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Mechanical Engineering Technology

MEC 1012


MEC 1012 - Design Communication II
Assignment 6
Design and Data for Prototypes

This assignment is due at the end of your TXL meeting in week 15.


Many prototyping technologies use geometric computer models as a basis for fabrication. If you design using computer models then you’re most of the way there already, but some format translation will likely be necessary. We’ll focus on Vermont Tech’s CNC machining and Fused Deposition Modeling (FDM, “rapid prototyper” http://www.efunda.com/processes/rapid_prototyping/fdm.cfm ).

We’ll review sheet metal modeling and then use the flat pattern geometry to feed the CNC programming process. At production volumes, sheet metal parts are often punched and formed with costly custom dies. While CNC is also used for production it can be very cost effective for the low volumes (numbers of manufactured parts) associated with prototyping. We’re programming CNC with a 2D system called SpectraCAM, so we’ll make a 2D dxf file with a carefully located origin.

FDM is most effective for small, intricate plastic parts that might otherwise need costly molds. The rapid prototyper takes an stl file format based on the layering scheme of FDM.


        Model an object for FDM (or use an existing model) with a volume no greater than one cubic inch. Try to minimize the need for support material (i.e a box with an open top needs little, but a closed top needs a lot. Hopefully, each student will have an opportunity to build their part. If you’re not using all of you allotted volume, you may ‘donate’ it to another student.

        Model a sheet metal part for which Inventor can successfully generate a flat pattern. Consider looking over the sheet metal parts in the samples project (C:\Program Files\Autodesk\Inventor 8\Samples\Models\Sheet Metal\)


        Produce an ipt and the associated stl file. If your part exceeds a cubic inch, indicate who ‘donated’ the extra volume.

        Produce a sheet metal ipt and the associated dxf file with origin located in a noted location.



Keep it simple. Completeness and quality are more important than complexity.

Typical stuff you’ve seen before shown in this color

Developed by Mary Waldo and Paul Johnson April 2005