Quick diagnosis
If a resin print detaches cleanly from the build plate in the first few layers, while the resin itself still cures fine everywhere else, the exposure and FEP checks in Fix Failed Resin Prints are the wrong place to start. This is almost always a gap problem: the plate sits too far from the screen for the first layers to bond, or it was never actually level in the first place.
1. Level the plate the way MSLA printers actually check it
Eyeballing a resin build plate is not leveling it. The standard method on Elegoo Mars-style printers and most budget-to-midrange MSLA machines uses a sheet of ordinary paper as a feeler gauge: loosen the plate’s mounting screws, lower it onto the screen with a sheet of paper in between, and adjust until you feel light, even resistance dragging the paper out from all four corners and the center. If one corner drags free while another holds the paper in place, the plate is tilted relative to the screen, and that tilt alone can starve one side of the first layer of contact while crushing the other.
2. Set Z-zero, then check what “too far” actually looks like
Once the plate is level, the Z-zero position (sometimes called the home offset) decides how close the plate sits to the screen for layer one. Too much clearance and the first layers print in open air with nothing to bond to, so the whole model or a support raft lifts straight off during the first few peel cycles. Too little clearance squashes the first layers into a thin, overly wide skirt, which is a different problem covered by the exposure adjustments in the general resin-failure guide. Save the Z-zero position only after the paper-drag test in step 1 feels consistent everywhere, not just in the center.
3. Recheck after any plate, vat or transport change
Removing the build plate to clean it, swapping vats between resins, and moving the printer are the most common reasons a previously good calibration stops working. The screws that hold the plate to its arm can shift by a fraction of a millimeter during any of these, which is enough to reopen the exact gap this guide is about. Re-run the leveling check afterward rather than assuming the last calibration still holds.
4. Clean and lightly rough the plate surface
Correct spacing does not help much if the plate itself is too smooth or coated in cured resin film to grip anything. Wipe the plate with isopropyl alcohol to strip old resin residue and release-agent buildup, then go over it with fine sandpaper (400 to 600 grit works on most anodized aluminum plates) in a light cross-hatch pattern. This gives the first layer physical texture to key into, on top of the correct distance from step 2, and it is worth doing any time adhesion has been inconsistent even after leveling checks out.
Resin plate adhesion checklist
- Plate leveled with the paper-drag test at all four corners and the center, not just visually.
- Z-zero saved only after leveling feels even everywhere.
- Calibration rechecked after removing the plate, changing vats or moving the printer.
- Plate cleaned with isopropyl alcohol and lightly sanded if prints still fail to hold.
- Exposure time and FEP condition ruled out separately if this checklist does not fix it.
If the plate is level and prints still will not hold, the cause is more likely exposure time or a damaged FEP film, covered in Fix Failed Resin Prints. A print that comes loose from the plate but stays stuck to the film itself, rather than falling away entirely, points to a different fix in Fix Resin Prints Stuck to the FEP.