Newbie - Unable to get large prints to complete

  • I am new to 3D printing. Have a Creality CR10S V2. I have calibrated the e-steps, set the z offset, and leveled the bed. I can print calibration cube and benchy but when I try other larger prints I have issues. I just changed out the filament and put in a new bowden tube. I am using PETG with nozzle temp of 250 and bed temp of 90. Any suggestions?

  • There are two possibilities to explain the darkened blobs.

    1. You have only tightened the nozzle at room temperature not realizing that thermal expansion will open a gap between the heat break and the nozzle allowing filament to leak out through the threads in the heat block. Fore small prints this is not noticeable because the flow from the leak is very slow and only result is a small build up on the top of the heat block. Longer prints will cause enough flow to spill over the heat block down the nozzle and onto the part. The darker color suggests mixing with darker filaments or char from being cooked. You need to tighten the nozzle at a temperature at least 10 degrees C above your highest print temperature to prevent leaking in the heat block. I use the second file.

    2. You are over extruding filament which causes filament to build up on the nozzle until it become large enough to char and slough off onto your part. This happens in all over extrusion conditions because the layer height is higher than the set height and the nozzle has to plow through it on the next layer.
      The solution is to run a "First Layer" test part to adjust the flow to result in the correct layer thickness for your part. You cannot get the correct layer height if you have changed the Z offset from the calibrated value for adhesion (squish) because Cura depends on it being exactly what you set. If you decrease it the first layer will be too thin and you cannot properly set the % flow and you will be under extruding.

  • did that layer shift?

    your first layers look ok, so I am thinking overheating, possibly due to overtight rather than loose. or possibly electronics,

    check rollers, not too tight, not too loose, use two fingers and make sure you can turn them while preventing the axis from moving, they should not be real easy to turn but struggling with two fingers would be too tight. guessin Y, so bed, from the picture orientation. would check X as well anyway.

    belts, again, too loose or too tight, should be similar to an elastic band stretched between two fingers. if smaller prints are ok, then probably too tight causing overheating stepper and/or stepper driver.

    make sure electronis controller fan is running and is unobstructed, overheating here might do it

    see which stepper motor is hottest while printing and give this axis the most attention to belts and rollers.

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