How to Add Supports to Resin Prints: Placement and Settings

A resin print hangs upside down from the build plate, and every layer is peeled off the release film before the next one cures. Learning how to add supports to resin prints is really learning where that peel force and the part’s own weight will win: at islands, overhangs and low points that would otherwise start printing in mid-air. The order that avoids most failures is fixed. Orient first, lift the model, auto-generate, check every island, then place and size the manual supports by hand.

What a resin support actually does

Formlabs describes the structure in three parts: a raft that adheres to the build platform, scaffolding that stems from the raft, and touchpoints where the scaffolding meets the model. It lists overhangs, spans and unsupported minima as the geometry that needs support, and warns that even a self-supporting bridge can warp or fail without it. A minimum, in Formlabs’ definition, is the lowest point of any area of the model relative to the platform; Prusa calls the spots where an object would start in mid-air islands. The first layer of such a region has nothing under it, so a tip has to be there before it cures.

FDM supports are a lattice that fights gravity. Resin supports are thin pillars that fight the peel, which is why tip geometry matters more than tip count. The FDM side is covered at slicerguide.com.

Step 1: orient before you support

Prusa’s orientation article explains the 45-degree tilt most resin prints get: large flat horizontal surfaces need a lot of force to separate from the bottom of the tank, and tilted objects spread their supports more evenly. Rotate until the island count is as low as it will go, because avoiding a support beats removing one.

Chitubox’s support guide sets the thresholds: an overhang tilted less than 45 degrees from the vertical may print without support, and a bridge under 5 mm may span on its own. Formlabs’ Form 4 specifications are looser because of its low-force peel: 10 degrees from level as the minimum unsupported overhang angle, 5 mm as the maximum unsupported overhang length, and 29 mm as the maximum span for a 5 mm wide, 3 mm thick beam. On a hobby LCD printer with a FEP vat, the Chitubox numbers are the rule and the Formlabs numbers are the ceiling.

Hollow anything bulky first. Prusa’s hollowing article gives the reasons: a smaller area per layer needs less force to detach from the display, and a lighter model needs fewer supports. Add at least two drain holes and keep the wall at or above the 1 mm minimum.

Step 2: lift the model and auto-generate

Set the Z lift height first. Chitubox defines it as the distance between the lowest point of the model and the platform, default 5 mm, and Anycubic’s Photon Workshop guide gives the reason: raising the model before adding supports stops it fusing with the raft and protects the bottom surface. Then run the auto-supporter on a Medium preset. Chitubox and Lychee ship Light, Medium and Heavy; PreForm’s Auto-Generate All does the same job, with the caveat on that page that more supports raise both the chance of success and the post-processing work.

Two knobs decide how much it adds. Anycubic’s support angle is the angle between the supported surface and the horizontal plane, and a larger angle generates more supports; its anchor distance is the spacing between anchor points, and a shorter distance generates more. Chitubox illustrates the same pair at 30 versus 60 degrees and 1.0 versus 0.5 mm.

Step 3: find every island and support it by hand

Auto-support misses islands, and every slicer can show them. Anycubic’s Check Islands colours each layer green for supported, yellow for connected but possibly hanging, and red for completely unsupported. PreForm highlights unsupported minima in red and has offered a Support All Minima button since 3.32.0, but its warning does not stop a job from starting, so the check is yours. Lychee’s Island Detector highlights the largest islands and draws white rings that mark the lowest point of each section.

Lychee’s manual supports page gives the routine. Scrub the layer slider until only the bottom major islands show, put Medium or Heavy supports on them about 2 mm apart and close to the edges, then switch to Light and Mini supports for the smaller islands and details, with each tip meeting the surface at roughly 90 degrees. Chitubox uses A, D and E for add, delete and edit; PrusaSlicer adds a point on left-click and removes on right-click.

Step 4: size the contact

Tip diameter and depth trade strength against the mark left behind. Lychee’s support components page puts it plainly: a larger tip diameter has more strength to hold the model and leaves a larger impact site, and penetration is the depth the tip enters the object. Chitubox illustrates its tip upper diameter at 0.3 and 0.6 mm; PrusaSlicer’s listed defaults are a 0.6 mm head front diameter, 0.6 mm head penetration and a 1.3 mm pillar. Formlabs’ advanced settings page adds the compensation rule: increase Density when you reduce Touchpoint Size, and expect a higher Height Above Raft to ease removal at the cost of a less stable base.

Settings to start from

Chitubox, on an Elegoo Mars or Anycubic Photon Mono class LCD printer, standard resin at 0.05 mm:

Setting	Start value	Why
Tilt	45° on the long axis	Spreads supports and cuts per-layer peel area (Prusa)
Z lift height	5 mm	Chitubox default; keeps the model off the raft (Anycubic)
Preset	Medium auto, Heavy by hand on bottom islands	Lychee’s placement routine
Support angle	Between Chitubox’s 30° and 60° examples; raise it while islands stay red	Larger angle, more supports (Anycubic)
Touch tip distance	0.5 to 1.0 mm auto; about 2 mm hand-placed on base islands	Chitubox examples; Lychee spacing
Tip diameter	0.3 mm on detail, 0.6 mm where the load is	Chitubox’s two illustrated values; PrusaSlicer’s 0.6 mm default
Contact depth	Near PrusaSlicer’s 0.6 mm penetration	Deeper is stronger and leaves a bigger mark (Anycubic)
Raft	Skate or cross grid	Chitubox options

Change one variable per print, and never shrink tip size and density in the same slice.

How to verify

1. Scrub the layer slider from the raft upward before slicing. Pass criterion: no red or yellow layer, and every island beginning on a tip.
2. Print it and read the failure. A cured sheet on the film with nothing on the plate is a first-layer problem, covered in resin print not sticking to the build plate. A part left on the film with its tips snapped or pulled out is a contact problem: go up one preset on the bottom islands or add tips 2 mm apart before touching exposure; the Photon Mono version is at anycubicguide.com. A clean split at one Z height is layer separation, not a support fault.
3. Only then tune exposure, with the stepped test in how to calibrate resin exposure time, rather than adding supports to a layer that is not bonding.
4. Inspect the marks after removal. If a mark is larger than the detail beside it, drop tip diameter on that area only and keep density, then wash and cure as usual.

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• Resin Types Compared: Which Anycubic Resin to Print With — anycubicguide.com
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