3D printing supports: when to use them, settings and removal
Supports are the scaffolding the slicer prints under the parts of a model that would otherwise hang in the air. They solve the gravity problem, but you pay for them in plastic, in machine time and in the minutes you spend removing and sanding. This guide puts it all in one place: when you need them, how to avoid them, what each setting does and how to charge for them.
When a part needs support
A filament printer can only lay plastic on top of something. A straight wall rests on the full layer below it. On a sloped wall, each layer sticks out a little past the one before. Up to a point that works; past it, the line droops.
In practice, three rules cover almost everything:
- The 45° rule. A face at 45° or more to the bed (that is, leaning no more than 45° out from vertical) usually prints without support, because each layer still rests half its width on the one below. Any flatter, and the line starts to droop.
- The slicer's threshold angle. In Bambu Studio and OrcaSlicer it is called Threshold angle and defaults to 30°: a face at less than 30° to the bed gets support. Bambu Lab's support wiki page (checked November 2026) calls that value safe for most materials. There, a higher number means more support. Cura works the other way around: Support Overhang Angle is measured from vertical, and a higher number means less support.
- A bridge is not an overhang. A line stretched between two points that hold it prints in midair if the span is short, like a real bridge. What brings it down is a loose end: Bambu's slicer treats an overhang held at only one end and a tip left hanging in the air, away from the rest of the part, as critical, and supports them even when they are small.
Horizontal holes are overhangs too: the top of a round hole lies nearly flat. A small hole usually closes without support; a large one can come out with a sagging top.
Before you turn on supports: try not to need them
The cheapest support is the one that doesn't exist. Four tricks, from simplest to most work:
- Rotate the part. A large flat face goes on the bed. A T-shaped part upside down has no overhang at all.
- Swap a flat overhang for a 45° chamfer. If you design the part, a ramp under the ledge prints on its own. A rounded fillet under an overhang is worse than a chamfer, because the top of the curve is almost flat.
- Make horizontal holes teardrop-shaped. A point at the top of the hole, instead of a round ceiling, removes the flat part. For a screw, nobody notices.
- Split the part in two. Printing two halves without supports and gluing them usually gives a better finish than one whole part full of supports.
To see how big the difference is, we sliced two parts each way:
| Part and how it was printed | Support only | Total filament | Total time |
|---|---|---|---|
| T part upright, normal supports | 28.3 g | 42.2 g | 54 min |
| T part upright, tree supports | 15.5 g | 29.4 g | 1 h 39 min |
| T part upside down | 0 g | 13.9 g | 27 min |
| Flat ledge, normal supports | 4.3 g | 18.1 g | 27 min |
| Flat ledge, tree supports | 2.3 g | 16.1 g | 34 min |
| Ledge with a 45° chamfer | 0 g | 14.7 g | 24 min |
Illustrative example. T part: a 60 × 60 × 4 mm top on a 15 × 15 mm column, with the top 40 mm above the bed. Ledge: a 20 × 40 × 40 mm wall with a 15 mm step sticking out 30 mm up; in the chamfered version, the underside slopes down at 45° to the wall. Estimates from OrcaSlicer 2.4.2 with the Bambu Lab X1 Carbon 0.20mm Standard profile (0.4 mm nozzle), PLA Basic and the rest of the profile unchanged: between rows, only the part's orientation, the chamfer or the support type changed. "Support only" is the total minus the same part sliced without supports. These are slicer predictions, not measurements.
- Flipping the T part took filament from 42.2 g or 29.4 g down to 13.9 g, and time from 54 min or 1 h 39 min down to 27 min. With supports turned on, the slicer generated none in that orientation.
- The chamfer added 0.9 g to the part (14.7 g, against 13.8 g for the flat step sliced without supports), but in total it used 1.4 to 3.4 g less than the flat step with supports, took 3 to 10 fewer machine minutes and needed no cleanup.
- Orientation changes strength. A part is weakest between one layer and the next. If a hook will carry weight, lay it down so the layers run along the arm, even if that takes some support.
The settings that decide the result
The names below are the ones in Bambu Studio and OrcaSlicer, on the Support tab. Several only show up with advanced mode turned on.
| Setting | What it does | Default | When to change it |
|---|---|---|---|
| Threshold angle | A face at less than this angle to the bed gets support | 30° | Raise it only if an overhang sags; lower it if it adds too much support |
| On build plate only | Keeps supports from starting on top of the part | Off | When a support mark would ruin a visible face |
| Top Z distance | Gap between the top of the support and the part | Same as the layer height, up to 0.2 mm | More gap if it won't come off; 0 only with a different material at the interface |
| Bottom Z distance | Gap between the base of the support and the part, when the support starts on top of it | Same as the top | Raise it if the support base sticks to the part |
| Top interface layers | A solid "tabletop" at the top of the support | 2 | 3 for a smoother underside |
| Top interface spacing | Space between the tabletop lines | 0.5 mm | Smaller is smoother and holds on tighter |
| Support/object xy distance | Side gap between the support and the wall | 0.35 mm | Raise it if the support sticks to the side |
| Base pattern spacing | Distance between the lines in the body of normal supports | 2.5 mm | Larger saves plastic and is more fragile |
| Branch diameter | Starting thickness of the tree branches | 2 mm | Thicker is sturdier and harder to remove |
| Raft layers | Prints the part on a mat of support | 0 | Parts with little contact with the bed, or that warp |
Defaults from the Bambu Lab X1 Carbon profiles, identical in Bambu Studio and OrcaSlicer (checked in the profile files, November 2026). The Z gap follows the layer height: 0.08 mm on the 0.08 mm profile, 0.12 mm on the 0.12 mm one, and it stays at 0.2 mm from the 0.20 mm profile up. Supports come turned off; when you turn them on, the type is tree, and tree supports have a hollow body, without the 2.5 mm lines.
The trade-off is always the same: a bigger gap comes off more easily and leaves a rougher underside; a smaller gap leaves a smooth face and a support that holds on tighter. With the same spool for part and support, Bambu Lab does not recommend a Z distance of 0: the support fuses into the part. With a different material at the interface, such as support filament or PLA under PETG, 0 works, because the two don't stick to each other.
Three more options worth knowing:
- Support painting. With the support brush, you mark where support is required (enforcer) and where it is blocked (blocker). The "manual" types only generate support where you painted.
- Support critical regions only: keeps only the support under overhangs held at one end and under loose tips. Good for a part that almost holds itself up.
- Enable ironing support interface, in Bambu Studio: smooths the top of the tabletop before the part is printed on it. The process is the same as in the guide to ironing settings.
Step by step in Bambu Studio
The path is the same in OrcaSlicer.
- Lay the part on its best face. The Lay on face tool puts the face you click flat on the bed, and Auto orientation tries positions on its own. Check the result: it doesn't know which face will be visible.
- Turn on supports. On the Support tab, check Enable support and pick the Type: tree(auto) or normal(auto).
- Fix by hand what the automatic mode got wrong. With Support painting, paint where support is required and where it is blocked.
- Slice and look underneath. Click Slice plate and, in Preview, drag the layer slider down to the overhang: you can see whether the tabletop covers the whole face and whether support started where it shouldn't.
- Check the cost before printing. In the Line Type view, support and interface show in their own colors, with the time for each. Slice again without supports, or with the part rotated, and compare weight and time.
Normal, tree or only where you paint
Normal supports fill the whole volume under the overhang; tree supports grow branches only up to the contact points. According to Bambu Lab, normal supports usually leave a better face under large, flat overhangs, and tree supports use less material on small, curved ones. The Tree Hybrid style mixes the two: a grid under large flat areas, branches everywhere else.
The full comparison, with filament and time for each style on two parts, is in the guide to tree vs normal supports.
Supports for each material
- PLA: the easiest. The 0.2 mm default comes off well. On silk PLA and other brittle filaments, Bambu Lab recommends switching the tree's "hollow" pattern to another one, because hollow branches break.
- PETG: sticks hard to itself. Keep the gap at 0.2 mm or more. The best trick is to print only the interface in PLA: the two barely stick to each other.
- ABS and ASA: release well from supports, but warp. Start with a clean bed, a brim and an enclosed printer, as in the guide to warping; a raft, which Bambu Lab mentions for ABS, is one more option.
- TPU and other flexibles: the support bends along with the part and is hard to pull off. Whenever you can, orient the part so it doesn't need any.
Support filament is a material made to release from the part. With an AMS or a dual nozzle, it allows a Z distance of 0 and an underside almost as smooth as the top:
| Support filament | Works with | Note |
|---|---|---|
| Bambu Support for PLA | PLA, PLA-CF | Absorbs little moisture |
| Bambu Support for PLA/PETG | PLA and PETG | Works for both |
| PVA | PLA | Dissolves in water; picks up moisture easily |
| Bambu Support for PA/PET | Nylon, PET-CF | Picks up moisture easily |
Bambu Lab recommends using support filament only at the interface and regular filament for the body, to spend less time and less of the expensive material. Every filament swap still costs purge, as the guide to multicolor waste explains. And never mix temperatures: Support for PLA under ABS or PC, or Support for PA/PET under PLA or PETG, can clog the nozzle.
Without support filament, PLA and PETG work as supports for each other: a PLA part with a PETG interface, or the other way around. Bambu Lab published a PLA Basic and PETG HF mutual support guide (checked November 2026). How the two differ is in PLA vs PETG.
How to remove supports without marking the part
Tools that handle almost everything: flush cutters, needle-nose pliers, a thin scraper, a deburring tool (the swivel blade for trimming edges) and 220, 400 and 600 grit wet sandpaper.
- Start with the biggest piece. On normal supports, loosen them from the side and break them off in blocks. On tree supports, pull by the trunk while twisting; the branches usually come off with it.
- Trim what's left flush with the cutters, without twisting against the part.
- Run the deburring tool along the edges of the face that was supported.
- Wet sand, from the coarsest grit to the finest. The water holds the dust and keeps the PLA from heating up.
- White marks? On PLA, the whitened plastic where the support broke off gets its color back with a quick pass of a heat gun, held at a distance. Go easy on the heat: PLA softens at around 60 °C.
Wear safety glasses: pieces of PLA support break into shards that fly. Always cut away from the hand holding the part.
With moisture-sensitive materials such as nylon, PVA and Support for PA/PET, remove the supports within 2 hours, according to Bambu Lab: after that the material softens and leaves residue on the part. The rest of the finishing, from sanding to packaging, is in the guide to finishing and packaging.
Common problems and how to fix them
| Problem | Likely cause | What to do |
|---|---|---|
| Supports won't come off or tear a piece off the part | Z distance 0 with the same material, an interface that's too dense, or PETG | Go back to 0.2 mm and 0.5 mm interface spacing, or use another material at the interface |
| The underside comes out rough or with sagging lines | A large gap or 0 interface layers | Use 2 or 3 interface layers and smaller spacing |
| The support fell over or bent partway up | Tall, thin supports, or a first layer that didn't stick | Tree Strong or thicker branches; a clean bed, as in the guide to the first layer |
| Support started on top of the part and left a mark | Support resting on the part itself | Turn on On build plate only or paint a blocker |
| A spot was left without support | The small overhang was dropped or treated as a bridge | Paint an enforcer or lower Max bridge length |
| The support stuck to the side wall | XY distance too small | Raise the XY distance |
| Print time shot up | Organic tree with lots of thin branches | Try Tree Slim, Tree Hybrid or normal |
What about resin printers?
With resin, the logic changes. The part prints upside down, hanging from the build plate, and each layer is peeled off the bottom of the vat. That's why almost every part needs supports, and the resin slicer warns you about islands: bits that start in midair, like the tip of a finger or a chin.
- Tilt the part. Tilting it shrinks the area of each layer and the force that peels it off the vat.
- Remove supports after washing. Many people take supports off after washing and before the final cure, while the resin is still softer and marks less. A thin part or one with tight dimensions can warp without its supports; in that case, cure first.
- Wear nitrile gloves and work in a ventilated space. Uncured resin irritates skin. Don't pour liquid resin, or the water or alcohol from washing, down the sink: cure the leftovers in the sun before you throw them out.
What each resin part costs, with washing and curing, is in the guide to resin printing cost.
How much supports add to the price of a part
Supports go into the price in three parts: the plastic, the machine time and the labor of removing and sanding. On the example T part, with normal supports:
- Plastic: 28.3 g extra (42.2 g − 13.9 g). At $0.02 a gram, that's $0.57. The per-gram math is in the guide to cost per gram.
- Machine: 27 more minutes with the printer busy.
- Cleanup: 5 minutes removing and sanding, at $30 an hour, is $2.50.
Not counting the machine, that's $3.07 extra on a part that would cost about $0.28 in plastic upside down. For an order of 20 identical parts, that adds up to about $61 in plastic and cleanup alone.
In the calculator, the weight and time the slicer shows already include supports. Cleanup is on you: add those minutes to labor.
Frequently asked questions
Auto supports went where they weren't needed. What should I do?
In Bambu Studio and OrcaSlicer, lower the threshold angle (from 30° to 25°, for example), paint the areas where support is blocked or turn on Support critical regions only. If the problem is support on top of the part, turn on On build plate only. To find a model that doesn't need supports in the first place, look for "support-free" or "no supports" in the description.
What's the best Z distance for supports to come off easily?
With the same filament for part and support, 0.2 mm is Bambu Lab's default and comes off well with PLA. With PETG, start at 0.2 mm and go up in 0.05 mm steps if it still sticks. Use a distance of 0 only with support filament at the interface.
Is support filament worth buying?
It is if you have an AMS or a dual nozzle and often print parts whose underside shows, such as miniatures and snap-fit parts. For ordinary parts, the right settings and a well-oriented part are enough. If you do buy it, use it only at the interface.
Can I reuse the plastic from supports?
Not in any practical way at home: turning it back into filament takes a shredder and an extruder, and it's hard to keep the filament diameter consistent. The way to save is to generate less support, by rotating the part or using tree supports.