3D Hubs connects 3D printers owners to people looking to 3D print their designs. Before 3D printer owners are allowed onto the platform they must first pass a “Marvin quality check”.
Marvin is 3D Hubs brand mascot (left figure, Marvin 3D printed in Nylon). It has been designed with 3D printing in mind and makes an excellent test for 3D printers. The model is symmetric, made of sharp angles, overhanging parts and half bridges making it a relevant test for the majority of 3D printers (FDM, SLS or SLA technologies).
In order to pass the Marvin printability test, you’ll need to know how to adapt your printer settings to a calibration model. This guide will help you avoid the common 3D printing pitfalls and show you how to tweak your CAD designs to obtain good print results (on your own printer or via a platform).
Basic tips to combine SOLIDWORKS with 3D printing
Let’s start with a quick recap on the main 3D printing technologies: Fused Deposition Modeling (commonly referred as FDM), Stereolithography (SLA) and Selective laser sintering (SLS).
As these use different workflow and have different constraints, knowing the basic is required to pick the right technique for your project:
FDM printers usually print out of plastic materials like ABS or PLA. The printer extrude and depose material starting from bottom to top of its build plate. It prints layer by layer and your model will require support materials for its overhanging parts (with an angle over 45 degrees). It’s a good method to print cheap prototypes and test mechanical parts (PLA preferred).
SLA printers use a liquid resin which becomes solid when in touch with UV light. The laser will solidify each layer of resin one by one. This method also require the generation of support structures. A photo-resin based system is great to print high detailed parts and models containing intricate parts.
SLS printers use a laser to sinter thin layers of powder one after the other to form your design. This method allow for prints in a broad variety of materials (metal, nylon) and is a great pick to produce high detail prints and even functional end product.
3D printers rely on a standard format to handle 3D models: stl. It is possible to export a model from SOLIDWORKS by using File > Export as > Stl.
However SOLIDWORKS 2015 makes it easier to handle files for 3D printing thanks to the new Print3Dfeature and Windows 8.1 support of 3D printer drivers.
If you have your own 3D printer, you can easily send a model to print from SOLIDWORKS. Select File > Print3D and fill in the options (type of printer, resolution). The SOLIDWORKS team wrote an extensive guide about it here.
Now if you don’t own a 3D printer or want to know more about the export workflow for 3D printing read our tips below:
Export as an stl, quick tip: Check the units you used in SOLIDWORKS (Tools > options > document properties tab > units) and export your stl with the same units File > save as > .stl (binary preferred) > options (bottom of the window) > Pick the right unit).
Note that you can import an stl in SOLIDWORKS easily, it can be useful for example to compare the size of the exported file to its original SLDPRT/SLDASM version). Remember to use the import options and import as a solid body if you want to be able to edit parts of your model.
Double check your imports units too and Use the Evaluate tab if you need to compare your stl’s dimensions to the ones of your original design.
Advanced tips to get your models ready for 3D printing
Now that we addressed the basic 3D printing workflow let’s get into specifics. SOLIDWORKS contains lots of useful features that will help you improve the quality of your 3D prints.
Resolution of your prints
This will greatly impact the resolution of your print with any type of 3D printing medium – especially with FDM machines. The smaller the layer height the better the resolution of your print. Layer height also has a strong effect on how smooth rounded surfaces are printed.
Here’s the resolution table 3D Hubs 3D printing services use:
Low Resolution : 250 – 400 microns
Medium Resolution : 100 – 250 microns
High Resolution : 50 – 100 microns
Ultra Resolution : 20 – 50 microns
If you plan on using an High or Ultra resolution for 3D printing your model, be sure to export it with a fine resolution (File > Export > Stl > Options OR within the Print3D panel under resolution). If you don’t you risk to end up with visible faces, like on the right figure below:
Checking the minimum wall size of your model is important. Too thin walls might make your model non-printable or break after completion.
An easy way to check the size of your walls is to use the Thickness Analysis utility tool in SOLIDWORKS, use the table below for reference:
Material related tips
Fitting and material tolerance
If you intended to use FDM 3D printing to produce mechanical or intricate designs, take into account the recommendations below:
FDM printers mostly print out of ABS and PLA plastics. When printed ABS cools down it shrinks of approximately 8% whereas PLA only shrinks about 2%. These values are indicative and can vary depending on the ABS/PLA being used.
This is especially important to consider if you want to print an assembly with moving parts or multiple pieces that need to fit together for example.
Resistance and saving on material costs
A good rule of thumbs is to always think about the printing technique you are going to use for your CAD model. FDM and SLA printers require the generation of supports to be able to print overhanging parts. Support structures can be removed after a print completion but it leaves mark and can induce a long post-processing cleaning. Obviously it will also impact the amount of material needed to complete the job.
For SLA prints Use the Align feature to get your model under the best alignment and then generate only the minimum required amount of supports. (This step will be handled by the SLA printer proprietary slicer software).
ABS produces stiff parts and it handles stress tests better than PLA. Prefer PLA if the model you want to print has a lot of sharp angles or needs to be more flexible than ABS. We gathered tips and test prints in our 3D printing materials guide, not only plastics but also more exotic materials like Nylon or full-color sandstone.
SLA and SLS related tweaks
When using a photo-resin based system (SLA), keep in mind that the liquid needs a way to escape from volumes that may trap the resin. Same applies for SLS printers (using powder). Take this into account by creating escape holes on your model or parts.
Printing large object and assemblies
Every printer has a different bounding box size, which can impact how your model will be printed. The bounding box refers to the maximum X,Y,Z coordinates a printer can print in one piece.
If your model is larger than the size of the bounding box you can break it down in multiple parts using the Split tool. Then add snap hooks or mounting bosses so you’ll be able to assemble it back. TheFasten your Design! tutorial will give you more details.
An easy way to know if your model will fit in the printers bounding box is to create one with SOLIDWORKS. This tutorial explains it all.
If the model you’d like to get 3D printed is an assembly there’s two ways to go:
- Split it up in multiple parts, to be printed separately or on the same print bed.
- Print the whole assembly in one time is manageable too but you should take into account tolerance between parts (see the Tolerance section above).