Over the last 12 months since owning the felix I’ve found that to keep it printing accurately I regularly check the following to make sure my prints are accurate and strong.
Level the print bed – this varies from machine to machine but rule of thumb is a paper thickness between your extruders and the print bed, measure across each corner to make sure it’s level and adjust as required.
Calibration of all axis steps/mm – Move 50mm and measure that 50mm then adjust in the firmware the steps /mm using the formula below. If these are out on one axis quite a bit then there must be a mechanical problem i.e. belts stretched.
New_steps = (wanted_length/measured_length)*old_steps
Course calibration of extruders – mark filament and extrude 50mm and adjust in the firmware until it’s correct using the above formula.
Fine adjustment of extruders is performed through the slicing software using a thin wall test object, usually print a calibration cube with no top or bottom, no infix and 1 extrusion width on the perimeter, this will print out an object who’s wall thickness is exactly one extrusion width, when finished, the thickness must be measured and compared to the extrusion thickness of set within the slicer software, adjustments are made again using the formula above with the extrusion multiplier instead of steps/mm as the target. e.g. if your slicer software expects an extrusion with of 0.41 for the extrusion thickness, then after calibration you should be pretty close to this. Factors that effect this will be you filament diameter
This fine adjustment of the extruder must be performed for every roll of filament you use as the thickness of the filament will effect this, of course no two batches of filament are the same. Then saved within your slicer under a different filament profile.
Calibration of Dual Extruder – If you have more than one extruder then this is a little tricky, first the extruders heights at the tip must be exact, if not then one extruder will drag across and rip up your print. This can be tricky to adjust, especially on the Felix, the only proper way is to shim up the heads until exact. Not only must they be aligned on the Z Axis but also in the X and Y axis as when an extruder is selected it must go to exactly the same spot on X – Y Axis as the previous extruder. This is adjusted in the firmware.
Once the main calibrations are done, then every time I get a new spool of filament I run a thin wall and a Temperature test, as mentioned above, the thin wall calibrates the filament diameter to the extrusion width, and a temperature test find the best temperature to be printing at.