Flexible steel sheets

Updated 4 months ago ​by Tomáš Chvalina

The new MK52 Magnetic HeatBed holds removable steel sheets with the PEI surface. Those are great to easily remove the printed objects from the PEI surface. However, even these must be properly used, and that is what you can learn in this article.

Flexible steel sheets

Aligning the steel sheet on the heatbed

The MK52 heatbed has embedded high curie temperature magnets. These magnets are able to firmly hold removable spring steel sheets. There are two pins at the end of the heatbed that will align perfectly with cut out slots in the spring steel sheets. Make sure the bed is clean and there isn’t any debris on it before you put on the steel sheet

Align pins for the steel sheet on the heated bed.
Never print directly on the heatbed.

    Flexible steel sheet surface preparation

    There is no major difference in the print surface. So please visit PEI print surface preparation for information about preparation before printing and Increasing PEI adhesion if you want to know how to increase the adhesion.

    Swapping between different steel sheets - Live adjust Z

    With swapping between the Powder coated and Smooth PEI steel sheets, you might face an issue with your printer's Live adjust Z setting. This might be a problem because each of the print surfaces has slightly different thickness. Don't worry, it is almost impossible to damage either of them by not tweaking the Live Adjust Z. However, we recommend doing the following:

    1. Perform the First layer calibration for Powder coated and Smooth PEI steel sheets separately. You can run the First layer calibration through the LCD menu - Calibration - First layer calibration
    2. Write down both of you final values of the First layer calibration.
    3. Each time you swap your desired steel sheet, re-enter the Live adjust Z value in the LCD menu. This can be done in the LCD menu - Settings - Live Adjust Z.
     If you have performed the Bed level correction before, it will not be affected by this procedure.

    Printing on steel sheets

    At this moment there are two types of flexible steel sheets, Powder coated and Smooth PEI, and for most of the cases, both of them perform perfectly fine. However, there are some differences you should consider before using or buying them. 

    Powder coated steel sheet
    • Live adjust Z is more forgiving,  and generally, the first layer should be a bit more squished than on the Smooth PEI surface. 
    • For objects with a smaller base, you should consider adding a brim
    • Great for extensive printing of PETG as it is a lot less vulnerable to any kinds of damage.
    • Better for models printed with flexible filaments as it is easier to detach them from the print surface.
    Smooth PEI sheet
    • Live adjust Z should be set a little higher as the surface is perfectly flat.
    • If you plan to print models with a small base, Smooth PEI is the better choice.
    • If you plan to print PETG for most of the time, Smooth PEI will wear down a lot faster than Powder coated surface.
    • Flexible filaments will stick perfectly fine, but if you plan to print bigger flexible objects, Powder coated steel sheet makes it easier to detach printed models

    Other than that, both types are perfect for everyday use.

    Removing printed objects

    1. Await until the steel sheet cools down.
    2. Take it off and bend it inwards or outwards - depending on the size and quantity of printed object/s. 
    3. Do so until you can easily remove the printed object/s.
    4. For very thin models, you can still use a spatula.

    Bubbles underneath the PEI

    Over time you might see small bubbles underneath the PEI. That is nothing serious as it does not affect the print quality and it shall disappear over time. Here are 2 tips which will make the bubbles to disappear faster:

    1. Swap the side of the steel sheet you were printing on. This will speed up the "recovery" of the PEI surface. 
    2. Bubbles usually appear around the spot you print the most. So, try to print around the whole surface of the heated bed and not just at one spot.

    Do not hesitate to contact us at info@prusa3d.com if you would have any following questions.


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