ], 
- "hide_heading": 0, 
- "hide_toolbar": 0, 
- "in_create": 0, 
- "in_dialog": 0, 
- "is_submittable": 0, 
- "issingle": 0, 
- "istable": 1, 
- "modified": "2014-10-29 13:02:24.631554", 
- "modified_by": "Administrator", 
- "module": "Manufacturing", 
- "name": "Workstation Operation Hours", 
- "name_case": "", 
- "owner": "Administrator", 
- "permissions": [], 
- "read_only": 0, 
- "read_only_onload": 0, 
- "sort_field": "modified", 
- "sort_order": "DESC"
-}
\ No newline at end of file
diff --git a/erpnext/projects/doctype/time_log/time_log.js b/erpnext/projects/doctype/time_log/time_log.js
index 2c74bb3..e255843 100644
--- a/erpnext/projects/doctype/time_log/time_log.js
+++ b/erpnext/projects/doctype/time_log/time_log.js
@@ -5,6 +5,16 @@
 
 frappe.ui.form.on("Time Log", "onload", function(frm) {
 	frm.set_query("task", erpnext.queries.task);
+	if (frm.doc.time_log_for == "Manufacturing") {
+		frappe.ui.form.trigger("Time Log", "production_order");
+	}
+});
+
+frappe.ui.form.on("Time Log", "refresh", function(frm) {
+	var is_manufacturing = frm.doc.time_log_for=="Manufacturing" ? true : false;
+	frm.toggle_reqd("production_order", is_manufacturing);
+	frm.toggle_reqd("operation", is_manufacturing);
+	frm.toggle_reqd("operation_status", is_manufacturing);
 });
 
 // set to time if hours is updated
@@ -45,7 +55,7 @@
 				$.each(doc.production_order_operations , function(i, row){
 					operations[i] = (i+1) +". "+ row.operation;
 				});
-			frappe.meta.get_docfield("Time Log", "operation", me.frm.doc.name).options = operations.join("\n");
+			frappe.meta.get_docfield("Time Log", "operation", me.frm.doc.name).options = "\n" + operations.join("\n");
 			refresh_field("operation");
 			})
 		}
@@ -60,14 +70,10 @@
 			},
 			callback: function(r) {
 				if(!r.exc) {
+					console.log(r.message)
 					cur_frm.set_value("workstation", r.message)
 				}
-				doc.workstation = r.workstation;
 			}
 		});
 	}
 });
-
-if (cur_frm.doc.time_log_for == "Manufacturing") {
-	cur_frm.cscript.onload = cur_frm.cscript.production_order;
-}
diff --git a/erpnext/projects/doctype/time_log/time_log.json b/erpnext/projects/doctype/time_log/time_log.json
index 4afc0a0..3b27ab8 100644
--- a/erpnext/projects/doctype/time_log/time_log.json
+++ b/erpnext/projects/doctype/time_log/time_log.json
@@ -152,7 +152,7 @@
    "read_only": 0
   }, 
   {
-   "depends_on": "eval:doc.time_log_for == 'Project'", 
+   "depends_on": "eval:doc.time_log_for", 
    "fieldname": "project", 
    "fieldtype": "Link", 
    "in_list_view": 1, 
@@ -200,7 +200,7 @@
  "icon": "icon-time", 
  "idx": 1, 
  "is_submittable": 1, 
- "modified": "2014-12-18 17:21:01.520646", 
+ "modified": "2014-12-19 14:20:41.381152", 
  "modified_by": "Administrator", 
  "module": "Projects", 
  "name": "Time Log", 
diff --git a/erpnext/projects/doctype/time_log/time_log.py b/erpnext/projects/doctype/time_log/time_log.py
index db08abc..541154a 100644
--- a/erpnext/projects/doctype/time_log/time_log.py
+++ b/erpnext/projects/doctype/time_log/time_log.py
@@ -8,7 +8,6 @@
 from frappe import _
 from frappe.utils import cstr, comma_and, flt
 
-
 class OverlapError(frappe.ValidationError): pass
 class OverProductionError(frappe.ValidationError): pass
 class NotSubmittedError(frappe.ValidationError): pass
@@ -21,8 +20,10 @@
 		self.validate_overlap()
 		self.validate_timings()
 		self.calculate_total_hours()
+		self.validate_time_log_for()
 		self.check_workstation_timings()
 		self.validate_production_order()
+		self.validate_operation_status()
 
 	def on_submit(self):
 		self.update_production_order()
@@ -74,6 +75,11 @@
 		from frappe.utils import time_diff_in_seconds
 		self.hours = flt(time_diff_in_seconds(self.to_time, self.from_time)) / 3600
 
+	def validate_time_log_for(self):
+		if self.time_log_for == "Project":
+			for fld in ["production_order", "operation", "workstation", "operation_status"]:
+				self.set(fld, None)
+
 	def check_workstation_timings(self):
 		"""Checks if **Time Log** is between operating hours of the **Workstation**."""
 		if self.workstation:
@@ -82,28 +88,39 @@
 
 	def validate_production_order(self):
 		"""Throws 'NotSubmittedError' if **production order** is not submitted. """
-
 		if self.production_order:
 			if frappe.db.get_value("Production Order", self.production_order, "docstatus") != 1 :
 				frappe.throw(_("You can make a time log only against a submitted production order"), NotSubmittedError)
 
+	def validate_operation_status(self):
+		if self.time_log_for=="Manufacturing" and self.production_order and self.operation:
+			if self.operation_status == "Work in Progress":
+				latest_time_log = self.get_latest_time_log()
+				if latest_time_log and latest_time_log[0].operation_status == "Completed":
+					frappe.throw("Operation is already completed via Time Log {}".format(latest_time_log[0].name))
+
 	def update_production_order(self):
 		"""Updates `start_date`, `end_date`, `status` for operation in Production Order."""
 
 		if self.time_log_for=="Manufacturing" and self.operation:
 			dates = self.get_operation_start_end_time()
-			op_status = self.get_op_status()
-			actual_op_time = self.get_actual_op_time()
 
+			latest_time_log = self.get_latest_time_log()
+			op_status = latest_time_log[0].operation_status if latest_time_log else "Pending"
+
+			actual_op_time = self.get_actual_op_time()
 			d = self.operation.split('. ',1)
 
 			frappe.db.sql("""update `tabProduction Order Operation`
 				set actual_start_time = %s, actual_end_time = %s, status = %s, actual_operation_time = %s
 				where parent=%s and idx=%s and operation = %s""",
-				(dates.start_date, dates.end_date, op_status, actual_op_time,
-					self.production_order, d[0], d[1]))
+				(dates.start_date, dates.end_date, op_status,
+					actual_op_time, self.production_order, d[0], d[1]))
 
-			frappe.get_doc("Production Order", self.production_order).save()
+			pro_order = frappe.get_doc("Production Order", self.production_order)
+			pro_order.ignore_validate_update_after_submit = True
+			pro_order.calculate_operating_cost()
+			pro_order.save()
 
 	def get_operation_start_end_time(self):
 		"""Returns Min From and Max To Dates of Time Logs against a specific Operation. """
@@ -118,12 +135,10 @@
 			(self.production_order, self.operation))
 		return actual_time[0][0] if actual_time else 0
 
-	def get_op_status(self):
-		status = frappe.db.sql("""select operation_status from `tabTime Log`
+	def get_latest_time_log(self):
+		return frappe.db.sql("""select name, operation_status from `tabTime Log`
 			where production_order=%s and operation=%s and docstatus=1
-			order by to_time desc limit 1""", (self.production_order, self.operation))
-
-		return status if status else self.status
+			order by to_time desc limit 1""", (self.production_order, self.operation), as_dict=1)
 
 @frappe.whitelist()
 def get_workstation(production_order, operation):