Our initial design for the wheelchair attachment would have taken over 40 hours to print at the density we wanted, so we printed a smaller version of the part. The reason we didn’t want to (or couldn’t) have our part printing for 40 hours is because the likelihood of failure during printing increases exponentially after about 10 hours. For this reason, as well as the fact that we weren’t going to have someone constantly watching over the print, we wanted to have our print time be as short as possible.
In order to bring the print time down but still keep the high infill density to keep the strength of the part, we decided to only print two of the four compartments. This would allow us to see if the general features such as the slot height and the t-slot would work for our application. We need the top of the part to be strong because Jake, the user of this compartment, does not have very good mobility of his hands, so he will most likely bump it many times or hit it a little hard while trying to open it. We do not want this compartment to break once we send it to him, so we need that portion of the part to have a high infill. If we could have a higher infill near the t-slot and top of the compartment and have a lower infill on the lower part, that would definitely work, but the printers we have do not allow us to do that.
We used the FlashForge printer for this whole prototype. We were originally going to have to use the Taz 5 printer (which we used for the first successful print of the t-slot) because that was the only one that would fit our entire part, but since we scaled it down, we could print on any printer for the prototype.
The main part shown below was printed too small and won’t fit a credit card. This was due to a flaw in the CAD model design and not shrinkage. The total height was 2 inches when we needed the inner compartment height to be 2 inches. The new CAD model has the correct heights and we will be using SLS to print the final part. The reason we are choosing SLS is not only for its strength, but also for the ability to print the hinge, door, pin, and compartment all in one assembly and not have to assemble them once the print is finished.
The lid fit well with the main body, we will have to either print or use metal for the hinge pin. We will also be adding a magnet or some type of feature to close the lid.
