You can calibrate your bowden extruder by following these steps. You can also find more detailed instructions, with pictures, here.


1) Connect your printer to MatterControl. Ensure hot end and heated bed (if applicable) are turned off and cool to the touch. 


2) Remove Bowden tube from the hot end side. Leave it attached on extruder side.


3) Feed filament (any filament except flexible filaments like Ninjaflex) through your extruder until it just starts to come out of the Bowden tube.


4) Using a razor blade or sharp scissors, cut the filament flush/square with the Bowden tube. You want a nice, flat cut so that it’s more easily measurable in the next steps. Make sure filament is flush with the opening of Bowden tube.

 

5) In MatterControl, go to Settings & Controls and click on the Controls tab. Select “100mm” under the Extrude/Retract buttons, and Extrude 100mm 


6) When the filament is done extruding, measure from the end of the filament to the end of the Bowden tube. Write your measured amount down. For best results, repeat this process 3-4 times – align filament with edge of Bowden tube, extrude 100mm, measure – and take the average. 

If the measured amount is MORE than 100mm, then you are overextruding. 

If the measured amount is LESS than 100mm, then you are underextruding.

  

8) Now we need to locate the current value your printer is using to calculate extrusion distance – Extruder Steps per MM. If you have a dual extrusion machine, this can be named Extruder 0, Extruder 1, or Extruder 2, depending on your printer. 

In MatterControl, Settings & Controls > Configuration > EEProm Settings Configure

Every printer/firmware combination will look a little different in this window. We are looking for the “Extruder Steps/MM” box. It can be shortened to “Extr0” or “Extr1”, but it should be easy enough to locate.

  

We need to do some basic math to calculate the proper steps/mm for your machine

The formula is simple:

New Steps/mm = (Old/Current steps/mm) x [100 / (measured distance filament traveled)]

If you measured 101.3mm, and your current steps/mm is 93, then your calculation would be  93 x (100 / 101.3) = 91.80

Now you just need to enter your new value into your EEProm settings and you're done.


9) In MatterControl, Settings & Controls > Configuration > EEProm Settings Configure

Enter the new value in the proper box, click Save in the bottom left corner.


10) The last step is simply confirming our new value. Set the filament back flush with the Bowden tube and extrude 100mm. Measure, and you should be right at 100mm. If not, you can repeat the same process, paying special attention to getting as accurate a measurement as possible.