Calibration and Maintenance
Bed leveling and the first layer, e-steps, flow, temperature and retraction tuning, input shaping and routine upkeep.
Calibration in the right order
A printer is a system of adjustments that interact, so calibrate in an order where each step does not undo the previous one. Change one thing at a time, print a small test, and write the result down.
- 1. Mechanical: square, tight and clean: no loose screws, wobble, or worn parts.
- 2. Bed and first layer: level, then set the Z-offset.
- 3. Extruder: e-steps (and filament diameter).
- 4. Temperature for each filament, then flow rate.
- 5. Retraction and pressure advance.
- 6. Dimensions: steps per millimeter, belt tension, and a calibration cube.
- 7. Speed and acceleration: input shaping, then the speed and acceleration limits.
Mechanical checks first
- Tighten and square the frame. A flexing frame ruins every later calibration: check the screws, the gantry (parallel to the bed) and the squareness with a measuring square.
- Check wheels, rails and bearings: carriages should move smoothly without wobble; eccentric nuts on V-wheels should have no play and no binding.
- Check belts and pulleys: grub screws tight on the flat of the shaft, belts straight and tensioned.
- Check the hotend and nozzle: the nozzle tightened hot to the heat break (a leak shows as plastic around the block), the fan running, and the thermistor and heater secure.
- Check the extruder: a clean gear, correct idler tension, and a PTFE tube that is fully seated.
- Check the electrical connections, particularly the bed and heater connectors (see Troubleshooting and Safety).
Bed leveling and the first layer
Nearly every print failure starts with the first layer. The bed must be flat and parallel to the gantry (leveling), and the nozzle must start at the right distance (the Z-offset): about one layer height from the bed, so the plastic is squashed.
Worked example: squish and Z-offset
- A 0.20 mm first layer squashed to about 75 % of its height is 0.15 mm thick: the nozzle sits about 0.15 mm from the bed, so the line, which would be 0.45 mm wide in free air, is wider and flatter, pressed into the bed.
- If the first layer is too thin and translucent, raise the nozzle by 0.05 mm; if the lines are round and not touching, lower it by the same. Adjust in 0.02 to 0.05 mm steps while the first layer prints (live Z-offset).
- Check with a first-layer test pattern (a single large square, or several squares across the bed): all squares should have the same thickness and no gaps, and the lines should be joined without ridges.
- Probe-based mesh leveling measures the bed at a grid of points and corrects the Z moves; it handles small warp, but it does not replace a flat bed and a straight, parallel gantry. Heat the bed and the nozzle (and the chamber) before measuring, because everything expands.
- Clean the bed with isopropyl alcohol (and warm water and dish soap for PEI) before leveling: oily fingerprints stop adhesion.
- Manual leveling: a sheet of paper or a feeler gauge (0.1 mm) at each corner and the center, with the bed hot.
- Slow the first layer (20 to 30 mm/s) and use a hotter first layer, a wider line, and no fan.
Extruder calibration (e-steps)
The extruder must push as much filament as the firmware thinks. The e-steps (steps per millimeter of filament, or the rotation distance in Klipper) tell it how far the gear turns. To check: heat the nozzle, mark the filament 120 mm above the extruder entry, command an extrusion of 100 mm slowly (about 2 mm/s), and measure how much actually moved.
Worked example: new e-steps
- New e-steps = old e-steps × requested ÷ actual. You commanded 100 mm and measured only 96.5 mm moved, with 415 steps/mm in the firmware: 415 × 100 ÷ 96.5 = 430.1 steps/mm.
- In Klipper the rotation distance scales the other way: new = old × actual ÷ requested.
- Repeat the test: the result should now be within 1 mm (1 %). Save it with M92 E430.1 and M500, or in the configuration file.
- A fine e-step value does not fix a worn gear, a slipping idler, a partial clog or a spool that fights the extruder: if the number changes from test to test, fix the mechanics first.
Temperature tower and flow rate
A temperature tower is a tall model whose temperature changes with height. Print one for each new spool, then look at the layers (stringing, bridging, overhangs, surface) and pick the temperature of the best-looking block.
Worked example: a temperature tower
A tower for PLA starts at 230 °C and drops by 5 °C per block down to 190 °C: that is 9 blocks of 10 mm, so the tower is 90 mm tall and the temperature changes at heights of 10 mm, 20 mm and so on; the slicer or a G-code script sets each change at the right layer. If the best block is the one at 205 °C, use 205 °C for ordinary printing, perhaps 5 to 10 °C higher for fast prints, because the flow limit rises with temperature.
Then calibrate the flow rate (extrusion multiplier): print a single-wall cube (vase mode or one perimeter, no infill and no top), measure the wall thickness with calipers in several places, and compare it with the line width the slicer set.
Worked example: flow multiplier
The slicer set a 0.45 mm line but the wall measures 0.47 mm (over-extrusion). New flow = old × target ÷ measured = 100.00 % × 0.45 ÷ 0.47 = 95.7 %. Calibrate flow after e-steps and temperature, per filament: different brands and colors of the same plastic can differ by a few percent.
Retraction and pressure advance
- Retraction test: print a retraction tower (two or more thin pillars a short distance apart, or a tower that changes the retraction distance with height) from 0.4 mm to 1.6 mm on a direct drive (4 to 6 mm on a Bowden) and choose the smallest value that leaves no strings.
- Dry the filament first: wet filament strings whatever the retraction.
- Retraction speed 25 to 45 mm/s; travel speed as high as the printer allows, which cuts oozing time.
- Pressure advance / linear advance: print the calibration pattern provided by Klipper or Marlin (a series of lines with different K values), and select the value that gives sharp corners and uniform line ends. Re-run it for each filament.
Dimensional accuracy and belts
Print a 20 mm calibration cube (or a longer stepped bar) and measure it with calipers on each axis. If the sizes are off by the same percentage on all axes the cause is shrinkage or the slicer’s scale (see Strength, Accuracy and Fits); if only one axis is wrong, the steps per millimeter or the belt is at fault.
Worked examples: steps and belt tension
- Steps/mm. A 20 mm cube measures 20.12 mm in X with 80 steps/mm. New = 80 × 20 ÷ 20.12 = 79.52 steps/mm. (Only change this if the error is on that axis and is not shrinkage; a 0.6 % error on a 20 mm cube is 0.12 mm.)
- Belt tension by frequency. A belt span of length L under tension T and linear density μ vibrates at f = (1 ÷ 2L) √(T ÷ μ). With μ = 4.5 g/m (a 6 mm GT2 belt), L = 150 mm and T = 10 N the belt rings at 157 Hz. To reach a target of 100 Hz use T = 4 L² f² μ = 4 × 0.15² × 100² × 0.0045 = 4.1 N. Pluck the belt near its middle and read the frequency with a phone tuner app; follow your printer’s recommended tone.
- Both belts of a CoreXY must match in tension or the head moves on a skew; a belt that is too loose gives play and ringing, too tight wears bearings and loads the motor.
Input shaping and acceleration
Fast moves excite the frame’s resonance and leave ripples (ringing) after sharp corners. Input shaping in Klipper (and newer Marlin) measures the resonance frequency with an accelerometer or a ringing tower, then shapes the motion so that the vibration cancels. It allows accelerations to be raised from about 2 000 to 5 000 mm/s² or more without ringing. Measure first (a good frame has a high, well-damped resonance, often 40 to 70 Hz), choose the shaper, then set the acceleration and speed to the point where print quality still holds. See the worked example in FDM Printer Hardware.
Routine maintenance
| When | Task |
|---|---|
| Before each print | Clean the bed; check the filament path and spool; check the nozzle for ooze; start the print and watch the first layer |
| Every few prints | Wipe the rods and rails; check the filament path for dust and the gears for plastic dust; level the bed if it drifts |
| Monthly | Check belt tension, all the screws and pulleys; clean the fans; check the heater and bed connectors for heat discoloration; lubricate rods and lead screws as the maker says |
| Every 1 to 3 kg of filament | Change a brass nozzle sooner (every 0.5 to 1 kg for abrasive filaments); replace the PTFE tube of a Bowden; check the extruder gear for wear |
| Yearly | Replace worn belts, fans and the build sheet; re-run all the calibrations; check the thermistor and the thermal runaway protection |
| After a jam | Do a cold pull (heat, push filament in, cool to about 90 °C for PLA, then pull out), which removes debris and residue from the nozzle |
| After a firmware or hardware change | Re-check thermal protection, endstops, the temperature display and the first layer |
- Keep a log of settings per filament and per printer; it saves hours.
- Update firmware carefully: read the release notes, back up the configuration, and test thermal runaway protection afterwards.
- PID tune the hotend and bed after any change of heater, thermistor or fan (M303 in Marlin, PID_CALIBRATE in Klipper).
Related
- 3D Printing and Additive Manufacturing: the overview of this guide.
- FDM Printer Hardware: what each calibration adjusts.
- Slicer Settings and Print Quality: the settings you are tuning.
- Troubleshooting and Safety: a failed print traced to its cause.
- 3D Printing Tolerancing Guide: clearances for fits.
FAQ
How often should I level the bed?
With a mesh probe, before every print costs little time. A solid printer with a stable bed needs leveling only after changes or when the first layer varies. Always heat everything first.
Do I need to re-calibrate for every new spool?
Temperature and flow vary a little between brands, colors and even batches, so run a temperature tower and a flow test for each new type. E-steps and belt tension belong to the printer and rarely change.
My e-steps change every time I measure: why?
Usually the extruder is slipping, the idler tension is wrong, the gear is dirty or worn, or the filament is dragging. Fix the mechanics first and measure again.
What is a cold pull?
A cleaning method: heat the nozzle, push filament in so it melts through, cool it a little so that the plastic is semi-solid, then pull the filament out, taking residue and debris with it.
References
- Klipper, Marlin and RepRapFirmware documentation (e-steps and rotation distance, pressure advance, input shaping, PID tuning).
- Prusa Knowledge Base and Ellis’ Print Tuning Guide (first layer, flow and temperature calibration practice).
- Any vibration text for the vibrating string, f = (1 ÷ 2L) √(T ÷ μ) (belt tension by frequency).
Last reviewed: October 2026. Values are typical: follow the printer maker’s calibration procedure where one exists.