As you navigate the additive manufacturing (AM) process, there’s a myriad of boxes to check off along the way. Each of which will move you closer towards creating and manufacturing your product. The items on your to-do list typically span the gamut, including everything from design and layout configuration to material selection and digital file conversion.
Within this process lies a level of design flexibility and freedom that can cause discrepancies regarding the feasibility of printing your 3D model. This is especially true for designs that are highly complex in nature. So, how do you ensure your 3D model design is ready for printing? Here’s what you need to know.
Properly Assessing Printability
While adhering to standards like Design for Printability (DFP) can bolster your rate of success when it comes to printing functional 3D products and parts, you’re still vulnerable to encountering faults and weaknesses within the process. Through printability checking, which includes testing and assessing the digital file of your 3D model, you’ll ensure that your part or product is, indeed, ready for printing.
Follow RapidMade’s Pre-Printing Checklist
To put your mind at ease, we’ve created a quick guide to ensure you’ve done your due diligence before printing.
1 | Ensure Your Design & Print Technology Are Compatible: Each material and print process comes with its own set of guidelines on what will or will not work compatibility-wise when it comes to printing your parts or products. You can get process specific print guidelines on our instant quote page for each print technology: https://www.rapidmade.com/instant-quote
2 | Inspect Thickness of Walls, Wire, Gaps and other Features: Every little nook and cranny of your model must meet thickness standards of your chosen print process in order for it to survive printing, post-production, and packaging. If walls are too thin they may break or not print at all. If gaps and holes are too small they may fuse together.
3 | Hollow Models Require the Creation of Escape Holes: If you’re working with a hollow model, excess material must be able to free itself from the product during the printing process. Within material guidelines, you’ll find details regarding the escape holes needed for successful printing. In general, however, if you’re in doubt, always err on the side of using more, larger escape holes. Material inside hollow models can be recycled if we can remove it so we do not have to charge for unused resin inside your model.
4 | Weight & Balance Checks: When viewing a digital file, it’s easy to overlook real-world implications. For example, your model will ultimately have to hold up to the law of physics. This means you’ll always want to double-check your model to make sure you’ve accounted for weight distribution. Similarly, your model must possess the ability to support its own weight. This is particularly important with scaled down models representing tougher materials like metal.
5 | Safeguard Areas That Are Vulnerable: For designs that include features like appendages or wires on figurines, it’s important to keep in mind that these outstretched elements can easily fracture and break free during, as well as after, the printing process. That’s why it’s essential to triple-check joint strength. For the best results, include added support around these areas to stave off unwanted breaking during production. Keep in mind, not only do most products need to survive post processing and handling but shipping too.
6 | Double-Check Dimensions: While you likely specified the size and scale of your model before beginning the upload process, it’s a best practice to reexamine these dimensions once more before greenlighting the order. This is particularly important because STL files have no units! You could export a model designed commonly in inches or millimeters, sometimes even centimeters or meters. If you print a model in millimeters when you meant to print it in inches, the final product would be 25.4 times smaller than intended.
7 | Adequate Clearance for Any Moving Elements: In order to function properly, your design needs to account for clearance between moving parts. Without doing so, you’ll run the risk of your parts fusing together during the printing process. Parts printed separately that mate together also need to have enough clearance so that when you assemble them they actually fit together.
8 | Understanding Print Tolerances: Each printing technology has varying degrees of accuracy and repeatability, also known as tolerance. Print tolerances are generally looser than machining or injection molding and must be understood to make sure your parts meet your requirements without additional post processing. Most 3D printers have a minimum tolerance (ex. +/-0.010”) and a scaling tolerance that increases the larger the feature gets (ex. +/-0.2%.) Always make sure to use the larger tolerance number when assessing the accuracy of your parts.
9 | Assess Design Details: Any engravings or embossings included in your design will have to meet certain requirements in order to print clearly. Confirm you’ve met these guidelines before printing.
By investing time in checking and analyzing your digital file, it’ll ensure your design has been optimized for printing and manufacturing.
10 | Broken files: STL files used for printing can export poorly, particularly with some softwares like Revit or Sketchup where creating real parts from a 3D design is an afterthought. Real engineering software like Solidworks or AutoCAD tend to produce clean files that need minimal fixing. Broken file errors include inverted triangles, unstitched borders between triangles, gaps and holes in your model and floating bodies. The goal for a print ready file is what is called a “Water Tight STL.”
11 | Low or High Polygon Resolution: Because your STL file is just a bunch of points and triangles (polygonal model) the export size of your triangles matters! This can be a tricky line to walk because if you export with too high of a resolution your model will be massive and difficult for software and machine to process - often including unnecessary data, like over-defining a flat surface or having smaller triangles than your printer resolution. Conversely you can make your triangles way too large resulting in facetting. A round surface intended to be smooth will have a bunch of angled edges on it - making a sphere look more like a cut gemstone. 99% of files should be in the sweet spot of 2 - 25 megabytes. Unless you are printing something as simple as a cube (small data) or as complex as the Statue of David (large data) it is expected your model should print well if it falls in that file size range.
An Added Layer of Protection
So, your model passed the first round of checks. Guess that means it’s time to get your print on. Not quite yet. While software and technology are largely effective in ensuring model integrity, they do face limitations from time to time. Because of this, RapidMade leverages human inspection, putting extra eyes on your design to ensure there are no supplemental issues that the computer may have overlooked. Should our engineers identify any obstacles, we will provide suggestions surrounding ways to tweak your model for success.
RapidMade engineers serve as an added resource – working alongside you to ensure parts and products satisfy commercial production standards, including high-volume, industrial-scale manufacturing. Our goal is to be a second set of eyes and ears throughout the process to ensure your needs are met with quality and efficiency.