What causes the FEP to be dented during resin printing?

Question

Just a simple question about my FEP sheet getting dented after print. I just bought an Elegoo Mars 2 Pro and had trouble getting it to stick to the bed, after some painful bed leveling and realizing my exposure times were too low for maroon resin, I finally got it to stick to the bed by the 4th print.

Now before I start my next print, I want to know what causes the indents in the FEP sheet below so I can prevent it from happening again.

Is it too High exposure time, bed leveled too low/tight, or both? Now I will also note, that this print was with the standard rook test print the mars recommends you do first, also that my print was very hard to remove from the bed when finished, I had to use a lot of force to rip it off.

Answer 1

The rook is normally difficult to remove, it's designed this way.

Have you tried resetting the height of you build Plate? If it makes a grinding sound when doing the first 2 or three layers your build plate might be traveling too low.

Also try re-leveling your build plate, e.g. I pushed so hard when I tried to take my rook off that I un-leveled it.

Answer 2

You have not done anything wrong!

Usually, each resin type is suitable for a specific VAT floor. For example, for PDMS floor you should use very specific types of resins.

FEP is known to be very strong and difficult to ruin. But still a couple of things you need to consider:

• When the resin cures it does generate a substantial amount of heat, you definitely can decrease it by a better level (less resin) or dimming (slower chemical reaction). Some FEPs could stand 450 °C.
• Separation force, it will depend on the area being solidified and how strong the resin stick to your FEP.
• How tightened the FEP is also important. You do not want it to be very tight.