dxfngc

@@ -37,10 +37,10 @@

     <para>

-      To illustrate the usage of dxfngc, suppose a stencil for a logo shall be

-      cut with a CNC mill.  The basic shape of the stencil is a circle.  The

-      logo is formed by two holes with a specific shape (see <xref

-      linkend="logo_stencil"/>).

+      To illustrate the usage of dxfngc, suppose a stencil for the

+      <emphasis>BlinkenArea</emphasis> logo shall be cut with a CNC mill.  The

+      basic shape of the stencil is a circle.  The logo is formed by two holes

+      with a specific shape (see <xref linkend="logo_stencil"/>).

     </para>

@@ -54,6 +54,10 @@

       <caption>The logo stencil to be cut on the CNC mill.</caption>

     </figure>

+    <sect2>

+

+      <title>Creating the Drawing</title>

+

       <para>

         First, the 2D drawing is created with a CAD program in DXF format.  The

@@ -74,10 +78,139 @@

                  Border and holes are on separate layers.</caption>

       </figure>

-    <programlisting>

-foo();

-bar();

-    </programlisting>

+    </sect2>

+

+    <sect2>

+

+      <title>Writing the Script</title>

+

+      <para>

+

+        The next step is to write the dxfngc script.  Such a script is shown in

+        <xref linkend="logo_script"/>.  All lines starting with a hash

+        character (<code>#</code>) are comments.  They will be ignored by

+        dxfngc.  During processing of the script, dxfngc manages three three

+        data objects in memory: the current settings, the current drawing and

+        the list of G-code commands.  Initially, the settings are set to some

+        reasonable defaults.  The drawing and the G-code are empty.

+

+      </para>

+

+      <para>

+

+        The first section of the example script fills the G-code list with

+        some setup commands to configure the CNC mill.  This is done using

+        the <code>cmd</code> command.  All the text folloing <code>cmd</code>

+        is treated as a G-code command and is appended as a new command to

+        the G-code list in memory.  Afterwards, the settings for processing the

+        drawing to G-code are configured.  This includes the Z coordinates

+        and the feed rates for moving and cutting as well as the diameter of

+        the cutting tool.  Please see !!!TODO!!! for a description of all

+        settings.

+

+      </para>

+

+      <para>

+

+        The <code>read_dxf</code> reads a CAD drawing in DXF format.  In this

+        example, the logo drawing shown in <xref linkend="logo_drawing"/> is

+        read.  This loads all layers of the DXF file to memory.  The layers can

+        then be processed with the cutting commands (see !!!TODO!!!) to produce

+        G-code.  The <code>cut_inside</code> command is used here to cut the

+        holes.  It will calculate the path of the cutting tool to be half its

+        diameter further to the inside of the holes.  This makes sure the hole

+        has the desired size and shape after cutting - or more precise as close

+        to it as possible with the selected cutting tool.  The

+        <code>cut_outside</code> command is used for cutting the border of the

+        stencil.  It basically works the same way, but moves the path of the

+        cutting tool further to the outside.

+

+      </para>

+

+      <para>

+

+        After all G-code for cutting has been created, the G-code commands

+        for finishing (e.g. turning off the CNC-mill) are appended using

+        <code>cmd</code> like for the setup.  Finally, the G-code accumulated

+        in memory is written to an output file useg <code>write_ngc</code>.

+

+      </para>

+

+      <figure xml:id="logo_script">

+        <title>Logo Script</title>

+        <programlisting><![CDATA[# add setup G-code commands

+cmd G21

+cmd G90

+cmd G64 P0.01

+cmd G17

+cmd G40

+cmd G49

+

+# configure settings

+set_precision 0.01

+set_tool_diameter 3

+set_move_z 5

+set_base_z 0

+set_cut_z -3.2

+set_cut_z_step 1.1

+set_feed_drill 100

+set_feed_mill 200

+set_layer_mode path_by_path

+

+# read drawing

+read_dxf logo.dxf

+

+# generate G-code for actual cutting

+cut_inside holes

+cut_outside border

+

+# add finishing G-code commands

+cmd M2

+

+# write G-code to output file

+write_ngc logo.ngc]]></programlisting>

+      </figure>

+

+    </sect2>

+

+    <sect2>

+

+      <title>Running the Script</title>

+

+      <para>

+

+        Once drawing and script are ready, the script can be run using the

+        <code>dxfngc</code> tool.  (It is assumed here it has already been

+        compiled. See !!!TODO!!! for instruction for compiling.)  As the script

+        contains the filenames of input and output files, it is sufficient to

+        provide the filename of the script file to dxfngc:

+

+      </para>

+

+      <programlisting><![CDATA[./dxfngc logo.txt]]></programlisting>

+

+      <para>

+

+        If everything goes well, this will produce a G-code file.  Otherwise an

+        error message will be printed that informs about what went wrong.

+        (There might also be some output like <code>dimeModel::largestHandle:

+        65535</code>, which is coming from inside the DXF library used

+        internally.  This output can be ignored.)

+        <xref linkend="logo_g-code"/> shows the produced G-code rendered by

+        LinuxCNC.

+

+      </para>

+

+      <figure xml:id="logo_g-code">

+        <title>G-code for Logo Stencil</title>

+        <mediaobject>

+          <imageobject>

+            <imagedata fileref="logo_g-code.png" format="PNG" width="100%"/>

+          </imageobject>

+        </mediaobject>

+        <caption>G-code for the logo stencil, rendered by LinuxCNC.</caption>

+      </figure>

+    </sect2>

   </sect1>

@@ -157,7 +157,7 @@

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