I have the Mars 2 Pro which has a screen that can easily mark or scratch, and yes there can be annoying issues when leveling the build plate.
What I do now to set up the build plate is use two pieces of paper ! I use regular 80 gm A4 paper which measures 0.10 mm in thickness and a piece of oven proof or grease proof paper which measures 0.04 mm in thickness. The oven proof paper has a very smooth surface which prevents sharp airborne dust particles attaching to it which could otherwise scratch the screen.
To protect the screen the oven proof paper is placed under the A4 paper, then I zero and tighten the build plate. That difference of 0.04 mm is all that is needed to get the adjustment right as a piece of A4 on its own for some reason still makes the adjustment too tight between the screen and the plate, resulting with too much tension to be pulled out easily. Plus the surface of the build plate has a sandblasted surface which also grips the paper!
Once the two hex socket bolts have been tightened for the build plate there will still be some tension felt on the paper, but remember one piece is nearly half the thickness of the other.
Finally after raising the Z axis I place the vat into its position then lay a piece of trimmed oven proof paper that's the width of the FEP and overhangs the front edge of the vat so I am able to pull on it to test the tension. Press "Home" then check to see if there is too much downward force on the FEP.
This has worked every time for me and made setting zero pretty easy without any fapping about adjusting the offsets!
What I do now to set up the build plate is use two pieces of paper ! I use regular 80 gm A4 paper which measures 0.10 mm in thickness and a piece of oven proof or grease proof paper which measures 0.04 mm in thickness. The oven proof paper has a very smooth surface which prevents sharp airborne dust particles attaching to it which could otherwise scratch the screen.
To protect the screen the oven proof paper is placed under the A4 paper, then I zero and tighten the build plate. That difference of 0.04 mm is all that is needed to get the adjustment right as a piece of A4 on its own for some reason still makes the adjustment too tight between the screen and the plate, resulting with too much tension to be pulled out easily. Plus the surface of the build plate has a sandblasted surface which also grips the paper!
Once the two hex socket bolts have been tightened for the build plate there will still be some tension felt on the paper, but remember one piece is nearly half the thickness of the other.
Finally after raising the Z axis I place the vat into its position then lay a piece of trimmed oven proof paper that's the width of the FEP and overhangs the front edge of the vat so I am able to pull on it to test the tension. Press "Home" then check to see if there is too much downward force on the FEP.
This has worked every time for me and made setting zero pretty easy without any fapping about adjusting the offsets!