Extruder Calibration

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Why do we need to calibrate our extruder?

It allows you to make sure that the proper amouint of filament is provided to your hotend.

Why do we need to calibrate the extruder on each machine?

The quantity of plastic pushed by the extruder depends mainly on the diameter of the extrusion gear.

Why calibrate the extruder?

It will increase the procission and quality of your prints because the proper amount of plastic will be provided to the hot end..

Why do you need to do this calibration on each machine?

The quantity of plastic pushed inside the hotend depends mainly on the drive gear diameter of the extruder.

This gear is machined with a different tolerance. So the gear diameter will vary from one model to another one and from one brand to another one..

How to proceed?

We adjust the amounts of steps / mm required to push the filament 1mm.

The overall procesdure is as follow:

  1. We extrude a certain length of filament, let’s take 200mm.
  2. We measure with a graduated ruller how much filament has been pushed.
  3. We then use a cross product to adjust the value of our machine.
  4. Then we check that the new value is good by extruding again 200mm and we measure again.
  5. We adjust when needed and we reapeat step 4 ntill we find the proper value.
  6. Finally to ensure the measurment error is very small we extrude 400mm or 600mm  of material (something you can measure with your ruller) , We then slightly adjust the EStep/mm to get our final setting.
  7. At this stage your extruder should be properly calibrated and the quality of your prints should greatly increase.

Step by Step :

  • If you are in Bowden mode, remove the PTFE tue at the exit of the extruder. (You need to push the small cap at the base of the tube and then pull the tube at the same time)
    Then push the filament so that the tip is at the same level as the extruder shell.
  • If you are in Direct drive, you will need to unmount the extruder from it’s support, so that you can measure at the very edge of the extruder exit.
  • Cleanly cut the filament to that it’s easier to measure.

  • The Provided SD card contains a set of Gcode that will help you in this process. You can find them here:

 

  • You will find severall files (ExtrudeXXXmm.gcode and RetractXXXmm.gcode)

  • Depending the firmware version, you will need to pre heat your hot end before extruding.
  • With your LCD browse inside the SD card into the folder  and print « Extrude200mm.gcode » .

  • Measure how many mm of filament is extruded. (IMake sure to use a fine Ruller to avoid measurements issues)

  • In order to make sure to avoid any slippery that may affect your next measurements (and probably make your measurements weird), It is strongly advised to perform these steps several times by resetting the filament position and extruding again 200mm.
  • If your measurements are consistent you can proceed to the folowing steps.

Slippery case:

  • In the opposite scenario, you will need to investigate where the slippery comes from.
  • Here are some hints :
    • The extruder spring is not tight enought.
    • The filament spool is forcing on the filament, preventing the extruder to pull it properly ( Look for any nodes on the filament, the spool itselft must be free)
    • The extruder compression finger might be broken, and the bearing is improperly applying pressure on the filament.
    • your Extrusion gear is improperly screwed, the motor is turning but your extrusion gear is slipping.
    • The extrusion gear might be full of plastic or dirty
    • Something is tempering with your filament
  • If you solved this issue you will need to check again by doing again the previous steps.

 


 

Computation of the proper Epas/mm value
Use of « cross product »

  • Once you have checked that your extruder is slippery free you will be able to compute the new ESteps/mm by using the following formula:

 (Actual EStep / mm ) * (Expected extruded filament length) / (Length of measured extruded filament) = new EStep/mm

Example detailed below : 150 * 200 / 198 = 151.5 ESteps/mm

In order to obtain the ESteps/mm of your extruder you will need to navigate inside your LCD display  » Controle>Mouvements>EStep/mm » (last parameter of the list)

Example explaination :

if you have extruded 200mm of filament

  • Expected extruded filament length = 200mm

If you measured 198mm

  • Length of measured extruded filament = 198mm

if your Estep/mm is 150 step/mm ( » Control>Mouvements>EStep/mm« )

  • Actual EStep / mm = 150 pas/mm

you get:

New EStep/mm = 150 * 200 / 198 = 151.5 (Please take good care of the decimale)


 

Applying our new EStep/mm

  • Now that you calculated the new EStep/mm for your extruder you need to apply this parameter to you machine using the LCD display:  « Control>Mouvements>EStep/mm« 
  • Do again the test to extrude 200mm of filament. The extruded filament length should be better .If you still have some error it’s often due to the precission of the initial measurement. (90% of the time)
  • Once you get something close to 200mm , then extrude again 200mm, you should be able to measure 400mm. This steps allows you to reduce the measurement error based on 200mm.
  • At this stage you can apply your final fined tuned EStep/mm..
  • You can also use « Retract200mm.gcode » to double check that your filament properly comes back to it’s position of orgine.


 

Congratulation, Make sure to save your settings !

You have now completed the calibration process of your extruder.

Make sure that your new setting is properly saved inside your printer EEPROM:

  • « Control> Save config« 
  • Wait a few seconds and switch down the printer. Switch it back on and check that the setting has properly been saved (« Control>Mouvements>EPas/mm« )

 

Resources :

For those that lost the content of the original SD card provided with the Scalar M or Scalar XL you can download the calibration Gcode here by clicking in the Zip icon or the link below:

Calibration_Gcodes.Zip