Origin Axis challange

Lesson 1 A How to Modeling Skills Exercise

My solution:

To start I used a recessed slot and tab arrangement with a 4-40 flat head screw which achieves the objective, however, if this were placed on a shaker table to top would vibrate badly.

To alleviate this problem I put in a series of tongue and groves to pin it together both at the bottom and along the sides. Along the bottom are a set of simple slots with chamfers in which a series of tongue features fit into the slot with a 2 degree draft to ensure the fit without interference.

Along the sides are a similar set of slots, however, in order to ensure that these would fit and prevent rotation regardless of the screw and bottom features I placed a hexagonal pin on the mating sides.

While this may not achieve the desired result of ensuring that the assembly would not dampen the vibration, the use of a screw would not be desirable due to the angular contour of the construct.

I considered using a dove tail type of arrangement along the corners but decided against it because if built such a solution would require exceptionally tight tolerances and most likely result in 4 points of contact which as stated is a problem.

Objective: mechanically assemble a hollow tetrahedron

Requirements and Instructions to get started:

Requirements:

• Utilize the inherit origin plain's and axis that are provided in the native file of your CAD software. Every sketch used to build the part must directly or indirectly reference the origin, plain's or axis. Every part must utilize the origin, plains or axis for the assembly process.

• Robust design: The model must be scale-able. This will demonstrate the robustness of the model when changes are made to the model. Method Suggestions: skeleton modeling, parametric associations.

• Mechanical means of assembly using pins, screws or other means of assembly such that when completed the results would have a high probability of providing a tight fitting assembly that would not fall part and may be constructed in such a way that once completed, might not be able to be disassembled with out being destroyed.

Instructions to start:

• Plan out how you will control the size of the tetrahedron using skeleton techniques or other means as suggested above. For more on skeleton modeling click here.

• Create a hollow tetrahedron and section it into 4 parts. Hint, this is one of the rare times you will need to use an offset work plane from the origin planes to achieve the required geometry.

• Remember, the edges of the resultant parts will need to be trimmed to allow the edges to be re-assembled such that they do not create an interference. See the examples shown