Platform won't stop at resin vat

[cliffyk]

i have recently found¹ that using a piece of standard 20# copy paper folded in half (i.e. two thicknesses of paper, 0.18 mm in total) seems to work best. The OEM FEP is 0.15 mm thick si using a double thick layer of paper when performing the alignment provides a 0.03 mm (30 micron). "buffer" zone--and in theory an 80 micron bottom layer--seems to work best for me, seems top minimise the "elephant foot" phenomenon as well.

Using just a single layer of paper (0.09 mm) as a gauge sets the platen 0.04 mm (40 microns) too low and "into" the FEP.

I wish Elegoo specified a better gauge thickness for rhe alignment proces. "Sheet of paper" is not a standard unit of measure nor a worldwide standard unit of anything--but as the FEP is what normally lives b'twixt the platen and the LCD using a gauge of that thickness (0.15 mm) or a bit better seems much more sensible....

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¹ - I found this on my first print after installing the Jackson Products Twin-Rail Z-Axis. When printing the first layer the printer let out a squawk when it moved to the "0" position. I speculate that the dramatically increased rigidity of the Jackson mast was not as tolerant of the 40 micron "compression" mis-alignment caused by using just one thickness of paper as a gauge as was the OEM assembly, causing the stepper motor to complain. Using the double thickness of paper as a gauge fixed it all up. BTW the quality of my printouts has improved tremendously since installing the new mast--a night and day difference...