It was a crisp 45 degrees when I entered the empty parking lot of Vertus High School before dawn on Saturday of Labor Day weekend. I didn’t expect to see anyone else there. The electronic lock on the front door responded to my key fob and I successfully disarmed the alarm, then ambled through the halls to the Rochester e-NABLE Lab. Joy filled my heart as I saw the brown hand on the CR-10 printer through the window, and I rushed into the lab to see what else was printed.
Sadly, the hand on the PrintrBot Simple (that our intern, Melvin had hacked-up with a “Volcano” hot end for speed printing) was only half finished when it had run out of filament. Oh, well. One prototype would do for our intern, Prashant to take with him as he returned home to Jaipur, India. I smiled as I saw that the flexible tan hand on the Ultimaker 3 Extended was also done, and that it looked perfect!
I pried the brown PLA hand off the CR-10 build plate and tore away the support material. The thumb fit perfectly in the palm to make a brand new version of the Gripper Thumb Terminal Device. I imagined that I could hear the Mission Impossible theme song playing in my head as I sat down with the Dremel tool and soldering iron to urgently clean up the rough surface where the support material had left residue on the back of the palm. I decided to use pegs made from filament for the thumb pivot, for attaching the rubber ring, and for locking in the 1/2-20 bolt that would fasten the device to a socket. The pegs would look better than the metal screws I normally used, and “cosmesis” (the appearance of the device) was the reason we wanted to make this special design for Prashant to take along.
Now flash back to the day before: On Friday, while packing up a printer that someone had donated for him to take back to India, Prashant had noticed an old prototype of the Gripper Thumb that I had left on the table. The old device was actually more than a year old, and I had searched for it among my boxes of old prototypes because it had a flat surface on the back of the hand and fingers (due to being printed flat and thermoformed to bend the finger joints). We had a request for a hand that was more flat on the back. At the “Open Prosthetics Unconference” in Portland, Oregon two weeks earlier, Dr. Pooja Mukul had requested that we flatten the back of the hand a bit for what she considered to be a better appearance for the amputees back home. It turns out that she also lives in Jaipur, and Prashant wanted to take her a sample.
The problem was that the old prototype was black in color, and it needed to be closer to skin color. I sat down at the computer and began to search through my hundreds of Tinkercad files for the particular design we were seeking. Turns out that it was based on a design that Peter Binkley had created for me using one software called “Blender” and another called “MakeHuman”. I never did learn how to use either of those design tools, but the STL files that Peter had sent me could be imported into Tinkercad, and that’s how I had created the design with the flat back. It took me about an hour on the computer to get a new design that Prashant, Jon and I agreed was the one to go with, so we prepared to print it on both the CR-10 and the “Volcano” printers.
Well, it turns out that there was a problem with getting both of those printers to work! I couldn’t help thinking about what I have designated as the “dirty little secret” among makers: “3D printers are not easy to use!” While we struggled to get the printers going, Jon successfully got Melvin on a video conference. Melvin was already back home in Honduras, but he is our “printer whisperer” who can work magic with the printers, and he did his miracle work in a few minutes by remote control with Octoprint in the lab! So we got the printers going and finished up the day with a little training exercise in adapting PETG plastic sheets to be thermoformed into Prashant’s arm design as an alternative to the printed-flat PLA design that he normally used for thermoforming. Meanwhile, the printers chugged away.
Well, it was still only 6:45AM on that Labor Day Saturday when I messaged Jon and Prashant with a picture of the hand and asked about meeting them at the bus station where Prashant was to depart for New York City at 8:00AM. Jon messaged me back that he was just about to leave his house to give Prashant a ride to the bus station, and he offered to stop by the lab and pick up the hand.
I got back home in time to have breakfast with my wife, Joyce, who listened to my recounting of the adventure. Since it was fresh on my mind, I decided to write down the story and to share it with you all.
So, was this an ordinary 24 hours at the Rochester e-NABLE Lab?
Nope! Such days may be typical, but when you are working on e-NABLE projects, it is never an ordinary day!