Meet Peggy, this little kitty was rescued by some friends of mine. When she was found the lower portion of her rear legs were gone (sorry about the image).
She was not born without them but the cause of the loss remains a mystery.
I was asked to design a wheelchair for Peggy to keep her mobile and keep the stumps off the floor (as they can easily get infections) until she reaches the ripe age of 1 when she can get some prosthetics fitted.
There were lots of options but I decided to go with a 3D printed seat designed to be adjustable.
Step 1: The Design
I took a number of measurements from Peggy in order to determine the base size for the model.
Ultimately, as she grows the 2 options were to make larger chairs or to make this one as adjustable as I could to keep up with her.
I designed the seat section in Fusion 360.
I started out by creating a boss that covered the full area of the finished seat.
Then a dish was removed using the revolve tool to make a space for her belly.
I then removed some scoops for her legs to hang over and catch the rear of the seat, this was done over 2 sketches to create the correct shape.
I created a profile for the top and bottom of the seat.
I push cut some hex holes to act as a guide and to provide a flat surface for the mounting bolts (see this later)
I also created a hex retainer for the lateral adjustment nut and bolt.
In order to ensure that the model was completely symmetrical, I cut it in half, deleting one side and then mirrored the model.
Lastly I radiused all of the edges to ensure it would be comfortable.
Step 2: 3D Printing
I don't own a 3D printer so I sent it out to my local 3D hub.
The guy there gave me some advice on material and in the end, we agreed upon Protopasta Carbon Fiber PLA.
This gave a good balance of weight and strength.
Step 3: Assembly
The initial assembly shows the unit fully closed up, as Peggy grows, the wheelchair will get wider and taller.
The 2 bolts coming from the bottom of the seat carry 2 nuts and attach the seat to the base.
The base is a small plastic project box with wheels taken from some cheap shoe mounted wheel things (the name escapes me) but these were only 10 Euro per set.
I initially made a nylon strap with a plastic buckle but it just looked too big so I switched over to a velcro strap.
This was fitted to the seat by first melting a hole in the side of the seat with a hot drill bit, this prevented me cracking the seat or drilling in too far.
It then used some automotive upholstery rivets, these little plastic guys go into the hole and have 3 legs, you then force a pin down the inside which spreads the rivet and locks it in place, then just trim off the excess on the pin.
Step 4: Finished Wheelchair
I added some rubber matting from the top of my toolbox for cushioning. This stuff is also super non-slip.
The whole unit weighs just over 240g.
Step 5: Trials
We gave Peggy a little time to sound out the chair.
Then strapped her in for a little trial.
There was some initial worry but she did move about on it.
There is a long way to go with training her to use the wheelchair and to stay on it. She is quite skinny and has managed to slip out. Her owners are going to have a look at further attaching the chair to her harness in order to keep it with her.
You can follow her progress and adventures on her facebook page
This is my first aid for a disabled animal, so if there are any tips or suggestions I am open to them, just stick them in the comments. Also, Peggy will need prosthetics around this time next year so please follow her page and donate if you can when the time comes. Thanks!!!