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5 Most Common Problems with the Prusa i3 MK1: Troubleshooting Guide

5 Most Common Problems with the Prusa i3 MK1: Troubleshooting Guide

The Prusa i3 MK1 is the blueprint for the most common 3D printing designs on the market today. Born from the open-source RepRap project, the MK1 is still considered by many to be a flagship in user-friendly machines that opened up the world of 3D printing to hobbyists.


With the ever-increasing breadth of community-created resources and inexpensive 3D printing options, 3D printing has rapidly becoming a highly accessible and user-friendly technology. However, 3D printing beginners and veterans alike are still likely to run into a variety of obstacles during the printing process or with their machines. This article covers the top five most commonly reported issues with the Prusa i3 MK1 and provides simple troubleshooting options.

5 most common Prusa i3 MK1 problems

  • Poor first layer adhesion
  • Layer shifting
  • Stringing
  • Layer separation
  • Blobbing
  • Poor first layer adhesion


Poor first layer adhesion

Regardless of the printer being used, poor adhesion at the first layer of the print is by far the most common issue reported by hobbyists and is likely to be a new 3D printer user’s first experience with a failing print. Good first layer adhesion is crucial as it not only supports the rest of the model but also creates a “seal” with the print bed to keep the model from shifting or falling throughout the printing process. Issues with first layer deposition or adhesion almost always lead to a failed print.


Re-calibrate the first layer settings

Whenever you calibrate your 3D printer, work with a new filament, or perform troubleshooting procedures, we always recommend having a small test print or two ready to run. Using these test prints, you can typically pinpoint the problems with the first layers and fine-tune your printer’s settings accordingly.

One of the most common first layer issues faced by Prusa users is a miscalibrated Z-distance. The printer’s Wizard is outfitted with a First Layer Calibration feature that allows users to modify the distance between the nozzle and print surface. Re-calibrating this distance can deal with faulty first layer deposition.

Navigate to “LCD-menu” > “Calibration” > “First Layer Calibration.” Use the knob to manually adjust the Z-distance during calibration. Periodically carrying out this calibration is crucial as your printer can undergo minor changes throughout its lifespan and various types of filament may react differently to the same printing conditions.  

Clean or modify the print surface

Check that your print bed is clean and free of dust or debris. A dirty print bed keeps the molten plastic from gripping the bed and hardening evenly. Before each print, thoroughly wipe down the print surface with a designated cleaning solution or 90%+ isopropyl alcohol.

If your prints simply are not sticking or you notice lifting later in the print, consider wiping down the print bed with acetone. Note that isopropyl alcohol or acetone should not be used before printing with PETG. When using any material with your FDM printer, you can also use an adhesive (such as a craft glue stick) to promote adhesion at the print surface.

Change the printing temperature

Starting with the manufacturer’s recommendations, increase the hot end temperature in 5 °C increments. Higher printing or bed temperatures can promote adhesion. Take caution when making these changes because overly high printing temperatures will keep the filament from hardening properly, leading to droopy or uneven layers.

Decrease the printing speed

Decreasing the printing speed allows the filament to bond for a longer period before additional filament is deposited. Drop the speed to around 75% for first three layers then revert the setting to normal for the remainder of the print.


Layer shifting

Layer shifting an easily identifiable issue as layers will be offset minutely from the preceding layers as the print goes on. Shifting usually occurs due to improper movement along a specific axis, which causes the extruder head to become misaligned. Layer shifting can also occur in larger prints if power to the machine fluctuates throughout the duration of the print.

To properly address layer shifting, you first have to identify along which axis the misalignment is occurring. Consider the orientation of your print and check which direction the offset layers are being moved. If the layers appear to be pulled to the left or right (facing the printer), then your X-axis is misaligned. If the layers appear to be pulled forward or backward, then the Y-axis is misaligned.


Change the printer’s power mode settings

When printing larger or highly complex models, ensure that the printer is running in Normal mode. Power mode settings can be accessed by navigating to “LCD-menu” > “Settings” > “Mode.”

Check the X/Y belt

Manually check the tension for the belt correlating to the axis you’ve identified as being misaligned. Overly tight or loose belts can lead to inconsistent layer deposition.

Check the axis pulleys

Check that the pulley on the motor shaft is secured while allowing the idler pulley to move freely on the opposite end. “Staircasing” layer shifting—layers being offset in a step-wise manner—is often caused by a loose pulley.




Stringing is among the most common problems faced by 3D printing hobbyists as it can occur even with the most well-tuned printers when working with tricky filaments. Stringing occurs when filament is deposited as the print nozzle moves from one point on the model to another when no filament should be extruded. This is particularly common with highly flexible filament types.


Reset the printing settings

Programs like PrusaControl have stock settings for certain printing applications that include a recommended retraction distance. If you are not using preset settings, try reducing your retraction distance slightly to allow the machine to retract more filament between deposition points.

Decrease print speed

Printing at an overly high print speed can cause the nozzle to move too quickly between points on the print and cause stringing. Several factors influence how high or low your print speed should be for optimal deposition, but many makers find that slightly decreasing print speed can give the filament enough time to melt properly before moving to the next part of the print.

If you are switching between filament types or thicknesses, we recommend running a short test print to check stringing, as minor speed adjustments may be necessary under different print conditions.

Adjust the print temperature

Typically, filament that is extruded an overly high temperature will tend to “drip” or string around the print. Slightly lowering the temperature can reduce the risk of stringing.



Layer separation

Layer separation, also known as delamination, refers to a problem in which layers do not properly adhere to one another throughout the print. While similar to poor first layer adhesion, this issue often occurs for different reasons. The most frequent culprits are hot end problems, poorly calibrated layer height settings, and non-optimized temperature settings.


Clean the hot end

Even a minor clog in the hot end can lead to major problems in layer adhesion, particularly further along larger prints. If the hot end is clogged, the amount of filament being extruded will not match the amount the printer is attempting to extrude, leading to an insufficient amount of material for adhesion.

While the nozzle is warm, wipe it down with an alcohol wipe or slightly damp cloth. The steam and movement may be enough to loosen small blockages.

Heat the hot end to the normal printing temperature and gently clean the nozzle using a small metal instrument, such as a needle or tack. If issues with the hot end persist after cleaning, you may wish to replace the part. Quick cleaning and maintenance like this should be carried out periodically to avoid layer separation in the middle of a project.

Change the layer height settings

An overly large layer height can contribute to layer delamination in prints, so lowering the layer height may be sufficient for addressing minor separation. Layer height refers to the distance along the Z-axis that the printhead shifts before beginning to extrude filament on a new layer.

Layer height settings are based on your nozzle diameter, with a common layer height for a 0.4 mm diameter nozzle being 0.2 mm. Lower layer heights are optimal for highly detailed prints, while larger layer heights are often associated with stronger prints.

If your printer is outfitted with a standard 0.4 mm nozzle and the layer height settings exceed 0.2 mm, try reducing the height to 0.2 mm. This setting can be decreased down to 0.16 mm, but layer height settings lower than this will impair your print quality.

Increase the bed or hot end temperature

Increasing the bed temperature can help with layer separation at lower parts of the print, while increasing the hot end temperature can help with layer separation that persists throughout the model.

As always, temperature changes should only be carried out in increments in 5 °C, and we recommend running a small test print to avoid excessive changes or filament waste.




Blobs and blemishes on the surface of your prints can typically be addressed with post-processing techniques like sanding. However, frequent blobbing is frustrating and can affect the functional capability of some prints—particularly those that are printed to precise measurements for specific applications.


Clean the hot end

Sometimes, blobbing occurs because of a partially blocked nozzle. Throughout the print, this blockage can lead to varying amounts of built-up melted filament to extrude all at once, causing bumps in the layer.

As noted above, wiping down the nozzle while it is warm can remove small amounts of filament, while a needle or other small object can be used to dislodge hardened filament further up in the component.

Lower print speed and temperature

Blobbing can be caused by minor overextrusion. To reduce the amount of filament being extruded, reduce the print speed and temperature in small increments (by 5 mm/s and degrees, respectively) to yield a smoother print.

Adjust retraction distance

Fine-tuning the retraction distance can help reduce the amount of filament left over from the previous extrusion event as the nozzle moves around the print. Similar to stringing, blobbing can occur when too much filament remains between deposition points.

Decrease the retraction distance slightly and try a test print. As always, stick to making changes in small increments.

Previous article How to Fix Under Extrusion- What Causes Under Extrusion on Your 3d Prints and How to Fix Them

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