diff --git a/src/slic3r/GUI/RammingChart.cpp b/src/slic3r/GUI/RammingChart.cpp
index 54ea436eaa..b1a1ed8c73 100644
--- a/src/slic3r/GUI/RammingChart.cpp
+++ b/src/slic3r/GUI/RammingChart.cpp
@@ -115,6 +115,7 @@ void Chart::mouse_right_button_clicked(wxMouseEvent& event) {
 
 
 void Chart::mouse_clicked(wxMouseEvent& event) {
+    m_uniform = (event.GetModifiers() == wxMOD_CONTROL);
     wxPoint point = event.GetPosition();
     int button_index = which_button_is_clicked(point);
     if ( button_index != -1) {
@@ -136,7 +137,13 @@ void Chart::mouse_moved(wxMouseEvent& event) {
     }    
     int delta_x = pos.x - m_previous_mouse.x;
     int delta_y = pos.y - m_previous_mouse.y;
-    m_dragged->move(fixed_x?0:double(delta_x)/m_rect.GetWidth() * visible_area.m_width,-double(delta_y)/m_rect.GetHeight() * visible_area.m_height); 
+
+    if (m_uniform)
+        for (ButtonToDrag& b : m_buttons)
+            b.move(fixed_x?0:double(delta_x)/m_rect.GetWidth() * visible_area.m_width, m_dragged->get_pos().m_y - b.get_pos().m_y + -double(delta_y)/m_rect.GetHeight() * visible_area.m_height); 
+    else
+        m_dragged->move(fixed_x?0:double(delta_x)/m_rect.GetWidth() * visible_area.m_width, -double(delta_y)/m_rect.GetHeight() * visible_area.m_height); 
+
     m_previous_mouse = pos;
     recalculate_line();
 }
@@ -263,7 +270,7 @@ std::vector<float> Chart::get_ramming_speed(float sampling) const {
     std::vector<float> speeds_out;
     
     const int number_of_samples = std::round( visible_area.m_width / sampling);
-    if (number_of_samples>0) {
+    if (number_of_samples>0 && !m_line_to_draw.empty()) {
         const int dx = (m_line_to_draw.size()-1) / number_of_samples;
         for (int j=0;j<number_of_samples;++j) {
             float left =  screen_to_math(wxPoint(0,m_line_to_draw[j*dx])).m_y;
diff --git a/src/slic3r/GUI/RammingChart.hpp b/src/slic3r/GUI/RammingChart.hpp
index d28dfc90e4..33faa2eed1 100644
--- a/src/slic3r/GUI/RammingChart.hpp
+++ b/src/slic3r/GUI/RammingChart.hpp
@@ -23,7 +23,7 @@ public:
     {
         SetBackgroundStyle(wxBG_STYLE_PAINT);
         m_rect = wxRect(wxPoint(legend_side,0),rect.GetSize()-wxSize(legend_side,legend_side));
-        visible_area = wxRect2DDouble(0.0, 0.0, sampling*ramming_speed_size, 20.);
+        visible_area = wxRect2DDouble(0.0, 0.0, sampling*ramming_speed_size, 40.);
         m_buttons.clear();
         if (initial_buttons.size()>0)
             for (const auto& pair : initial_buttons)
@@ -31,7 +31,7 @@ public:
         recalculate_line();
     }
     void set_xy_range(float x,float y) {
-        x = int(x/0.5) * 0.5;
+        x = int(x/0.25) * 0.25;
         if (x>=0) visible_area.SetRight(x);
         if (y>=0) visible_area.SetBottom(y);
         recalculate_line();
@@ -104,20 +104,18 @@ private:
         }
         return (-1);
     }
-        
-        
+
     void recalculate_line();
-    void recalculate_volume();
-     
-    
+
     wxRect m_rect;                  // rectangle on screen the chart is mapped into (screen coordinates)
     wxPoint m_previous_mouse;        
     std::vector<ButtonToDrag> m_buttons;
     std::vector<int> m_line_to_draw;
     wxRect2DDouble visible_area;
     ButtonToDrag* m_dragged = nullptr;
-    float m_total_volume = 0.f;  
-    
+    float m_total_volume = 0.f;
+
+    bool m_uniform = false; // testing only
 };
 
 
diff --git a/src/slic3r/GUI/WipeTowerDialog.cpp b/src/slic3r/GUI/WipeTowerDialog.cpp
index 3b74c10910..da56e2c305 100644
--- a/src/slic3r/GUI/WipeTowerDialog.cpp
+++ b/src/slic3r/GUI/WipeTowerDialog.cpp
@@ -8,6 +8,7 @@
 #include "BitmapCache.hpp"
 #include "GUI.hpp"
 #include "I18N.hpp"
+#include "slic3r/GUI/format.hpp"
 #include "GUI_App.hpp"
 #include "MsgDialog.hpp"
 
@@ -109,11 +110,11 @@ RammingPanel::RammingPanel(wxWindow* parent, const std::string& parameters)
 #endif
  	sizer_chart->Add(m_chart, 0, wxALL, 5);
 
-    m_widget_time						= new ::SpinInputDouble(this,"", wxEmptyString, wxDefaultPosition, wxSize(ITEM_WIDTH(), -1), style, 0., 5., 3., 0.5);
+    m_widget_time						= new ::SpinInputDouble(this,"", wxEmptyString, wxDefaultPosition, wxSize(ITEM_WIDTH(), -1), style, 0., 5., 3., 0.25);
     m_widget_time->SetDigits(2);
     m_widget_volume							  = new ::SpinInput(this,"",wxEmptyString,wxDefaultPosition,wxSize(ITEM_WIDTH(), -1),style,0,10000,0);
-    m_widget_ramming_line_width_multiplicator = new ::SpinInput(this,"",wxEmptyString,wxDefaultPosition,wxSize(ITEM_WIDTH(), -1),style,10,200,100);
-    m_widget_ramming_step_multiplicator		  = new ::SpinInput(this,"",wxEmptyString,wxDefaultPosition,wxSize(ITEM_WIDTH(), -1),style,10,200,100);
+    m_widget_ramming_line_width_multiplicator = new ::SpinInput(this,"",wxEmptyString,wxDefaultPosition,wxSize(ITEM_WIDTH(), -1),style,10,300,100);
+    m_widget_ramming_step_multiplicator		  = new ::SpinInput(this,"",wxEmptyString,wxDefaultPosition,wxSize(ITEM_WIDTH(), -1),style,10,300,100);
 
 #ifdef _WIN32
     update_ui(m_widget_time->GetText());
@@ -133,6 +134,15 @@ RammingPanel::RammingPanel(wxWindow* parent, const std::string& parameters)
 	gsizer_param->Add(m_widget_ramming_line_width_multiplicator);
 	gsizer_param->Add(new wxStaticText(this, wxID_ANY, wxString(_(L("Ramming line spacing")) + " (%):")), 0, wxALIGN_CENTER_VERTICAL);
 	gsizer_param->Add(m_widget_ramming_step_multiplicator);
+    gsizer_param->AddSpacer(40);
+    gsizer_param->AddSpacer(40);
+
+    std::string ctrl_str = shortkey_ctrl_prefix();
+    if (! ctrl_str.empty() && ctrl_str.back() == '+')
+        ctrl_str.pop_back();
+    // TRN: The placeholder expands to Ctrl or Cmd (on macOS).
+    gsizer_param->Add(new wxStaticText(this, wxID_ANY, format_wxstr(_L("For constant flow rate, hold %1% while dragging."), ctrl_str)), 0, wxALIGN_CENTER_VERTICAL);
+
 
 	sizer_param->Add(gsizer_param, 0, wxTOP, scale(10));