Ergonomic Umbrella Grip Pt. 2: Casted

Context and Solution

This was (of course) a continuation of project 3, where we took our clay models and created silicone molds to cast resin versions. I used the mold to cast three resin copies of my ergonomic umbrella handle. Below is my iterations and final, refined version.

Sketching and Modeling

Though the model already existed, it still required some sketching to make sure that the model would sit well in the silicone pours. Additionally, because I was casting with a dowel in my handle, there were special considerations I had to take into account regarding the positioning of the grip and where my pour hole would be. With some advice from Chris, I opted to have the pour hole be off to the side (perpendicular to the parting line).

Casting

The process of casting was fun, but relatively time intensive. Doing the silicone mold pours was tricky because I wanted to make sure the parting line was as straight as possible. Smoothing clay against clay proved to be a very delicate task. 

On my first pour, I wanted to get a feel for the mixing and the material, so I opted to pour it without a dowel. It came out quite nicely, with minimal bubbles and a relatively smooth exterior.

I did a second, failed pour because I was deceived by the overflowing funnel. As it turns out, there was no way for the air to get out and I did not think to move the mold around to give it some breathing room. This resulted in a half pour, to somewhat interesting effect:

On my third pour, I tried it with the dowel in for the first time. Conscious about the mistake I made in the last pour, I made sure to move the mold around as I poured and squeezed it to make sure there were no bubbles. This resulted is an almost perfect pour, except for a large bubble on the back.

Final Cast and Finishing

The final cast came out the best, though not perfectly. Still some bubbles on the back finger grip, but ultimately came out mostly smooth. I sanded per Chris' suggestion of starting with lower grit sandpaper and working my way up to finer grits. Perhaps not best practice, but I found that the files in the makerspace made the best finishing tools and resulted in a smooth feel of the grip.

Reflection and Future Versions

If I were to continue to cast these models, I believe the next thing I would try is to make the models without bubbles. The dowels made it difficult to figure out how they could get into the pressure chamber, and I suspect going without is what caused the bubbles. Additionally, I'd like to try to take the fidelity higher by deburring the model and polishing it. That would give it a true industrial finish.