New experimental option z_steps_per_mm. #1827

lib/Slic3r/GUI/Tab.pm

@@ -1084,7 +1084,7 @@ sub build {
     my (%params) = @_;
     
     $self->init_config_options(qw(
-        bed_shape z_offset has_heatbed
+        bed_shape z_offset z_steps_per_mm has_heatbed
         gcode_flavor use_relative_e_distances
         serial_port serial_speed
         octoprint_host octoprint_apikey
@@ -1233,6 +1233,7 @@ sub build {
             $optgroup->append_single_option_line('use_volumetric_e');
             $optgroup->append_single_option_line('pressure_advance');
             $optgroup->append_single_option_line('vibration_limit');
+            $optgroup->append_single_option_line('z_steps_per_mm');
         }
     }
     {

lib/Slic3r/Print/Object.pm

@@ -33,6 +33,17 @@ sub support_layers {
     return [ map $self->get_support_layer($_), 0..($self->support_layer_count - 1) ];
 }
 
+sub _adjust_layer_height {
+    my ($self, $lh) = @_;
+    
+    if ($self->print->config->z_steps_per_mm > 0) {
+        my $min_dz = 1/$self->print->config->z_steps_per_mm * 4;
+        $lh = int($lh / $min_dz + 0.5) * $min_dz;
+    }
+    
+    return $lh;
+}
+
 # 1) Decides Z positions of the layers,
 # 2) Initializes layers and their regions
 # 3) Slices the object meshes
@@ -53,7 +64,9 @@ sub slice {
         my @nozzle_diameters = map $self->print->config->get_at('nozzle_diameter', $_),
             @{$self->print->object_extruders};
         
-        $self->config->set('layer_height', min(@nozzle_diameters, $self->config->layer_height));
+        my $lh =  min(@nozzle_diameters, $self->config->layer_height);
+        
+        $self->config->set('layer_height', $self->_adjust_layer_height($lh));
     }
     
     # init layers
@@ -113,7 +126,7 @@ sub slice {
         
             # look for an applicable custom range
             if (my $range = first { $_->[0] <= $slice_z && $_->[1] > $slice_z } @{$self->layer_height_ranges}) {
-                $height = $range->[2];
+                $height = $self->_adjust_layer_height($range->[2]);
         
                 # if user set custom height to zero we should just skip the range and resume slicing over it
                 if ($height == 0) {

slic3r.pl

@@ -347,6 +347,8 @@ $j
                         (default: 100,100)
     --z-offset          Additional height in mm to add to vertical coordinates
                         (+/-, default: $config->{z_offset})
+    --z-steps-per-mm    Number of full steps per mm of the Z axis. Experimental feature for
+                        preventing rounding issues.
     --gcode-flavor      The type of G-code to generate (reprap/teacup/repetier/makerware/sailfish/mach3/machinekit/smoothie/no-extrusion,
                         default: $config->{gcode_flavor})
     --use-relative-e-distances Enable this to get relative E values (default: no)

xs/src/libslic3r/PrintConfig.cpp

@@ -1501,6 +1501,12 @@ PrintConfigDef::PrintConfigDef()
     def->sidetext = "mm";
     def->cli = "z-offset=f";
     def->default_value = new ConfigOptionFloat(0);
+
+    def = this->add("z_steps_per_mm", coFloat);
+    def->label = "Z full steps/mm";
+    def->tooltip = "Set this to the number of *full* steps (not microsteps) needed for moving the Z axis by 1mm; you can calculate this by dividing the number of microsteps configured in your firmware by the microstepping amount (8, 16, 32). Slic3r will round your configured layer height to the nearest multiple of that value in order to ensure the best accuracy. This is most useful for machines with imperial leadscrews or belt-driven Z or for unusual layer heights with metric leadscrews. Set to zero to disable this experimental feature.";
+    def->cli = "z-steps-per-mm=f";
+    def->default_value = new ConfigOptionFloat(0);
 }
 
 PrintConfigDef print_config_def;

xs/src/libslic3r/PrintConfig.hpp

@@ -427,6 +427,7 @@ class PrintConfig : public GCodeConfig
     ConfigOptionFloat               vibration_limit;
     ConfigOptionBools               wipe;
     ConfigOptionFloat               z_offset;
+    ConfigOptionFloat               z_steps_per_mm;
     
     PrintConfig(bool initialize = true) : GCodeConfig(false) {
         if (initialize)
@@ -488,6 +489,7 @@ class PrintConfig : public GCodeConfig
         OPT_PTR(vibration_limit);
         OPT_PTR(wipe);
         OPT_PTR(z_offset);
+        OPT_PTR(z_steps_per_mm);
         
         // look in parent class
         ConfigOption* opt;