Archives February 2021

Assembly Design

Recently I was given a task to design a stand that would hold a display and the PCB that controlled it. While there was a past version of it, due to changes in the display that stand would no longer work. After looking to the previous design for ideas and obtaining all of the necessary design constraints from the software engineers who requested this stand, I set to work. I drew each initial part before starting in on the 3D modeling process.


Drawing out everything and paying attention to the details of where holes were located helped to make sure that the 3D modeling phase went much quicker. After the initial design of the individual pieces had been completed, I put them all into an assembly to view how the pieces interacted with one another. Using the interference detection in SolidWorks allowed me to know for a fact whether or not the parts could be assembled together without impinging on one another.

After an initial design was created, it was shown to the software engineers who requested design changes. Iteration took place and eventually the model below was created.

Iteration

Rarely does the first prototype ever end up being the final design of the product. Here is a view of how I iterated an important piece in a design.

This piece was a bridge that would hold a PCB in place on a stand that also held the display that it would control. After this first iteration, it was apparent that there was no good way to secure the PCB into place, and changes needed to be made. It was decided that it would be made on an SLS printer so that many parts could be made quicker than if it were to be made on a different 3D printer like an FDM or SLA printer.

The first change was to add holes on the left and right faces such that this bridge would not be able to move or fall out of its placement within the assembly. Next, the two holes on the upper face were added so that dowel pins could be pushed through to act as posts to go through holes that were located in corners of the PCB. It was also decided that the PCB shouldn’t be cantilevered over the edge so the extrusion was made to hole the PCB better.

After obtaining some input from those on the software team about the previous design, it was decided that the extrusion needed to be modified so that the heat from the back of the PCB could escape and not heat the SLS material. Countersinks were also added to faces to allow for screws to be used in place of the dowel pins to ensure they wouldn’t fall out. It also cleaned up the look of the assembly once all of the components were attached as well.

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