Reset the FEP Counter
on Your Saturn 4 Ultra
The complete guide to replacing your PFA release film, clearing the layer counter, and running the full maintenance routine that keeps your 16K prints flawless — print after print.
Your Elegoo Saturn 4 Ultra is one of the most capable MSLA printers ever built for the desktop — a 16K mono LCD, smart tank heating, and an AI camera watching every layer. But even a flagship machine will quietly degrade if you ignore the basics. Chief among them: the release film sitting at the bottom of your resin vat.
The Saturn 4 Ultra tracks every layer it prints and will flag you when the PFA/FEP release film is due for replacement. A lot of users replace the film correctly, then stare at a counter that still reads "Change Release Film" and wonder what they did wrong. Nothing — you just need to reset the counter manually through the settings menu. This guide walks you through that exact step, the full film swap procedure, and the complete maintenance schedule to keep your printer running at peak performance.
What Is the FEP/PFA Counter?
The Saturn 4 Ultra uses a Chitu Systems-based control board that logs the cumulative number of layers printed. Every time the UV LCD fires and a layer cures, the counter increments by one. ELEGOO uses this count as a proxy for release film wear — because each layer peel cycle stresses the film slightly, pulling the cured resin away from the vat bottom.
The printer's onboard firmware will display a warning — "Replace Release Film" or "Change your PFA/FEP" — when the count reaches the preset threshold (typically around 60,000 layers). This is a helpful nudge, not a hard lockout. You can dismiss the warning and keep printing, but at that layer count the film is statistically likely to be approaching the end of reliable service life.
"The release film is a wearing part. Replace it regularly according to machine prompts to ensure the success rate of printing." — ELEGOO Saturn 4 Ultra Official User Manual
Why the Counter Matters
A degraded film dramatically increases the chances of print failures — failed adhesion, complete plate-drops, or worse, cured resin bonding to the film and tearing it, sending resin flooding onto your LCD screen. A $12 replacement film beats a $200+ LCD replacement every time.
Importantly: the counter does not automatically reset when you swap the film. You must navigate to the maintenance menu and confirm the reset manually. Skipping this step means the warning will persist even with a brand-new film installed.
When to Replace — Visual Signs
The layer counter is a scheduling guide, not the final word. Your eyes are the best diagnostic tool. Inspect the release film regularly by shining a light through it and looking at the surface in a well-lit area. Replace immediately if you observe any of the following:
Keep 2–3 spare PFA films on hand at all times. A film failure at midnight shouldn't mean waiting days for shipping. ELEGOO's official replacement films for the Saturn 4 Ultra are the correct fit — third-party films exist but confirm the dimensions match before buying.
What You'll Need
Gather everything before you start. Working with wet resin mid-swap creates opportunities for spills and skin contact.
Photopolymer resin is a skin sensitizer and potential allergen. Always wear gloves and work in a well-ventilated area. If resin contacts bare skin, wash with soap and water immediately — do not use IPA alone to clean skin. Dispose of IPA-soaked wipes by exposing them to sunlight to cure any resin before bin disposal.
Replacing the PFA Release Film — Step by Step
The Saturn 4 Ultra uses a two-piece aluminum frame system that sandwiches the PFA film. The process is straightforward but requires attention to film orientation and tension. Take your time — a rushed install creates bubbles, uneven tension, and early failure.
Empty and Clean the Resin Vat
Pour all resin back into its bottle through a filter to catch cured flakes. Wipe the vat interior with IPA and lint-free cloths until it is fully clear. Let it dry completely. Look for any cured resin stuck to the current film — if there is debris bonded to the film's surface, it confirms it is time to replace.
Remove the Vat from the Printer
Lift the resin vat straight up off the LCD screen. Place it on a protected, flat surface. Avoid dragging it across the Mylar tape around the screen edges — that tape protects the LCD from resin seepage and must not be disturbed.
Unscrew the Bottom Frame
Using the 3.0mm hex wrench, remove all the screws from the bottom frame of the vat. The Saturn 4 Ultra vat uses multiple screws around the perimeter — keep them in a small dish so none go missing. Note the orientation of the bottom frame before removing it; reinstalling it backwards is a common mistake that prevents the vat from seating properly on the printer.
Separate the Frame and Remove the Old Film
With screws removed, gently separate the bottom frame from the vat body. Peel the old PFA film away. Inspect both frame surfaces for any stuck resin or debris and clean thoroughly with IPA. A clean seating surface is essential for a bubble-free new install.
Install the New PFA Film
Place your foam backing block on a flat surface. Lay the bottom frame (frame-side down) on the foam. Place the new PFA film over the frame opening so it overhangs evenly on all sides. The foam creates a slight downward bow in the film, which provides the correct amount of slack for printing. Place the vat body over the film, sandwiching it between the vat bottom and the frame. Align everything carefully before pressing together.
Tighten the Frame Screws — In Order
Reinsert all screws by hand first, then tighten in a cross-pattern (similar to tightening lug nuts on a wheel) to ensure even film tension. Do not overtighten — snug is correct. Uneven tightening creates tension hotspots that lead to tears during printing.
Trim Excess Film
Using a utility knife or sharp scissors, carefully trim the overhanging PFA film flush with the outside edge of the frame. Hold the knife at a slight angle and run it smoothly along the frame edge. Rough tears leave loose material that can foul the vat walls.
Inspect the New Film
Hold the vat up to a light source and look through the film. It should be perfectly clear and evenly tensioned — no wrinkles, no bubbles, no loose areas. Tap the film gently with a fingertip; it should feel taut like a drum head, not floppy. A properly installed film emits a clear, sharp sound when tapped.
Reinstall the Vat on the Printer
Carefully lower the vat back onto the printer, seating it fully on the LCD screen. Check that it sits flat and even. Then re-run your build plate leveling procedure — even if you haven't changed the Z-offset, a fresh film install is always a good moment to verify the level is still correct.
After installing a new film, it is normal for the first 1–2 prints to have slightly more resistance during the peel cycle as the film seats and stretches to its working tension. This is expected behavior — do not increase lift speed aggressively on the very first print.
How to Reset the FEP Counter
This is the step most tutorials skip. You've replaced the film — now clear the counter so the printer's tracking starts fresh from zero. The reset path on the Saturn 4 Ultra's Chitu-based touchscreen interface is:
Navigate to Settings
From the home screen, tap the Settings icon (gear icon, usually in the lower toolbar or accessible from the main menu).
Open the Tools / Maintenance Menu
Inside Settings, look for a Tools or Maintenance submenu. On the Saturn 4 Ultra running current firmware, this is typically labeled Tools. Tap to enter.
Find the Release Film / FEP Counter Option
Scroll through the Tools menu to locate Reset Release Film, FEP Reset, or Film Life Reset — the exact label depends on your current firmware version. Tap it.
Confirm the Reset
A confirmation dialog will appear. Tap Confirm or Yes. The layer counter will reset to zero and the "Change Release Film" notification will be dismissed.
Verify the Counter Is Cleared
Return to the main screen or the film status screen and confirm the counter now reads 0 layers. If the warning banner persists after a full reset, restart the printer — power cycle it completely and the notification should clear.
Menu label wording varies slightly across firmware versions. If you cannot locate the FEP counter reset option, first check that your firmware is up to date: Settings → Version Upgrade → Local Upgrade (or accept the OTA prompt if your printer is network-connected). Updated firmware often consolidates and relabels maintenance options.
Full Saturn 4 Ultra Maintenance Schedule
FEP replacement gets all the attention, but a well-maintained Saturn 4 Ultra involves a handful of quick habits at multiple intervals. Here is the complete schedule.
- Clean build plate with IPA and scraper
- Inspect resin vat for cured flakes or debris
- Wipe down printer exterior
- Check LCD edges for resin seepage
- Filter resin if returning to bottle
- Deep clean resin vat with IPA
- Inspect release film condition visually
- Inspect LCD screen surface for cloudiness or dead pixels
- Clean vat-to-printer contact points (heating contacts)
- Wipe Z-axis column and carriage
- Run Exposure Test (Settings → Tools → Exposure Test)
- Verify auto-leveling / re-level build plate
- Check carbon filter — replace if odors increase
- Check release film layer count on printer screen
- Verify exposure settings still dialed for your resin
- Lubricate Z-axis lead screw with lithium grease
- Check all frame and vat screws for looseness
- Deep clean build plate surface
- Review and update firmware if available
- Replace PFA release film (~60,000 layers or on visual damage)
- Replace LCD screen (~2,000+ print hours or dead pixels appear)
- Replace carbon filter (when odors increase noticeably)
- Recalibrate Z-offset after any mechanical changes
Z-Axis Lubrication — The Overlooked Task
The Z-axis lead screw is the mechanical heart of your printer. It drives the build platform up and down with the precision your 16K LCD relies on — any backlash, binding, or roughness here translates directly to layer shifting, Z-banding, or inconsistent layer heights in your prints.
How to Lubricate the Z-Axis
Lower the Build Plate
Move the build platform to a mid-height position so you have clear access to the exposed lead screw above it. Do this through the printer's manual control menu (Settings → Move or similar).
Wipe the Lead Screw
Using a lint-free cloth, wipe down the entire accessible length of the lead screw to remove old dried grease, dust, and debris. Do not use IPA directly on the lead screw — it strips grease from the threads and can get into the lead nut.
Apply Lithium Grease
Apply a small, even bead of lithium grease along the length of the lead screw threads. A little goes a long way — do not glob it on or the excess will fling off during operation and contaminate your resin vat or LCD.
Work It In
Manually move the build platform up and down several times (using the printer's control menu) to distribute the grease evenly through the lead nut. Wipe off any excess that squeezes out. Listen for the lead screw during this process — it should move with a smooth, quiet hum, not a grind or squeak.
If your Z-axis is making friction or grinding noises, lubricate immediately regardless of schedule. Operating a dry or under-lubricated lead screw accelerates wear on both the screw and the lead nut — and lead nut replacement is a more involved repair than a simple grease application.
LCD Screen Care — Protecting Your Most Expensive Component
The Saturn 4 Ultra's 16K mono LCD (15,120 × 6,230 pixels) is the centerpiece of the machine and its most expensive consumable, rated at approximately 2,000+ hours of print time. The Mylar tape surrounding it is not fully airtight — any resin that seeps through a compromised release film can creep under that tape and onto the LCD surface, causing permanent damage.
Daily LCD Cleaning
After every print session, remove the vat and inspect the LCD surface. If any resin is present, clean it immediately with a lint-free cloth lightly dampened with IPA. Use gentle, straight strokes — never circular scrubbing motions, which can create micro-scratches that scatter light and reduce resolution.
LCD Health Test
Run the built-in exposure test monthly to check for dead pixels or uneven illumination: navigate to Settings → Tools → Exposure Test (or Tools → Exposure depending on firmware). The entire LCD will illuminate uniformly. Look for any dark spots, dim areas, or visible scan lines — these indicate pixel death or backlight degradation. Catching early degradation lets you plan a screen replacement before it starts affecting print quality.
If you won't be printing for more than 48 hours, ELEGOO officially recommends emptying the resin vat and storing your resin in its sealed bottle. Leaving resin sitting in the vat for extended periods accelerates film degradation and can allow resin to partially cure from ambient light, creating debris that scratches the film and LCD on the next print.
Pro Tips for Longevity
Clean the Tank Heating Contacts
The Saturn 4 Ultra features smart tank heating that maintains the resin at 30°C — a critical feature for print consistency, especially with temperature-sensitive resins. The heating is delivered through contact points at the base of the printer where the vat sits. Resin residue on these contacts degrades heating performance. Wipe them with an IPA cloth regularly to keep the connection clean.
Use a Drip Tray
ELEGOO includes a drip tray accessory specifically to catch resin runoff when you lift the build platform after a print. Install it. The few seconds it takes to snap on before a print session will save you from cleaning cured resin drips off the printer body and the vat rim.
Filter Your Resin Every Time
Never pour resin back into its bottle without filtering it through a paint strainer or resin filter funnel. Cured flakes are nearly invisible in opaque resins and will sink to the bottom of your vat. On the next print, they can lodge between the build platform and the release film, causing failed adhesion or tearing the film.
Keep the Printer Level
Verify your workbench and the printer's surface are level. Resin naturally pools to the low side of the vat. If the printer is tilted, resin coverage over your build area becomes uneven, especially on larger prints that push toward the edges of the vat.
Update Firmware Regularly
ELEGOO pushes firmware updates that address layer timing refinements, maintenance menu improvements, and AI camera performance. Update when prompted or manually via Settings → Version Upgrade → Local Upgrade with the firmware package on USB. Updated firmware has occasionally moved the FEP counter reset to a different menu path, so staying current avoids confusion.
Frequently Asked Questions
- "Saturn 4 Ultra FEP Counter Reset: The Step Most People Miss After Changing Their Release Film"
- "Complete Elegoo Saturn 4 Ultra Maintenance Guide — From Film Replacement to Z-Axis Lubrication"
- "Why Your Saturn 4 Ultra Still Says 'Change Film' (And How to Actually Fix It)"
We Keep Your Printer Printing
From film replacements and Z-axis tune-ups to full resin printer overhauls — Dreaming3D's repair team in San Diego has you covered.
Call 858-342-6984 · Email dreaming3dprinting@gmail.com · San Diego, CA