Custom Chair
Contents |
Abstract
This chair is for a child with Spina Bifida. The main need is a Bumbo chair with a few modifications to make it more stable and modular so toys can be attached. Findings and project outcome will be added later.
Team members
Acknowledge help of others
Problem Statement/Overview of the Need
The main goal of the project is to create a more safe and longer lasting version of a Bumbo chair. The chair must be difficult to flip over, of adequate size for several years of use and durable enough to last for those several years of use.
Design Specifications
1. Must be more stable to support the child rocking and not tipping over like the previous chair.
2. Building off specification 1, we would like to add an attachment that would allow rocking.
3. Remove the middle divider so that there will be more room to put the child's legs.
4. A seat buckle to keep child in the seat, especially when rocking.
5. Interior of the seat needs to padded with foam or some other cushion to provide comfortability for the child.
6. Have a tray to support toys and finger foods.
Background research
There are already many different kinds of Bumbo chairs on the market. They are widely available both on online retailers and in various stores. However, none of them are designed to be used by children that are much older than infants. Therefore, they are too small for a slightly older child to sit in, especially one with braces on their legs. They all also have fairly narrow bases making them prone to tip over if the child rocks back and forth while sitting in the chair. These two problems are the main things we aim to fix with our design. In addition, we will be attempting to add a way for the child to improve core strength while sitting in the chair and a way to attach toys to the tray.
Example of a Bumbo chair
Bumbo chair with a tray
Conceptual Design
Design Concept 1
- Description: Similar to a regular Bumbo chair that is already on the market, this design has a similar design but without the divider between the legs. This will allow the child to have more room to sit comfortably while wearing leg braces and give room to grow so the chair can be used for a longer time without the child outgrowing it.
Design Concept 2
- Description: Similarly to the first design, this design doesn't have a middle divider either. In addition, another upgrade we wanted to add was an attachment where the child could rock herself back and forth because she loves to move around. That way, the child could rock back and forth as much as they want when the rockers are attached, but they can also be easily removed when they are not needed.
Design Concept 3
- Description: Our third design also doesn't have a middle divider, but it has the option of a detachable tray. This would add a lot more functionality such as allowing them to leave the child in the chair when she is eating or attaching toys to the chair via suction cups.
Evaluate concepts/select candidate
We rated each design on a letter scale.
| Parameters | Design 1 | Design 2 | Design 3 |
|---|---|---|---|
| Stability | A+ | A | A+ |
| Comfort | A | A | A |
| QoL Features | C | A | A+ |
| Affordability | A+ | A | A |
| Overall Rating | B | A | A+ |
While all of these designs solved the main two problems with regular Bumbo chairs (stability and life span) we ultimately decided to go with the third design. The first design was our first idea and didn't really have much to it other than being more stable and having more leg room. From there, we expanded our design to include things such as a removable tray and a way to more easily rock while in the chair. We also felt that it was more important for the chair to have a tray as that adds much more usability than it having rockers. Therefore, our winning candidate was the third design.
Detailed Design
The final design we have selected will be a combination of all 3 concepts above allowing us to provide the family with all of the options they requested.
Detailed description of selected design
The chair will consist of two materials, MDF(Medium-Density Fibreboard) and some sort of foam. The chair, tray, and rocker attachments will be formed out of the MDF. The chair will have cutouts for the tray and rockers to slide onto the chair along with latches attached to keep them in place. This will allow the most support for the tray and rockers for when the child is bouncing around. In the seat, there will be a hallowed out section which is where we will lay the foam to provide comfort. The foam will be cut to the specific dimensions we need and then placed into the section. Around the bottom of the chair, there will be some type of covering to provide padding so when they place the chair on their couch, it will not tear into anything.
Analysis
The 3 types of analysis we performed were weight, stress, and safety analyses.
Engineering analysis 1
Weight Analysis
The chair should be as light as possible so that it can be easily moved around. Our first design came out to weigh around 48 lbs with the rockers and tray attached. This is way too much and we started trying to come up with ways to significantly reduce the weight. We decided to make cut-outs in the bottom and back of the chair. This got our weight down to about 24 lbs. In summary, our final weight was 24 lbs which is much better than where we started but still might be too heavy. We are still thinking of ways to get the weight down to under 20 lbs.
Physical Properties
Engineering analysis 2
Stress Analysis
Ran a stress analysis to visualize where the stress concentrations would be when a load of 20 lbs was applied to the seat and 5 lbs on the back rest. The area with the most stress is the area where the arm rests connect to the back.
Stress Analysis
Engineering analysis 3
For this analysis, we looked at any of the possible safety concerns that this chair could have. These included things such as pinch points, any sharp edges, and the overall stability of the chair.
| Pinch Points | Sharp edges | Stability |
|---|---|---|
| The slider where the tray attaches | The latches that lock the tray and rockers in place | Wider base than a traditional bumbo chair |
| The slider where the rockers attach | Any edges not well sanded | Square base allows for less chance of tipping |
CAD Drawings
Bill of Materials
Assembly Instructions
Fabrication Process
Testing and implementation
The main component of testing for the chair was sitting the child in it to see how she fit and to make sure everything stayed attached as it should. We ran into a problem with the rockers not staying attached but were able to come up with a very quick and easy solution that works very well. Another issue we ran into was the spacing between the leg space and the tray. We solved this by attaching the tray to the top of the arms allowing us plenty of room for the girl to sit and move her legs. Overall, these small changes we made improved the look and the functionality of the chair.
Photos of Completed design
Instructions for safe use
Like anything made for a small child, the chair should not be used unless a parent is watching. The rockers should not be attached if a parent is not able to watch the child in the event she is able to knock herself over. The clamps that attach the tray have the potential to pinch a finger, therefore should be attached prior to sitting the child in the chair.
Project Summary, Reflection
This project has helped each of us in our pursuit of our degree. By being able to work on something as important as this, we were able to introduce ourselves to being given a problem and designing a solution. We also got hands on experience on working with materials to ultimately build the chair you see. The best part of this whole project was getting to help a family and to see how happy they were with the finished product. We are very pleased with the experience of being able to work on a project as helpful as this to a family in need.
