Inclusive Design

The smaller working parts underneath the chair are 3D printed ABS plastic, coated in a high build putty primer and then coated in an acrylic topcoat.  I am aiming to further refine the components of the chair in order to develop a smoother functioning product and iron out any creases present within the build of the first prototype. 

I used the 6 axis robot CNC milling machine in order to fabricate my seat for the prototype. The model was split in half in order to get the details on both sides of the design. I used laminated marine ply in order to get the strength my chair needed. 

The pieces are aluminium to save weight, and become easier to push the bearings in and bend the links to their desired shape in comparison to sheet steel. 

Earlier in the week I received my frame back from Bendtech based in clayton. The steel frame was CNC mandrel bent due to the bends being fairly complex using several planes. The ERW tubes were TIG welded and are of fantastic quality and I couldn't be happier. Due to my short timeframe I am working in, the frame is to be sent off for powder-coating before the holes can be drilled. This is not ideal however necessary for potential prototype trouble shooting once I have received all the parts.  The bottom image is the foot-tube; connecting the seat to the footrest. This was bent out of 3mm aluminium using the same process. The reason for aluminium is to reduce the weight of the seat lifting up, although I had to use a 3mm wall thickness to maintain a constant bend Geometry.

Here I did a test on the TrueBend to see if the links I designed would be able to be bent on the angles that I would like. It didn;t work as well as I planned, only one half can be bent perfected and the other must be done on the Magnabend, a not to precise tool but will get the job done. 

I received the OEM parts newly anodized and replaced the previous bearings inside the fork. I am very happy with the outcome of these, the bearings spin nicely and they look brand new!

I received the parts back that I had stripped of the original anodizing that had numerous dents and dings. In order to re-anodize, I sanded and used scotch-brite to get a nice surface finish. Some dints are deeper than others however, once all black, I'm fairly certain the light reflections won't find them. If it becomes an issue, using a primer putty to fill in the gaps, then an automotive spray.

This image contains all the parts from 2 disassembled brakes and forks ready to have the current anodizing stripped in order re-anodize for a nicer finish. 

Today I received some OEM parts from Dynamic Wheelchair Solutions in Clayton. I was lucky enough to get my hands on casters wheels, forks, brakes and 24" rear wheels which I proceeded to CAD up in order to get my design ready for manufacture.

Using the software Autodesk 123D make, I printed 1:1 profiles my proposed seat design. Even though the model is not a working model, it was good to get a sense of scale and potential areas of weakness. I will do another quick model with update dimensions however using a different profile orientation in order to be able to sit on it.

The process isn't fully finished however once the frame is solid I will be able to test my design in a properly. 

This mock up was completed in order to test the geometry in CAD to see if it was correct. I realised it needs tweaking before I fabricate a steal mock-up.

Today I picked myself up 2 gas struts, gassed at 100N each. Because the application was just a mock-up, I felt the full 450N each would be been too strong to be able to test and adjust easily. If the project was taken into manufacture the gas strut would be customised to each users specific weight, but for the context of a university project, I will keep it similar to my weight so I can alter and develop the chair by testing myself. 

Here are some shots from the mock-up prototype making process. The 2 latter shots are me testing out the height of the chair. To further prototype I will begin to try a few different lengths of the links as well as getting other users. One thing that became apparent is the angle to which you are when then seat is raised. To be at the users most efficient, I feel the angle needs to be leveled close to parallel to the ground. I will continue to modify the mock-up and also introduce gas struts.

Here is a similar application of gas springs of my project. Here when the gas struts are at full extension, the wheelbase shortens enables to centre of gravity to be shifted.

Today Richard and I checked out Mobilty Plus in Preston. They generously gave us some parts from the workshop so we could CAD them up and gain a greater understanding of their functionality. We also witnessed the construction methods alongside alternative materials selection. Such as some of the piping in the images above shows >1mm wall thickness titanium, 2mm aluminium and 2mm strengthened aluminium. 

Today I got my hands on a foldable wheelchair to examine and understand correct proportions when developing my design. It was also be a good opportunity to prototype with it.