ChituBox vs. Lychee for Pre-Supported STL Files: What You Need to Know
Pre-supported STL files behave differently in ChituBox and Lychee. Here's how the two slicers handle imported supports, where each one causes problems, and which settings actually matter when you're not placing your own.
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Pre-supported files hand you someone else’s support work. What you still need to figure out is what happens next: specifically, what happens when you drop that pre-supported file into a slicer and the slicer starts trying to be helpful.
That’s where people lose prints.
ChituBox and Lychee both have opinions about pre-supported files. Those opinions are not always correct. Understanding the differences between the two slicers (how they handle imported geometry, what settings they apply automatically, and where each one quietly breaks things) saves you the resin and the frustration of finding out mid-print.
What “Pre-Supported” Actually Means to a Slicer
From the slicer’s perspective, a pre-supported STL is just geometry. The supports are not tagged or identified as supports. They’re triangles and vertices the same as any other part of the model. The slicer has no way to know that the thin pillars in the file are support structures placed intentionally by the creator.
Both ChituBox and Lychee will see the entire file as a single mesh and apply their settings uniformly. Neither slicer will specifically recognize pre-existing supports unless they were generated inside that same slicer instance in the same session.
This matters because:
- Auto-detect features in both slicers may flag the support tips as islands or unsupported features and add their own supports on top of the creator’s.
- Slicer-side raft and base settings apply to the bottom of whatever geometry exists. In a pre-supported file, that’s typically the ends of the support columns.
- Scale operations affect the whole mesh including supports, and support tip diameters scale with the model.
None of these are catastrophic if you know about them. They all become problems if you don’t.
ChituBox and Pre-Supported Files
ChituBox is the default slicer for most Elegoo and Chitu Systems printers. It ships in the box and most early tutorials point to it. It’s capable, but its auto-support behavior is aggressive by default.
The auto-support problem
When you import a pre-supported STL into ChituBox and the auto-support function is turned on (or you accidentally trigger it), ChituBox will add supports to the existing support tips. The tips of pre-existing supports are thin columns sticking down into empty space, which look like unsupported islands to the auto-generator. ChituBox generates new supports onto those tips, resulting in a doubled-support nightmare that takes an hour to clean up and adds significant print time and resin use.
The fix is simple but non-obvious: disable auto-support generation before importing a pre-supported file. In ChituBox, go to Supports and make sure Auto-Support is not set to trigger on import. Confirm this every time you open a pre-supported file. The setting does not always persist between sessions depending on your version.
ChituBox 1.x vs. 2.x behavior
If you’re on an older printer running ChituBox 1.x, auto-support is a manual trigger. You have to click the button for it to run. This is more forgiving. You just don’t click it.
ChituBox 2.x changed the behavior. Some builds run auto-support analysis on import and display recommendations visually, which is easy to dismiss without realizing the underlying support generation has happened. Check the model after import: if you see doubled-up structures around the base of support columns, auto-support ran. Undo with Ctrl+Z and disable auto-support in settings before reimporting.
Scale and the raft
ChituBox’s default print profile often has the model sitting directly on a raft. For pre-supported files, the raft attaches to the base of the support columns, which is correct. The issue is that ChituBox may auto-offset the model upward slightly from the raft depending on your platform settings. If it does, there’s a gap between support column bases and the raft. Those columns will be printing into empty air and won’t adhere to anything.
After import: use the Edit > Set on Platform option to confirm the lowest point of the mesh is sitting at Z=0. Then verify the raft is actually connecting to the geometry, not floating below it.
Exposure settings for pre-supported files
Pre-supported files don’t require different exposure settings than unsupported files. The same layer height and exposure time apply. What changes is the bottom layer behavior. Pre-supported files typically have support columns running from the base to the model, so the first several layers are printing narrow columns rather than a wide raft. Those narrow columns need solid adhesion to survive the peel cycle.
If your prints are failing at the base and pulling off the raft early, don’t immediately assume the pre-supports are bad. Check bottom layer count and exposure first: 8–10 bottom layers at extended exposure (I run 40 seconds on the Saturn), and confirm the raft thickness is at least 1.5mm. Thin rafts under dense support column arrays can flex and peel.
Lychee and Pre-Supported Files
Lychee is a better fit for pre-supported files for one specific reason: its island detection is more controlled. You can run the analysis without triggering automatic support addition, which means you can see what the slicer thinks about the file without it making changes underneath you.
Import and island detection
When you import a pre-supported STL into Lychee, nothing runs automatically. You have to explicitly trigger analysis or support generation. That’s the right behavior for pre-supported files. You want to look at what’s there before the slicer starts changing it.
After import, run the Analyze function. It will flag islands and overhangs. On a well-supported pre-supported file, you should see a small number of islands (possibly zero) and yellow or green on most of the model. Red areas indicate genuine unsupported features that the file creator may have missed.
The important thing: Lychee’s analysis shows you problems without fixing them automatically. You decide whether to add supports to any flagged areas. ChituBox, depending on version and settings, may silently fix things, and in doing so create new problems.
Lychee’s “Support Management” view
Lychee has a dedicated Support Management panel that’s particularly useful for pre-supported files. When you’re working with an imported pre-supported mesh, use this panel to:
- Visually scan the support column bases and confirm they’re all touching the raft
- Identify any columns that are floating (support tip without a base connection)
- Check for columns that are connected to detail areas where the tip size looks oversized
You can add individual manual supports in this view without triggering a full auto-support pass. That’s the workflow for pre-supported files with gaps: spot-add where needed, leave the creator’s work intact everywhere else.
Lychee Pro: the resin savings on pre-supported files
One practical advantage of Lychee Pro for pre-supported files is the hollowing tool combined with the ability to see exactly where support columns attach. If you’re hollowing a large monster model that came pre-supported, you need to confirm the support column bases are still connecting to a solid region after hollowing. The Pro version lets you visualize both the hollow and the support geometry simultaneously. ChituBox’s hollowing workflow is less transparent about this. You can accidentally hollow a model to a shell thickness that undercuts the support column attachment points.
Key Differences Side by Side
| Behavior | ChituBox | Lychee |
|---|---|---|
| Auto-support on import | Version-dependent, can fire silently | Manual trigger only, never auto |
| Island detection | Runs with support generation | Independent analysis tool |
| Pre-support doubling risk | High without settings adjustment | Low by default |
| Support management view | Basic | Detailed, with geometry overlay |
| Platform zero-point handling | Can offset on import, verify manually | Honors mesh position reliably |
| Hollowing visibility | Limited | Clear geometry preview (Pro) |
| Learning curve for pre-supported workflow | Moderate (default settings fight you) | Low (passive by default) |
Common Mistakes with Pre-Supported Files in Both Slicers
Scaling the model after import. If you scale a pre-supported file (even to correct millimeter vs. meter import errors) the supports scale with it. A 0.3mm support tip at correct scale becomes 0.03mm at 1/10 scale, which won’t survive printing. Pre-supported files should be imported at the exact scale the creator intended. If your slicer imports the file in meters instead of millimeters (common with some exports), use the slicer’s unit correction option, not the scale tool. Unit correction changes the interpretation of the measurement without modifying the geometry.
Adding your own auto-supports on top of the creator’s. Already covered for ChituBox specifically, but Lychee users can make the same mistake by clicking Auto-Support without thinking. On a pre-supported file, auto-support will generate columns connecting to support tips as if they’re model geometry. The result is supports growing on supports, which looks wrong before printing and prints worse. Before clicking anything in the support panel, ask yourself: is this file already supported?
Not checking for floating columns. Sometimes pre-supported files export with a support column that isn’t connected to the raft. The creator placed it while the model was oriented differently and it didn’t export cleanly. These floating columns look fine in the 3D view but don’t print. The column disconnects from nothing and cures loose in the vat. In Lychee, the analysis tool flags these. In ChituBox, you’re looking manually. Rotate the view and check the base of every column cluster before slicing.
Trusting the creator’s exposure recommendation for your resin. Pre-supported file creators often publish settings: layer height, exposure time, printer model. That exposure time is specific to their resin, their printer’s LCD age, and their ambient conditions. Use it as a starting point, not a destination. If the creator prints on Elegoo ABS-Like and you’re using Siraya Tech Blu, the exposure times are different. Run a calibration print if you’re on a new resin regardless of what the pre-support creator recommends.
Not verifying layer count at the failure zone. If a pre-supported print fails at a specific layer, look at what’s happening at that layer in the slicer preview. Scrub through the layers to the failure point and check: is there a horizontal cross-section where a lot of new geometry is appearing at once? Large new masses appearing without support underneath them will fail. Good pre-supports handle this, but not all pre-supported files are from quality creators. Some are tested minimally and shipped with gaps.
Which Slicer Should You Use for Pre-Supported Files?
If you’re currently on ChituBox because that’s what came with your printer, it works fine for pre-supported files once you turn off auto-support and verify the platform zero-point on import. The workflow is a bit more manual verification, but the output is the same.
If you’re choosing between them and pre-supported files are a regular part of your workflow, Lychee’s passive analysis approach is easier to work with. The slicer doesn’t try to fix things before you’ve looked at them, which is the behavior you want when the file came pre-configured by someone else.
The free tiers of both slicers handle pre-supported files without issue. You don’t need Lychee Pro specifically for pre-supported workflow. The Pro features that matter (hollowing visualization, advanced raft options) are valuable for other parts of the workflow but not essential for printing a pre-supported file.
Where Lychee Pro earns its keep with pre-supported files is large models: creatures, vehicles, terrain pieces over 80mm. The combination of clear hollowing visualization and better raft management at scale makes Lychee Pro the better tool for that specific use case.
The Short Version
Use Lychee if you’re starting fresh or already own Pro. The passive import behavior is better suited to pre-supported files by default.
Use ChituBox if that’s what your printer runs natively and you’re comfortable with manual verification on import. Disable auto-support, confirm platform zero, check for floating columns. The prints come out the same.
Both slicers produce equivalent output when configured correctly. The difference is how much the slicer fights you while you’re getting there.
For full slicer settings coverage specific to Lychee, the Lychee slicer settings for miniatures guide goes deep on layer height, exposure, anti-aliasing, and support presets. For a walkthrough of manual support placement when you outgrow pre-supported files, the supports guide covers placement strategy from scratch.