Replacing the FEP film in a resin printer’s vat looks more intimidating than it needs to be. There are plenty of screws, but the process is manageable when you keep the parts organized and work through the frame one stage at a time.
In this tutorial, I demonstrate the replacement on an ELEGOO Mars 3 vat. The old film is pockmarked, has resin residue, and has started leaking. I walk through removing it, fitting the replacement, trimming the excess, and reinstalling the vat.
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Choose replacement film intended for your particular vat. The hands-on demonstration below uses the Mars 3; use your printer’s instructions for the exact frame assembly and tensioning requirements.
What I use in the tutorial
- The replacement FEP sheet.
- The Allen keys supplied with the printer.
- A small container for keeping the screws together.
- Sharp scissors for trimming excess film.
- Alcohol for cleaning resin residue, and gloves while handling the vat and frame.
Even after cleaning, residue can remain between the frame pieces. I keep my gloves on as I take the assembly apart.
1. Remove the old film assembly
With the vat removed from the printer and cleaned, I turn it over and work through the screw groups. First come the corner screws, followed by the screws holding the film frame to the vat. Once those are out, the frame lifts away.
The smaller screws hold the two frame pieces together around the film. Remove those to separate the frame and release the old sheet. Keep the different screw groups organized so they can go back into their original positions.
2. Prepare the replacement sheet
The replacement sheet in the video has a protective layer on each side. Peel both layers away before installing it—the second layer can be easy to miss.
Lay the new film over the frame and center it. Leave material extending beyond the screw positions all the way around so there’s room to secure the sheet and trim it afterward. Align the other frame piece over it.
3. Secure the film in the frame
I use the small Allen key to make openings at the screw positions, then reinstall the small frame screws. Starting around the corners helps hold the pieces in alignment as I work around the frame.
Keep the frame lined up throughout this stage. The video shows the sheet becoming more secure as the frame is reassembled.
4. Trim the excess film
Once the film is secured between the frame pieces, use sharp scissors to cut away the material extending beyond the frame. I work around the outside and keep the trimmed edge tidy.
5. Reassemble and tension the vat
Next, the frame goes back into the vat. I start the corner fasteners without fully tightening the first one, giving myself room to align the other corners. Then I work through the remaining fasteners.
As the assembly is tightened, the film becomes taut. In the video, I demonstrate the change in sound as the sheet tightens, comparing it to a drum. Follow the tensioning method specified for your own vat rather than relying on a guessed torque or frequency.
6. Clean and reinstall
After reassembly, I clean away the smudges and remaining residue, put the vat back on the printer, and tighten it in place. I estimate roughly 10–15 minutes for the replacement in the video, depending on how comfortable you are with the process.
Watch the full FEP replacement tutorial
Video chapters
- 0:00 — Introduction and setup
- 1:37 — Removing the old vat film
- 3:08 — Preparing the new film
- 4:24 — Installing the new film
- 6:36 — Trimming excess film
- 7:36 — Tightening and tensioning
- 9:32 — Final assembly and cleaning