Category Archives: Adventures In Creation

MPCNC Post Processor

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This is my MPCNC post processor, it works for me. Use it at your own risk!

Your mileage may vary!

 

 
# -*- coding: utf-8 -*-
# ***************************************************************************
# * *
# * (c) sliptonic (shopinthewoods@gmail.com) 2014 *
# * (c) Gauthier Briere - 2018, 2019 *
# * (c) Schildkroet - 2019-2020 *
# * (c) Ian Jobson - 2020 - 2021 *
# * *
# * This file is not yet part of the FreeCAD CAx development system. *
# * *
# * This program is free software; you can redistribute it and/or modify *
# * it under the terms of the GNU Lesser General Public License (LGPL) *
# * as published by the Free Software Foundation; either version 2 of *
# * the License, or (at your option) any later version. *
# * for detail see the LICENCE text file. *
# * *
# * FreeCAD is distributed in the hope that it will be useful, *
# * but WITHOUT ANY WARRANTY; without even the implied warranty of *
# * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the *
# * GNU Lesser General Public License for more details. *
# * *
# * You should have received a copy of the GNU Library General Public *
# * License along with FreeCAD; if not, write to the Free Software *
# * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 *
# * USA *
# * *
# ***************************************************************************/

import FreeCAD
from FreeCAD import Units
import PathScripts.PostUtils as PostUtils
import argparse
import datetime
import shlex
import PathScripts.PathUtil as PathUtil

TOOLTIP = '''
Generate g-code from a Path that is compatible with the MPCNC Marlin controller.
import mpcnc_post
mpcnc_post.export(object, "/path/to/file.gcode")
'''

# ***************************************************************************
# * Globals set customization preferences
# ***************************************************************************

# Default values for command line arguments:
NUMBERTOOL = 1 # there has to be one tool to start with
PAUSE_FIRST_TOOL = False # should we create an M0 for the first tool
OUTPUT_COMMENTS = True # default output of comments in output gCode file
OUTPUT_HEADER = True # default output header in output gCode file
OUTPUT_LINE_NUMBERS = False # default doesn't output line numbers in output gCode file
OUTPUT_BCNC = False # default doesn't add bCNC operation block headers in output gCode file
SHOW_EDITOR = True # default show the resulting file dialog output in GUI
PRECISION = 3 # Default precision for metric (see http://linuxcnc.org/docs/2.7/html/gcode/overview.html#_g_code_best_practices)
TRANSLATE_DRILL_CYCLES = False # If true, G81, G82 & G83 are translated in G0/G1 moves
PREAMBLE = '''G90
G21
''' # default preamble text will appear at the beginning of the gCode output file.
POSTAMBLE = '''M117 Job End
''' # default postamble text will appear following the last operation.

SPINDLE_WAIT = 0 # no waiting after M3 / M4 by default
RETURN_TO = ("0","0",) # no movements after end of program

# Customisation with no command line argument
MODAL = False # if true commands are suppressed if the same as previous line.
LINENR = 100 # line number starting value
LINEINCR = 10 # line number increment
OUTPUT_TOOL_CHANGE = True # default output M0 tool changes pause the machine until the resume is hit
DRILL_RETRACT_MODE = 'G98' # Default value of drill retractations (CURRENT_Z) other possible value is G99
MOTION_MODE = 'G90' # G90 for absolute moves, G91 for relative
UNITS = 'G21' # G21 for metric, G20 for us standard
UNIT_FORMAT = 'mm'
UNIT_SPEED_FORMAT = 'mm/min'
PRE_OPERATION = '''''' # Pre operation text will be inserted before every operation
POST_OPERATION = '''''' # Post operation text will be inserted after every operation
TOOL_CHANGE = '''M0
''' # Tool Change commands will be inserted before a tool change

# ***************************************************************************
# * End of customization
# ***************************************************************************

# Parser arguments list & definition
parser = argparse.ArgumentParser(prog='grbl', add_help=False)
parser.add_argument('--comments', action='store_true', help='output comment (default)')
parser.add_argument('--no-comments', action='store_true', help='suppress comment output')
parser.add_argument('--header', action='store_true', help='output headers (default)')
parser.add_argument('--no-header', action='store_true', help='suppress header output')
parser.add_argument('--line-numbers', action='store_true', help='prefix with line numbers')
parser.add_argument('--no-line-numbers', action='store_true', help='don\'t prefix with line numbers (default)')
parser.add_argument('--show-editor', action='store_true', help='pop up editor before writing output (default)')
parser.add_argument('--no-show-editor', action='store_true', help='don\'t pop up editor before writing output')
parser.add_argument('--precision', default='3', help='number of digits of precision, default=3')
parser.add_argument('--translate_drill', action='store_true', help='translate drill cycles G81, G82 & G83 in G0/G1 movements')
parser.add_argument('--no-translate_drill', action='store_true', help='don\'t translate drill cycles G81, G82 & G83 in G0/G1 movements (default)')
parser.add_argument('--preamble', help='set commands to be issued before the first command, default="G17 G90"')
parser.add_argument('--postamble', help='set commands to be issued after the last command, default="M5\nG17 G90\n;M2"')
parser.add_argument('--inches', action='store_true', help='Convert output for US imperial mode (G20)')
parser.add_argument('--tool-change', action='store_true', help='Insert M0 for all tool changes')
parser.add_argument('--wait-for-spindle', type=int, default=0, help='Wait for spindle to reach desired speed after M3 / M4, default=0')
parser.add_argument('--return-to', default='', help='Move to the specified coordinates at the end, e.g. --return-to=0,0')
parser.add_argument('--bcnc', action='store_true', help='Add Job operations as bCNC block headers. Consider suppressing existing comments: Add argument --no-comments')
parser.add_argument('--no-bcnc', action='store_true', help='suppress bCNC block header output (default)')
TOOLTIP_ARGS = parser.format_help()

# ***************************************************************************
# * Internal global variables
# ***************************************************************************
MOTION_COMMANDS = ['G0', 'G00', 'G1', 'G01', 'G2', 'G02', 'G3', 'G03'] # Motion gCode commands definition
RAPID_MOVES = ['G0', 'G00'] # Rapid moves gCode commands definition
SUPPRESS_COMMANDS = [] # These commands are ignored by commenting them out
COMMAND_SPACE = " "
# Global variables storing current position
CURRENT_X = 0
CURRENT_Y = 0
CURRENT_Z = 0

# ***************************************************************************
# * to distinguish python built-in open function from the one declared below
if open.__module__ in ['__builtin__', 'io']:
pythonopen = open

def processArguments(argstring):

global NUMBERTOOL
global PAUSE_FIRST_TOOL
global OUTPUT_HEADER
global OUTPUT_COMMENTS
global OUTPUT_LINE_NUMBERS
global SHOW_EDITOR
global PRECISION
global PREAMBLE
global POSTAMBLE
global UNITS
global UNIT_SPEED_FORMAT
global UNIT_FORMAT
global TRANSLATE_DRILL_CYCLES
global OUTPUT_TOOL_CHANGE
global SPINDLE_WAIT
global RETURN_TO
global OUTPUT_BCNC

try:
args = parser.parse_args(shlex.split(argstring))
if args.no_header:
OUTPUT_HEADER = False
if args.header:
OUTPUT_HEADER = True
if args.no_comments:
OUTPUT_COMMENTS = False
if args.comments:
OUTPUT_COMMENTS = True
if args.no_line_numbers:
OUTPUT_LINE_NUMBERS = False
if args.line_numbers:
OUTPUT_LINE_NUMBERS = True
if args.no_show_editor:
SHOW_EDITOR = False
if args.show_editor:
SHOW_EDITOR = True
PRECISION = args.precision
if args.preamble is not None:
PREAMBLE = args.preamble
if args.postamble is not None:
POSTAMBLE = args.postamble
if args.no_translate_drill:
TRANSLATE_DRILL_CYCLES = False
if args.translate_drill:
TRANSLATE_DRILL_CYCLES = True
if args.inches:
UNITS = 'G20'
UNIT_SPEED_FORMAT = 'in/min'
UNIT_FORMAT = 'in'
PRECISION = 4
if args.tool_change:
OUTPUT_TOOL_CHANGE = True
if args.wait_for_spindle > 0:
SPINDLE_WAIT = args.wait_for_spindle
if args.return_to != '':
RETURN_TO = [int(v) for v in args.return_to.split(',')]
if len(RETURN_TO) != 2:
RETURN_TO = None
print("--return-to coordinates must be specified as ,, ignoring")
if args.bcnc:
OUTPUT_BCNC = True
if args.no_bcnc:
OUTPUT_BCNC = False

except Exception as e:
return False

return True

# For debug...
def dump(obj):
for attr in dir(obj):
print("obj.%s = %s" % (attr, getattr(obj, attr)))

def export(objectslist, filename, argstring):

if not processArguments(argstring):
return None

global UNITS
global UNIT_FORMAT
global UNIT_SPEED_FORMAT
global MOTION_MODE
global SUPPRESS_COMMANDS

print("Post Processor: " + __name__ + " postprocessing...")
gcode = ""

# write header
if OUTPUT_HEADER:
gcode += linenumber() + ";Exported by FreeCAD\n"
gcode += linenumber() + ";Post Processor: " + __name__ + "\n"
gcode += linenumber() + ";Output Time:" + str(datetime.datetime.now()) + "\n"

# Check canned cycles for drilling
if TRANSLATE_DRILL_CYCLES:
if len(SUPPRESS_COMMANDS) == 0:
SUPPRESS_COMMANDS = ['G98', 'G80']
else:
SUPPRESS_COMMANDS += ['G98', 'G80']

# Write the preamble
if OUTPUT_COMMENTS:
gcode += linenumber() + ";Begin preamble\n"
for line in PREAMBLE.splitlines(True):
gcode += linenumber() + line
# verify if PREAMBLE have changed MOTION_MODE or UNITS
if 'G90' in PREAMBLE:
MOTION_MODE = 'G90'
elif 'G91' in PREAMBLE:
MOTION_MODE = 'G91'
else:
gcode += linenumber() + MOTION_MODE + "\n"
if 'G21' in PREAMBLE:
UNITS = 'G21'
UNIT_FORMAT = 'mm'
UNIT_SPEED_FORMAT = 'mm/min'
elif 'G20' in PREAMBLE:
UNITS = 'G20'
UNIT_FORMAT = 'in'
UNIT_SPEED_FORMAT = 'in/min'
else:
gcode += linenumber() + UNITS + "\n"

for obj in objectslist:
# Debug...
# print("\n" + "*"*70)
# dump(obj)
# print("*"*70 + "\n")
if not hasattr(obj, "Path"):
print("The object " + obj.Name + " is not a path. Please select only path and Compounds.")
return

# Skip inactive operations
if PathUtil.opProperty(obj, 'Active') is False:
continue

# do the pre_op
if OUTPUT_BCNC:
gcode += linenumber() + "(Block-name: " + obj.Label + ")\n"
gcode += linenumber() + "(Block-expand: 0)\n"
gcode += linenumber() + "(Block-enable: 1)\n"
if OUTPUT_COMMENTS:
gcode += linenumber() + ";Begin operation: " + obj.Label + "\n"
for line in PRE_OPERATION.splitlines(True):
gcode += linenumber() + line

# get coolant mode
coolantMode = 'None'
if hasattr(obj, "CoolantMode") or hasattr(obj, 'Base') and hasattr(obj.Base, "CoolantMode"):
if hasattr(obj, "CoolantMode"):
coolantMode = obj.CoolantMode
else:
coolantMode = obj.Base.CoolantMode

# turn coolant on if required
if OUTPUT_COMMENTS:
if not coolantMode == 'None':
gcode += linenumber() + ';(Coolant On:' + coolantMode + ')\n'
if coolantMode == 'Flood':
gcode += linenumber() + 'M8' + '\n'
if coolantMode == 'Mist':
gcode += linenumber() + 'M7' + '\n'

# Parse the op
gcode += parse(obj)

# do the post_op
if OUTPUT_COMMENTS:
gcode += linenumber() + ";Finish operation: " + obj.Label + "\n"
for line in POST_OPERATION.splitlines(True):
gcode += linenumber() + line

# turn coolant off if required
if not coolantMode == 'None':
if OUTPUT_COMMENTS:
gcode += linenumber() + ';(Coolant Off:' + coolantMode + ')\n'
gcode += linenumber() +'M9' + '\n'

# do the post_amble
if OUTPUT_BCNC:
gcode += linenumber() + "(Block-name: post_amble)\n"
gcode += linenumber() + "(Block-expand: 0)\n"
gcode += linenumber() + "(Block-enable: 1)\n"
if OUTPUT_COMMENTS:
gcode += linenumber() + ";Begin postamble\n"
for line in POSTAMBLE.splitlines(True):
gcode += linenumber() + line

if RETURN_TO:
gcode += linenumber() + "G0 X%s Y%s" % tuple(RETURN_TO)

# show the gCode result dialog
if FreeCAD.GuiUp and SHOW_EDITOR:
dia = PostUtils.GCodeEditorDialog()
dia.editor.setText(gcode)
result = dia.exec_()
if result:
final = dia.editor.toPlainText()
else:
final = gcode
else:
final = gcode

print("Done postprocessing.")

# write the file
gfile = pythonopen(filename, "w")
gfile.write(final)
gfile.close()

def linenumber():
global LINENR
global LINEINCR
if OUTPUT_LINE_NUMBERS:
s = "N" + str(LINENR) + " "
LINENR += LINEINCR
return s
return ""

def format_outstring(strTbl):
global COMMAND_SPACE
# construct the line for the final output
s = ""
for w in strTbl:
s += w + COMMAND_SPACE
s = s.strip()
return s

def parse(pathobj):

global DRILL_RETRACT_MODE
global MOTION_MODE
global CURRENT_X
global CURRENT_Y
global CURRENT_Z
global NUMBERTOOL
global TOOL_CHANGE

out = ""
lastcommand = None

precision_string = '.' + str(PRECISION) + 'f'

params = ['X', 'Y', 'Z', 'A', 'B', 'C', 'U', 'V', 'W', 'I', 'J', 'K', 'F', 'S', 'T', 'Q', 'R', 'L', 'P']

if hasattr(pathobj, "Group"): # We have a compound or project.
if OUTPUT_COMMENTS:
out += linenumber() + ";(Compound: " + pathobj.Label + ")\n"
for p in pathobj.Group:
out += parse(p)
return out

else: # parsing simple path
if not hasattr(pathobj, "Path"): # groups might contain non-path things like stock.
return out
if OUTPUT_COMMENTS:
out += linenumber() + ";Path: " + pathobj.Label + "\n"
for c in pathobj.Path.Commands:
outstring = []
command = c.Name
######################################################################
# Intercept the command here and modify it to insert the comment char
######################################################################
message = command
#print(message)
message_start = message[0]
#print(message_start)
if message_start == '(':
message = message.replace(message_start, ';' + message_start)
#print(message)
command = message
message_start = message[0:2]
#print(message_start + "---From Message[0:2]")
if message_start == 'M6':
TOOL_CHANGE = TOOL_CHANGE.rstrip("\n")
if NUMBERTOOL == 1 and PAUSE_FIRST_TOOL == False :
message = message.replace(message_start, ';' + TOOL_CHANGE)
NUMBERTOOL += 1

else:
message = message.replace(message_start, TOOL_CHANGE)
NUMBERTOOL += 1

#print(message)
#print (NUMBERTOOL)
#print ("^^^is the tool number")
command = message
#######################################################################
# End of Intercept mods
#######################################################################
outstring.append(command)

# if modal: only print the command if it is not the same as the last one
if MODAL:
if command == lastcommand:
outstring.pop(0)

# Now add the remaining parameters in order
for param in params:
if param in c.Parameters:
if param == 'F':
if command not in RAPID_MOVES:
speed = Units.Quantity(c.Parameters['F'], FreeCAD.Units.Velocity)
if speed.getValueAs(UNIT_SPEED_FORMAT) > 0.0:
outstring.append(param + format(float(speed.getValueAs(UNIT_SPEED_FORMAT)), precision_string))
elif param in ['T', 'H', 'D', 'S', 'P', 'L']:
outstring.append(param + str(c.Parameters[param]))
elif param in ['A', 'B', 'C']:
outstring.append(param + format(c.Parameters[param], precision_string))
else: # [X, Y, Z, U, V, W, I, J, K, R, Q] (Conversion eventuelle mm/inches)
pos = Units.Quantity(c.Parameters[param], FreeCAD.Units.Length)
outstring.append(param + format(float(pos.getValueAs(UNIT_FORMAT)), precision_string))

# store the latest command
lastcommand = command

# Memorizes the current position for calculating the related movements and the withdrawal plan
if command in MOTION_COMMANDS:
if 'X' in c.Parameters:
CURRENT_X = Units.Quantity(c.Parameters['X'], FreeCAD.Units.Length)
if 'Y' in c.Parameters:
CURRENT_Y = Units.Quantity(c.Parameters['Y'], FreeCAD.Units.Length)
if 'Z' in c.Parameters:
CURRENT_Z = Units.Quantity(c.Parameters['Z'], FreeCAD.Units.Length)

if command in ('G98', 'G99'):
DRILL_RETRACT_MODE = command

if command in ('G90', 'G91'):
MOTION_MODE = command

if TRANSLATE_DRILL_CYCLES:
if command in ('G81', 'G82', 'G83'):
out += drill_translate(outstring, command, c.Parameters)
# Erase the line we just translated
del(outstring[:])
outstring = []

if SPINDLE_WAIT > 0:
if command in ('M3', 'M03', 'M4', 'M04'):
out += linenumber() + format_outstring(outstring) + "\n"
out += linenumber() + format_outstring(['G4', 'P%s' % SPINDLE_WAIT]) + "\n"
del(outstring[:])
outstring = []

# Check for Tool Change:
if command in ('M6', 'M06'):
if OUTPUT_COMMENTS:
out += linenumber() + ";Begin toolchange\n"
if not OUTPUT_TOOL_CHANGE:
outstring[0] = "(" + outstring[0]
outstring[-1] = outstring[-1] + ")"
else:
for line in TOOL_CHANGE.splitlines(True):
out += linenumber() + line

if command == "message":
if OUTPUT_COMMENTS is False:
out = []
else:
outstring.pop(0) # remove the command

if command in SUPPRESS_COMMANDS:
outstring[0] = ";(" + outstring[0]
outstring[-1] = outstring[-1] + ")"

# prepend a line number and append a newline
if len(outstring) >= 1:
out += linenumber() + format_outstring(outstring) + "\n"

return out

def drill_translate(outstring, cmd, params):
global DRILL_RETRACT_MODE
global MOTION_MODE
global CURRENT_X
global CURRENT_Y
global CURRENT_Z
global UNITS
global UNIT_FORMAT
global UNIT_SPEED_FORMAT

strFormat = '.' + str(PRECISION) + 'f'

trBuff = ""

if OUTPUT_COMMENTS: # Comment the original command
outstring[0] = ";" + outstring[0]
outstring[-1] = outstring[-1] + "!"
trBuff += linenumber() + format_outstring(outstring) + "\n"

# Conversion du cycle
# Pour l'instant, on gere uniquement les cycles dans le plan XY (G17)
# les autres plans ZX (G18) et YZ (G19) ne sont pas traites : Calculs sur Z uniquement.
if MOTION_MODE == 'G90': # Deplacements en coordonnees absolues
drill_X = Units.Quantity(params['X'], FreeCAD.Units.Length)
drill_Y = Units.Quantity(params['Y'], FreeCAD.Units.Length)
drill_Z = Units.Quantity(params['Z'], FreeCAD.Units.Length)
RETRACT_Z = Units.Quantity(params['R'], FreeCAD.Units.Length)
else: # G91 Deplacements relatifs
drill_X = CURRENT_X + Units.Quantity(params['X'], FreeCAD.Units.Length)
drill_Y = CURRENT_Y + Units.Quantity(params['Y'], FreeCAD.Units.Length)
drill_Z = CURRENT_Z + Units.Quantity(params['Z'], FreeCAD.Units.Length)
RETRACT_Z = CURRENT_Z + Units.Quantity(params['R'], FreeCAD.Units.Length)

if DRILL_RETRACT_MODE == 'G98' and CURRENT_Z >= RETRACT_Z:
RETRACT_Z = CURRENT_Z

# Recupere les valeurs des autres parametres
drill_Speed = Units.Quantity(params['F'], FreeCAD.Units.Velocity)
if cmd == 'G83':
drill_Step = Units.Quantity(params['Q'], FreeCAD.Units.Length)
elif cmd == 'G82':
drill_DwellTime = params['P']

if MOTION_MODE == 'G91':
trBuff += linenumber() + "G90" + "\n" # Force des deplacements en coordonnees absolues pendant les cycles

# Mouvement(s) preliminaire(s))
if CURRENT_Z < RETRACT_Z: trBuff += linenumber() + 'G0 Z' + format(float(RETRACT_Z.getValueAs(UNIT_FORMAT)), strFormat) + "\n" trBuff += linenumber() + 'G0 X' + format(float(drill_X.getValueAs(UNIT_FORMAT)), strFormat) + ' Y' + format(float(drill_Y.getValueAs(UNIT_FORMAT)), strFormat) + "\n" if CURRENT_Z > RETRACT_Z:
trBuff += linenumber() + 'G0 Z' + format(float(CURRENT_Z.getValueAs(UNIT_FORMAT)), strFormat) + "\n"

# Mouvement de percage
if cmd in ('G81', 'G82'):
trBuff += linenumber() + 'G1 Z' + format(float(drill_Z.getValueAs(UNIT_FORMAT)), strFormat) + ' F' + format(float(drill_Speed.getValueAs(UNIT_SPEED_FORMAT)), '.2f') + "\n"
# Temporisation eventuelle
if cmd == 'G82':
trBuff += linenumber() + 'G4 P' + str(drill_DwellTime) + "\n"
# Sortie de percage
trBuff += linenumber() + 'G0 Z' + format(float(RETRACT_Z.getValueAs(UNIT_FORMAT)), strFormat) + "\n"
else: # 'G83'
next_Stop_Z = RETRACT_Z - drill_Step
while 1:
if next_Stop_Z > drill_Z:
trBuff += linenumber() + 'G1 Z' + format(float(next_Stop_Z.getValueAs(UNIT_FORMAT)), strFormat) + ' F' + format(float(drill_Speed.getValueAs(UNIT_SPEED_FORMAT)), '.2f') + "\n"
trBuff += linenumber() + 'G0 Z' + format(float(RETRACT_Z.getValueAs(UNIT_FORMAT)), strFormat) + "\n"
next_Stop_Z -= drill_Step
else:
trBuff += linenumber() + 'G1 Z' + format(float(drill_Z.getValueAs(UNIT_FORMAT)), strFormat) + ' F' + format(float(drill_Speed.getValueAs(UNIT_SPEED_FORMAT)), '.2f') + "\n"
trBuff += linenumber() + 'G0 Z' + format(float(RETRACT_Z.getValueAs(UNIT_FORMAT)), strFormat) + "\n"
break

if MOTION_MODE == 'G91':
trBuff += linenumber() + 'G91' # Restore le mode de deplacement relatif

return trBuff

print(__name__ + ": GCode postprocessor loaded.")