diff --git a/docs/figs/opt_stiffness_wz_coupling.pdf b/docs/figs/opt_stiffness_wz_coupling.pdf
index 9b73ae7..2a18285 100644
Binary files a/docs/figs/opt_stiffness_wz_coupling.pdf and b/docs/figs/opt_stiffness_wz_coupling.pdf differ
diff --git a/docs/figs/opt_stiffness_wz_coupling.png b/docs/figs/opt_stiffness_wz_coupling.png
index 5cbd350..148cfed 100644
Binary files a/docs/figs/opt_stiffness_wz_coupling.png and b/docs/figs/opt_stiffness_wz_coupling.png differ
diff --git a/org/optimal_stiffness.org b/org/optimal_stiffness.org
index 0f5d64f..c2bcf58 100644
--- a/org/optimal_stiffness.org
+++ b/org/optimal_stiffness.org
@@ -333,17 +333,24 @@ We plot the change of dynamics due to the change of the spindle rotation speed (
       set(gca,'ColorOrderIndex',i);
       plot(freqs, abs(squeeze(freqresp(Gk_wz_err{i,1}('Ex', 'Fx'), freqs, 'Hz'))), '-', ...
            'DisplayName', sprintf('$k = %.0g$ [N/m]', Ks(i)));
-      for j = 1:length(Rz_rpm)
-          set(gca,'ColorOrderIndex',i);
-          plot(freqs, abs(squeeze(freqresp(Gk_wz_err{i,j}('Ey', 'Fx'), freqs, 'Hz'))), '--', ...
-           'HandleVisibility', 'off');
-      end
+      set(gca,'ColorOrderIndex',i);
+      plot(freqs, abs(squeeze(freqresp(Gk_wz_err{i,length(Rz_rpm)}('Ey', 'Fx'), freqs, 'Hz'))), '--', ...
+       'HandleVisibility', 'off');
+      set(gca,'ColorOrderIndex',i);
+      plot(freqs, abs(squeeze(freqresp(Gk_wz_err{i,1}('Ey', 'Fx'), freqs, 'Hz'))), '--', ...
+       'HandleVisibility', 'off');
+      % for j = 1:length(Rz_rpm)
+      %     set(gca,'ColorOrderIndex',i);
+      %     plot(freqs, abs(squeeze(freqresp(Gk_wz_err{i,j}('Ey', 'Fx'), freqs, 'Hz'))), '--', ...
+      %      'HandleVisibility', 'off');
+      % end
   end
   hold off;
   set(gca, 'XScale', 'log'); set(gca, 'YScale', 'log');
   ylabel('Amplitude [m/N]'); xlabel('Frequency [Hz]');
   xlim([freqs(1), freqs(end)]);
-  legend('location', 'southeast');
+  ylim([1e-10, inf]);
+  legend('location', 'northeast');
 #+end_src
 
 #+header: :tangle no :exports results :results none :noweb yes