Support Settings: Tree or Normal Supports?
Contents
If the model has a section hanging in the air, the printer cannot print it into empty space. It needs a temporary structure underneath, to be removed afterwards, called a support. Overhangs flatter than 45 degrees from vertical and long bridges usually need support. The hard part is finding the balance: the support should hold the part firmly but leave no marks on the surface when removed.
When are supports needed?
An FDM printer prints each layer on top of the previous one. If a new layer sticks out too far past the one below it, it hangs in the air and sags.
- The 45° rule: Overhangs at 45° or less from the vertical axis can usually be printed without support. Flatter ones need support. With good cooling, PLA can go up to 50–60°.
- Bridges: Horizontal sections spanning the air between two supports. A well-tuned printer can print 20–50 mm bridges without support. See Bridging settings.
- Details that start in the air: Sections with nothing underneath (for example the outstretched arm of a figure) always need support.
Avoiding supports
Support should always be the last resort, because it uses material and time and leaves marks on the surface.
- Rotate the part: Placing the part at a different angle on the bed often reduces supports or removes them entirely.
- Split the part: Cutting a complex model in two, printing the halves separately and gluing them can give a cleaner result than a supported print.
- Use chamfers in your design: In your own models, use 45° chamfers instead of sharp horizontal overhangs.
- Make holes teardrop-shaped: Giving the top of a horizontal hole a pointed (teardrop) shape lets it print without support.
Support types
Normal (linear, grid) support
Vertical columns or a grid are printed under the overhang.
- Suited to wide, flat overhangs.
- Simple and predictable.
- Uses more material and touches the part over a larger area.
Tree support
Trunks start on the bed and branch as they climb, reaching only the points that need support.
- Ideal for figures, organic shapes and small overhanging details.
- Uses less material and is usually easier to remove.
- Touches the part at fewer points, so there are fewer marks.
- Slicing takes longer, and on wide flat overhangs it may not work as well as normal support.
Cura, PrusaSlicer, OrcaSlicer and Bambu Studio all offer tree supports.
Important support settings
| Setting | Suggested start | What it does |
|---|---|---|
| Overhang angle (threshold) | 45–55° | Sets the slope beyond which support is printed |
| Top Z distance | 0.2 mm (on 0.2 mm layers) | The gap between support and part; decides how easily it comes off |
| XY distance | 0.6–0.8 mm | How far the support stays from the part's side walls |
| Support density | 10–20% | How full the support is inside |
| Support interface | On, 2–3 layers | Makes the surface touching the part smoother |
| Supports on build plate only | Optional | Stops supports from starting on top of the part |
Z distance is the most critical setting
The vertical gap between support and part decides how easily the support comes off and how smooth the underside of the part will be.
- Too small (0–0.1 mm): The support fuses to the part and is very hard to remove.
- Right (usually one layer height): The support holds firmly and separates by hand.
- Too large (0.3 mm and up): The support comes off easily, but the underside of the part sags.
PETG tends to stick to the part more, so with this material you need to increase the Z distance a little.
Support interface
The support interface prints the top few layers of the support, the ones that touch the part, more densely. The underside of the part comes out smoother. If you set the interface density too high, removal gets harder.
Removing supports
- Remove them after the part has cooled completely.
- Break large supports off in stages with pliers or flush cutters.
- Clean up the remaining thin pieces with a hobby knife and needle files.
- Smooth the surface with sandpaper.
- Wear eye protection; hard plastic pieces can fly off as you remove them.
Soluble support
On printers with dual extruders or a multi-material system, support can be printed in materials such as PVA (dissolves in water) or HIPS (dissolves in limonene). This gives excellent results on complex internal geometry but needs extra material and hardware.
The support has fused to the part. What should I do?
Increase the Z distance and lower the support interface density. If the temperature is too high, the bond between support and part gets stronger, so lowering the temperature a little also helps.
The support tips over while printing. Why?
Thin, tall supports can break away from the bed. Add a brim to the support base, increase the density a little or make the tree support trunk thicker.