How to Design 4 Common Metal 3D Printing Features

Click to watch an on-demand webinar on how to design for direct metal laser sintering (DMLS).

Direct metal laser sintering (DMLS) is not intended to replace traditional metal manufacturing like casting, metal injection molding, or machining. Rather, it’s a product development tool that opens up new design possibilities. Product designers and engineers commonly rely on metal 3D printing to manufacture complex geometries, reduce the number of components in an assembly, or even lightweight objects.

Here’s a look at how to design 4 common features found in metal 3D-printed parts.

1. Self-Supporting Angles
A self-supporting angle describes the feature’s angle relative to the build plate. The lower the angle, the less the likely it is to support itself.

Support angles built with direct metal laser sintering

Designing support angles no less than 45 degrees will ensure a quality surface finish and detail.

Each material will perform slightly different, but the general rule of thumb is to avoid designing a self-supporting feature that is less than 45 degrees. This tip will serve you well across all available materials. As you can see in the picture above, as the angle decreases, the part’s surface finish becomes rougher and eventually the part will fail if the angle is reduced too far.

Metal 3D printing overhangs

Overhangs are sudden changes in a part’s geometry.

2. Overhangs
Overhangs differ from self-supporting angles in that they are abrupt changes in a part’s geometry—not a smooth slope. DMLS is fairly limited in its support of overhangs when compared to other 3D printing technologies like stereolithography and selective laser sintering. Any overhang greater than 0.020 in. (0.5mm) should have additional support to prevent damage to the part. When designing overhangs it is wise to not push the limits as large overhands can lead to reduction in a parts detail and worse, lead to the whole build crashing.

3. Channels and Holes
Internal channels and holes are one of the primary benefits of DMLS since they are impossible with other manufacturing methods. Conformal channels provide even cooling throughout a part and aid in reducing a component’s weight.

Designing internal channels in metal 3D-printed parts.

Internal channels can help reduce a part’s weight or be used for cooling.

It’s recommended that channels do not exceed a diameter of 0.30 in. (8mm). Similar to unsupported structures, as you exceed 0.30 in., the downward facing structures will become distorted. A tip to work around this constraint is to avoid designing circular channels. Instead, design channels with a tear drop or diamond shape. Channels that follow these shapes will make for a more uniform surface finish within the channel and allow you to maximize the channel’s diameter.

4. Bridges
A bridge is any flat down-facing surface that is supported by 2 or more features. The minimum allowable unsupported distance we recommend is 0.080 in. In relation to other 3D printing technologies, this distance is relatively short due to the stresses of the rapid heating and cooling. In the picture below, you will see how the bridge pulls in the supporting structures as the unsupported distance increases. Parts that exceed this recommended limit will have poor quality on the downward facing surfaces and not be structurally sound.

Bridges that are too long will have rough downward facing surfaces.

Learn More About Metal 3D Printing Design
If you would like to learn more about how to design for DMLS and metal 3D printing in general, check out our webinar “Designing for DMLS.” You’ll find more details and tips on how to optimize your part design for metal 3D printing, select the right material, and reduce multi-part assemblies. Click here to view the on-demand webinar.

The Short List is a regular compilation of quick tips, trends and timely topics of interest.

Webinar: Designing for Selective Laser Sintering

This is the final part in our series of “Designing for 3D Printing” webinars. Just as we’ve looked at stereolithography and direct metal laser sintering in previous webinar, this presentation will provide insights into how to design for selective laser sintering (SLS), a discussion on material options, and recommended applications for SLS.

Post build

The presentation will include the following:

  • Comparison of SLS materials
  • Design guidelines for functional prototypes and production parts
  • Moldability considerations for effective development
  • Open Q&A session

TITLE: Designing for 3D Printing: Selective Laser Sintering
PRESENTER: Eric Van Roekel, SLS production manager
DATE: Thursday, October 27 at 1 p.m. CDT
REGISTER: Click here to sign up  

Can’t make it that day? You can still register and we’ll send you an on-demand version to watch when convenient. Also, feel free to forward this invite to your colleagues.

3D Printing Boosts Rocket Project for Engineering Students

University of Minnesota engineering students are readying a 3D-printed rocket engine for launch sometime later this year, with help from Proto Labs.

This cutaway view of the engine shows the cooling channel, which is one long tube that spirals down inside the wall.

David Deng, a senior aerospace engineering student at the U of M’s Twin Cities campus, is leading the extracurricular effort to design, build, and eventually fly a liquid-propellant rocket as project manager of LPRD Rocketry. The group’s name, pronounced “leopard,” is an acronym for Liquid Propellant Rocketry Design. The group includes aerospace engineering students and others studying electrical engineering, computer science, mechanical engineering, and materials science.

The primary design challenges the group faced included the small overall size of the engine itself, and the need to also somehow incorporate a cooling system inside the engine.

David Deng (right), and the University of Minnesota student group LPRD Rocketry (left).

“The manufacturing of [the rocket engine] is incredibly difficult using conventional methods, especially for a very small engine,” Deng said. “The struggle was how do we [add] a single cooling channel through this entire engine, coiling around the side of it? That’s where Proto Labs came in. 3D printing is essentially the only way to get regenerative cooling on an engine this small and have it be a single channel.”


VIDEO: Lockheed Martin Drone Takes Flight with help from Proto Labs

The drone market in the U.S. is expected to soar to an $82-billion industry in the next decade, the New York Times recently reported. With that robust market in mind, Lockheed Martin, the aerospace, defense, and technology giant, developed a small, fold-up, lightweight drone, the Indago Quadcopter UAV (unmanned aerial vehicle), turning to Proto Labs for quick-turn prototyping and low-volume production.

Proto Labs’ automated design for manufacturability (DFM) and quoting system was especially helpful in taking the Indago from 3D-printed prototypes to injection-molded parts, and getting finished parts delivered in days and weeks. The video tells the story:


3D Printing Experts Discuss Technology’s Future

3D printing is the topic of conversation in our latest Journal issue, which focuses on the technology’s next dimension—how additive manufacturing is poised to make a giant leap forward in capabilities.3D printing

The cover story includes interviews with three leaders from the 3D printing industry who offer insight on a variety of topics, such as advancements in new machines and materials, a growing demand for 3D printing for production parts, and notable trends in software.

Another feature, “A Cloud-Based Future for CAD,” explores how 3D CAD design software is increasingly moving to cloud-based models, a trend with benefits for both product developers and manufacturers.

Elsewhere in the Journal, our Eye on Innovation column features a driverless bus, a 3D GoPro, and a DIY Bluetooth.

Read the entire Journal here.

We’re always on the hunt for though-provoking content, so send your cool project or article idea to our editor at

Thanks and enjoy the issue!