Support Materials

When an STL model of a cube or a cylinder is oriented and positioned the right way on the build surface, its process setup is relatively simple, and the part can be printed self-supported, without the use of supports. However, printed part geometries are usually very complex and can include complicated features such as overhangs and bridges. Most of the time, these features are impossible to print without the aid of additional support structures built in parallel.

While support structures can be printed in the model material, with the second toolhead on the AON-M2 you have the option to print with a second material, allowing the use of support materials. Support materials are specially tailored for compatibility with the model material. They are designed to be both an effective anchor and support while printing and yet also easily removed once the print is complete. They allow for the production of much more complex geometries and improve the surface finish of the printed part. Support materials can significantly reduce the time and effort necessary for post-processing, and often come at a lower cost than model materials.

This article covers different types of support materials and when and how to use them, along with tips for support placement, removal, and printing efficiency. Specific information about support-model material pairings can be found in the material information pages in this section.

Breakaway Support

As its name states, breakaway support is meant to be broken off the printed part. Breakaway support materials are designed to stick to the model material while hot, but detach easily when cooled down. If no compatible support material has been developed for a specific model material, support structures can be printed from the model material. These are still considered breakaway support although they can be quite difficult to remove.

Post-processing consists of manual removal of the material and may require the use of pliers, a sharp blade, or a file. Cut-resistant gloves are recommended for this process as the broken edges of support can be quite sharp.

A putty knife is useful to remove breakaway supports from a large, flat area. Maneuver the knife between model and support at the edge and begin gently prying the two apart. Pushing the knife into the space between model and support as you create it will help apply force to the interface and eventually the support structure should pop off entirely.

Support structures that are printed between model surfaces, rather than up from the build platform, can be more difficult to remove. Use a slotted screwdriver or another similar tool to remove the weaker middle section of the support first. This makes it much easier to pull the dense support layers off the model.

A well-tailored breakaway support material can produce quite a smooth surface finish on the model, however, when using the model material for support, supported surfaces may need to be sanded or otherwise smoothed to improve surface finish.

Be cautious of model geometry when using breakaway support. It may be quite difficult to remove support from some geometries, such as horizontal through-holes and small features.

Soluble Support

Soluble support is made from a different material than the printed part. This material, when immersed in water or another solvent, dissolves after a certain time. Soluble supports can have a stronger interface bond with the model material since they do not need to be broken off to be removed.

This type of support is convenient for out of reach features such as internal conduits and tight spaces. It also eases the support removal process and reduces post-processing manipulations. It is also preferable as it generally gives a nicer surface finish and is easier to remove from small features.

Soluble supports are less common and tend to be more expensive than breakaway materials. If not soluble in water, they require strong chemical solvents, which must be chosen carefully to avoid damaging the model.

When to use

Printed part geometries can contain a wide variety of features. Extreme angles, complex surfaces, and even some simple structures can be impossible to print without the aid of supports. Knowing when to use support structures is key to successful and efficient production.

Overhangs

An overhang feature is any section of a print that extends outward beyond the previous layer, requiring extrusion onto open-air past the edge of the layer below. Whether an overhang will require support depends on the material, and can change with nozzle size and layer height. As a general rule of thumb, an overhang less than 45˚ from the vertical will be able to be printed without support while keeping a good surface finish. Angles over 45˚ require the use of support material to maintain the integrity of the part.

Bridging

Bridging occurs when a printed segment horizontally links two raised points. The length of the bridge is the distance it must print in the air from one point to the other. Some materials can allow for longer distances but as a general rule of thumb, bridge segments over 5 mm require support.

Horizontal Holes

Holes that are on the XZ or YZ planes when printed - holes that run horizontally through the part - may require support to maintain their geometry. Small diameter holes, up to 10 mm, can be printed without support. For larger holes, supports are only necessary for the middle section, about one third, of the hole to support the most extreme overhangs and bridge across the top.

Floating/Moving Parts

Additive manufacturing allows building functional moving assemblies in one print session. Floating/moving parts in these assemblies need to be supported during the printing process but will be free to move afterward. When available, soluble supports facilitate post-processing since breakaway support may be too complex to remove due to the geometry of the object.

Rafts

Support materials can also be used to create an interface between the build platform and the model by printing a raft from the support material. A support material raft may be useful for several reasons:

  • Help with surface adhesion
  • Facilitate bed removal process
  • Compensate for bed surface defaults
  • Reducing warping

Printing Tips

Learn how to customize your support settings in Simplify3D by referring to the support tab of our Simplify3D section.

Bridging settings

Simplify3D flags sections of a layer where material is extruded over open space rather than over the part. If the section has an area above the specified threshold, it will apply Bridging settings to this section. Bridging settings are not just applied to bridges, but also to overhangs, horizontal holes, and any other feature that requires support. They are applied whether or not support structures have been generated to print below the flagged section. This allows custom settings to be applied to the first layer of model material printed onto the support.

The first layer of model material onto support material should be printed similarly to the first layer of the part onto the build platform: slowly. Setting the speed multiplier well below 100% will help the model material to adhere well to the support structure. Supported features with small details or sharp angles in the XY plane often require an even lower speed multiplier. Some materials may also benefit from a small increase in the extrusion multiplier.

You can learn more about Bridging settings in the Other tab section of our Simplify3D guide.

Calibration is key

When using two different materials, both toolheads need to be calibrated. Setting the right offsets for each toolhead will ensure that the material is extruded at the right coordinates and therefore that the part is printing adequately.

Learn how to calibrate the Z offsets in the Bed Leveling section. Learn how to calibrate the X and Y offsets in the X-Y Tool Calibration section.

Orientation

Changing the printing orientation of your part can reduce the quantity of support required as well as reducing printing time. Orient the part such that overhangs are under 45˚, bridges face upward, and holes run parallel to the Z-axis or angled less than 45˚. Prioritize reducing angled and curved overhangs; perfectly horizontal supported surfaces such as bridges are much easier to support and come out with the best surface finish.

Printing orientation also affects the mechanical strength of the finished part. Printed parts are strongest in X and Y. You may need to select on orientation that requires more support structures to achieve the desired strength for your model features.

Reduce Printing Time

When using two different materials, both toolheads will print at each layer. Tool changes involve a necessary purge and prime process which increases printing time and material use. It is possible to reduce the number of tool changes by configuring those two settings:

Combine support every 2-3 layers

By printing a thick support layer every 2 or 3 model layers, you limit the number of tool changes by a significant factor. This technique is best suited for printing the bulk of support structures that must be built quite tall before reaching the part. It should not be used for layers with dense support directly under the part as increasing the support layer height decreases the support structure resolution in Z.

Dense support

For models with many layers where the support structures do not have dense support layers, printing the main supports with the model material can greatly reduce tool changes. Select the model material toolhead as the Support Extruder and use the support material toolhead only as the Dense Support Extruder. Tool changes will only be required for layers with dense support - those directly above or below the model surface. We recommend having at least 4 layers or the layer equivalent of 1 mm of dense support to make sure the material is deposited properly and provides a nice flat surface.

Compatibility

Support materials are specially selected to be compatible with the model material.

Support materials must adhere to the model material throughout the printing process, and once it is complete, they must be easily removed without leaving marks or residue. They should also adhere to the same build platform as the model material. However, this can be substituted by the use of a raft. The support material must be processable within the same environmental (bed and chamber) temperature range as the model material. If the environmental temperature of the printing process is higher than one of the materials’ glass transition temperatures (Tg), then that material may become too soft to feed and extrude properly.

The materials must also have similar extrusion temperatures. If the extrusion temperature of the support or model material is much higher than the other, the material might begin to degrade. If the material begins to degrade, then there may be an impact on strength, shock, or aesthetic properties.

Check the page in this section for your model material to find a compatible support material.

Tool Change Script

Using two different materials requires both toolheads. For each layer, the main material will print first then if required, the support material will print.

When using the FFF profiles provided by AON3D, you will find a custom script of G-code commands in the Simplify3D Scripts tab under Tool Change Script. This script dictates the behavior of the machine when there is a toolhead change. We recommend not to modify it in any way.

Here is what happens when there is a tool change:

  • The unused toolhead goes back to its initial X position
  • The new active toolhead will purge a small quantity of material
  • The toolhead will move back and forth twice to wipe the excess of material onto the brush
  • The toolhead will resume the printing process

Last modified: December 13, 2019