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adjustable test mount

Spring 2018 - starry
Purpose

To design a mount for test purposes that positions the unit in either a 0 or 5 degree uptilt at a specified distance from the pole.

design elements

  • Beach chair-inspired swing bar to adjust unit to uptilt

  • 304 Stainless Steel construction, all 18-8 hardware

  • No tools needed for tilt adjust

  • Compatible with existing mounting scheme on back of unit

  • Carriage bolt mounting method allows for multiple pole diameters

  • Significant time and effort reduction from previous process

design narrative

Prior to this project, when running tests that involved both angles, test engineers had to switch the unit between a five degree fixed plate and a normal plate, which involved a tedious process of removing many fasteners, dismounting, switching out the plate, and remounting each time they wanted to test. This project served as an easy-adjust solution.

initial concept

The initial design for this concept took a lot of thinking about hardware selection, and some calculations to ensure that I achieved a five degree angle when the mount was tilted. I prototyped this in 304 Stainless (using Rapid sheet metal for fab). I selected the metal thickness based on a measurement I took from a current mount for this unit, which turned out to be mistakenly transcribed and I used too thin of a sheet metal, which resulted in flexing of the front plate due to the weight of the unit.

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First Prototype - Angled Position
First Prototype - CAD Model

This prototype had a few issues. I oversized the holes where the shoulder screws sit by selecting Solidwork's loose-fit hole feature, and this left too much space where the pivot on the front plate was able to shift forward under weight, creating unwanted downtilt. The tabs were difficult to grab over the head of the shoulder screw, and were possible pinch points for fingers in a test setting. And as stated above, the sheet metal was too thin. This led to a formal design review, which yielded the final concept below. Upon reflection, I should have analyzed the structure with FEA before going to fabrication and assembly.

final concept

In this design, I increased the sheet metal thickness, tightened up the hole tolerances, replaced the shoulder screws and threaded rod I was using for clevis pins secured with E-clips, added short 45 degree flanges to the front for added rigidity, and devised a pull handle method to avoid the pinch point with the tabs.

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Final Concept - Normal Position
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Final Concept - CAD
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Final Concept - Angled Position

Below are a couple part drawings, as well as the user guide for this assembly.

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Part Drawing - Base
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Part Drawing - Link
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User Guide
conclusions & acknowledgements

I learned a lot from this project, and highlight a few takeaways below:

  • The ability to better design with Sheet Metal tools in SolidWorks

  • Being able to bring a concept from paper sketch to CAD in a way that left the CAD open to easy changes for iterations

  • Practice organizing and running design reviews with team members and presenting my work, the problems I solved, and the ones that still need solving

  • Applying basic GD&T to the part drawings I created in order to ensure correct geometry of the uptilt

  • Catering to the needs of the testing team and creating a solution that doesn't need any tools on hand to adjust

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Thanks to Elliot for his help on this project and the rest of the ME team for their guidance and design feedback.

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