Mechanical Engineering 3-D Printing Machine

 


Introduction:

The Department of Mechanical Engineering at the University of Minnesota owns a Stratasys Dimension SST 1200es 3-D printing machine. It is located in the Mechanical Engineering Building , Room 176, the Student Shop.

The 3-D printer allows users to take any object drawn in a  3D software package such as PRO-E or Solidworks and converts it into a solid plastic model.  This  allows students to prototype their designs and  test fit parts  as part  of the design process,  helping to ensure a functional final product.  The 3-D printer maintained by the ME department builds models out of ABS plastic  by extruding a bead of 0.010 thick material in progressive layers. The model is supported by layers of  soluble support resin that  can be removed  manually, or by soaking in a sodium hydroxide solution.  The end result is a permanent ABS model of your part.

User Notes:

The printer builds on a 10x10 inch platform and can build up to 12 inches high, so all models must fit within those dimensions. While the modeler extrudes a bead of plastic 0.010 inches thick this does not necessarily mean that you can build a feature 0.010 inches thick.  A good rule of thumb is no feature should be thinner than 0.05 inches, although that will vary from part to part. The precision of the model dimensions also varies from part to part. Dimension doesn't publish any values for model precision, so if your application requires close tolerances, you will probably have to test several models.

Note that 3-D printing is slow. Small parts with few features take several hours to build while complex parts can take one or more days. Because the machine builds a part in horizontal slices from the bottom up, any overhanging features must have support material built up to them from the bottom. (This support material is broken away after the part is finished.) Thus, the number of overhanging features in a part often contributes more to the total build time than does the part's overall size. This, among other things, is something to be considered when determining whether 3-D printing is an appropriate technology for prototyping your part.

To build a model, send the machine manager a .STL file. In most CAD programs there is an option to "save as" .STL. A good guide for first time users is available here. Please be aware that this is a basic guide and you may have to play around with some of the variables (such as chord height and angle) to produce a model that you are happy with.

Printing Costs:

The 3-D printer machine is a free resource for students currently registered in any Mechanical Engineering class with an academically related prototyping project.  All other university affiliated individuals (students in other departments, researchers, etc.) will be charged the cost of the modeling material for their part, which is currently about $10.00 per cubic inch -ABS + support (ask Peter Zimmermann for details). Please note that 3-D printing is not an instantaneous process, and that you should contact us well in advance of running your part in order to ensure that your pieces are ready when you need them. In the event that there are several requests for modeling within the same time period the modeling order is determined by the machine manager. At most other times, pieces are run on a first come first serve basis. Contact Peter Zimmermann, the 3-D printer machine manager if you would like to print a part on the machine.

Resource Links:

Stratasys rapid manufacturing and prototyping systems

Dimension SST dimension printing technology

Contacts:

3-D Print Machine Manager: Peter Zimmermann, zimme049@umn.edu.