Best Practices. 3D Printing for. Contributors: Olimpio DeMarco and Dan Topjian, Z Corporation, Burlington, MA

Transcription

1 Best Practices 3D Printing for Contributors: Olimpio DeMarco and Dan Topjian, Z Corporation, Burlington, MA Andrew Esquivel, Peak Solutions LLC, Portland, OR Jason Rossitto, Payette, Boston, MA September 2008

2 Introduction Google s SketchUp or SketchUp Pro software can certainly be used to create great models for printing on Z Corporation s 3D printers. However, the user must take into consideration that SketchUp does not automatically create solid model geometry for printer output. As SketchUp creates models in polyframes, and not polymeshes, all open shells must be closed off so that each shell is without holes (and that each shell is capable of holding water ). If this principle is maintained as the SketchUp model file is created for 3D printer output, the user will less likely encounter potentially problematic geometry; geometry which would then require extensive post file fixing efforts. SketchUp provides an easy and unique way of modeling (adding) new geometry onto existing geometry for example, quickly adding one smaller box on top of another larger box. Since SketchUp does not automatically close off existing shells, this type of modeling can cause problematic geometry. Z Corporation recommends that the user create each object/shell individually to ensure that each shell is completely closed off and that a joining surface is not accidentally shared between two adjoined shells, thereby causing one shell to be potentially open (and not a complete solid). Then, each closed shell can be placed into position to create the desired model. Preparing the Model in SketchUp for 3D Printing Before exporting the model for 3D printing via STL, VRML or 3DS format, a number of things should be considered in SketchUp to ensure a high quality 3D print. These considerations have to do with geometry construction and feature sizes. Modifications can be made post export in Z Edit Pro or another STL editor, but SketchUp users will find it more efficient to prepare a 3D printable version of their design in SketchUp. These tips are not organized in any particular priority, and the order of changes should not affect the file export.

3 Consider the following building designed in SketchUp: The model above has been modified to enable a successful 3D print. Let s take a look at some changes that were made to the model. First, make sure that the model does not contain any open geometry planes. Also ensure that when you create geometry, that all planar surfaces are extruded to an appropriate printing size such as 3 4 mm.

4 Close up all open planes to make the model water tight. You can draw rectangular Face entities to close up these open faces and make it water tight.

5 In the model below, the highlighted flat component is too thin to print. So, extrude these panels to at least 3 mm to make them 3D printable

6 Using components, with a single click in SketchUp, these slabs are extruded to provide more support for 3D printing.

7 If you have transparent surfaces such as windows, in the Materials dialog box, set opacity to 100% to enable 3D printing.

8 Avoid planar surfaces or intersecting planes such as the ones shown below. Delete planes if possible or extrude to 3 4 mm thick if you want to print. The wall highlighted with the red circle is an infinitely thin plane which will not print.

9 Thicken all thin walls to at least 3 4 mm for 3D printing.

10 Finally, delete windows as below and any other features such as entourage, internal systems, handrails, etc. that are too small or not important for the 3D print. You may also choose to thicken any particular feature that you want to highlight in your design.

11 Let s take a look at another design to illustrate additional best practices for 3D printing. The home below has a reversed face that is not visible in the current view.

12 The default color in SketchUp for reversed faces is a shade of purple. It is recommended that the user change the default to a more visible color such as yellow. This can be done in the Styles dialog box.

13 Now, once the building is rotated, the reversed face is easily identified.

14 Of course, once the reversed face is visible, a simple mouse right click will give you the option to reverse the faces to be consistent with all the other surfaces.

15 Another common issue with a surface modeling product like SketchUp is the inside surface. For successful 3D printing, you need to avoid the use of inside surfaces within a volume to be printed.

16 In the scenario above, the surface sitting on top of the terrain and under the staircase foundation would cause a gap in the 3D print. The solution is to eliminate this surface and trim the foundation geometry to the terrain.

17 A best practice that should be applied when printing from any CAD, BIM, or visualization software is to consider the amount of material to be printed. To lighten your 3D print and reduce material costs, hollow out areas such as the underside of your model as shown below. If you prefer, this hollowing operation can be done after exporting the SketchUp model in the Z Edit Pro software supplied with your Z Printer. Additional tutorials for 3D printing from SketchUp can be found on this link from the Google SketchUp web site Also, the ZCentral web site has an application note on this topic. For additional questions, please contact the Z Corporation Applications Engineering Team at applications@zcorp.com.