Photograph of 3D printer LCD showing Marlin Firmware Move Axis for Extruder

Calibrating Your Filament Extruder

Dimensional Accuracy there are a few variables that your 3D printer uses in order to calculate how much of filament to extrude. Probably the first order of call would be the extruder steps per mm. Without the correct amount of steps your print will be over or under sized, or not as fine quality as it could be. This is where calibrating your filament extruder comes into play, with how much filament should be supplied to your printers nozzle.

So what are Steps Per MM? 

In essence, it is how many movements the motor requires for 1mm of plastic to be extruded in a given direction. 

To help us ensure accuracy when producing 3d prints. We need to calibrate the extruder motor so that it extrudes the correct amount of filament passing to the nozzle.

We need to remove the filament from the heating element. In order to do so, we need to heat up the extruder to normal temperatures say 210˚C. Then you will be able to remove your filament manually. This is simply the opposite way around from how you installed the filament when following your manufactures instructions. 

Many printers have a safeguard built into them, that will not allow you to move the extruder until the heating element is above a certain temperature. Now as we are going to be needing the extruder to be able to move, ensure the extruder is set to 210˚C

Let’s get measuring the extruder.

Calibrating your filament extruder can sound complicated. So how do the go about this? Firstly you need to warm up your extruder to about 200˚C or higher in the case of ABS. It all depends on filament type. The reason we need to heat up the nozzle so that we can firstly remove the filament if it is already loaded. The second, most 3D printers will not allow us to run the extruder motor without the nozzle temperature being high. This is to save threading the filament in the extruder motor because it cannot go anywhere when it is cold and preserving the life of the motor itself.

So with the your nozzle heated pull out the filament, or if you are using a Bowden style fitting then pull out the tube. Cut the end of the filament so it is flush and flat. Via the menu on your printer move the extractor 10mm so we have a little bit of filament out. On the filament itself make a line on where it exists the Bowden tube with a marker. If you do not use a tube and instead comes straight out of the extruder you need to make the mark at the point of exiting the extruder gearing. When marking of the filament I use a metallic silver thin tipped marker, as it shows up on most filament colours.

photograph showing felt marker lines to measure the amount of filament extruded for calibrating extruder

  1. Now via your menu, move the extruder 100mm.
  2. Cut off the filament flush with the tube or extruder gearing. *see tip below
  3. Lay the filament flat on the desk and measure. I find it easiest to use masking tape along most of the filament, straightening the filament gently as I go.
  4. The filament should have a length of 100mm if it doesn’t we need to correct this.
  5. Goto find the Stepper Motor Steps Calibration and change the figures in there and it will give you a new Steps Per MM value to insert into Marlin or directly into your 3D printer if it allows you too.

An example of what to input would be:
Stepper Motor Steps Calibration:
Expected Dimension in mm: 100 mm
Actual Dimension in mm: What you measured (lets say 112mm)
Current Steps Per MM: This will be in Marlin or printers menu. (Lets say 400)

You should see 357.143 Steps per mm as your new steps for your extruder motor.
Save this value in Marlin by uploading to your printer or setting the value in your menu system followed by save settings, store settings or save to EEPROM.

Image screenshot of Marlin Firmware showing steps, DEFAULT_AXIS_STEPS_PER_UNIT and max freed rate, DEFAULT_MAX_FEEDRATE

Now repeat the whole process again to ensure accuracy. You will probably find that it will take a few tries to get nailed down but once you have save and forget. The only other time you will need to redo this is if you change 3D printers mainboard, change the stepper driver, changed the stepper motor, or change the extruder gearing type.

Thats it we have finished calibrating your filament extruder, the more you do these calibrations the easier it gets and becomes somewhat 2nd nature.

If you cannot get close to the extruder find a reference point on the filament mark now extrude 100 mm and then mark a new line on the filament using your reference point. Measure the distance between the two lines.

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