Support interface: the dense layer between support and part

What the interface does

The body of a support is deliberately sparse, so it prints quickly and can be removed. Directly under an overhang, though, you need a more continuous base, otherwise the layers of plastic would sag between thin lines. So a denser interface is printed there, separated from the model by a small gap so that it can be snapped off. The number of layers and the pattern are described in the OrcaSlicer wiki.

The rule of thumb is simple. More interface layers mean a flatter and cleaner overhang, but also more plastic, a longer print and supports that hold more firmly.

What affects the result

• Number of layers. One dense layer is quick, three give a smoother surface.
• The gap between the interface and the part. A small one holds better and the surface is more accurate, a large one snaps off easily but the overhang is rougher.
• Pattern. Continuous lines or concentric circles come off in one piece, while a grid holds more firmly.
• Material. PETG bonds to the interface more than PLA, so it snaps off harder.

How to think about it in the design

The underside of an overhang will always be a little different from the other surfaces, even with an interface. If a surface has to be nice or accurate, turn the model so it is away from the supports, or design it as an overhang with a gentle slope. You can read more about removal in the support removal entry.

What happens with the overhang. Even with a good interface the underside of an overhang will be slightly wavy, because it is printed over a gap, not on a solid base. The interface only improves the smoothness of the surface, it does not make it perfect. You get the cleanest result by avoiding overhangs: a slope up to about 45 degrees can be printed without supports, see bridge for horizontal spans.

The interface in your order

We generate supports, including their interface, automatically, and they are included in the price. We choose these settings ourselves according to the model and material. In the calculator you choose the material, infill strength, scale and number of pieces, and the rest is in the price.