3D printing is rapidly becoming a more mainstream manufacturing method. If you are involved in product design, you may be designing parts that will be prototyped with a 3D printer or even go into full production as a printed version. Over the last 10 years as an R&D Engineer for various industries, I have had to model many parts using SOLIDWORKS with 3D printing in mind. In this blog article I hope to leave readers with some useful tips about print orientation, global variables, and design for printing without supports I’ve gathered along the way. These principles apply specifically to FDM printing but may be useful in other methods as well.
Print Orientation
When discussing print orientation there are many factors to take into consideration. Ideally parts need a large enough print bed contact area so that the part doesn’t wobble during printing. If there is not enough bed contact area, the print can become detached. If the bed contact area is too large with too sharp of corners it can warp and pull away from the build plate during printing.
The best orientation typically has the least number of overhangs. Large overhangs generally require support material to be printed as well, and that extra material printing can drastically increase print times and post processing time. One should consider printing objects from different orientations if prior attempts have had unexpected results, or they are trying to minimize print times.
The print orientation will have an impact on the strength of the part. Imagine the layers that will be created, they are weaker when dealing with horizontal rather than vertical shear forces (See Figure 1). The spring would be stronger printed in the flatter orientation shown. Note that the Print3D feature of SOLIDWORKS is being used here to visualize the printer area and print lines.
In SOLIDWORKS the standard “top plane” is not the same as if you were looking at your printer bed. If you would like your model to match the way your slicer will import the file, the settings can be changed to make SOLIDWORKS have a Z up coordinate system from the orientation toolbar (See Figure 2).
Global Variables
When modeling a printed part, it may be desirable to draw something with an exact thickness. Maybe something will be strong enough with three print walls. Other features might be intended to be broken off later that would be better only being one wall thick. This also applies to print layers. Sometimes it may be desirable for something to only be five layers thick etc. When I design printed parts in SOLIDWORKS typically I set up at least two global variables (nozzle diameter = N and layer height = L) as shown in the screenshot below. From that point when something needs to be x walls thick, I can simply input = ”N” * X for the dimension. The same goes for layer thicknesses. The advantage to this is if the part then needs printed on a different machine with a different nozzle size etc., it becomes quite simple to change the design intent across the entire part. All of the equations used in the model will show up in the same area to edit the global variables as well. Keep in mind that every dimension used does not have to be a precise value based on nozzle diameter or layer height. If there is part of a model that doesn’t show up when the file is sliced, it is likely that area is thinner than the nozzle being used. See Figure 3.
Design for Printing without Supports
Sometimes support material is unavoidable. Some parts need to be printed in a position where there is some overhang. Once the desired print orientation is nailed down, the model can be edited to minimize the number of supports required with a few different methods.
Making a more gradual lead into the overhang (typically with a chamfer) is a really good way to minimize the amount of support required. In some cases, the overhang can be minimized enough that the printer can bridge the overhanging span if it has proper cooling.
After the lead ins to the overhangs have been modified, if there are still areas that require support that are far away from the build plate, supports can be drawn into the model that start higher up. Draw the supports in a way that makes the lead in more gradual. If global variables have been set up for the nozzle diameter this is a good chance to use those to make the supports only one nozzle width so that they can be removed more easily.
