Double wall 3D prints or not?

Know how double walls or overlapping perimeters in 3D printing can improve part strength, but may increase material use and design complexity.

Choosing the right print strategy for a 3D print is as important as choosing the right material. It will always be tailored to your application, one of the decisions you can make is to print with a double perimeter or double wall.

A double wall in Large Format 3D printing or large format additive manufacturing (LFAM) refers to a specific structural design or feature where a 3D printed object or component has two (parallel) walls, that overlap each other or that are separated by a defined gap or void space. This design element can serve various functional or structural purposes, depending on the specific requirements of the printed part.

Overlapping double Perimeter in large format 3D printing refers to a design approach where two or more layers or walls of material overlap or intersect, this can have benefits over using a single perimeter wall.

1. Improved Strength and Rigidity: Overlapping double walls can significantly improve the strength and rigidity of the 3D printed part. The intersections create additional material bonds, making the structure more robust and capable of withstanding higher loads and stresses. This is advantageous in applications where structural integrity is critical.
2. Vibration Dampening: The additional strength and stiffness of the added material, dampens the vibration in the part. This can help improve the dimensional accuracy of subtractive operations
3. Increased Details: Sometimes it is necessary to use a double perimeter to increase the accuracy of the part after printing. While 3D printing, there has to be a certain ratio between your layer height and layer thickness, you can’t make a layer indefinitely thin and still maintain the desired layer width. By 3D printing 2 smaller and thinner layers next to each other, you can still have your desired layer width but with a smaller layer height and thus a more detailed end part. A double bead can also help printing beyond overhang angles otherwise impossible by a single parameter.

1. Thermal Control: The inclusion of a second perimeter adds additional heat energy into the 3D print, which, if applied wrong, can cause internal stresses to build up between the 2 perimeters. 

Double Perimeter with gap in between

A double perimeter with a gap between the 2 perimeters can have multiple benefits over the use a single perimeter wall.

1. Insulation: One of the primary purposes of a double wall is to provide thermal insulation. By having two layers separated by an air gap, it helps to reduce heat transfer through the 3D printed object. This is useful in applications where temperature control or energy efficiency is essential, such as in building components or equipment housings.
2. Fluid Control: Double walls can be used to create channels or passages for the controlled flow of fluids or gases within a 3D printed component. This is valuable in applications like fluid conduits.
3. Soundproofing: In acoustic applications, double walls can help in soundproofing or noise reduction. The air gap between the walls can trap and absorb sound waves, or be filled with a sound-damping material. Making it suitable for soundproof barriers or enclosures

However, using double perimeters also have downsides. Overall it will increase material consumption and thus weight, the increase can exceed the pellet extruder’s maximum output and negatively influence the strength of the part. The added wall will also result in extra complexity when 3D printing and designing, if the design is not right the overlapping layer may not touch or overlap too much and result in print defects.

In conclusion, the use of overlapping double walls in large format 3D printing should be carefully considered based on the specific requirements of the application. While it can provide advantages such as enhanced strength and thermal properties, it also comes with drawbacks such as increased material usage and complexity. Designers and engineers should evaluate these trade-offs and determine whether the benefits outweigh the disadvantages for their particular use case