How to Replace FEP Film on Elegoo and Anycubic Resin Printers
FEP film is the consumable you'll replace most often. Here's when to do it, what you need, and the step-by-step process, including the tension check most guides skip.
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FEP film is the clear layer at the bottom of your resin vat. It takes more abuse than any other part of your printer. Every layer of every print peels against it. Resin that partially cures on it adds micro-scratches over hundreds of exposures. A vat suction event — where a print sticks to the FEP instead of the build plate — can tear it outright.
Replacing FEP is a routine maintenance task, not a repair. I swap mine on my Saturn at the first sign of cloudiness or visible scratch patterns, usually every 30–50 hours of print time. You don’t need to be precious about it. The film costs a few dollars per sheet and the replacement takes about 20 minutes once you’ve done it a couple times.
This guide covers Elegoo and Anycubic printers specifically — Saturn, Mars, Photon Mono, and similar MSLA machines. The process is nearly identical across models because the vat design is essentially the same: a metal frame with an FEP sheet tensioned across it, held in place by screws around the perimeter.
When to Replace FEP
Cloudiness or haziness. Hold the vat up to a light source. Fresh FEP is optically clear. When it starts looking milky or frosted in areas, UV transmission through those spots is reduced — this causes layer artifacts and increases the chance of prints sticking to the FEP instead of the build plate.
Visible scratches. Surface scratches from plastic scrapers (and especially metal scrapers) scatter the UV exposure. If you can see scratch patterns when you hold the vat at an angle to the light, the film needs replacing.
Recurring failures in the same spot. If prints consistently fail at the same location on the build plate — same X/Y area, print after print — the FEP is usually the cause. The failure pattern corresponds to where the FEP is cloudy or scratched.
After a torn FEP incident. If the film tears, replace it immediately. Resin will enter the printer chassis through a torn FEP and damage the LCD screen. This is one of the more expensive repair scenarios on these machines.
After a hard suction event. When a print welds itself to the FEP and you have to pry it off, check the film carefully afterward. The peel forces from a stuck print can create micro-tears or creases that aren’t immediately visible.
The film doesn’t need to be replaced on a schedule. If it’s clear, leave it. Replacing FEP unnecessarily wastes material and introduces the risk of incorrect tension — a correctly tensioned old film is better than an incorrectly tensioned new one.
What You Need
Replacement FEP film. Get film sized for your specific printer model — dimensions vary by vat size. Most printer brands sell their own branded FEP in multipacks; generic FEP cut to size also works. For Elegoo and Anycubic machines, search your specific model number on Amazon:
- Elegoo FEP film replacement — match to your model (Mars, Saturn, etc.)
- Anycubic FEP film replacement — match to your model (Photon Mono, etc.)
Standard FEP thickness for these machines is 0.1–0.15mm. Don’t substitute with thicker film; it affects exposure calibration.
The correct screwdriver or wrench. Most Elegoo and Anycubic vats use M3 hex screws around the perimeter. You need a 2.5mm hex key (Allen wrench) or a hex-head screwdriver. The Saturn uses a slightly different arrangement — check your manual if you’re not sure. I keep a small hex key set on my printer shelf specifically for this.
IPA (isopropyl alcohol, 91%+) and paper towels. For cleaning the vat frame after removing the old film.
Nitrile gloves. The inside of the vat will have residual resin, even if you’ve been running it nearly empty. Wear gloves the entire time.
A plastic scraper. For removing any cured resin residue from the vat frame during cleaning.
Replacement screws (optional but useful). The M3 screws on these vats are small enough that they’ll strip if you overtighten them repeatedly. If any screws feel loose in the hole before you even tighten them, they’re stripped — replace the set. A pack of M3 screws from a hardware store or Amazon costs almost nothing.
Safety glasses. Residual resin in the vat can splash.
Safety First: Prep the Workspace
Before touching the vat, drain it.
Pour the resin back into its bottle using a resin filter funnel to catch any debris. Don’t skip the filter step — any partially cured flakes that make it back into your resin supply will cause print failures later.
Once drained, wipe the inside of the vat with a paper towel to remove as much liquid resin as possible. The vat won’t be completely clean — there will be film residue — but you want the bulk of the liquid out before you start disassembly. Work over paper towels to catch drips.
For disposal: IPA-soaked paper towels and resin-contaminated materials should be cured in sunlight before disposal. Set them outside in a clear bag for an hour. Cured resin is non-hazardous; liquid resin is not.
Step-by-Step FEP Replacement
1. Remove the vat from the printer
Lift the vat straight up and off the printer. Set it on a stable, paper-towel-covered surface. Don’t tilt it until you’ve confirmed it’s fully drained.
2. Remove the screws around the vat perimeter
The FEP is held in by screws running around the perimeter of the vat frame. These pass through the outer frame, through the FEP sheet, and into the inner frame below.
Remove all screws and set them somewhere they won’t roll. I put them in a small ceramic dish. Count them before you start so you know if one goes missing.
Some vats have a top frame and a bottom frame sandwiching the FEP. Some have a single frame with the FEP tensioned directly. Either way, the process is the same — remove the screws, lift the frame.
3. Remove the old FEP sheet
Lift the frame off. The old FEP will either come with the frame or stay in the vat bottom — it depends on whether it’s fused at the edges from resin. If it’s stuck, peel it away carefully. Don’t scrape it off with metal.
4. Clean the vat frame
Wipe both mating surfaces of the frame — top and bottom — with an IPA-soaked paper towel. Remove any resin residue, dried resin, or debris. If there’s cured resin that won’t wipe off, use a plastic scraper.
Inspect the frame surface for warping or damage. A warped frame won’t hold FEP tension evenly, and you’ll get print failures along the warped edge. On budget machines this occasionally happens after a hard crash or prolonged heat exposure. If the frame is visibly warped, you need a replacement vat, not just a new film.
5. Position the new FEP sheet
Lay the new FEP sheet flat on the bottom frame. Center it so it covers all the screw holes with some overlap at the edges. The film ships with a protective layer on one or both sides — peel it before installation. (I’ve made the mistake of installing FEP with the protective film still on. It prints fine for about two layers and then delaminates catastrophically.)
Don’t stretch or pull the film during positioning. Just lay it flat and let it sit naturally.
6. Align and place the top frame
Set the top frame down over the FEP. Align the screw holes by eye. The frame will usually self-locate if you lower it straight down.
7. Install screws finger-tight first
Thread all the screws in by hand until they’re snug but not tight. Do not tighten any single screw fully before the others are in — this creates uneven tension that you’ll feel immediately as the FEP pulls diagonally toward the tightened corner.
8. Tighten in a cross pattern
Tighten the screws in a cross pattern — like tightening wheel lug nuts. Start with one screw, skip to the opposite side, then move 90 degrees and repeat. Work your way around until all screws are firm.
The target tension: when you tap the center of the FEP with a fingertip, it should make a clear, resonant sound — similar to the sound of tapping a drum head. Dull thud = too loose. High-pitched ping or no give at all = too tight. Most guides skip the tension check, but it matters. Loose FEP causes suction failures. Overly tight FEP causes micro-tears at the screw holes.
On the Saturn, I typically do two rounds in the cross pattern — one to get all screws snug, one to bring them to final torque. Don’t use a power driver; hand-tightening is enough and avoids stripping.
9. Check for and trim any excess film (if applicable)
On some vat designs, the film needs to be trimmed flush with the frame edges after installation. Check your printer’s documentation — most Elegoo and Anycubic machines don’t require trimming since the film comes pre-cut to the vat dimension, but if your replacement film is slightly oversized, fold and trim the overhang rather than letting it wrinkle.
10. Inspect before reassembly
Hold the assembled vat up to a light. The film should be evenly transparent across the entire surface with no visible wrinkles, creases, or cloudy spots. Light should pass through evenly. If you see a crease, loosen the screws, re-seat the film, and re-tighten.
Common Mistakes
Installing with the protective film still on. The new FEP ships with a thin protective layer. It looks almost identical to the FEP itself. Peel it before installation. If you’re not sure which side is which, both sides usually have it — peel both.
Tightening in a circle rather than a cross pattern. This pulls the FEP diagonally and creates tension that’s uneven across the vat. The edges at the non-tightened corners will be loose. You’ll see it as a diagonal sag when you hold the vat to the light.
Over-tightening. The screws are small and the frame is usually aluminum or thin plastic. Over-tightening strips the threads. If you feel a screw going easy when it was firm before, stop and replace that screw.
Reusing gaskets. Some vats have a rubber gasket or o-ring between the frame and the film. These compress and take a set over time. If your vat has a gasket, replace it with the film. Reusing a compressed gasket is how you get resin leaking through the vat bottom onto your LCD screen.
Not checking for drips before the first print. After reassembly, pour a small amount of resin into the vat and leave it for a minute. Check the underside of the vat for any drips. If the seal is good, you’ll see nothing. If there’s a drip, the film isn’t sealed at one of the screw positions — loosen, re-seat, and re-tighten.
Test Print Before Printing Real Models
Before loading a full plate of miniatures onto fresh FEP, run a test print.
A 20mm solid square, 5mm tall, printed in the center of the build plate works fine. This takes about 10 minutes and confirms:
- The FEP tension is correct (the print will peel cleanly off the FEP each layer rather than sticking)
- The seal is holding (no resin leaking through)
- Your exposure settings are still calibrated (a solid square should print with clean, sharp edges)
If the square prints cleanly, you’re good. If it sticks to the FEP and comes off with the vat rather than the build plate, you either need to re-level the build plate or the FEP is too loose — both are solvable.
How Often Should You Replace FEP?
There’s no fixed interval. The film lasts longer if you:
- Only use plastic scrapers on the vat (never metal)
- Filter your resin before pouring it back in the bottle (prevents cured debris from scratching the surface)
- Avoid over-exposure settings that increase the force required for each peel
As a rough guide: if you’re printing 3–5 sessions per week, expect to replace FEP every 4–8 weeks. If you print occasionally, the film may last months. Let the condition of the film tell you, not a calendar.
Keep two replacement sheets on hand. Tearing FEP mid-build with no replacement available means the print session is over.
FEP film, build plate FEP, IPA, nitrile gloves, and paper towels are the consumables worth keeping stocked. Buying in bulk from Amazon or AliExpress cuts cost significantly over time.