diff --git a/lib/Slic3r/GUI/Projector.pm b/lib/Slic3r/GUI/Projector.pm
index 1e2446545..af12b6b8c 100644
--- a/lib/Slic3r/GUI/Projector.pm
+++ b/lib/Slic3r/GUI/Projector.pm
@@ -39,7 +39,7 @@ sub new {
     my $sizer = Wx::BoxSizer->new(wxVERTICAL);
     
     $self->config(Slic3r::Config->new_from_defaults(
-        qw(serial_port serial_speed bed_shape start_gcode end_gcode)
+        qw(serial_port serial_speed bed_shape start_gcode end_gcode z_offset)
     ));
     $self->config->apply(wxTheApp->{mainframe}->config);
     
@@ -599,8 +599,6 @@ sub start_print {
         
         # send custom start G-code
         $self->sender->send($_, 1) for grep !/^;/, split /\n/, $self->config->start_gcode;
-        $self->sender->send(sprintf("G1 Z%.5f F%d",
-            $self->config2->{z_lift}, $self->config2->{z_lift_speed}*60), 1);
     }
     
     $self->is_printing(1);
@@ -621,6 +619,10 @@ sub start_print {
 sub stop_print {
     my ($self) = @_;
     
+    if ($self->sender) {
+        $self->sender->disconnect;
+    }
+    
     $self->is_printing(0);
     $self->timer->Stop;
     $self->_timer_cb(undef);
@@ -633,7 +635,6 @@ sub print_completed {
     # send custom end G-code
     if ($self->sender) {
         $self->sender->send($_, 1) for grep !/^;/, split /\n/, $self->config->end_gcode;
-        $self->sender->disconnect;
     }
     
     # call this before the on_print_completed callback otherwise buttons
@@ -675,7 +676,7 @@ sub project_next_layer {
     $self->on_project_layer->($self->_layer_num) if $self->on_project_layer;
     
     if ($self->sender) {
-        my $z = $self->current_layer_height;
+        my $z = $self->current_layer_height + $self->config->z_offset;
         my $F = $self->config2->{z_lift_speed} * 60;
         if ($self->config2->{z_lift} != 0) {
             $self->sender->send(sprintf("G1 Z%.5f F%d", $z + $self->config2->{z_lift}, $F), 1);
diff --git a/xs/src/libslic3r/GCodeSender.cpp b/xs/src/libslic3r/GCodeSender.cpp
index 9d3a45477..e284ef701 100644
--- a/xs/src/libslic3r/GCodeSender.cpp
+++ b/xs/src/libslic3r/GCodeSender.cpp
@@ -125,10 +125,12 @@ GCodeSender::disconnect()
     this->io.post(boost::bind(&GCodeSender::do_close, this));
     this->background_thread.join();
     this->io.reset();
+    /*
     if (this->error_status()) {
         throw(boost::system::system_error(boost::system::error_code(),
             "Error while closing the device"));
     }
+    */
 }
 
 bool