【3D Printing Application】Hollow and Thin-Shelled Models: Save Half the Material and Time!
Under normal circumstances, stereolithography (SLA) 3D printers can print 3D objects with extremely high density (solid). However, when you don't need to print functional parts with such high strength, consider using a hollow design. Not only does it save a significant amount of material, but it also drastically reduces printing time!
We recommend attempting to print the following designs using a hollow approach:
•Art and Sculptures
•Scale Models
•Early Concept Models
•Large Modules and Multi-part Assemblies
Using the hollowing tool in PreForm and Meshmixer (free), you can print following these three simple steps:
Step 1: Find the Right Orientation
During the SLA printing process, your model is printed layer by layer, and the object is pulled out of the liquid resin as the heated platform moves upwards along the Z-axis. Because SLA's forming technology involves liquid resin in a resin tank being solidified by laser light, when you print hollow objects, some resin may remain inside the printer. We recommend finding the correct print orientation and adding holes to prevent resin residue.
Open your object model in PreForm and orient it for optimal printing. The side closest to the heated platform should be the side that won't be visible on the object or where holes can be placed without affecting the overall functionality of the part. Also, try to avoid multiple overhangs, as they can cause resin to remain inside.
Orient your 3D print model optimally in PreForm; it will print best, keeping the expected hole locations in mind.
Step 2: Hollow Out Your Model
First, open your 3D object in Meshmixer. To easily find the hole locations (Edit > Transform), you can set them to be the same as in PreForm. Go to the hollowing tool (Edit > Hollow) and adjust the settings according to your layer thickness.
Meshmixer will create a shell within your model based on the offset you specify. The next step is to generate holes. Place one hole as close to the heated platform as possible, and at least one on your preferred surface. This will help resin and air escape during printing, and isopropyl alcohol (IPA) drain out during cleaning. However, sometimes adding holes can disrupt flat surfaces. To prevent this, use the Make Solid (Edit > Make Solid) function to create an easily workable mesh. Note that this might reduce the quality of your mesh unless you use the slider to maintain quality.
How to achieve the best printing results:
•Wall thickness directly affects the strength of your print. Since hollow prints have no internal structure or support, large models with thin outer walls will be more fragile.
•The thinner the walls, the less material your print requires, making it lighter. If you need a solid or stronger part, you can also choose to print the model with inexpensive epoxy resin or plaster.
Set your preferences in Meshmixer and add holes to the model (marked in red in the image above).
Once done, confirm the settings and export the object file from Meshmixer in .STL format.
Step 3: Print Your Model
Now you can start printing. Import the modified 3D model into PreForm and, as in the previous steps, position the holes as close to the heated platform as possible. From now on, printing and post-processing are the same as with a standard SLA printer.
Actual time and material savings depend on your machine model and settings. In our example, for a 112mm x 85mm x 114mm model with a 2mm offset and 0.1mm layer thickness, the results are as follows:
Overall Comparison
|
| Solid | Hollow |
|---|---|---|
| Material | 246.28 ml | 77.37 ml |
| Print Time | 15 hours 35 minutes | 7 hours 47 minutes |
Completed hollow model, using Formlabs resin (Formlabs Standard White Resin)
Visit our materials page for more information on Formlabs resins, and if you'd like to test the effects of an SLA 3D printer, you can contact us at 3D Mart!
(Article translated from: https://formlabs.com/blog/how-to-hollow-out-3d-models/ )