How to leave small gaps in cutting paths?

[leonardshelby]

I'd like to prevent cut out parts from blocking the plotter. Is there a way to add small gaps in the (laser) contour cuts?

WhatsApp Image 2019-06-23 at 16.28.15.jpeg (122.51 KiB) Viewed 201 times

[quick61]

I'd like to prevent cut out parts from blocking the plotter. Is there a way to add small gaps in the (laser) contour cuts?

WhatsApp Image 2019-06-23 at 16.28.15.jpeg

In Path Workbench > Path > Path Dressup > Tag Dress-up. That will get you what your looking for.

Mark

[leonardshelby]

Hey Mark,

thanks, that seems to be what I was looking for. I'll give it a try

Also, is there a way to remove the third axis in gcode? I am removing gcode manually in a text editor for now.

[quick61]

Hey Mark,

thanks, that seems to be what I was looking for. I'll give it a try

Also, is there a way to remove the third axis in gcode? I am removing gcode manually in a text editor for now.

There was a thread on this - https://forum.freecadweb.org/viewtopic.php?f=15&t=32658 but for now, there is no laser/plasma/waterjet/etc tool or post processor in path. If your handy at coding, you can always take a run at adding it to the path workbench. I'm sure your effort would be received well by the guys that are working on it now.

Mark

[leonardshelby]

I don't think I'll be able to help as I can't code. The tag feature doesn't work for laser/plasma/.. other cutting tools as well. It would require a G0 movement instead of Z changes. I will try to edit these by hand, too :/

I'll have a look at the code though, once I have spare time

[TheMarkster]

Hey Mark,

thanks, that seems to be what I was looking for. I'll give it a try

Also, is there a way to remove the third axis in gcode? I am removing gcode manually in a text editor for now.

Which postprocessor do you use?

[leonardshelby]

I'm running grbl 1.1f on an arduino, so I have set the Processor to grbl in FreeCADs job settings. If that is the postprocessor you are referring to?

[chrisb]

You control this with the depth parameters and stepdown of the operations.

[leonardshelby]

@chrisb This does not work with lasercutters - often times they don't even have a Z axis (and if they do, it is used for focusing). The laser has to move without being turned on (G0) to leave gaps in the material. Alternatively you could travel faster in xy and/or reduce the laserpower to leave an "engraved gap".

[TheMarkster]

I'm running grbl 1.1f on an arduino, so I have set the Processor to grbl in FreeCADs job settings. If that is the postprocessor you are referring to?

Attached is a patched grbl.py postprocessor file. You would need to replace your file with this one in FreeCAD/Mod/Path/PathScripts/post/grbl_post.py (Probably should rename the original to something like grbl_post.py.backup)

grbl_post.py

(12 KiB) Downloaded 2 times

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#***************************************************************************
#*   (c) sliptonic (shopinthewoods@gmail.com) 2014                        *
#*                                                                         *
#*   This file is 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                                                                   *
#*                                                                         *
#***************************************************************************/


TOOLTIP='''
Generate g-code from a Path that is compatible with the grbl controller.

import grbl_post
grbl_post.export(object,"/path/to/file.ncc")
'''

import FreeCAD
import PathScripts.PostUtils as PostUtils
import argparse
import datetime
import shlex
import traceback


now = datetime.datetime.now()

parser = argparse.ArgumentParser(prog='grbl', add_help=False)
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('--comments', action='store_true', help='output comment (default)')
parser.add_argument('--no-comments', action='store_true', help='suppress comment 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='4', help='number of digits of precision, default=4')
parser.add_argument('--preamble', help='set commands to be issued before the first command, default="G17\nG90"')
parser.add_argument('--postamble', help='set commands to be issued after the last command, default="M05\nG17 G90\n; M2"')
parser.add_argument('--tool-change', help='0 ... suppress all tool change commands\n1 ... insert M6 for all tool changes\n2 ... insert M6 for all tool changes except the initial tool')
parser.add_argument('--no_z', action='store_true', help='eliminate z axis operations from gcode\n')

TOOLTIP_ARGS=parser.format_help()

#These globals set common customization preferences
OUTPUT_COMMENTS = True
OUTPUT_HEADER = True
OUTPUT_LINE_NUMBERS = False
OUTPUT_TOOL_CHANGE = False
SHOW_EDITOR = True
MODAL = False #if true commands are suppressed if the same as previous line.
COMMAND_SPACE = " "
LINENR = 100 #line number starting value

#These globals will be reflected in the Machine configuration of the project
UNITS = "G21" #G21 for metric, G20 for us standard
MACHINE_NAME = "GRBL"
CORNER_MIN = {'x':0, 'y':0, 'z':0 }
CORNER_MAX = {'x':500, 'y':300, 'z':300 }
PRECISION = 4
NO_Z = False

RAPID_MOVES = ['G0', 'G00']

#Preamble text will appear at the beginning of the GCODE output file.
PREAMBLE = '''G17 G90
'''

#Postamble text will appear following the last operation.
POSTAMBLE = '''M5
G17 G90
; M2
'''

# These commands are ignored by commenting them out
SUPPRESS_COMMANDS = [ 'G98', 'G80' ]

#Pre operation text will be inserted before every operation
PRE_OPERATION = ''''''

#Post operation text will be inserted after every operation
POST_OPERATION = ''''''

#Tool Change commands will be inserted before a tool change
TOOL_CHANGE = ''''''
SUPPRESS_TOOL_CHANGE=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 OUTPUT_HEADER
    global OUTPUT_COMMENTS
    global OUTPUT_LINE_NUMBERS
    global OUTPUT_TOOL_CHANGE
    global SHOW_EDITOR
    global PRECISION
    global PREAMBLE
    global POSTAMBLE
    global SUPPRESS_TOOL_CHANGE
    global NO_Z

    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
        print("Show editor = %d" % SHOW_EDITOR)
        PRECISION = args.precision
        if not args.preamble is None:
            PREAMBLE = args.preamble
        if not args.postamble is None:
            POSTAMBLE = args.postamble
        if not args.tool_change is None:
            OUTPUT_TOOL_CHANGE = int(args.tool_change) > 0
            SUPPRESS_TOOL_CHANGE = min(1, int(args.tool_change) - 1)
        if args.no_z:
            NO_Z = True
            CORNER_MIN = {'x':0, 'y':0 }
            CORNER_MAX = {'x':500, 'y':300 }

    except Exception as e:
        traceback.print_exc(e)
        return False

    return True

def export(objectslist,filename,argstring):
    if not processArguments(argstring):
        return None

    global UNITS

    for obj in objectslist:
        if not hasattr(obj,"Path"):
            print("the object " + obj.Name + " is not a path. Please select only path and Compounds.")
            return

    print("postprocessing...")
    gcode = ""

    #Find the machine.
    #The user my have overridden post processor defaults in the GUI.  Make sure we're using the current values in the Machine Def.
    myMachine = None
    for pathobj in objectslist:
        if hasattr(pathobj,"Group"): #We have a compound or project.
            for p in pathobj.Group:
                if p.Name == "Machine":
                    myMachine = p
    if myMachine is None:
        print("No machine found in this project")
    else:
        if myMachine.MachineUnits == "Metric":
           UNITS = "G21"
        else:
           UNITS = "G20"


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

    #Write the preamble
    if OUTPUT_COMMENTS: gcode += linenumber() + "(begin preamble)\n"
    for line in PREAMBLE.splitlines(True):
        gcode += linenumber() + line
    gcode += linenumber() + UNITS + "\n"

    for obj in objectslist:

        #do the pre_op
        if OUTPUT_COMMENTS: gcode += linenumber() + "(begin operation: " + obj.Label + ")\n"
        for line in PRE_OPERATION.splitlines(True):
            gcode += linenumber() + line

        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

    #do the post_amble

    if OUTPUT_COMMENTS: gcode += "(begin postamble)\n"
    for line in POSTAMBLE.splitlines(True):
        gcode += linenumber() + line

    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.")

    gfile = pythonopen(filename,"w")
    gfile.write(gcode)
    gfile.close()


def linenumber():
    global LINENR
    if OUTPUT_LINE_NUMBERS == True:
        LINENR += 10
        return "N" + str(LINENR) + " "
    return ""

def parse(pathobj):
    out = ""
    lastcommand = None
    precision_string = '.' + str(PRECISION) +'f'
    global SUPPRESS_TOOL_CHANGE
    global NO_Z

    #params = ['X','Y','Z','A','B','I','J','K','F','S'] #This list control the order of parameters
    params = ['X','Y','Z','A','B','I','J','F','S','T','Q','R','L'] #linuxcnc doesn't want K properties on XY plane  Arcs need work.
    if NO_Z:
        params = ['X','Y','A','B','I','J','F','S','T','Q','R','L'] #remove the Z
    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
            outstring.append(command)
            # if modal: only print the command if it is not the same as the last one
            if MODAL == True:
                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:
                            outstring.append(param + format(c.Parameters['F'] * 60, '.2f'))
                    elif param == 'T':
                        outstring.append(param + str(int(c.Parameters['T'])))
                    else:
                        outstring.append(param + format(c.Parameters[param], precision_string))

            # store the latest command
            lastcommand = command

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

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

            if command in SUPPRESS_COMMANDS:
                outstring.insert(0, ";")

            #prepend a line number and append a newline
            if len(outstring) >= 1:
                if OUTPUT_LINE_NUMBERS:
                    outstring.insert(0,(linenumber()))

                #append the line to the final output
                for w in outstring:
                    out += w + COMMAND_SPACE
                out = out.strip() + "\n"

        return out


print(__name__ + " gcode postprocessor loaded.")

Once you have the file copied to the above folder and restart FreeCAD you should now have an postprocessor argument "--no_z".

no_z.png (92.81 KiB) Viewed 128 times

I can't really test this except by generating gcode and checking to see if it contains any z coordinates, which I did and which it did not have in my test. Since you're using an arduino it's possible this might get bypassed or something, not sure.

Note: when previewing the gcode you might still see some z moves, but in the output gcode file they should all be gone.