Introduction: 3D Printed Ping Pong Paddle Prosthetic

About: GRiP designs and manufactures 3D printed assistive devices for children and adults with upper limb differences all throughout the nation.

We are a group at the University of Florida called GRiP and we make prosthesis for children with upper limb differences and this was one of our projects going into Hand Camp 2017, where we let the kids play with some of the prosthesis we make! We hope everyone can enjoy what we have created here!

Step 1: Take Measurements

Measurements are important to ensure that the prosthetic fits properly and it's functionality for the user can be maximized. You are going to measure the length of the persons forearm (for the cuff). This may be difficult with a ruler, consider using a piece of string for curved/round surface measurements and measure the resulting length of the string with a ruler. Important measurements to take include the circumference of the forearm and the overall length. Write these down as they will be used in the next step to help modify the existing STL.

Step 2: Edit Parts File

Now that you have taken the measurements, we will use these to modify the existing parts in SolidWorks so that the prosthetic's functionality can be maximized. Not all parts will need to be edited, mainly just the bicep and/or forearm cuff if necessary; however, everything will need to be printed. Download and open both the part file and the 3D printer file: ___________ .SLDPRT, ___________ .STL . This part is flat and will be 3D printed flat and you will end up thermoforming it in the next step to shape it and give the cuff a nice custom fit. Open the SLDPRT file in SolidWorks (any year should work fine) and change the length/width as needed to fit the measurements that you took in the previous step. Remember that this is not necessarily a one-size-fits-all part. Save the new file as an STL and prepare for printing!

Step 3: Print the Pieces

Almost any 3D printer can be used to print these parts as long as you use thermoformable PLA. After you have your new, custom STL file saved to a USB, take it to a 3D printer and print! Setting can vary but this is what we used: Rafts, Supports, Layer Height: 0.20mm, Infill: 20%, Number of Shells: 2, Extruder Temp.: 215C. Only the bicep/forearm cuffs will need to be thermoformed, everything else will just be used as is so if you don't have enough PLA, save it for only the important bits and the rest can be printed out of ABS or whatever other filament you have. Print and wait for your parts to be finished!

Step 4: Thermoforming

After your parts have been printed, clean and set aside everything that doesn't need to be thermoformed. Here you will only really need the bicep/forearm cuff. Using a heat-gun or hot water water, thermoform the cuff to desired shape. Using a heat-gun or water, thermoform the piece as needed. Be careful not to burn yourself! The pieces can be re-thermoformed multiple times to attain the desired shape. It may also be helpful to have the user there as well to really match the curvature of their arm. Don't make it too tight! Leave some space for some adhesive foam on the inside for added comfort and reduced rubbing.

Step 5: Assembly

Place fishing rod in the basin on the cuff.
Cover the rod with the z-piece and secure it in place with screws. If rod is not tightly secured, drill a screw through the bottom of the rod through the base of the cuff. Put padding on the inside of the cuff, as to not cause any irritation to the skin. Loop velcro through the cuff to be used to secure the cuff to the arm.

Note: The photo shown in this step does not include the screws, washers, or bicep cuff.

Step 6: Play Pong

Have fun!