Soap Dish Challenge

Design Brief

Assignment: Complete the Soap Holder Design Challenge. Follow the design brief and use a morph chart to brainstorm ideas for a structure that you will model using a CAD software or OnShape or TinkerCAD. Document your design process on your website and submit the link to this assignment.

Background: You have a friend who has decided to use soap bars and shampoo bars to reduce their carbon footprint and possible reduce the amount of plastics that end up in the ocean. The bars get packaged in compostable materials and reduce the amount of plastics being used for packaging. Your friend has expressed frustration about the bars sliding around the shower and their counter tops near sinks. When the bars sit in water they seem to melt. Your friend is concerned about getting the most washes out of each bar of soap so that their carbon footprint is reduced.

Problem Statement: With the skills you have gained of 3D modeling you will design a soap bar holder that will make your friend confident that they are not wasting the product.

Structure Requirements:

1. Hold a 6 oz bar of soap 2” x 3.5” x 1.5”

2. A drainage system to prevent the bar from sitting in water

3. Have an aesthetic form that would be desirable for the user

Constraints:

1. Designed using TinkerCAD or OnShape

2. Be made out of two or less parts.

3. No larger than 8" in any direction

First Design - Owl Soap Dish

Brainstorming & Sketching

When I first heard the assignment I had an idea flash into my head of a brightly colored owl soap dish to match the decor of my bathroom at home. This was a very convergent thought, but I decided to work through a design for the dish because I couldn't get my brain to stop thinking about it.

My first consideration was the space in which it'd be used. I share a bathroom with my family of four which includes me, my husband, and our two teenagers. Our counter tends to be cluttered. So I wanted something that wouldn't take up too much space while allowing for the soap to be held securely. I decided that the size should provide a 1-inch space around all sides of the soap keeping the size fairly small and compact. I wanted rounded edges for safety and aesthetics. I also rounded the inside of the bottom tray, to make it easier to clean. To minimize the amount of filament needed and keep the print time reasonable, I planned the walls to be fairly thin at 1/8". I also planned small shelves set into the dish bottom to hold the drainage tray up so that water can collect below.

For drainage, I wanted a decorative element that was similar to other decorative elements in my bathroom. I opted to use an owl stencil to create holes in a tray held in place above the bottom of the dish. I want this centered in the top tray, large enough and open enough to provide drainage under a full bar of soap. Again I wanted this to be fairly thin to minimize print time. I will need to print and test to ensure that the 1/8" thickness will hold a 6-ounce bar of soap well, but I think it will.

Below are my initial sketches for the soap dish.

Designing in CAD

Using Tinkercad I designed a two-piece soap dish. It is 5.5" L x 4" W x 1" H. The removable tray has an owl cutout to allow for drainage. I originally planned 4 shelves to hold up the tray, but when I decided to add semi-circle cut out to make tray removal easier, I realized that the placement of the shelves would no longer work. I decided to move the shelves so that they didn't conflict with the semi-circles. But then they were no longer centered, which would lead to instability. So I added twice as many shelves than originally planned so that the tray would be more stable. This may make the bottom slightly harder to clean, but I think it's worth it.

One of my concerns is that I did not leave enough of a gap (1/32") between the bottom and the insert for it to be easily removed for cleaning. I am also concerned that the inner bevel on the top tray is not enough to divert water into the bottom. Given the somewhat limited tools of Tinkercad, I wasn't able to have as much control over that as I'd like. I am also concerned that the owl design, while attractive, may not provide enough drainage for the soap and may be a challenge to 3D print. Also, the shelves to hold up the tray may make the dish harder to clean, overall. I will know how these elements work out after doing a trial print.

I was also concerned that the curves on the bottom of the dish would be too sharp and would require supports. I want to minimize post-processing, and removing supports from the bottom would take away from the smoothness of the design. When I looked at the model in Cura, it was clear that some supports were needed. So rather than have to do post-printing clean-up, I changed the model to have rounded edges, but a flat bottom. This successfully eliminated the need for supports.

I plan to also design a solid bar shampoo holder for the shower using OnShape to see if that gives me more control over these kinds of elements.

Images of the current design are below. Feel free to take look or remix it on Tinkercad. The STL files are available for download Thingiverse.

Slicing into G-Code

I sliced the STL in Cura using the Ender 3 settings as described. However, when I inspected the Preview, it was clear that there were spots that would not print with these settings. I increase the wall thickness and horizontal expansion to ensure there were no beaks. I also opted for the Dynamic print settings because the top piece has so much detail. This means the print will take twice as long, but the final dish should look better. I also ran the bottom through the Mesh Tools plugin to make sure the bottom was watertight.

The G-Code for the top is available here and for the bottom here.

Second Design - Raindrop Shower Holder

Brainstorming & Morph Chart

For my second design, I wanted to really give brainstorming and divergent thinking with a morph chart more time and effort. So I created a morph chart with the categories Dish Shape, Drainage Type, Drainage Pattern, Dish Position, and Decorative Elements. These probably are not as distinct as they could be, because as I started adding ideas I found that there was a fair amount of crossover. However, I did generate a lot of different options using this method, which I like. I think this may have been aided by working on the chart over several days. I added ideas I got from the discussion group on the project as well as through brainstorming with my family. This made the process feel a bit less overwhelming. I also used both words and drawings, which helped me feel less stressed about my artistic abilities when it came to representing my ideas.

I also gave myself permission to pick multiple items from each category if I wanted, since there was a fair amount of overlap. I was aiming to make something for the shower that could hold a bar of shampoo which lead me to select a hanging design. It also made a covered design important to me; I hate wasting soap when it gets run over by water in the shower. Again I want a rounded design so no one gets injured if they knock into the holder. I opted for a raised bed rather than open holes because I want to direct any water away from the wall to reduce soap scum clean up. I selected a geometric pattern for the drainage grate because I knew I wanted to practice with that type of work in OnShape. And I selected a natural, nature-based shape because that's simply my preference.

Sketching the design

The next step was planning out the design in my sketchbook. After more chats with my eldest, we decided a raindrop shape would be fun and would also allow for a cone to protect the soap from the splashing and the shower head. After some research I found that most clip art raindrops feature a 1:2 or 3:4 ratio of the width at the widest spot to the height of the droplet. I initially planned my holder to be 4.5" W x 2.5" L x 9.5" H, but then realized that my design cannot be more than 8" in any direction. So I will need to adjust the sizing when designing in CAD. It annoys me that my drawing's dimensions are off, but since I'm taking into CAD anyway, I'll let it go.

I also realized that the cone will need to printed as a separate piece and attached in some way, because printing this as one item would generate a of supports that would be challenging to remove. I could make the cone solid, but since I need to add a hole for a suction cup it seems easier to make a flat back with the hole nad then an attachable cone. This would also give users the ability to not use the cone if they don't want it and give space to add additional trays if needed.

The bottom tray to also rest on a cone, but will be made of a solid shape for easier printing and construction. This bottom cone will be angled gently on top to allow water to run off, but the raised geometric shapes will be level, so that the soap doesn't slip. The biggest challenge for printing will be ensure that the raised pattern is sloped at less than a 45 degree angle so that supports are not required, which would make post printing clean-up necessary (and annoying).