If possible, try to hollow out your part. In doing so you can avoid extra charges and shrinkage issues in the thicker sections. You can read about the appropriate wall strength recommendations in the section on wall thickness above.
When you hollow out your part, our production team will need to integrate one or more drainage or escape holes. Usually, these are placed at the lowest point(s) of your part once it has been oriented and positioned on the build platform.
These holes ensure that the pressure of the liquid resin inside and outside your part remains at the same level. This prevents the deformation of your design. Uneven pressure can be compared to a glass of water filled to the brim: the liquid bulges at the edges and as a result, the laser scans too much material, causing your part to deform.
Secondly, the holes will be used to remove the excess resin inside the part once the printing process has been finished and your part has been removed from the 3D printer. Your part can then be emptied, cleaned and cured in a UV oven to achieve optimal strength. If the drainage holes weren’t present, the liquid resin would stay trapped.
As the position of the drainage holes depends on the orientation, our specialized production team need to decide where to place the holes. Wherever possible they will place the holes on the surface which is the least visible or that is easier to fill afterward.
You can, of course, include holes in your design yourself if you want them to be in a specific location. However, it’s possible that our team may need to add extra holes depending on the print orientation.
Some hollow parts require support material on the inside to reinforce the structure. This support structure might not be removed if we cannot access it. For more information take a look at the Internal Support section further down below.