As of this writing, 3D printers are not plug-and-play devices. Some amount of tweaking, tuning and calibration is needed to get optimal results. Different filaments and nozzles may require incremental adjustments. Adjustments may drift over time. Knowing how to do some basic calibration can save expensive frustration in the middle of a large print.
For the Mk3, there are serveral kinds of calibration:
- Printer calibration required to compensate for minor hardware variances.
- Extruder calibration to compensate for the amount of filament the extruder actually feeds versus what is specified.
- First-layer or Live-Z calibration of the initial gap between the nozzle and print surface. This adjustment is critical to getting even first layers that adhere to the print surface throughout the entire print.
- Filament calibration required to compensate for minor variances between filaments.
These notes are based on my experiences with the Prusa i3 Mk3 printer. If you are using a different printer, please verify the hardware details are same. These pages may be a bit rough as I revise them and add new material. Please check back regularly for updates.
The Mk3 requires very little in the way of regular calibration. Once set properly, the printer retains values and does enough automatic compensation that a full “XYZ calibration” is rarely required. However, there are situations where a full calibration from factory defaults is required:
- If you’ve just assembled or re-assembled your printer.
- If you’ve transported or moved your printer and physical jostling may have occurred.
- If you’ve upgraded firmware and are getting inconsistent results.
There are several calibrations I like to use for full printer recalibration:
- XYZ Calibration from the settings menu. This ensures the printer “knows” where hardware limits are.
- PID (temperature) tests to optimize printer performance for my regular print temperatures.
- Extruder correction. The Prusa ECOR tower tunes the extrusion rate to avoid moire effects.
More on PID and ECOR.
Platform stability and belt tension
Note that the extruder calibration recommended for most 3D printers is not in this list. The idea of those procedures is to ensure that an instruction to print 100mm of filamnet actually pushes out 100mm of filament. These makes good sense in cases where there’s a high variability between printers. However, Prusa, much like Apple, puts out hardware with known components. The microsteps are well defined. While you can go through this process if you like, you’ll most likely find that you’re making very miniscule adjustments to the default 280 microsteps.
Prusa extruder calibration procedure.
First layer calibration¶
First-layer calibration is usually only needed if you’ve changed nozzles or made other adjustments that may have changed the position of the extruder. It can be helpful to adjust the Live-Z setting based on the type of filament. For printing PETG or other materials that don’t require the “squish” of PLA, 0.20mm is recommended, although I find 0.02mm sufficient in most cases. This is a simple value you can calculate once per filament and simply adjust in slicer settings.
For individual filaments, a bit of extra calibration can compensate for variances between manufacturers. Filament diameter and print properties can make a difference in print results. Individual filament adjustments I like to make are:
- Linear Advance
- Filament diameter
- Extrusion multiplier
- Temperature tower
More on filament calibration
Linear Advance is a feature of the Marlin firmware used in the Prusa i3 Mk3 that attempts to compensate for the difference in filament flow as the nozzle accelerates and decelerates as it approaches corners and line ends. Physical printing parameters mean that the nozzle is not moving at the ideal settings throughout a move even if the same speeds are specified.
LA calibration print
A print of a humble 20mm cube is one of the best tools to test basic calibration:
- Sliced with your normal slicer settings, it’s a good test for overall finish, comparing effects of layer height, z-seam alignment and overall dimensional accuracy.
- Sliced with a single external perimeter set to exactly nozzle size, 0 infill and 0 top layers, it provides a good test of dimensional accuracy and extrusion width.
Quick extrusion test prints
I like to print some test parts to make sure everything is working well:
A 20mm hollow cube printed in vase mode with 1 perimeter, 0 top layers and 0 infill. The perimeter extrusion width is set based on the nozzle size, so I can measure the overall dimensions and wall thickness to get a sense for how well I’m calibrated. This provides an overall calibration check before moving on to more complex prints.
20mm puzzle partof my own design to test fit and bridging in a short (10-15m, depending on settings) print. These should stack easily with a bit of cleanup. An M5 bolt should fit cleanly through the hole. Print with support to test ease of removal, or without to get a sense for bridging. If I can print this with a new filament or settings and fit it with others, I know I’ve got the basics working.
NirDobovizkim’s simple extrusion test that prints in minutes and can be used to calibrate your extrusion multiplier.
gaaZolee’s Smart compact temperature calibration tower is a highly customizable temperature tower.
Ryden’s Stringing Test is a simple piece for testing stringing settings.
iDig3Dprinting’s XYZ 20mm Calibration Cube is a small cube with labels on the X, Y and Z faces to test ghosting.
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