Lift mill between steps to zsafe if path is not a closed loop

If path is not a closed loop moving to the beginning of the path at any milling depth might move across copper areas. Proposed fix for #477.
pcb2gcode · Oct 11, 2020 · d2dd0f4 · d2dd0f4
1 parent 1c2422a
commit d2dd0f4
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Showing 3 changed files with 43 additions and 1 deletion.
diff --git a/ngc_exporter.cpp b/ngc_exporter.cpp
@@ -23,6 +23,7 @@
 #include "ngc_exporter.hpp"
 #include "options.hpp"
 #include <boost/algorithm/string.hpp>
+#include "bg_operators.hpp"
 #include <iostream>
 using std::cerr;
 using std::flush;
@@ -147,6 +148,14 @@ void NGC_Exporter::cutter_milling(std::ofstream& of, shared_ptr<Cutter> cutter,
   for (unsigned int i = 0; i < steps_num; i++) {
     const double z = cutter->zwork / steps_num * (i + 1);
 
+    /* Lift between steps if this is not the first pass and the path
+       is not a closed loop. */
+    if (i > 0 && path.front() != path.back()) {
+      of << "G00 Z" << cutter->zsafe * cfactor << " ( retract )\n";
+      of << "G00 X" << ( path.begin()->x() - xoffsetTot ) * cfactor << " Y"
+         << ( path.begin()->y() - yoffsetTot ) * cfactor << " ( rapid move to begin. )\n";
+    }
+
     of << "G01 Z" << z * cfactor << " F" << cutter->vertfeed * cfactor << " ( plunge. )\n";
     of << "G04 P0 ( dwell for no time -- G64 should not smooth over this point )\n";
     of << "G01 F" << cutter->feed * cfactor << "\n";
@@ -172,7 +181,7 @@ void NGC_Exporter::cutter_milling(std::ofstream& of, shared_ptr<Cutter> cutter,
         of << "G01 F" << cutter->feed * cfactor << '\n';
         in_bridge = false;
       }
-      
+
       // Now cut horizontally.
       of << "G01 X" << (path.at(current).x() - xoffsetTot) * cfactor
          << " Y"    << (path.at(current).y() - yoffsetTot) * cfactor << '\n';
@@ -196,6 +205,15 @@ void NGC_Exporter::isolation_milling(std::ofstream& of, shared_ptr<RoutingMill>
     const double z = mill->zwork / steps_num * (i + 1);
     linestring_type_fp::const_iterator iter = path.cbegin();
     of << "( Mill infeed pass " << i+1 << "/" << steps_num << " )\n";
+
+    /* Lift between steps if this is not the first pass and the path
+       is not a closed loop. */
+    if (i > 0 && path.front() != path.back()) {
+      of << "G00 Z" << mill->zsafe * cfactor << " ( retract )\n";
+      of << "G00 X" << ( path.begin()->x() - xoffsetTot ) * cfactor << " Y"
+         << ( path.begin()->y() - yoffsetTot ) * cfactor << " ( rapid move to begin. )\n";
+    }
+
     if (leveller) {
       leveller->setLastChainPoint(point_type_fp((path.begin()->x() - xoffsetTot) * cfactor,
                                                 (path.begin()->y() - yoffsetTot) * cfactor));

diff --git a/testing/gerbv_example/am-test-millinfeed/expected/back.ngc b/testing/gerbv_example/am-test-millinfeed/expected/back.ngc
@@ -1218,6 +1218,8 @@ G01 X-6.00239 Y4.84342
 G01 X-5.98995 Y4.85858
 G01 X-5.97905 Y4.86948
 ( Mill infeed pass 2/3 )
+G00 Z0.08000 ( retract )
+G00 X-5.87775 Y4.96385 ( rapid move to begin. )
 G01 Z-0.00533
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000
@@ -1369,6 +1371,8 @@ G01 X-6.00239 Y4.84342
 G01 X-5.98995 Y4.85858
 G01 X-5.97905 Y4.86948
 ( Mill infeed pass 3/3 )
+G00 Z0.08000 ( retract )
+G00 X-5.87775 Y4.96385 ( rapid move to begin. )
 G01 Z-0.00800
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000
@@ -2485,6 +2489,8 @@ G01 X-8.40082 Y6.22091
 G01 X-8.41295 Y6.31967
 G01 X-8.41625 Y6.33476
 ( Mill infeed pass 2/3 )
+G00 Z0.08000 ( retract )
+G00 X-8.86575 Y5.61847 ( rapid move to begin. )
 G01 Z-0.00533
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000
@@ -2663,6 +2669,8 @@ G01 X-8.40082 Y6.22091
 G01 X-8.41295 Y6.31967
 G01 X-8.41625 Y6.33476
 ( Mill infeed pass 3/3 )
+G00 Z0.08000 ( retract )
+G00 X-8.86575 Y5.61847 ( rapid move to begin. )
 G01 Z-0.00800
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000
@@ -2868,6 +2876,8 @@ G01 X-9.08987 Y6.18713
 G01 X-9.08875 Y6.17951
 G01 X-9.58375 Y6.06524
 ( Mill infeed pass 2/3 )
+G00 Z0.08000 ( retract )
+G00 X-9.13425 Y6.78153 ( rapid move to begin. )
 G01 Z-0.00533
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000
@@ -2890,6 +2900,8 @@ G01 X-9.08987 Y6.18713
 G01 X-9.08875 Y6.17951
 G01 X-9.58375 Y6.06524
 ( Mill infeed pass 3/3 )
+G00 Z0.08000 ( retract )
+G00 X-9.13425 Y6.78153 ( rapid move to begin. )
 G01 Z-0.00800
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F6.00000

diff --git a/testing/gerbv_example/lift-mill/expected/front.ngc b/testing/gerbv_example/lift-mill/expected/front.ngc
@@ -260,6 +260,8 @@ G01 X48.25997 Y-13.93878
 G01 X48.26000 Y-13.33500
 G01 X45.28711 Y-13.33500
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X36.84527 Y-13.33500 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000
@@ -593,6 +595,8 @@ G01 X47.93529 Y-20.22130
 G01 X48.09762 Y-20.14901
 G01 X48.25997 Y-20.06628
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X39.51498 Y-17.61998 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000
@@ -696,6 +700,8 @@ G01 X41.38999 Y-15.94244
 G01 X41.38999 Y-15.90998
 G01 X41.35338 Y-15.87337
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X41.35338 Y-16.98658 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000
@@ -728,6 +734,8 @@ G01 X45.93628 Y-14.29690
 G01 X45.82546 Y-14.42596
 G01 X45.84408 Y-14.44518
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X45.58916 Y-14.53497 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000
@@ -801,6 +809,8 @@ G01 X46.27926 Y-16.46959
 G01 X46.05061 Y-16.13405
 G01 X47.74222 Y-16.13499
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X45.84408 Y-15.87477 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000
@@ -872,6 +882,8 @@ G01 X46.04159 Y-18.32498
 G01 X46.16701 Y-18.32498
 G01 X46.23567 Y-18.40126
 ( Mill infeed pass 2/2 )
+G00 Z1.00000 ( retract )
+G00 X46.04159 Y-18.32498 ( rapid move to begin. )
 G01 Z-0.06000
 G04 P0 ( dwell for no time -- G64 should not smooth over this point )
 G01 F80.00000