This section aims to answer some of the most common questions we receive from people looking to print their STL files. For people just starting out with 3D printing, don’t expect to simply buy a 3D printer and be able to print STL files without going through with the whole learning process. 3D printing is an entire hobby in and of itself and there can be quite the learning curve and time commitment to making consistently good quality parts. We offer STL files to the lighting community so that people with 3D printers can make parts at home for their own use and assume that the user of the STL files has good working knowledge of how to use 3D printers and troubleshoot 3D printing problems. If you need more comprehensive help with 3D printing or making successful prints then you should look at many of the online resources that are available.
Starting off with the basics, a frequent question we get asked is what material should I print the parts with? Almost universally the recommendation is going to be PETG because it is very well suited for use our hobby. PETG is great because it combines good flexibility, decent UV resistance, relatively easy printing without the need for specific ventilation and it is reasonably priced. Flexibility is very important for parts like clips, mounting brackets and anything where something like PVC or EMT is getting inserted into an opening. If the part can’t flex when the pipe or conduit is inserted, then it will be prone to failure. On parts such as prop mounts the need for flexibility isn’t as great, but still serves a purpose in making the parts less brittle. With regards to other filaments, a filament like ASA is great for UV, but lacks the flexibility of PETG and requires ventilation while printing. It is also much more expensive compared to PETG filament and as such isn’t widely used in this hobby. PLA filament and its derivatives are perhaps the most ubiquitous of all types of filament, however PLA lacks the flexibility of PETG and does not do well with UV exposure. Additionally PLA does not handle heat very well and can deform if exposed to it. You might not think that heat matters in the winter months, but aside from people who have displays in warmer climates, many people store their displays in attics, sheds or garages those can get very hot in the offseason.
The next consideration is the relationship of nozzle size and layer height and how that impacts strength of the part. A pretty simple concept to understand is that a larger nozzle can flow more filament than a smaller nozzle and with this higher volume of filament out of the nozzle comes the ability to print not only wider lines, but taller lines. This means that you can print parts more quickly using a larger nozzle, but this comes at the expense of detail and quality in the finish of the part. Strength is also impacted by layer height. Printing at a lower layer height relative to nozzle size creates a wider and flatter layer of plastic that has more surface area to bond with subsequent layers versus a taller layer which has a more circular extrusion shape and less contact area with subsequent layers. Click here to see a good article with more info on nozzle size and the relationship with layers and strength. The most common nozzle size used in consumer level printers is 0.4mm which provides a good balance of speed with the ability to have reasonably detailed parts. With this in mind we have optimized our prop mounts for printing at layer heights of 0.25mm which strikes a good balance of speed, quality and strength on a 0.4mm nozzle. Note that features such as EMT / PVC holes should print without any supports and have clean bridging without any areas printing in mid air when a 0.25mm layer height is used. If a specific STL requires other settings for layer height it will specifically say so on the product page.
Perhaps the biggest consideration has to do with the shell of the part and the infill which is by far the most common question that we receive. Generally speaking when more strength is needed on a part it’s more important to increase the number of shells compared to simply increasing infill. A high infill percentage will add little strength if the shell is very thin. The choice of infill pattern is also plays an important role as it impacts not only overall strength, but print time and overall machine wear and tear. Some infill patterns are very complex and add several hours of additional print time as well as lots of rapid movements in X & Y which over time leads to additional wear in things like belts and bearings. For most parts some of our favorite infills are cubic, grid, triangular and gyroid because they offer good strength relative to overall print time. There are certainly others out there that can be used for structural parts, but they typically will require longer print times. For printing clips which are inherently subject to lots of flexing, we recommend using either gyroid or cubic. As far as recommended shell and infill percentages go, we recommend minimum percentages that offer a good balance of strength and print time, but you can go up from there depending on whether additional strength is desired. For things like prop mounts and arch bases we recommend a minimum of 5 top / bottom layers with 5 walls and 30-35% infill. For props that have approximately 1500 pixels or more we recommend increasing the perimeter shells to 6 and the infill to the 40-45% range. On parts like mounting clips and power supply mounts we recommend a minimum of 4 top / bottom layers with 4 walls and 35% infill. On HD clips the infill percentages should at least 55%.
Collectively these recommendations should yield reasonably strong parts for the print time. Then it’s all about making sure your printer is dialed in, flowing well and making accurate parts. Most importantly take your time and don’t make any shortcuts and of course happy printing!
