2.2. Troubleshooting Mk3 bed adhesion and first-layer problems

Bed adhesion and first-layer calibration are the first great mysteries new users confront with the any 3D printer. They are two different tasks, but both must work well together for consistently good prints. Good bed adhesion is literally the foundation that your print is built on.

Note

These notes are based on my experiences with the Prusa i3 Mk3 and Artillery/Evnovo Sidewinder X1 printers. If you are using a different printer, please verify the hardware details are similar.

Problems with bed adhesion or first-layer adjustment can cause a variety of problems:

  • Part warping, curling, or lifting along edges or in corners.

  • Uneven vertical surfaces and bulges caused by layer lifting and compression of overlying layers.

  • Bumping or knocking noises as the nozzle moves over the print.

  • Spaghetti resulting from prints becoming dislodged and moving during printing.

  • The dreaded “blob of doom” caused by the part lifting and sticking to the nozzle as it extrudes filament.

  • “Elephant’s foot” on lower layers due to an overly-low first layer adjustment.

  • Uneven, stringy, or gappy first layers due to an overly-hgih first layer adjustment.

Bed adhesion should be strong enough to hold the print flat and securely against the forces of filament warping and nozzle friction. Filament should lay down cleanly on the PEI print surface and hold throughout the print. If adhesion is poor, your print is likely to fail or have problems at higher layers. Simply put, if your print doesn’t adhere well to the bed on the first layer, your print is very likely to fail. The first layer is key to good bed adhesion.

2.2.1. Causes of poor bed adhesion and first-layer problems

Assuming you have no fundamental hardware problems, there are two challenges you must overcome to get consistently good prints:

  1. A dirty print surface. The Prusa PEI print surfaces work amazingly well, but must be kept clean. Very clean. Once your printer is initially calibrated, most print shifting and adhesion issues can be resolved with regular cleaning. It doesn’t take more than an errant fingerprint or a spot of hand lotion on the filament to foul the PEI print surface. Refer to the print bed cleaning procedure for details on properly cleaning and maintaining the PEI print surface.

  2. Poor “Live-Z” initial nozzle height adjustment. If you’ve never been able to get a good first layer, have changed nozzles or done hardware adjustments, your “Live-Z” (the initial gap between the nozzle and print bed) needs to be calibrated.

    • Too high and molten filament won’t “squish” sufficiently to get a good grip on the surface, resulting in stringy, loose 1st layers. This leads to shifts and the resulting “spaghetti” results when a part pops loose and gets dragged around by the nozzle.

    • Too low and the nozzle digs into the freshly-laid down filament, causing distorted surfaces and nozzle snags. In addition to a stringy mess, this can result in the dreaded “Blob of Doom” that encases the nozzle, hotend, fan and other parts in a molten mass of melted filament.

Refer to the Live-Z calibration procedure for details on Live-Z calibration

A few notes:

  • On other printers, 1st layer calibration is a manual process that involves adjusting screws and using a sheet of paper to gauge the distance between the nozzle and bed. Disregard bed leveling or 1st layer calibration instructions for other printers. The Prusa i3 Mk3 handles this work for us.

  • It’s very common to see heavy sheets of glass used on other printers. These are laid atop severely warped print beds to get a more even print area. A large slab of glass adds tremendous weight to the Y carriage, often contributing to ringing print defects. Such measures are unnecessary on Prusa printers.

  • Mesh bed leveling is referred to as Auto Bed Leveling (ABL) on many other printers, and may require adding hardware and making firmware modifications to add this capability to other printers. Again, these capabilities are included as standard on the Prusa printers.

  • Ideally, setting a 0.2mm 1st layer height in your slicer will result in a 0.2mm layer height being printed, but results can vary. We may wind up squishing the 1st layer for better adhesion or backing off a bit to avoid dragging the nozzle.

Contact and feedback

You can find me on the Prusa support forums or Reddit where I lurk in many of the 3D printing-related subreddits. I occasionally drop into the Official Prusa 3D discord server where I can be reached as bobstro (bobstro#9830). You can email me directly at projects@ttlexceeded.com.

Last modified Apr 2, 2021. Last build on Apr 19, 2021.