Support Structures: When You Need Supports and How to Remove Them
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An FDM printer cannot print into thin air. Every layer needs something underneath it to rest on. If part of the model projects far beyond the layer below, it needs a support structure, also called support. It is printed along with the model and removed after printing.
When do you need supports?
Overhangs up to about 45 degrees are managed by almost any printer without supports. Each layer then projects only a small distance beyond the previous one. The shallower the overhang, the more hangs in the air, and beyond a certain angle it no longer works without support.
Bridges are a special case: the printer can span straight stretches between two points of support, often several centimetres. This requires good cooling.
The best support is none: You can often rotate a model so that fewer supports, or none at all, are needed. Before you switch on support, it is worth looking at the orientation.
Normal supports or tree supports?
| Type | Appearance | Advantages | Disadvantages |
|---|---|---|---|
| Normal (grid) | Grid directly under the overhang | Stable, simple | More material, harder to remove |
| Tree (organic) | Branches like a tree | Less material, easier to remove, fewer marks | Takes longer to calculate, less suitable for large flat overhangs |
For figures and organic shapes, tree supports are usually the better choice. For large, flat overhangs on technical parts, normal supports often work more reliably.
The most important settings
- Overhang angle: the angle from which supports are generated. Typically 45 to 55 degrees.
- Z distance: the gap between support and part, usually 0.1 to 0.25 mm. Larger means easier to release, but an untidy underside.
- Only on the print bed: supports are built only from the bed and not on the model itself. This avoids marks on visible surfaces.
- Contact layer (interface): a denser layer directly under the overhang. It provides a smoother underside.
Placing supports deliberately
All the major slicers allow you to paint supports on by hand or block them. That way you get support only where it is really needed. This saves material and finishing work. More on slicers in the slicer comparison.
Removing supports cleanly
- Let it cool down. Warm supports deform and tear material out of the part.
- Work with tools: side cutters, needle-nose pliers and a deburring tool are ideal.
- Work away from the part, do not pry into it.
- Smooth the remnants: with sandpaper or a deburring tool.
Soluble supports
With a printer that can handle two materials, you can print supports from water-soluble PVA. After printing, the part goes into water and the supports dissolve. This is ideal for complex shapes where supports would otherwise be hardly reachable. The Multicolour printing overview shows suitable printers.
Continue with: Layer height and Infill.